Hepatitis C Genotype Not Responsible for Serious Liver Disease

Hepatitis C
The newest development in treatment for HCV is pegylated interferon. The measure for evaluating treatment success has been achieving and maintaining undetectable HCV viral load. However, many people are unable to achieve that goal. Histological improvement is observed in non-responders to interferon or interferon/ribavirin therapy. The idea is to take advantage of that improvement and try to maintain it. Recent research has suggested that maintenance therapy of interferon may maintain that improvement, and delay histology or hepatitis disease progression.

This observation has given impetus to begin two large studies to test the concept of low-dose interferon maintenance therapy. In practice, doctors have been using maintenance therapy when they run out of the limited treatment options available. After a patient's therapy ends, a doctor may continue with maintenance therapy if the person did not achieve undetectable viral load. So, for those individuals who do not respond to HCV therapy, it remains possible that maintenance therapy may keep people alive and healthy until new treatments are available. And much attention is indeed being paid to researching new HCV treatments. In studies of pegylated interferon, more histologic improvement was noted in the individuals receiving pegylated interferon than in those treated with current dosage regimens of interferon. In fact, in a study of the Roche Pegasys, Pegylated Interferon for compensated cirrhotics, Heathcote reported that 31% of individuals who received IFN 3 MU three times per week had histologic improvement (8% had sustained virologic response), and 54% had histologic improvement with Pegasys (30% had sustained virologic response). However, for individuals with genotype 1 in that study, the sustained virologic response was much lower. Most coinfected individuals have genotype 1.

Pegylated Interferon
The latest data on both Pegylated interferons were presented at EASL in April. Pegylation is a process whereby polyethylene glycol (also known as PEG) is attached to the interferon and prevents the interferon from being rapidly eliminated from the body. Normally interferon stays in the body for about 24 hours but with pegylation it stays in the body for 7 days at longer lasting and higher levels. This permits once weekly injections. Currently, the only FDA approved administration of interferon is three times weekly subcutaneous injections. However, many think that the FDA approved dosing was inadequate because on days in between dosing the hepatitis C virus was left to replicate without any antiviral pressure from drug therapy. So currently, daily dosing of interferon is often used. As well, dosing with higher levels is also practiced. The expectation is that increased blood drug levels of pegylated interferon will increase the antiviral activity against HCV. The preliminary data below supports this. Over the course of a week interferon blood levels are kept high.

Pegylated Interferon Alfa-2b (Peg-Intron) Monotherapy and in Combination with Ribivarin
C Trepo reported for the Hepatitis Interventional Therapy Group on this phase III study comparing 3 doses of Schering-Plough's Pegylated-Intron alfa-2b. Following the first study report is a preliminary report comparing Peg Intron+ribavirin to Peg Intron alone. This study compares Pegylated Intron monotherapy to IFNalfa-2b 3 Million Units three times per week. It's a randomized, double-blinded, dose finding efficacy study of 1,200 treatment-naÔve individuals with chronic hepatitis C, elevated ALT and compensated liver disease. Study participants received 1 of 3 doses of Peg IFN alfa-2b: 0.5 ug/kg (n=315) once weekly by subcutaneous injection, 1.0 ug/kg (n=297) once weekly, or 1.5 ug/kg (n=304) once weekly. Or they were randomized to the control arm of IFN alfa-2b 3 MIU three times per week (n=303). Participants received the drug for 48 weeks and there were 24 weeks of follow-up. A liver biopsy was performed at baseline and after 72 weeks. The primary endpoint was a sustained loss of HCV viral load 24 weeks after treatment stopped.

The age across all 4 treatment groups was about the same at 43 years. There were about the same percent of men in all arms (63%). About 5% in each arm were Black. In the two low dose Peg IFN arms there were 67% genotype 1. In the Peg IFN 1.5 ug/kg arm there were 73% genotype 1 and 72% in the IFN alfa-2b arm. So 26-29% across all 4 arms were genotypes 2/3. Each arm had about 73% with HCV viral load >2 million.

Sustained Virologic Responses for Peg IFN Alfa-2B (at week 72) (See Table 15)

Sustained Response by Genotype & HCV Viral Load (See Table 16)

Overall, 49% and 23% at the end of treatment and the end of follow-up, respectively, in the Peg IFN 1.5 ug/kg dose arm had HCV RNA undetectable (<100 copies/ml). In the IFN alfa-2b MIU 3x/wk arm, 24% and 12% had undetectable HCV RNA at the end of treatment and after follow-up. In the Peg IFN 1.0 dose arm 41% and 25% had undetectable, respectively, at the end of treatment and after follow-up. And in the Peg 0.5 dose arm, 33% and 18% had undetectable.

White blood cell, platelets, and neutrophil counts went down during treatment but bounced back to normal after treatment ended. The WBC and the platelets went down a little more in the two high Peg IFN dose arms than the low Peg dose arm and the IFN alfa-2b arm. The difference in the platelets could be 50,000 between the arms. Depression, irritability and other psychiatric related adverse events were the same between arms.

Dose Discontinuation and Reduction
Dose discontinuation was 9%, 11%, and 9% in the three Peg IFN alfa-2b dose arms (0.5, 1.0, and 1.5 ug/kg), and 6% in the IFN alfa-2b 3 MIU 3x/wk arm, although the presenter said there was no real difference between the arms. The discontinuations occurred more often in the earlier parts of treatment. Discontinuations during weeks 1-24 were 4%, 7%, 6%, and 4% in the 4 arms. While discontinuations were 4%, 4%, 3%, and 2% during weeks 24-48. Dose reduction was more in the Peg arms--9%, 14%, 15%, and 6% in the 4 arms, respectively, but the presenter said this was due in part to more aggressive dose reduction as part of the protocol.

Peg-Interferon+Ribavirin: End Of Treatment and End of Follow-Up Virologic Response
Schering reported data from a comparison of Peg-IFN 2b with IFN 2b alone. End-of-treatment response: in the combination arm of high dose of 1.4 ug/kg Peg IFN+ribavirin 81% had undetectable HCV RNA while 50% in the Peg IFN alone arm had undetectable. In the 0.7 Peg IFN dose combination arm 69% vs 63% had undetectable, respectively, and in the low dose 0.35 ug/kg arm 58% in the combination arm and 50% in the Peg IFN alone arm had undetectable.

At the end of follow-up, 60% had undetectable in the 1.4 ug/kg combination arm versus 42% in the monotherapy arm. In the 0.7 ug/kg arm 53% vs, 44% had undetectable; and in the 0.35 dose arm 17% and 0% had undetectable.

Pegasys; PEG Interferon alfa-2a for Chronic Hepatitis C

S Zuezem reported for the Pegasys International Study Group on this phase III study of the safety and efficacy of this once weekly pegylated interferon from Roche. This study compares the efficacy and safety of Peg IFN alfa-2a administered once per week with an induction regimen of standard IFN alfa-2a administered 3 times weekly for 48 weeks. The primary study endpoint is undetectable HCV RNA (<100 copies/ml, Roche PCR assay), and normalized ALTs after a 24 week follow-up period. 531 patients were randomized to either 180 ug Peg IFN alfa-2a once weekly or to an induction regimen of 6 Million Intl. Units of IFN alfa-2a three times weekly for 12 weeks followed by a dose of 3 MIU three times weekly for 36 weeks. A biopsy was performed at baseline and after the 72 week period.

There were 67% men in both arms, average age 41 in both arms, 85% Caucasian in both arms, ALT 98 in Peg arm and 94 in other arm. Total HAI score was 8.6 in Peg arm and 9.0 in other arm. 12% had transition to cirrhosis or cirrhosis in Peg arm and 15% in other arm. Genotype 1 63% and 61% in Peg and other arm, respectively. Genotypes 2/3 also about same in both arms. HCV viral load 7.4 log in Peg arm and 8.2 in other arm.

At the end of follow-up (72 weeks) 45% normalized their ALTs in Peg arm and 25% in other arm. At the end of treatment (48 weeks), 46% and 35% normalized their ALTs in Peg and other arm, respectively (p<0.001). The overall virological response (<100 copies/ml) in the Peg arm was 69% at the end of treatment and 38% at the end of follow-up. For the other arm, 28% at the end of treatment and 19% at the end of follow-up had undetectable HCV viral load (p<0.001). At the end of follow-up 38% in the Peg arm versus 17% in the other arm had both normalized ALT and undetectable viral load (p<0.001). In the Peg arm, 63% had histological improvement in their liver at the end of follow-up compared to 55% in the other arm. Histologic improvement was defined as a decrease of at least 2 points in the Knodell Histologic Activity Index.

Sustained Virologic Response (undetectable after 72 week follow-up) Analysis By Genotype: (See Tables 17 & 18)

Rates of Withdrawals and Dose Modifications
Discontinuation for any adverse event or lab abnormality was 7% in the Peg arm and 10% in the induction arm. Dose modification for adverse event (AE) or lab abnormality was 18% in both arms, for AE 8% and 12%, respectively, and 14% for lab abnormality in Peg arm and 9% in induction arm--mostly due to neutropenia (decreased neutrophils)- it was 11% in Peg arm and 7% in other arm. The side effect profile was similar for both arms except in a few instances where the higher side effect rate occurred in the induction arm.
D4s & HCV: in HCV/HIV coinfection, HCV treatment should be considered early
Limited research and knowledge about HCV/HIV coinfection suggests that a coinfected person may be better off starting HCV therapy when CD4s are high--above 500 or at 800. Keep reading. The study reviewed below was reported at Durban by Hernan Valdez from Case Western in Cleveland and raises an interesting question. In his study, people with HCV/HIV did not respond to HCV antigen, but people with HCV alone did respond. Although responses to HCV antigens improved in HIV-infected persons who were receiving antiretroviral therapy, the responses did not reach the levels seen among HIV-negative HCV+ patients. So HAART may help improve response to HCV, but still the response is less than for those with HCV alone. This study suggests, as other studies have suggested, that having higher CD4 s may improve response to HCV, as it may help immune system control HCV better. Further, I think it may be the CD4 "repertoire" that is more important than absolute CD4 count. HIV viral load improvements should lead to CD4 increase. The key CD4 parameter most important for response to IFN/RBV therapy may be CD4 nadir prior to antiretroviral therapy for HIV. I would suggest that, as in HIV, if a person has lost the CD4 "repertoire" response to a particular antigen (in this case to HCV), maybe that will affect how the coinfected person responds to HCV either before or after HAART. If they've lost the CD4 repertoire for HCV, they just may not be able to respond well to HCV and they may not respond well to IFN+RBV therapy. In Valdez's study, levels of HCV viral load were noted to correlate with the weakness of lymphoproliferative responses to HCV antigens. Thus, one may expect improved control of HCV with immune restoration. So, it may be very important to identify and treat HCV in HIV before CD4s decline.

In a related study detailed below, a group out of Italy led by M. Pouti examined a group of 204 patients, all of whom had HCV infection. 84 of those had co-infection with HIV. This group looked at the relationship between liver fibrosis in those with HIV vs. those without HIV. This work has been done before by other groups, and the consensus seems to be that HCV has a more rapid progression in the HIV co-infected. Once again this was confirmed in this study. In addition, however, this group analyzed the HIV positive subjects to see if low cd4ís in the HIV/HCV co-infected translated in more advanced liver fibrosis. And indeed their main finding was that more advanced liver fibrosis, defined by the presence of stage 3 or 4 fibrosis, was associated with immune suppression defined as <500 cells/ml and was independent of gender, age, duration of infection (HCV), and ETOH use.

Commentary: The cut-offs for what was termed immune suppression are rather high in this study (<500 cd4ís). Still the results strongly suggest that starting HIV antiviral therapy early in those co-infected with HIV and HCV may slow the progression to liver fibrosis and cirrhosis. Puoti concluded antiretroviral combination therapy that aims at keeping high CD4 counts should be regarded as a priority in the care of HIV and HCV coinfected patients.

The information related in this article, when taken in consideration with additional knowledge and research, suggest that for the HCV/HIV coinfected patient, starting HCV therapy when CD4s are high could make a significant difference in the outcome of HCV therapy. Starting HCV therapy when a person has 500 or even 800-900 CD4s may be beneficial because the person may not have lost their HCV-specific CD4 response or the proliferative lymphocyte response to HCV. There is limited research supporting this notion and certainly no or little clinical research supporting this, but oftentimes clinical treatment precedes research. Starting HCV treatment when CD4s are depleted, at 250 for example, may be too late to allow for a good virologic response to HCV and a response to HCV therapy. By this time the patient may have less capacity to mount a response to HCV or HCV therapy. The patient may have lost his or her HCV proliferative lymphocyte or CD4 response capacity. When does the patient lose the lymphocyte proliferative response (LPR) to HCV? In HIV, that question remains unanswered with regards to LPR to specific pathogens or infections like PCP or CMV. In HIV there appears to be general agreement that the LPR or HIV-specific CD4 response is lost rather quickly after HIV infection. The same may be the case regarding HCV. If that is the case, it may be important to consider HCV therapy as soon as possible after learning one is HIV-positive when CD4s are high.

Immunological responses to hepatitis C and non-hepatitis C antigens in hepatitis C virus (HCV) infected and human immunodeficiency virus (HIV)-HCV coinfected patients

Hernan Valdez of Case Western University in Cleveland, USA reports on this study. Vigorous HCV-specific CD4 responses are associated with clearance of HCV viremia, but these are absent or of low magnitude in most patients with chronic HCV infection. HIV-HCV coinfected patients progress faster to cirrhosis and hepatocellular carcinoma than HCV-infected subjects. Although after treating HIV with HAART HCV progression may change. Valdez examined immune phenotype and function in HCV(+) subjects to better characterize immune function in HCV infection in the presence and absence of HIV infection.

Uninfected = Un (9), HCV-infected = HCV(+) (9), HCV-HIV infected = HIV/HCV (10), HCV-HIV infected on HIV treatment = HIV/HCV-Tx (9), and untreated HIV-infected, HCV-uninfected = HIV(+) (10) patients had blood drawn for flow cytometry, lymphocyte proliferation and ELISPOT assays. Entry criteria: no cirrhosis, >300 CD4 (HIV), no recent treatment with IFN or Hepatitis B coinfection.

Patients were well matched for age and gender. HCV infection tended to cause an increase in the percentage of activated CD8 cells (U = 2%, HCV(+) = 6%, p = 0.1). Proliferative responses to non-HCV antigens were comparable in HCV(+) and U subjects. A greater proportion of HCV(+) had a stimulation index (SI) >3 to NS3 compared to HIV/HCV and HIV/HCV-Tx (67%, 0%, 11%, p>0.006). The log SI to NS3 was significantly higher (p>0.04, p>0.009) in HCV(+) (median, IQR 0.6,0.5) than in HIV/HCV (0.3,0.5) or HIV/HCV-Tx (0,0.4). Among HCV-infected patients, HCV-VL correlated directly with ALT (r = 0.52, p>0.01) and inversely with the number of CD4+ lymphocytes (r = -0.55,p>0.008) and proliferation to NS3 (r = -0.55,p>0.008).

Valdez concluded that lymphocytes of HCV-infected patients fail to respond to HCV antigens while responses to other antigens are preserved. Infection with HIV potentiates this deficiency. Poor CD4+ T cell responses to HCV may determine the failure to control HCV propagation.

HCV and Brain Dysfunction
We know that HIV enters the brain shortly after a person is infected with HIV. It does appear as though individuals with HIV may experience symptoms related to this, such as reduced alertness or a slower thinking capacity due to HIV. At both recent liver conferences (DDW and EASL), two different research groups reported research findings suggesting that HCV in individuals with less advanced disease (non-cirrhotics or mild fibrosis) affects the brain and reduces its functioning capacity. This suggests that a person with both HCV and HIV may be affected even more with regards to brain functioning. Over the years people with HIV have complained about experiencing fatigue and/or itching. We now know that many people with HIV also have HCV, and that HCV can cause itching and fatigue. The findings reported at DDW and EASL suggest that HCV related fatigue may be associated with the affect of HCV on the brain.

It's known that individuals with advanced cirrhosis can experience hepatic encephalopothy which can cause brain disorder, but it's important to bear in mind that the participants in the studies discussed below did not have such advanced HCV disease, so the brain dysfunctioning found was not due to hepatic encephalopoathy.

At DDW, Ludwig Kramer and a research group from the University of Austria, reported that "cognitive processing was subclinically impaired in patients as compared to healthy subjects." They studied the impact of HCV infection on sensitive markers of cognitive brain function. Fifty-eight noncirrhotic patients with chronic HCV infection (age, 45±13 years, mean±SD) were studied by P300 event-related potentials (an objective measure of cognitive processing) and by the SF-36 questionnaire for assessment of health-related quality of life. Findings were compared to 58 matched healthy subjects. He found that P300 test results were impaired in patients with HCV compared to healthy volunteers, and concluded that patients with chronic HCV infection in the absence of cirrhosis exhibit a subclinical neurophysiological impairment. Cerebral function, however, seems to normalize with antiviral treatment. Although it was not apparent to me if normalization was tied with significant reductions in HCV viral levels, my feeling is that improvements in cerebral function can improve with HCV treatment despite no HCV viral level reductions. More detailed data and discussion are available below at the end of this report.

At EASL, DM Horton presented an oral talk on brain dysfunction in people with HCV for a UK research group from the Imperial College School of Medicine and St Mary's Hospital in London. First he reviewed two studies. He mentioned a UK study (Foster et al 1998) using the SF-36 questionnaire, and reported people with HCV compared to normal controls scored worse in physical and social functioning, energy and fatigue, and other measures. These results were independent of intravenous drug use. In a large US (Johnson et al 1998), 309 IVDUs both with or without HCV were tested for depression and those with HCV (57.2%) were found to have significantly more depressive symptomology than those who were negative to hepatitis (48.2%).

In an attempt to further define this neuropsychological syndrome, they administered a battery of neuropsychometric tests to 15 patients with histologically mild hepatitis C from liver biopsy. They tested for attention (included: simple reaction time, choice reaction time), working memory (numeric & spatial working memory), and secondary memory (delayed word recall). They found that patients with mild or minimal hepatitis C from liver biopsy were slower in tests of working memory. He noted that although they were slow, their accuracy on these tasks was preserved, and this has been described in chronic fatigue syndrome. There were no attention or secondary memory abnormalities.

In the view of these findings they asked themselves, if HCV infects cells in the CNS (central nervous system), does this cause cerebral metabolite abnormalities, and is cerebral HCV infection the cause of the observed neuropsychological symptoms? They carried out a proton cerebral magnetic resonance spectroscopy study to determine if metabolite abnormalities exist in the brain of patients with histologically mild hepatitis C. They randomly selected 30 patients with biopsy proven mild or minimal hepatitis due to HCV. As well, they studied 29 matched controls, and 12 eAG+ve patients with chronic HBV. No patient in the HBV or HCV groups had significant fibrosis or cirrhosis. The researchers reported seeing metabolic abnormalities in the testing in those with HCV compared to both normals (volunteers) and chronic HBV patients. There were no statistical differences between the normals and those with HBV. These abnormalities were not due to hepatic encephalopathy. They described the abnormalities as being similar to those abnormalities observed in HIV. Again, no patient in this study had significant fibrosis or cirrhosis. None of the study participants had used IV drugs in the 6 months preceding the study. There was no statistical difference in the study results between those with or without prior drug use. Those with prior drug use had the same abnormalities as those who never used IV drugs. The researchers concluded that prior drug use did not affect the outcome of the study.

Is there direct infection by HCV of the CNS? He presented a suggested potential model by which this could happen. Microglial cells in the brain turn over slowly and are replenished by circulating monocytes, possibly up to 30% in one year. Circulating monocytes are potentially infectable by HCV, and may carry the virus across the blood brain barrier into the brain and the microglial cells. Once in the cells they become activated and produce chemokines, cytokines, and neurosteroids which may mediate the neuropsychiatric symptoms described in this presentation. The question still remains--does HCV infect the microglial cells in the brain? The only way to answer this question is to conduct direct post mortem viralogic examination of brain tissue, which is being currently undertaken at Imperial College School of Medicine in London.

He also suggested that of equal or possibly greater importance is the possibility that the brain may act as a sancutary site for HCV, allowing immune evasion and protection against antiviral therapy. He suggested that cessation of viral production from the liver may occur during phase 1 of viral decline after starting HCV therapy, but the slower viral decline during phase 2 may be due to a continued release of virus from the brain. He suggested that an alternative explanation for possible brain dysfunction seen with HCV could be that systemic cytokines cross the blood-brain barrier and may exert an effect. But he discounted this theory because in this study patients with HBV had normal spectroscopy. HCV antiviral therapy has been administered to the study patients and results are pending. In the study reported at DDW, and discussed above, the study authors reported therapy improved cerebral function, and they suggest their data may indicate a direct action of HCV infection on the brain.

HCV/HIV Coinfection Prevalence & Sexual Transmission; End Stage Liver Disease
This report is comprised mostly of studies presented in Durban (but also includes information from other sources--journals, Retrovirus Conference) and details the prevalence of HCV in HIV infected individuals with various backgrounds, exposure risks and geographies-- from IVDUs to the potential for sexual transmission. Regarding the risk of sexual transmission, HCV infection appears to occur more often in persons with high risk sexual practices. Individuals with multiple sex partners appear to be more at risk for HCV infection, while individuals in long-term monogomous relationships appear to remain uninfected. These reports and previous ones are piecing together a picture of the prevalence of coinfection. A number of prevalence studies reported from various cities in the USA estimate that 60-90% of individuals with HIV due to IVDU has HCV as well. Based on these studies it appears that there is a risk for contracting HCV from sexual contact. The question remains --how much risk?

Occurrence of End Stage Liver Disease
Barbara McGovern reported at the 1999 November IDSA Conference on a look back at all HIV+ patients who died at her Boston based hospital from May '98 to April '99. She found ESLD due to HBV/HCV was the leading cause of death in patients with underlying HIV, even though 55% had undetectable HIV viral load and/or >300 CD4s. At Durban, Spinetti and an Italian research group reported increased mortality due to ESLD in the post HAART era compared to the pre HAART era (12% vs. 33%). Among the 308 in-hospital deaths occurring from 1987 to 1995, liver failure was defined as the cause of death in 35 patients (12%). Among the 46 in-hospital deaths observed from 1998 to 1999, liver failure was defined as the cause of death in 15 (33% p>0.01 vs. 1987-95). Multivariate analysis showed that in-hospital liver related mortality was independently associated with hepatitis B surface antigen reactivity (Odds Ratio, 9; 3.8-21.7), anti HCV reactivity (OR 5,1.4-21), and history of alcohol abuse (OR: 2.3; 1-5.2).

HCV and Breastmilk
There have been doubts about that HCV could be transmitted sexually or that it could be transmitted sexually at more than a very low rate. A recently published study found HCV in breastmilk, and a second recently published study found HCV in male semen. A Spanish research group reported breast milk HCV-RNA was negative in

nonviremic mothers and positive in 20% of the viremic mothers. The rate of HCV transmission was higher for infants of mothers with higher HCV viremia and also for infants whose mothers were HCV-RNA-positive in breast milk. The authors said larger studies are needed before advising avoidance of maternal breast feeding (Pediatr Infect Dis J 2000 Jun;19(6):511-6: Ruiz-Extremera A et al).

HCV in Male Semen
Using a sensitive testing method (PCR), a French research group reported eight seminal plasma samples of 21 (38%) were found to contain HCV-RNA (6/8 were HIV+, 2/8 were HIV-). HCV viral loads detected in semen were low, which suggests that the risk of HCV sexual transmission is probably also low. Further studies using experimental infection in a cell culture system or an animal model are needed to prove that HCV-RNA positivity in semen reflects the presence of infectious virus (Lancet 2000; 356: 42 - 43, Marianne Leruez-Ville et al).

Sexual Transmission of HCV & Transmission from Mother-to-Child
An Italian study reported recently that HCV was transmitted from mother to newborn 5% when HIV was not present but 17% when the mother had HIV. At the Feb. 2000 HIV Retrovirus Conference, Craib from British Vancouver reported on a study to determine HCV prevalence and identify risk factors in a group of sexually active homosexual men. In a random sample of 232 men, 120 were HIV+ (112 were HIV-). Of the 232 men 20 (8.6%) had HCV and HCV prevalence was significantly higher (6-fold) among HIV+ than HIV- men (17/120 14% vs 3/112 2.7%). They reported the risk factors for the HCV+ men. HCV+ men had more sexual partners in the past year (>= 20 partners: 80% vs 40%), and in their lifetime (>=100 partners: 90% vs 61%). They also had greater incidence of receptive fisting (30% vs 12%; p=0.40), insertive fisting (55% vs 25%; p=0.004), more often reported receptive oral-anal contact (100% vs 85%; p=0.067), more often reported injection drug use (21% vs 2%; p<0.001), cocaine use (50% vs 24%; p=0.013), MDA use (70% vs 36%; p=0.003), and amphetamine use (30% vs 13%; p=0.056). Multivariate analysis showed injection drug use (p=0.024), being HIV+ (p=0.056), low education level (p=0.031) and insertive fisting (p=0.032) to be independent risk factors for being HCV+.

Interferon Use During HAART To Reduce ALT
Zaltron and an Italian research group reported on this study and suggest that people on HAART (n=82) and treated with interferon due to elevated ALT can normalize ALT (33%), and maintain viral load reductions. The study reports only 2 individuals had VL increase of 0.5 log. IFN-a was given to people on HAART. Primary response was defined as ALT normalization in the presence of undetectable HIV RNA at 3 & 6 months. Fifty seven patients (30 treated) completed the third month and 43 (24 treated) the sixth month of the study. PR was observed at three and six months in 37% and 33% of treated patients and in none of untreated patients (p>0.01). Two patients in the treated group showed HIVRNA increase greater than 0.5 log copies/ml. Also seemingly important in this study is that CD4 count>500 and genotype 2 & 3 were associated with PR.

16% HCV Sexual Exposure Prevalence in Spanish Study

In a study designed to evaluate the prevalence, route of transmission and clinical significance that current co-infection with TT virus (TTV), hepatitis C virus (HCV), and hepatitis G virus (HGV) in HIV-1 infected patients, M Martinez from Barcelona, Spain analyzed the presence of HCV in plasma samples from 160 infected patients with parenteral (38 intravenous drug users 'IVDU's' and 41 patients with hemophilia) or sexual (39 homosexuals and 42 heterosexuals) risk of exposure, and in 168 volunteer blood donors. Alanine aminotransferase (ALT) levels and CD4+ T cell counts were also analyzed. Prevalences of HCV infection was higher among patients with parenteral (needles by drug abuse) (62% and 68%) than in those with sexual (17% and 16%) risk of exposure. But the study authors report 16% risk of sexual transmission. Some of this 16% could be due to unidentified drug use or an unwillingness to admit drug abuse.

HCV/HIV Coinfection Prevalence in the Swiss HIV cohort studies
To assess the impact of HCV infection on clinical progression and on survival of HIV+ subjects in the era of potent antiretroviral therapy (ART), G Greub of the ID Dept. at University Hospital in Lausanne Switzerland looked at 2766 individuals followed in the Swiss HIV Cohort Studies. They started potent ART between 01/01/95 and 03/31/99.

1011/2766 (36.6%) HIV+ subjects were HCV co-infected. 511/537 (95.2%) active drug user were HCV+ as compared to 22.4% in other groups.

HIV is associated with sexual risk and HCV with injection risk among young injection drug users in San FranciscoÖ312 Young IVDUsÖ29% had HBV, 45% had HCVÖ93% with HIV also had HCV.

K.A. Page-Shafe from the University of California San Francisco reported on this study examining HCV prevalence and risk factors for HIV hepatitis B (HBV) and C (HCV) among young injection drug users (YIDU) in San Francisco. YIDU (>30 years) recruited in 4 neighborhoods were questioned about injection and sexual behaviors, sources of clean needles, knowledge and use of needle hygiene, history of STD and overdose experience. Blood was drawn for HIV, HBV and HCV antibody testing.

312 YIDU participated, 193 (68%) males and 87 (31%) females. Median age was 22 (range: 15-29), and median number of years injecting was 5 (range 0-19). Prevalence of HIV, HBV (core antibody or surface antigen), and HCV was 6%, 29%, and 45%, respectively. 93% of those with HIV infection were co-infected with HCV or HBV. Variables independently associated 'OR ;(95% CI)' with HCV seropositivity were: age (per 5 yr. increase) '2.2;(1.3-43.7)', years injecting (per 5 yr. increase) '2.1;(1-3.5)', injected by a sex partner at initiation '3.9;(1.5-9.9)', ever injected with someone else's used needle '2.5;(1.2-5.2)', bleached last time injected with borrowed needle '0.5;(0.2-0.98)', snorted or smoked cocaine, methamphetamine, or heroin in the prior year '0.4; (0.2-0.8)', injected daily '4.4;(2.4-8.5)', and HBV '3.0;(1.5-6.0)'.

27/39 (69%) with HIV had HCV in Patients Presented in Emergency Room, Alberta, Canada

S. Houston at the University of Alberta, in Edmonton, Alberta Canada reported on 3057 subjects were entered in database. Subjects were younger, presented more frequently with trauma and more often went on to admission than the general ED population (all p>0.05). 71% presented with medical illnesses, 21% with trauma. 7% self-identified as aboriginal. 37(1.2%, 95%CI = 1-2) were HIV-seropositive; 2 others demonstrated a banding pattern characteristic of acute seroconversion. HIV infection was associated in multivariate analysis with aboriginal status, age and HCV infection. 27 of all 39 (69%) HIV-infected subjects and both seroconverters were HCV co-infected.

Histologic improvements of liver despite virologic failure of interferon (IFN)+ribavirin therapy in 3 HIV+/HCV+ patients

Shulman said in her poster that although the usual outcomes measured for HCV treatment in studies are HCV viral clearance and ALT normalization, follow up biopsy data in treatment failures in HIV- cohorts show improvements in histology in over 30%. Mitch Shiffman has published data (Gastroenterology 1999;117:1164-1172) suggesting that maintenance therapy may be useful in maintaining improved histology.

In an ongoing treatment trial of IFN alpha, 3 million units TIW + ribavirin 800mg/d , 3 patients with virologic failure at 6 months have received pre- and post-therapy liver biopsies. Patients had post-treatment liver biopsies between 1-3 weeks after discontinuing therapy.

All 3 (pt A, B, and C) patients were males ages 44, 47, and 50 with baseline CD4 counts 234, 202, and 779. HCV genotypes were 1a, 3a, and 2b, and HCV RNA levels of 16,000,000/ml, 10,000,000/ml, and 250,000/ml. 2 patients had cirrhosis at baseline. None of the 3 had a substantial change in HCV RNA with monthly monitoring. ALT remained at least 2X normal in all patients at all time points measured. Patient B did have a 5-fold reduction in ALT from his baseline. The other two had no significant reductions. Knodell scores improved in all three, 11 to 9, 16 to 13, and 15 to 8. Patient B had an apparent reduction in fibrosis as well.

Shulman concluded that, as has been shown in HIV- HCV+ patients, treatment of HCV with interferon-based therapy can lead to histologic benefits despite lack of HCV clearance or ALT normalization. Biopsy outcomes should be an important part of future therapeutic trials for these patients.

54% Sustained Response Overall Achieved in Patients With Chronic Hepatitis C;
61% Sustained Response Achieved With Optimized Weight-Based Dosing
Studies With Rebetron(TM) Combination Therapy Also Reported

DALLAS, Oct. 30 /PRNewswire/ -- Schering-Plough Corporation (NYSE: SGP) today reported that results of a pivotal Phase III clinical study, presented for the first time here at the Presidential Plenary Session of the 51st Annual Meeting of the American Association for the Study of Liver Diseases (AASLD), showed that combination therapy with once-weekly PEG-INTRON(TM) (peginterferon alfa-2b) Injection plus daily REBETOL(R) (Ribavirin, USP) Capsules achieved a 54% rate of sustained virologic response overall in previously untreated adult patients with chronic hepatitis C. Sustained virologic response across hepatitis C virus genotypes ranged from 42% to 82% in patients receiving PEG-INTRON plus REBETOL combination therapy. When analyzed on an optimized dose/body-weight basis (>10.6 mg/kg of REBETOL daily), sustained virologic response was 61% for all genotypes, 48% for genotype 1 and 88% for genotypes 2 and 3. Sustained virologic response (SVR) is defined as sustained loss of detectable (1) hepatitis C virus (HCV-RNA).

"These results are especially encouraging given the increasing interest among physicians in tailoring treatment doses to an individual patient's needs," said Michael P. Manns, M.D., professor and chairman, department of gastroenterology and hepatology, Hannover Medical School, Hannover, Germany. "We have learned from this study and previous studies with alpha interferon that, in addition to genotype, body weight is an important factor in determining optimal clinical outcome. These results demonstrate that the dosing flexibility provided by PEG-INTRON plus REBETOL has the potential to take combination therapy to the next level of hepatitis C treatment," Manns said.

Results of the PEG-INTRON plus REBETOL study represent the largest and most complete clinical data reported to date involving peginterferon and ribavirin combination therapy. In all, PEG-INTRON was the subject of seven presentations by study investigators at AASLD.
PEG-INTRON Plus REBETOL Combination Therapy
In an AASLD Presidential Plenary Session, study investigators presented results of a pivotal Phase III clinical study designed to establish the activity and tolerance of two dosing regimens of PEG-INTRON plus REBETOL compared to REBETRON(TM) Combination Therapy containing REBETOL (Ribavirin, USP) Capsules and INTRON(R) A (Interferon alfa-2b, recombinant) Injection, the current standard of care, in previously untreated chronic hepatitis C patients. A total of 1,530 patients from 62 sites worldwide (33 U.S., 5 Canada, 22 Europe, 2 other) were randomized to three treatment arms:

(A) PEG-INTRON Injection 1.5 mcg/kg once weekly (QW) plus REBETOL Capsules 800 mg/daily for 48 weeks (PEG 1.5/R);
(B) PEG-INTRON 1.5 mcg/kg QW plus REBETOL 1000-1200 mg/daily for four weeks followed by PEG-INTRON 0.5 mcg/kg QW plus REBETOL 1000-1200 mg/daily for 44 weeks (Peg 0.5/R); or
(C) INTRON A Injection 3 MIU/three times weekly plus REBETOL Capsules 1000-1200 mg/daily for 48 weeks (REBETRON).
The demographic/disease characteristics of patients in this study were similar to those in previous Schering-Plough hepatitis C registration studies: 66% male; mean age 44 years; mean body weight 83 kg, pretreatment HCV-RNA (NGI LLQ 100 copies/ml) >2 million copies 68%; and HCV genotype 1 (68%), genotypes 2 and 3 (29%), other genotypes (3%) (InnoLipa, Innogenetics).

Patients in the PEG 1.5/R arm achieved significantly higher SVR (54%) overall compared to patients in the REBETRON arm (47%), while patients in the PEG 0.5/R arm achieved numerically similar SVR (47%) to those receiving REBETRON. When analyzed on a dose/body-weight basis (>10.6 mg/kg of REBETOL daily), SVR was 61% overall for patients in the PEG 1.5/R arm, compared to 48% for patients in the PEG 0.5/R arm and 47% for patients in the REBETRON arm.

Consistent with previous studies, the rates of sustained virologic response in this study were greatly influenced by genotype, with patients in the PEG 1.5/R arm with genotype 1, the predominant genotype worldwide and the most difficult to treat, achieving 42% SVR compared to 34% and 33% for patients in the PEG 0.5/R arm and REBETRON arm, respectively. When analyzed on a dose/body-weight basis (>10.6 mg/kg of REBETOL daily), patients in the PEG 1.5/R arm with genotype 1 achieved 48% SVR compared to 34% for patients in both the PEG 0.5/R arm and the REBETRON arm. Patients with genotypes 2 and 3 in these treatment arms achieved 88%, 80% and 80% SVR, respectively.

The safety profile of both doses of PEG-INTRON plus REBETOL was similar to that for REBETRON, with no new types of adverse events observed. Discontinuation of therapy for adverse events was similar in all three treatment groups: PEG 1.5/R (14%), PEG 0.5/R (13%), REBETRON (13%), as was dose modifications, 42%, 36%, and 34%, respectively.

PEG-INTRON PLUS REBETOL PIVOTAL PHASE III STUDY
Sustained Virologic Response) 

RESULTS:     (A) PEG 1.5/R    (B) PEG 0.5/R    (C) REBETRON     A vs. C 

SVR               54%               47%              47%        p=0.01  

(overall) 

SVR               42%               34%              33%        p=0.02  

Genotype 1 

SVR               82%               80%              79%  

Genotypes 2&3 

Optimized Weight-Based Dosing  

(>10.6 mg/kg/daily REBETOL*) 

SVR               61%               48%              47%  

(overall) 

SVR               48%               34%              34%  

Genotype 1 

SVR               88%               80%              80%  

Genotypes 2&3 

 10.6 mg/kg/daily REBETOL = REBETOL 800 mg/daily for patient weighing 75kg.
PEG-INTRON

Additional PEG-INTRON presentations at AASLD included a study showing that treatment with PEG-INTRON resulted in higher rates of sustained virologic response in Black and Hispanic patients compared to standard alpha interferon therapy. Another study with PEG-INTRON showed that sustained virologic response is associated with marked improvement in hepatic inflammation and fibrosis, and also showed that patients who do not achieve a sustained response, i.e. those who relapse following treatment or who are nonresponders, also show improvement in hepatic fibrosis. Study investigators suggested that further evaluation is warranted to determine whether some patients may benefit from maintenance therapy with PEG-INTRON.

A study presented by John B. Wong, M.D., Tufts University, New England Medical Center, Boston, Mass., estimated the cost-effectiveness of PEG-INTRON plus REBETOL for a range of possible trial outcomes as compared to REBETRON Combination Therapy or no antiviral therapy. In his study, Wong concluded that if trial results suggest that PEG-INTRON plus REBETOL increases the relative rate of sustained virologic response, then 48 weeks of combination therapy with PEG-INTRON plus REBETOL should provide good value for its clinical benefit.

REBETRON Combination Therapy

Also presented at AASLD were results of several studies involving REBETRON Combination Therapy containing REBETOL (Ribavirin, USP) Capsules and INTRON A (Interferon alfa-2b, recombinant) Injection, the current standard of care in the treatment of chronic hepatitis C. In all, REBETRON was the subject of 92 study abstracts, INTRON A was the subject of 14 study abstracts and REBETOL was the subject of 50 study abstracts.

"Schering-Plough's commitment to developing improved treatments for hepatitis C is evidenced by the large number of studies with PEG-INTRON, REBETRON, INTRON A and REBETOL as well as new research leads reported at this year's meeting," said Robert J. Spiegel, M.D., senior vice president of medical affairs and chief medical officer, Schering-Plough Research Institute.

In an AASLD Presidential Plenary session, study investigators presented results of a randomized controlled trial designed to assess the safety and efficacy of 48 weeks of REBETRON Combination Therapy compared to no antiviral therapy in liver transplant patients with hepatitis C reinfection. Intent-to-treat analysis for loss of detectable* HCV-RNA showed that patients receiving REBETRON therapy had undetectable HCV-RNA at week 24 (29%), at end of treatment (25%) and at the end of the 24-week follow-up period (21%), compared to no patient in the control group achieving loss of detectable HCV-RNA at any point in the study (p=0.026 at week 48; p=0.019 at end of follow up).

In a presentation of a study evaluating the effect of dose reduction on sustained virologic response in patients with chronic hepatitis C, investigators analyzed results from two pivotal Phase III clinical studies with REBETRON Combination Therapy and concluded that patients who can be maintained on greater than 80% of their REBETRON regimen for the proposed duration of therapy may have an enhanced rate of sustained response. Investigators suggested that every effort should be made to continue the maximum tolerated doses of therapy for the duration of treatment. Toward this goal, Schering-Plough makes available free to all patients on REBETRON Combination Therapy its Be In Charge(TM) therapy-compliance and patient-counseling program.

Other presentations involving REBETRON Combination Therapy included several studies evaluating different dosing regimens, including induction dosing, and the use of the combination therapy in specific patient populations, including patients with decompensated cirrhosis, patients with inherited coagulation disorders, African American and Hispanic patients, pediatric patients, and patients who relapsed or were nonresponders following prior treatment.

Schering-Plough markets REBETRON Combination Therapy in the United States for the treatment of chronic hepatitis C in patients with compensated liver disease previously untreated with alpha interferon or who have relapsed following alpha interferon therapy. The company markets REBETOL Capsules in certain international markets, including the European Union (EU), for use in combination with interferon alfa-2b injection (INTRON A) for the treatment of both relapsed and previously untreated hepatitis C patients.

Warnings and Contraindications

Anemia associated with the use of REBETOL in combination with interferon alfa-2b (REBETRON Combination Therapy) may exacerbate symptoms of coronary disease or deteriorate cardiac function. It is advised that complete blood counts (CBC) be obtained at baseline and at weeks 2 and 4 of therapy or more frequently if clinically indicated. The most common adverse experiences associated with REBETRON Combination Therapy are "flu-like" symptoms, such as headache, fatigue, myalgia and fever, which appear to decrease in severity as treatment continues. Severe psychiatric adverse events, including depression, psychoses, aggressive behavior, hallucinations, violent behavior (suicidal ideation, suicidal attempts, suicides), and rare instances of homicidal ideation have occurred during combination REBETOL/INTRON A therapy, both in patients with and without a previous psychiatric disorder.

Combination REBETOL/INTRON A therapy must not be used by women, or male partners of women, who are or may become pregnant during therapy and during the 6 months after stopping therapy. Combination REBETOL/INTRON A therapy should not be initiated until a report of a negative pregnancy test has been obtained immediately prior to initiation of therapy. Women of childbearing potential and men must use effective contraception (two reliable forms) during treatment and during the 6-month post-treatment follow-up period. Significant teratogenic and/or embriocidal effects have been demonstrated for ribavirin in all animal species in which adequate studies have been conducted. These effects occurred at doses as low as one-twentieth of the recommended human dose of REBETOL. If pregnancy occurs in a patient or partner of a patient during treatment or during the 6 months after treatment stops, physicians are encouraged to report such cases by calling 800-727-7064.

REBETOL is an oral formulation of ribavirin, a synthetic nucleoside analog with broad-spectrum antiviral activity. Schering-Plough has exclusive rights to market oral ribavirin for hepatitis C in all major world markets through a licensing agreement with ICN Pharmaceuticals, Inc. (NYSE: ICN) of Costa Mesa, Calif.

INTRON A is a recombinant version of naturally occurring alpha interferon, which has been shown to exert both antiviral and immunomodulatory effects. Schering-Plough markets INTRON A, the world's largest-selling alpha interferon, for 16 major antiviral and anticancer indications worldwide.

PEG-INTRON is a longer-acting form of INTRON A that uses proprietary PEG technology developed by Enzon, Inc. (Nasdaq: ENZN ) of Piscataway, N.J. PEG-INTRON, interferon alfa-2b linked to a 12,000 dalton polyethylene glycol (PEG) molecule, is designed to provide a once-weekly product optimizing the balance between antiviral activity and elimination half-life. Schering-Plough holds an exclusive worldwide license to PEG-INTRON.

In the European Union, PEGINTRON(TM)(peginterferon alfa-2b) was approved on May 25, 2000, as once-weekly monotherapy for the treatment of adult patients with chronic hepatitis C, resulting in one Marketing Authorization with unified labeling that is valid in all 15 EU-Member States. PEGINTRON, the first and only pegylated interferon approved for marketing in the world, has been launched in seven countries: Austria, Finland, France, Germany, Portugal, Sweden and the United Kingdom. In the United States, Schering-Plough on Dec. 23, 1999, submitted a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) seeking marketing approval for PEG-INTRON for the treatment of chronic hepatitis C. The BLA is currently under FDA review.

Some 4 million Americans are infected with the hepatitis C virus, according to the Centers for Disease Control and Prevention (CDC). As many as 5 million Europeans (1 percent to 2 percent of the general population) are chronically infected with the hepatitis C virus, according to a study conducted by the World Health Organization (WHO). Chronic hepatitis C is the leading cause of chronic liver disease and the most common reason for liver transplant, according to WHO.

Schering-Plough Research Institute is the pharmaceutical research and development arm of Schering-Plough Corporation of Kenilworth, N.J., a research-based company engaged in the discovery, development, manufacturing and marketing of pharmaceutical products worldwide.

(1) Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay.
SOURCE Schering-Plough Corporation 

Hepatitis C Virus Genotype Linked To Cirrhosis
Clinical Infectious Diseases 2001;33:70-75.
06/07/2001 07:57:50 AM
By Anne MacLennan

Hepatitis C virus genotype 1b has been found to have an independent effect on risk of cirrhosis.

Genotypes of hepatitis C virus (HCV) have raised considerable interest as variables that influence chronic hepatitis C progression.

Thus, these researchers did a case-control study to estimate the effect of HCV genotypes on patients with cirrhosis.

Although no significant effects were observed relating to other variables in this study, the finding that HCV genotype 1b is linked with cirrhosis risk suggests that the genetic diversity of HCV phylogenetic variants may explain differences in biological behaviours, study authors note.

Participants in this study in Southern Italy were 184 residents of the area.

Forty-six were patients (cases) who had tested positive for anti-HCV antibody and HCV RNA and had recently been diagnosed with cirrhosis. Controls were 138 people drawn randomly from a residents' cohort in the same area.

Researchers recorded demographic and other information on the patients and also assessed presence of HCV infection, presence of HCV RNA and HCV genotypes.

In a series of crude, stratified and logistic regression analyses, HCV genotype 2a/c was found in 84 controls (60.9 percent) and nine case patients (19.6 percent).

As well, HCV genotype 1b was found in 45 controls (32.6 percent) and 34 case patients (73.9 percent).

Researchers observed no significant effects related to other variables.

Study authors conclude that the genetic diversity of HCV phylogenetic variants could explain differences in biological behaviours.

SourceURL: http://www.docguide     

In addition, within a single individual, HCV can change into slightly different forms, called "quasispecies,"  This may be what makes it difficult for the body to detect and eliminate HCV and why people with HCV report such a variety of symptoms or no symptoms at all.  All these various forms of HCV also pose problems for scientists trying to develop treatments and vaccines that can be effective against all mutations of HCV." ~ Bethann Roybal, "HCV - A Personal Guide to Good Health"

We now know that the genotype one may have an  influence on response to treatment with interferon.  The problem remains, however, that due to the mutations of one genotype into another, or the development of 'quasispecies', it can be debated that genotypes may not be as dependable as once thought.  Having said that, the following is a chart showing which types are more likely than others to influence response to interferon treatment:

Clinicians are experimenting with new dosage regimes and combination therapy (using Interferon with Ribavirin) to try to address this problem. ~ From "The Hepatic C Handbook", by Matthew Dolan

However, some doctors believe that the apparent influence of genotype may reflect the following:

The duration of the infection.  Because type 1b is 'older' in many countries, it may be that patients infected with this strain have had more time to progress.  The time the virus has been present is known to influence the degree to which disease has progressed.

Viral heterogeneity. The longer HCV has  been present, the more likely it is to have     mutated into viable quasispecies, makin  it a more difficult target for drug therapy.

Age of the patient.  This is also thought be a factor; the younger, the better.

Health of the liver. Good liver function and the absence of cirrhosis and fibrosis are good signs.

Fitness of the patient. This is also thought to have a bearing by many doctors.  Patients who are significantly overweight have been observed to have lower response rates.

Iron levels in the liver cells.  Also have a bearing; the lower, the better.  Patients with a history of heavy drinking tend to have higher levels of iron deposition in their liver cells.

~ From "The Hepatitis C Handbook", Matthew Dolan

Genotypes of HCV

DOES GENOTYPE PLAY ROLE IN HCV PROGRESSION?

There appears to be some controversy about this but several studies listed below suggest disease progression may be worse in genotype 1 than 2.

  The natural course of chronic hepatitis C: a comparison between patients with genotypes 1 and 2 hepatitis C viruses
M Kobayashi, E Tanaka, T Sodeyama, A Urushihara, A Matsumoto and K Kiyosawa

The Second Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.  

This study was conducted to clarify if the long-term histological outcome among patients with chronic hepatitis C differs according to whether they are infected with genotype 1 or 2 hepatitis C virus (HCV). We examined 140 patients with chronic hepatitis C. The HCV genotype was determined by the enzyme-linked immunosorbent assay (ELISA) based on genotypes 1 and 2 specific recombinant proteins; genotype 1 was found in 100 patients (96 were 1b and 4 were indeterminate) and genotype 2 in 36. The two groups showed no significant difference for any clinical background features.

Deterioration of the grade of liver histology during the follow-up period was seen in 68.0 percent of the patients with genotype 1 as compared with 41.7 percent of those with genotype 2 (P < .01). Similarly, the deterioration of the stage of liver histology was more common in the former group than in the latter (63.0 percent and 38.9 percent respectively; P < .05). The mean serum HCV-RNA titer was significantly higher in the patients with genotype 1 than in those with genotype 2 (P < .001), and multivariate analysis showed the titer was one of the independent factors of the deterioration of the stage (P = .0044). This phenomenon may be related in part to the difference in pathogenicity between the two HCV genotypes. In conclusion, our results suggest that more severe progression of chronic hepatitis C is seen in patients showing genotype 1b compared with those with genotype 2.

WHY IS INTERFERON MORE SUCCESSFUL IN GENOTYPE 2 THAN INDIVIDUALS WITH GENOTYPE 1? 

Effects of interferon treatment on the antiviral T-cell response in hepatitis C virus genotype 1b- and genotype 2c-infected patients

G Missale, E Cariani, V Lamonaca, A Ravaggi, A Rossini, R Bertoni, M Houghton, Y Matsuura, T Miyamura, F Fiaccadori and C Ferrari  Cattedra Malattie Infettive, Universita di Parma, Italy

The T-cell response to HCV peptides and recombinant core protein detected throughout the follow-up was significantly more vigorous in genotype 2c- than in genotype 1b- infected patients. This difference was the result of a greater enhancement of the T-cell response caused by IFN treatment in genotype 2c- compared with genotype 1b-infected patients. The different IFN modulatory effect on T cells from genotype 1b- and genotype 2c-infected patients illustrates an aspect of the virus-host interaction, which may contribute toward the explanation of why different genotypes differ in responsiveness to IFN treatment.

The T-cell response to HCV core protein was sequentially analyzed before and during IFN treatment in two groups of patients chronically infected with HCV genotype 1b (eight patients) or 2c (eight patients). Overlapping 20 mer peptides corresponding to the amino acid sequence of the prevalent viral population identified in the serum of each patient were used for the analysis of the T-cell proliferative response to avoid possible problems caused by amino acid differences between infecting virus and HCV proteins used in vitro. Recombinant HCV core antigen was used in parallel. The level of viremia was monitored by competitive polymerase chain reaction (PCR).

My take: The following study suggests individuals with cirrhosis don't progress more quickly whether they have genotype 1 or 2. This does not mean that genotype 1 or 2 may not affect progression prior to cirrhosis developing.

Lack of correlation between hepatitis C virus genotypes and clinical course of hepatitis C virus-related cirrhosis 

L Benvegnu, P Pontisso, D Cavalletto, F Noventa, L Chemello and A Alberti Clinica Medica Second, University of Padova, Italy.  

The influence of the hepatitis C virus (HCV)-genotype on liver disease severity was evaluated in 429 consecutive patients with chronic hepatitis C, including 109 with cirrhosis who were followed up prospectively, allowing for the assessment of the role of the HCV- genotype on disease outcome and on the development of hepatocellular carcinoma (HCC). HCV-1 was detected in 147 (46%) patients without cirrhosis and in 47 (43%) with cirrhosis

(P: not significant), being mainly HCV-1b. HCV-2 was found in 103 (32%) cases without cirrhosis and in 30 (27.5) with cirrhosis (P: not significant), being mainly HCV-2a. HCV-3 was detected in 32 (10%) patients without cirrhosis and in 2 (2%) with cirrhosis (P < 0.005). Infection with more than one genotype (HCV- 1/HCV-2 and HCV-1/HCV-3) was observed only in cirrhotic patients (6 of 109; 5.5%). During a mean follow-up of 67 +/- 22 months, 21 (19%) patients with cirrhosis showed worsening in Child's stage, 5 (4.5%) underwent liver transplantation, 23 (21%) developed HCC, and 24 (22%) died of complication of liver disease; the overall incidence of at least one of these events was 38.5%. By the Kaplan-Meier method and log-rank test, the cumulative probability of developing each or at least one of the above events did not differ in relation to the genotype of infecting HCV, apart from patients with mixed genotype infection who showed a significantly higher incidence of death (P < .05). These data indicate that HCV-genotypes do not have a significant effect on the severity and outcome of liver disease in patients with chronic HCV- infection. Patients with cirrhosis who are also infected by HCV-1 and HCV-2 had a similar prognosis and progression to HCC, while patients infected by more than one genotype showed the most unfavorable course of disease.

Results from following study correlate genotype 1 with developing liver cancer

Hepatitis C virus genotypes and risk of hepatocellular carcinoma in cirrhosis: a prospective study

S Bruno, E Silini, A Crosignani, F Borzio, G Leandro, F Bono, M Asti, S Rossi, ALarghi, A Cerino, M Podda and MU Mondelli Divisione di Medicina Generale III, Cattedra di Medicina Interna, Istituto di Scienze Biomediche San Paolo, Universita di Milano, Italy.

A prospective study was performed to establish whether infection with specific hepatitis C virus (HCV) genotypes was associated with an increased risk of development of hepatocellular carcinoma (HCC) in cirrhosis. A cohort of 163 consecutive hepatitis C virus antibody (anti- HCV)-positive cirrhotic patients was prospectively evaluated for the development of HCC at 6-month intervals by ultrasound (US) scan and alpha-fetoprotein (AFP) concentration. HCV genotypes were determined according to Okamoto. Risk factors associated with cancer development were analyzed by univariate and multivariate statistics. At enrollment, 101 patients (62%) were infected with type 1b, 48 (29.5%) were infected with type 2a/c, 2 (1.2%) were infected with type 3a, 1 (0.6%) was infected with type 1a, 3 (1.8%) had a mixed-type infection, and, in 8 patients (4.9%), genotype could not be assigned. After a 5- to 7-year follow-up (median, 68 months), HCC developed in 22 of the patients, 19 infected with type 1b and 3 with type 2a/c (P < .005). Moreover, HCC developed more frequently in males (P < .01), patients with excessive alcohol intake (P < .01), those over 60 years of age (P < .02), and in patients who did not receive interferon treatment (P < .02). Multivariate analysis showed that type 1b was the most important risk factor associated with tumor development (odds ratio 6.14, 1.77-21.37 95% confidence interval). Other independent risk factors were older age and male sex. Cirrhotic patients infected with HCV type 1b carry a significantly higher risk of developing HCC than patients infected by other HCV types. The latter may require a less intensive clinical surveillance for the early detection of neoplasia.

This study also suggests genotype 1 is more associated with disease severity than genotype 2.

Influence of different hepatitis C virus genotypes on the course of asymptomatic hepatitis C virus infection

D Prati, C Capelli, A Zanella, F Mozzi, P Bosoni, M Pappalettera, F Zanuso, L Vianello, E Locatelli, C de Fazio, G Ronchi, E del Ninno, M Colombo and G Sirchia  Centro Trasfusionale e di Immunologia dei Trapianti, Ospedale Maggiore, Milano, Italy.

BACKGROUND & AIMS: The association of liver disease with hepatitis C virus (HCV) genotypes mainly refers to patients with serious liver damage; little information is available on symptomless carriers. The aim of this study was to investigate the correlation of genotypes with clinical course, risk factors for infection, and antibody to HCV reactivity in asymptomatic subjects. METHODS: One hundred nine viremic blood donors with at least 1 year of follow-up were studied; 41 underwent liver biopsy. Genotypes were determined by line-probe assay. RESULTS: Genotype 1 was found in 47 (43.1%), genotype 2 in 48 (44%), genotype 3 in 8 (7.3%), genotype 4 in 2 (1.8%), and coinfections in 4 (3.7%). The relative risk (RR) for a raised pattern of alanine amino-transferase, aspartate aminotransferase, and gamma- glutamyl-transpeptidase was 2.1 (confidence interval [CI], 1.4-3.2), 1.7 (CI, 1.2-2.4), and 2.8 (CI, 1.6-4.9) in subjects with genotype 1 vs. 0.4 (CI, 0.2-0.7), 0.4 (CI, 0.3-0.7), and 0.4 (CI, 0.2-0.8) in subjects with genotype 2. Chronic hepatitis was found in 68%; the RR of chronic hepatitis was similar for genotypes 1 and 2 (RR, 1.1 [CI, 0.8-1.7] vs. RR, 1.0 [CI, 0.7-1.6]). Reactivity to NS4-derived antigens was infrequent in type 2-infected subjects. CONCLUSIONS: Genotype 2 was as frequent as genotype 1 but associated with less liver function impairment. The high prevalence of chronic hepatitis should be considered in counseling viremic asymptomatic donors.

Starting Virus Levels, Genotype Predict Response to Interferon Treatment

Viral genotype and baseline virus levels predict response to interferon (IFN) treatment for patients with chronic hepatitis C virus (HCV) infection. Therapy with interferon alfacon-1 (Infergen, Amgen) should be tailored for each patient's condition.

Today's standard treatments do not adjust therapy based on individual patient's requirements. But patients with genotype 2 or 3 virus generally respond better than those with genotype 1. So do patients with lower baseline virus levels. (About 70% of HCV patients in the U.S. have genotype 1 virus.)

F. Blaine Hollinger, M.D., Professor of Medicine, Virology, and Epidemiology at Baylor College of Medicine in Houston, says a clinical trial he did shows that many patients will respond if given enough interferon, "and if you give them daily doses, for example, instead of three times a week or every other day."

The study he presented at the 1999 meeting of the American Association for the Study of Liver Diseases provides evidence that optimal IFN doses and schedules may differ depending on genotype and baseline virus concentration.

The patients were divided into two groups, according to their baseline levels of virus (HCV RNA levels): low, with less than or equal to 106 copies/ml; and high, with greater than 106 copies/ml.

Researchers compared the effect of five different induction regimens of IFN alfacon-1 on virus elimination in these patients. They received one of five four-week IFN induction regimens: (1) 7.5 mcg twice a day; (2) 15 mcg once daily; (3) 15 mcg three times a week; (4) 9 mcg daily; or (5) 9 mcg three times a week. After the four-week induction period, all subjects received 9 mcg three times a week for an additional 44 weeks.

Patients with low baseline viral concentrations had rapid and consistent decreases in virus levels by week 4 with all induction dosing regimens except 9 mcg three times a week. Within 2 weeks, most patients on the effective regimens had low or undetectable virus levels. Levels continued to decrease or remained low after the 4 week induction period. Patients on the 9 mcg three times a week induction dose required 12 weeks of treatment before their virus levels became undetectable.

Patients with high baseline virus levels did not experience as rapid a decrease as did those with low baseline levels. And for some, levels rebounded after switching to 9 mcg three times a week. The researchers speculate that longer induction periods may be necessary for patients with higher baseline viral loads.

Besides the faster rate of viral decrease in patients with low baseline levels, more of them responded to every induction dosing regimen when measured at 4 and 12 weeks, compared to patients with high levels.

For patients with genotype 1 virus and low baseline virus levels, induction dosing with 15 mcg of IFN daily or 7.5 mcg twice daily produced a more rapid decrease in viral levels than the other induction doses. But genotype 1 patients had rebounds in their virus levels after switching to 9 mcg three times a week. Again, the researchers suggested that longer induction periods may be necessary for these patients.

Based on the rate of viral decrease, the researchers calculated the optimal induction period for genotype 1 patients. A dose of 15 mcg once daily required the shortest induction period, 10.4 weeks, to bring virus down to undetectable levels. The standard dose of 9 mcg three times a week required 13.7 weeks.

The researchers concluded that treatment of chronic HCV patients should be tailored based on their genotype and viral loads. Patients with low baseline viral concentrations or who are not genotype 1 can achieve maximum benefit when treated with 9 mcg of IFN alfacon-1 daily for 4 weeks and then switched to 9 mcg three times a week for 44 weeks. However, patients with high baseline viral levels or who are genotype 1 may do better if treated with 15 mcg of IFN alfacon-1 daily for 10 weeks, followed by 9 mcg three times a week for the duration.

Dr. Hollinger already individualizes therapy based on viral load and genotype, and he goes further by monitoring treatment efficacy along the way. "We often will. treat a patient for four weeks with high dose induction therapy, and then look and find out whether they have undetectable virus at that time," he says. "If they do, then I will switch them to every other day therapy. If they don't, I'll continue on for at least 10 weeks of daily therapy and then switch them to every other day after that and continue the therapy for perhaps in that case up to a year instead of six months."

Besides genotype and viral load, Dr. Hollinger thinks race may be another important parameter to consider. "We haven't looked yet at the response rates of African Americans versus Caucasians in this study, but I think that's probably a very important issue as well," he says. African Americans often have more resistant disease than Caucasians.

A report of Dr. Hollinger's study and several other highlights from the AASLD meeting are available at the Med On Scene site at www.medonscene.com. The site offers health professionals the opportunity to earn continuing medical, nursing, or pharmacy education credits by completing the educational activity based on AASLD meeting reports.

A service of Patients Network, Inc.

Amount of hepatic hepatitis C virus-RNA has been found to be correlated to genotype and response to interferon therapy but not to histologic lesions.

Moreover, clearance of hepatic hepatitis C virus (HCV) RNA is observed in sustained responders (SRs), which in turn indicates viral eradication.

Anne Gervais and colleagues from various departments of the Hôpital Beaujon AP-HP, Clichy, France did this study of the correlation between hepatic HCV RNA and histological lesions, viral genotype or response to alpha interferon therapy.

Study participants were 43 patients with chronic hepatitis C; 14 of them were SRs, and 29 were non-sustained responders (NSRs). The researchers obtained a liver tissue sample before and one year after treatment. Quantitation of hepatic HCV-RNA was done via competitive PCR.

Before treatment, HCV-RNA was detectable in all liver samples, and there was no link between hepatic HCV-RNA and the severity of liver lesions.

There was a significant association between old age and hepatic HCV-RNA and also, at the limit of significance, between genotype one and high hepatic HCV-RNA amounts (15x106 and 4.1x106 copies/g).

Pre-treatment hepatic HCV-RNA amounts were lower in SRs than in others (0.65x106 and 13.2x106 copies/g).

After treatment, no liver HCV-RNA was detectable in the SRs while in the NSRs, the HCV-RNA amounts were unchanged. Thus, the amount of hepatic HCV-RNA is correlated to genotype and response to interferon treatment but not to histologic lesions.

Furthermore, the hepatic HCV-RNA clearance seen in SRs suggests viral eradication, these authors conclude.

Journal of Hepatology, Vol. 35 (3) (2001) pp. 399-405. "Quantitation of hepatic hepatitis C virus RNA in patients with chronic hepatitis C. Relationship with severity of disease, viral genotype and response to treatment"

11/08/2001
By Anne MacLennan

Hepatitis C viral genotype influences the clinical outcome of patients with acute hepatitis C infection.

Most patients with acute hepatitis C virus (HCV) infection develop chronic hepatitis, and only about 15 to 20 percent of cases resolve spontaneously.

The HCV genotype has been recognized as a key factor affecting clinical course and outcome of chronic hepatitis C patients. However, the mechanism for the different outcomes in patients with acute HCV infection remains unclear.

This study by Shinn-Jang Hwang and colleagues from the Veterans General Hospital-Taipei, National Yang-Ming University School of Medicine, Taipei, Taiwan, China, sought to evaluate the role of HCV genotype in the clinical course and outcome of acute post-transfusion hepatitis C.

Participants were 67 patients with acute post-transfusion hepatitis C from a prospective study of post-transfusion non-A, non-B hepatitis. Thirty-nine of these patients (58.2 percent) were HCV genotype 1b.

Of all the patients, 53 (79.1 percent) progressed to chronic hepatitis. Significantly more patients with genotype 1b (89.7 percent) than non-1b genotypes (64.3 percent) developed chronic hepatitis.

Researchers found no significant difference in gender, mean age, amount of transfused blood, hepatitis symptoms, jaundice, incubation period, peak serum alanine transaminase, or serum HCV RNA titer between patients with HCV genotype 1b and non-1b infections.

People who developed chronic hepatitis had a significantly greater incidence of genotype 1b infection (66.0 percent versus 28.6 percent) and a longer incubation period (7.3 weeks) than patients whose infection was resolved (5.4 weeks).

Those patients with a genotype 1b infection that resolved spontaneously all had an incubation period of less than six weeks.

Further analysis revealed genotype 1b and an incubation period of six weeks were significant predictors for development of chronic hepatitis.

Thus, the HCV genotype can influence the outcome of patients with acute HCV infection, these authors conclude.

J. Med. Virol. 65:505-509, 2001. "Hepatitis C viral genotype influences the clinical outcome of patients with acute posttransfusion hepatitis C"

SLOW VIRAL DYNAMICS OF HEPATITIS C GENOTYPE 4

– ABSTRACT 969

 Hepatitis C Virus of genotype 4 (HCV-4) is the major HCV subtype in Middle Orient (e.g., up to 80% in Egypt) where a large number of patients are chronically infected. Some evidence exists that patients infected with HCV-4 respond to IFN as poorly as those infected with genotype 1 and contrary to the good response in genotype 2-3 infected patients. Indeed, it was previously shown (Neumann et al, JID, 2000) that the viral dynamics of genotype 1 are slower and the effectiveness of IFN to block its production is lower as compared to genotypes 2-3. However, there is no information on the viral dynamics of HCV-4.

 Interferon-Ribavirin combination treatment (3-6 MU of IFN-a-2a QD and Ribavirin 1200 mg/day) was administered to 5 naïve patients chronically infected with HCV genotype 4 in 2 centers in France. Viral load was frequently assessed during the first month of treatment (daily during the first week, and weekly thereafter) using the bDNA 3.0 (VERSANT HCV 3.0, Bayer) assay (limit of detection 3200 Eq/ml). Viral dynamics parameters were estimated based on the bi-phasic model for HCV dynamics during IFN treatment (Neumann et al, Science, 1998).

 It was found that viral kinetics of HCV-4 follow the same bi-phasic decline pattern as HCV of genotypes 1, 2 and 3. The mean effectiveness of IFN in blocking production of HCV-4 was 71.9% (with standard deviation of 12.6%) or 0.55 log eq/ml decline during 1st day of treatment, which is highly comparable to that of previous studies with genotype 1 using same treatment regimen (68-74%). In 2 patients with frequent samples during the first day it was possible to estimate the half-life of free virions as 3.5 and 3.7 hours, again comparable to the 3-4 hours half-life measured for genotype 1 and slower than 2 hours for genotype 2. The half-life of the 2nd phase viral decline slope ranged from 2.6 days to larger than 70 days similar to the large variation in 2nd slope observed in genotype 1 infected patients.

 In summary, the poor response to treatment in patients infected with HCV of genotype 4 can be attributed to the low effectiveness of IFN in blocking its virion production as compared to genotypes 2-3. HCV genotype 4 infected patients should be grouped with genotype 1 when therapy schemes are considered as function of genotype. HCV resistance to IFN treatment can be better understood by looking for the common viral properties of genotypes 1 and 4 as compared to those of genotypes 2 and 3.  

http://www.va.gov/hepatitisC/pved/genotypes_quasispecies.htm
Hepatitis C Virus Genotypes

The term "genotype" refers to HCV isolates from genetically distinct groups, which have arisen during the evolution of this virus. Hepatitis C virus demonstrates tremendous genetic diversity which has wide-ranging implications for diagnosis and treatment of HCV infection. Currently, there are six known hepatitis C genotypes, each with numerous subtypes.

Genotype variation can be found worldwide. However, the relative prevalence of different genotypes differs by geographic region. In the United States, for example, genotype 1 is the most prevalent whereas in Egypt genotype 4 accounts for the majority of infections.

Clinical Significance of HCV Genotypes

Determining the genotype of an individual patient's HCV isolate may have important treatment implications. Of utmost clinical significance is the role that genotypes play in response to treatment and in determining the optimum duration of treatment. For example, with all treatments tested to date, patients with genotypes 2 and 3 are more than twice as likely as patients with genotype 1 to achieve a sustained virologic response. In addition, when using combination therapy consisting of interferon and ribavirin, a 24-week course is recommended for genotypes 2 or 3 compared to 48 weeks for patients with genotype 1. Although the significance of genotype in treatment response is clear, the influence of genotype on the severity of liver damage and the rate of disease progression has not been well defined. Most investigations suggest one viral genotype is no more virulent than any other, and that other factors are responsible for the variation seen in medical outcomes of chronic hepatitis C infection.

Quasispecies and Viral Mutation

Within an individual viral isolate identified as a particular genotype, further genetic heterogeneity exists. Through spontaneous mutations, closely related yet significantly different viral genomes evolve over time. These are known as quasispecies. Production of quasispecies is likely to be important in the natural history of hepatitis C infection, since diversification is believed to be one mechanism by which the virus escapes the immune response of the host. Quasispecies differ from genotypes in that genotypes represent major genetic differences that vary in geographic distribution and epidemiologic associations, whereas quasispecies represent minor genetic differences in an individual infected with a single genotype. Quasispecies change in an individual over time, whereas genotypes do not. Quasispecies can be measured quantitatively (viral complexity) and qualitatively (viral divergence over time) although such tests are not currently available as clinical tools.

Clinical Significance of Quasispecies

HCV quasispecies have a number of important implications for practicing clinicians who treat HCV infection. A recent study1 demonstrated that during acute HCV infection, isolates which developed little genetic diversity in a particular region of the viral genome were associated with self-limited hepatitis, whereas the development of persistent infection was associated with the evolution of greater genetic diversity in this region. Thus, the dynamics of quasispecies evolution during acute infection may be an important determinant of host immune response and the future course of infection. HCV variants also can be used to prove linkage of infections that are associated epidemiologically. For example, molecular analysis has been used to link mother/infant pairs, to define HCV in apparently concordant sexual couples as virologically concordant or discordant, to prove nosocomial transmission of HCV between health care provider and patient, and to link needle stick recipients with the sources of infection.

References

Farci P, Shimoda A, Coiana A, et al. The outcome of acute hepatitis C predicted by the evolution of the viral quasispecies. Science 2000;288:339-344.

Additional Reading

Bukh J, Miller R. Diagnostic and clinical implications of the different types of hepatitis C virus genomes. J Hepatol 1992;14:35-40.

Bukh J, Miller R, Purcell R. Genetic heterogeneity of hepatitis C virus: quasispecies and genotypes. Semin Liver Dis 1995;15:41-63

Dusheiko G, Schmilovitz-Weiss H, Brown D, McOmish F, Yap PL, Sherlock S, McIntyre N, Simmonds P. Hepatitis C Virus Genotypes: An investigation of type-specific difference in geographic region and disease. Hepatology 1994;19:13-18.

Gretch DR. Diagnostic Tests for Hepatitis C. Hepatology (Suppl.)1997;26:43S-47S.

Simmonds P. Variability of hepatitis C virus. Hepatology 1995;21:570-582.

Viral genotype, alcohol influence hepatitis C outcome

WESTPORT, Jun 02 (Reuters Health) - Infection with hepatitis C virus (HCV) genotype 1b is associated with more severe liver disease than are other genotypes, and excessive alcohol intake worsens the course of the disease, Italian researchers report in the June issue of Gut.

Dr. S. Bellentani, of the University of Trieste, and colleagues there and at Pordenone General Hospital studied the prevalence, risk factors, and severity of HCV-related liver disease among 6,917 inhabitants of two northern Italian towns.

"The anti-HCV screening test was positive in 226 cases (3.2%)," Dr. Bellentani's team reports. "HCV RNA was detected in the serum in 162 cases (2.3%)." The prevalence of positivity of both tests increased with increasing age and "...was greater in women than men (ratio of men to women = 0.7) in all the age ranges considered."

"Of the 162 HCV RNA positive subjects, 20 (12%) had cirrhosis and five (3%) had [hepatocellular carcinoma]," the authors write. "Fourteen of the 20 patients with cirrhosis (70%) were infected with genotype 1b." Among the five patients with hepatocellular carcinoma, three were infected with genotype 1b, according to the journal article.

Alcohol significantly worsened the course of hepatitis C disease, the investigators observed. "The risk of developing cirrhosis for HCV RNA positive drinkers was three times higher than that for drinkers not at risk," they determined. All five patients with hepatocellular carcinoma were alcohol abusers and drank significantly more than the other patients with cirrhosis.

Using multiple regression logistic analysis, the authors found that "...the odds for a patient infected by both HCV genotype 1b and multiple genotypes of having cirrhosis and/or [hepatocellular carcinoma] was 31 times higher...than for those patients not infected by HCV."

"The risk for a subject infected by all the other HCV genotypes of having cirrhosis and/or [hepatocellular carcinoma] was lower...but still highly significant compared with HCV RNA negative subjects," Dr. Bellentani's group adds.

Based on these results, the researchers conclude that "...HCV infection, particularly with genotype 1b, is the major risk factor associated with the presence of cirrhosis and/or [hepatocellular carcinoma] in the general population, at least of Northern Italy."

Gut 1999;44:874-880.

-Westport Newsroom 203 319 2700

Genetic Complexity of Hepatitis C Virus

Robert H. Purcell, M.D.

History

Hepatitis C was first recognized as a separate disease entity in 1975 when the majority of cases of transfusion-associated hepatitis were found not to be caused by the only two hepatitis viruses recognized at the time, hepatitis A virus and hepatitis B virus. The disease was called "non-A non-B hepatitis," and it was demonstrated to be transmissible to chimpanzees. It was not until 1989, however, that the cloning and sequencing of the viral genome of the non-A non-B hepatitis virus was first reported and the virus was renamed "hepatitis C virus" (HCV). Tests for antibody to HCV quickly followed, and screening for such antibody remains a principal method of diagnosis.

Taxonomy and Nomenclature

Hepatitis C virus shares virological and genetic characteristics with the Flaviviridae. Its genomic organization is similar to that of the flaviviruses and pestiviruses and shares slight sequence identity with these viruses, especially the pestiviruses. Each of these groups of viruses comprises a separate genus within the Flaviviridae: flavivirus, pestivirus, and hepacivirus.

Properties of the Virion and Genome

Properties of the Virion

Hepatitis C virus is a spherical enveloped virus of approximately 50 nm in diameter. Its buoyant density in sucrose is only 1.06 g/cm3 but much of the virus in chronically infected individuals appears to be bound to antibody, which imparts a higher density of approximately 1.17 g/cm3.

Properties of the Genome

The genome of HCV is a single-strand linear RNA of positive sense. It is unsegmented. A 5' non- coding (NC) region consists of approximately 340 nucleotides and contains an apparent internal ribosomal entry site (IRES). Immediately downstream is a single large open reading frame (ORF) of approximately 9,000 nucleotides, encoding a large polyprotein precursor of approximately 3,000 amino acids that is cotranslationally or posttranslationally cleaved into separate proteins by a combination of host and viral proteases. A capsid protein, two envelope proteins (El and E2), and a small protein of unknown function (P7) are encoded in the 5' region of the ORF. At least six nonstructural proteins, including protease, helicase, and RNA polymerase enzymes and regulatory peptides, are arrayed in the 3' portion of the ORF. Finally, there is a 3' NC region that consists of approximately 50 nucleotides, a polypyrimidine track and a highly conserved terminal sequence of approximately 100 nucleotides.

Genetic Heterogeneity: Types, Subtypes, and Quasispecies

The genome of HCV is highly heterogeneous. The most highly conserved regions of the genome are parts of the 5' NC region and the terminal 3' NC region. The most highly conserved region of the ORF is the capsid gene. In contrast, the most heterogeneous portions of the genome are the genes encoding the envelope proteins. The 5' end of the E2 gene is the most heterogeneous region of all and has been named the "first hypervariable region" (HVRI ). A few strains have a second HVR just 3' of HVRl . The HVRI consists of approximately 90 nucleotides (30 amino acids) and is believed to be a major neutralization epitope of HCV: its heterogeneity appears to be the result of selective pressures by the host's humoral immune system.

Based on their genetic heterogeneity, HCV strains can be divided into major groups, called types or genotypes (and provisionally classified as separate species) of the virus (Table I). Within types, HCV isolates have been grouped into numerous subtypes. Finally, individual isolates consist of heterogeneous populations of the viral genomes that comprise "quasispecies" or "swarms" of closely related but different viruses. Some genotypes of HCV appear to be geographically restricted; others have worldwide distribution. More extensive genetic analysis of HCV has revealed that the hierarchical classification of isolates into types, subtypes, and isolates is somewhat artifactual and the viruses probably exist as a continuum of genetic diversityTABLE 1. Genetic Complexity of Hepatitis C Virus.

1. Bukh J, Miller RH, Purcell RH. Defining the genotypes of hepatitis C virus and their epidemiology. INTER-action 1995;3:10-5.
2. Choo QL, Kuo G, Ralston R, Weiner A, Chien D, Van Nest G, Han J, Berger K, Thudium K, Kuo C, Kansopon J, McFarland J, Tabrizi A, Ching K, Moss B, Cummins LB, Houghton M, Muchmore E. Vaccination of chimpanzees against infection by the hepatitis C virus. Proc Natl Acad Sci U S A 1994;91:1294-8 .
3. Conrad ME. Prevention of post-transfusion hepatitis. Lancet 1988;339(2):217.
4. Farci P, Alter HJ, Govindarajan S, Wong DC, Engle R, Lesniewski RR, Mushahwar IK, Desai SM, Miller RH, Ogata N, Purcell RH. Lack of protective immunity against reinfection with hepatitis C virus. Science 1992;258:135-40.
5. Farci P, Shimoda A, Wong D, Cabezon T, De Gioannis D, Strazzera A, Shimizu Y, Shapiro M, Alter HJ, Purcell RH. Prevention of HCV infection in chimpanzees by hyperimmune serum against the hypervariable region I of the envelope 2 protein. Proc Natl Acad Sci U S A. In press.
6. Hijikata M, Shimizu YK, Kato H, Iwamoto A, Shih JW, Alter HJ, Purcell RH, Yoshikura H. Equilibrium centrifugation studies of hepatitis C virus: evidence for circulating immune complexes. J Virol 1993;67:1953-8.
7. Houghton M. Hepatitis C virus. In: Fields BN, Knipe DM, Howley PM, eds. Fields Virology, Third Edition. Philadelphia: Lippincott-Raven Publishers 1996:1035-58.
8. Lai ME, Mazzoleni AP, Argiolu F, De Virgilis S, Balestrieri A, Purcell RH, Cao A, Farci P. Hepatitis C virus in multiple episodes of acute hepatitis in polytransfused thalassaemic children. Lancet 1994;343:388-90.
9. Shimizu YK, Feinstone SM, Kohara M, Purcell RH, Yoshikura H. Hepatitis C virus: detection of intracellular virus particles by electron microscopy. Hepatology 1996;23:205-9.
10. Shimizu YK, Igarashi H, Kiyohara T, Cabezon T, Purcell RH, Yoshikura H. A hyperimmune serum against a synthetic peptide corresponding to the hypervariable region I of hepatitis C virus can prevent viral infection in cell cultures. Virology 1996;223(2):409-12.
11. Yu MW, Mason BL, Guo ZP, Tankersley DL, Nedjar S, Mitchell FD, Biswas RM. Hepatitis C transmission associated with intravenous immunoglobulins. Lancet 1995;345:1173-4 .

Viral Load not Dependent on Genotype

Comparative analysis of quantification of viral load in patients infected with hepatitis C virus: quantiplex HCV RNA assay and amplicor monitor assay. Olaso V, Cordoba J, Lopez B, Arguello L, Molina J, Lainez B, Ortiz V, Pastor M, Prieto M, Berenguer J Servicio de Medicina Digestiva, Hospital "La Fe", Valencia, 46009, Espana.

OBJECTIVE: two standardized techniques, Quantiplex HCV RNA 2.0 (bDNA) and Amplicor Monitor, were evaluated for the quantification of hepatitis C virus (HCV) load. Our objectives were: 1) to determine the relationship between viral load and genotype, and 2) to evaluate viral load in serial serum samples and in patients with normal or slightly elevated liver enzyme values in an area with a high prevalence of genotype 1.

RESULTS: the viral loads detected with the two methods correlated significantly (r = 0.7, p ), but viral load was smaller with the Monitor than with the Quantiplex assay, and was independent of genotype. The Monitor/Quantiplex ratio was lower in patients with a non-1 genotype than in patients with genotype 1b. Virological characteristics were similar in patients with normal or slightly elevated enzyme levels and in patients with elevated enzyme values. Neither method showed a relationship between viral load and age, sex, duration of the infection, mode of transmission, or histological activity index.

CONCLUSION: viral load was not dependent on genotype. Measurement of viral load in a single serum sample adequately reflected the viral load measured in several serum samples from patients with chronic HCV infection. Patients with normal liver enzyme levels are not good candidates, in virological terms, for treatment with interferon

HCV Genotype May Influence Immune Response
By Brian Boyle, MD

It is estimated that as many as 170 million persons worldwide are infected with hepatitis C virus (HCV). HCV infection is also common in patients with HIV infection. The improving survival of HIV-infected persons brought about by highly active antiretroviral therapy (HAART), and the data which suggest that HIV hastens progression of HCV and vice versa, have made the treatment of HCV a pressing issue in HIV/HCV coinfected patients.

Cytotoxic T Lymphocytes are currently considered important in the elimination of HCV. A strong response to structural and regulatory HCV proteins has been reported in persons with acute HCV who spontaneously eliminate HCV. On the other hand, there is usually only a muted or transient immune response in patients who develop chronic HCV. Because of the impact of HIV on the immune system, it would be expected that the CD4+ cell response would be lower in HIV/HCV coinfected patients.

In a study published in The Journal of Infectious Diseases, the CD4+ T lymphocyte proliferative responses to HCV antigens were evaluated before and during an anti-HCV regimen consisting of interferon-a 2a (IFN) and ribavirin in 36 HIV/HCV coinfected patients. Investigators found that baseline immune responses to HCV were not predictive of sustained virologic response; however, sustained immune reactivity against HCV antigens was significantly associated with a sustained virologic response to treatment and a higher frequency of positive immune responses against HCV antigens and HIV p24 was observed among patients who had a sustained virologic response than among patients who did not respond to anti-HCV treatment.

Of the 36 patients, only 8 had patterns of persistent immune response to HCV infection and all were infected with HCV genotypes 3 or 4. Only those patients infected with genotype 3 had sustained immune and viral responses with HCV therapy, while none of the patients infected with HCV genotype 1 were sustained immunologic responders and only 1 was a sustained virologic responder.

The authors conclude, "CD4 response against HCV exists in patients coinfected with HCV and HIV. Notably, few CD4 responses were maintained or amplified during treatment in our study. Persistent immune response was significantly associated with a sustained virologic response. The few patients who displayed concomitant sustained virologic and immune responses were all infected with genotype 3 virus.

This suggests that HCV genotype may influence the specific immune response, which in turn is implicated in viral control. Alternatively, genotype 3 may be more sensitive to effects of IFN, and suppression of viral replication may enhance immune responses, as has been reported for hepatitis B virus infection."

08/14/02

High-dose IFN induction best for HCV genotype one
J Hepatology 2002; 37: 124–130

Induction interferon (IFN) therapy followed by a combination of IFN plus ribavirin offers the best chance of sustained response in patients chronically infected with Hepatitis C Virus genotype one, a study suggests.

Recognizing that the majority of genotype one patients do not respond to IFN plus ribavirin combination therapy, a team led by Hugo Rosen (Oregon Health and Science University, Portland) conducted a prospective induction trial with 28 infected patients.

The subjects were randomized to a daily or twice-daily high dose of IFN for six weeks, followed by 42 weeks of standard IFN therapy (three million units, three times a week), and ribavirin.

Sixteen patients continued in the study after showing a two-log drop in HCV RNA levels by week 12, with all but one testing HCV RNA-negative at week 48. Fourteen patients remained negative at 72 weeks.

However, the researchers say that both of the African-American patients registered with the trial failed to respond to therapy, with differences evident during the induction phase.

'This randomized study of induction IFN therapy followed by combination IFN plus ribavirin yielded the highest rate of sustained response (50%) reported to date in chronically HCV-infected patients with genotype one,' Rosen et al write in the Journal of Hepatology.

Noting the study's best correlate of response was the infected cell loss rate, they conclude its predictive value should be 'evaluated prospectively in larger studies, particularly in patients receiving pegylated IFN'.