Slow viral dynamics of hepatitis C virus genotype 4

IFN-λ: A New Class of Interferon with Distinct Functions-Implications for Hepatitis C Virus Research

Pegylated interferon-α and ribavirin (PEG-IFN/RBV) is widely used to treat chronic hepatitis C virus infection with notorious adverse reactions since the broad expression of IFN-α receptors on all nucleated cells. Accordingly, a Type III IFN with restricted receptors distribution is much safer as an alternative for HCV therapy. In addition, single nucleotide polymorphisms (SNPs) near the human IFN-λ3 gene, IL-28B, correlate strongly with the ability to achieve a sustained virological response (SVR) to therapy with pegylated IFN-α plus ribavirin in patients infected with chronic hepatitis C. Furthermore, we also discuss the most recent findings: IFN-λ4 predicts treatment outcomes of HCV infection. In consideration of the apparent limitations of current HCV therapy, especially high failure rate and universal side effects, prediction of treatment outcomes prior to the initiation of treatment and developing new alternative drugs are two important goals in HCV research.

IL28B favorable genotype and ultrarapid viral response as the earliest treatment predictors of a sustained viral response in a Georgian cohort infected with the hepatitis C genotype 1

OBJECTIVES

The early identification of factors contributing to the successful treatment of hepatitis C infection is important for researchers and clinicians. Studies carried out on the role of an ultrarapid viral response (URVR) for the prediction of a sustained viral response (SVR) have shown its high positive predictive value (PPV). However, data on the combined effect of URVR with IL28B genotypes for the prediction of SVR are lacking. Our aim was to study the role of URVR and IL28B genotypes in the prediction of SVR among patients in Georgia infected with genotype 1.

METHODS

Of a total of 156 patients enrolled in the study, 143 were included in the final analyses. Viral load testing for monitoring the viral response was carried out at 3, 24, 48, and 72 h and at 1, 2, and 4 weeks after the initiation of treatment. IL28B single nucleotide polymorphisms in rs12979860 were genotyped using real-time PCR methods.

RESULTS

Our study showed that URVR was the earliest treatment predictor among genotype 1 patients harboring the IL28B C/C genotype (PPV-100%). Moreover, the C/C genotype was found to have a high PPV among genotype 1 patients without URVR or a rapid viral response, unlike patients infected with genotype 2 or 3. URVR and IL28B C/C genotypes were not as predictive of an SVR among genotype 2 and 3 patients; however, rapid viral responses were highly predictive of an SVR in these patients.

CONCLUSION

Our results suggest that testing for IL28B genotypes and viral load at weeks 1 and 2 may improve the ability to predict an SVR among hepatitis C virus genotype 1 patients; this information may be useful to ensure patient compliance with treatment.

Prevalence of hepatitis C virus genotypes and impact of T helper cytokines in achieving sustained virological response during combination therapy: a study from Central India

Characterisation of host immune response to hepatitis C virus (HCV) genotypes may have an important prognostic and therapeutic implication. Genotype-3 was more prevalent in the examined cohort and demonstrated a significantly higher response to combination therapy than genotype-1. Sustained virological response (SVR) was 94.74% in genotype-3 and 45.45% in genotype-1. The patients who achieved SVR reported higher levels of circulating T helper 1 cytokines in comparison to subjects with no SVR in both the studied groups. Besides providing local prevalence, our study might also assist in understanding the host immune mechanisms involved to achieve SVR during combination therapy in chronic HCV patients.

HCV antibody response and genotype distribution in different areas and races of China

Hepatitis C virus (HCV) heterogeneity accounts for the failure of effective vaccine development and the lack of successful anti-viral therapy in some patients. Little is known about the immune response to HCV peptides and the region or race specific genotypes in China. The objective of this study was to characterize HCV antibody immune response to HCV peptides and HCV genotypes in different regions and races of China. A total of 363 serum samples were collected from HCV carriers in 6 regions in China. The immune response to HCV peptides was evaluated by ELISA. HCV genotypes were examined using nested RT-PCR. We found that the anti-HCV antibody neutralization rates were significantly different among the serum samples from different areas or from different races in the same area. For samples from Tibet and Sinkiang, the rates of neutralization by HCV peptides were only 3.2% and 30.8%, respectively. The genotypes of samples from Tibet and Sinkiang were apparently heterogeneic and included type I, II, III and multiple types (I/II/III, I/II, I/III, II/III). One specific sample with multiple-genotype (I/II/III) HCV infection was found to consist of type I, II, III, II/III and an unclassified genotype. These studies indicate that the anti-HCV antibody immune response to HCV peptides varied across regions and among races. The distribution of HCV genotypes among Tibetans in Tibet and Uighurs in Sinkiang was different from that in the inner areas of China. In addition, a "master" genotype, type II, was found to exist in HCV infection with multiple HCV genotypes.

Modelling of viral dynamics in hepatitis B and hepatitis C clinical trials

In the recent years, studies of hepatitis B (HBV) and hepatitis C virus (HCV) dynamics have drawn great attention as they provide insight into the process of virus elimination/production and of infected cells decay during antiviral treatment. Estimates of viral dynamic parameters may be used to determine the lifetime of HCV/HBV virions and of infected cells, to estimate how long patients need to be treated and to evaluate antiviral therapies. The implementation of viral dynamics studies is difficult because they involve an intensive blood-sampling schedule and subsequent viral load quantification. In the majority of these studies, a model proposed by Neumann et al. (Science 1998; 282:103-107) is used under various assumptions, such as ignoring the delay in initial viral load decay, assuming time-constant treatment efficacy in reducing virion production and/or complete blocking of new infections, etc. However, only recently the effect of some of these assumptions on the estimated parameters has been evaluated. In this paper we provide a detailed review of the model, its underlying assumptions as well as the assumptions usually made by researchers during the design and analysis of viral dynamics studies. Then, we investigate the effect of these assumptions on the estimated parameters using simulations and draw useful conclusions concerning the analysis of these studies. Real data examples from a clinical trial on hepatitis B are provided as illustrations.

Serum concentrations of ribavirin and pegylated interferon and viral responses in patients infected with HIV and HCV

The hepatitis C virus (HCV) infects a substantial proportion of patients infected with human immunodeficiency virus (HIV). Patients infected with both HCV and HIV respond poorly to anti-HCV treatment with pegylated interferon alpha and ribavirin. But few data are available on the influence of ribavirin and interferon concentrations on treatment outcome for these patients. This study investigated the relationship between the serum pegylated interferon and ribavirin concentrations 3 and 6 months after treatment initiation, and treatment outcome in 35 HCV-HIV coinfected patients. The pegylated interferon and ribavirin concentrations at months 3 and 6 were similar. The pegylated interferon concentrations at 3 months in responders and nonresponders were similar. However, responders tended to have higher ribavirin concentrations (2,322 ng/ml) than nonresponders (1,833 ng/ml; P = 0.08). Responders infected with HCV genotype 1 or 4 had higher ribavirin concentrations (2,672 ng/ml) than did similarly infected nonresponders (1,758 ng/ml; P = 0.04). ROC curve analysis showed that a ribavirin concentration of 2,300 ng/ml was the best threshold for predicting a nonresponse (ROC area = 0.80 +/- 0.12). Thus ribavirin concentrations influence treatment outcome in HIV patients infected with HCV genotype 1 or 4. Monitoring ribavirin concentrations could help adapt ribavirin concentrations and improve the sustained virological response.

High prevalence of hepatitis C virus infection and predominance of genotype 4 in rural Gabon

Hepatitis C (HCV) molecular epidemiology is documented poorly in central African countries. In response to this, a population-based study of 319 consenting adults resident in a remote village of Gabon was undertaken (mean age: 38 years; age range: 13-85+; sex ratio: 0.74). Screening for anti-HCV antibodies was performed using ELISA and recombinant immunoblot assay. Seropositive samples were assessed further with viral load and genotyping techniques. Sixty-six (20.7%) individuals were HCV seropositive. Viral loads ranged from 600 to 24.9 million IU/ml (median: 372,500). Seroprevalence and viral loads increased significantly with age (P < 10(-5) and P < 0.003, respectively). HCV sequences of the 5'UTR genome region were obtained from 60 (90.9%) samples and NS5B region sequences were obtained from 22 (36.6%) samples. All strains belonged to subtypes of genotype 4: 4e (72.7%), 4c (13.6%), 4p (4.5%), 4r (4.5%) and one unclassified genotype 4 strain. Evolutionary analysis of the subtype 4e sequences indicates a period of raised transmission during the early twentieth century.

Hepatitis C virus prevalence and genetic diversity among pregnant women in Gabon, central Africa

Background

Hepatitis C virus (HCV) infection is a major global public health problem in both developed and developing countries. The prevalence and genetic diversity of HCV in pregnant women in Gabon, central Africa, is not known. We therefore evaluated the prevalence and the circulating genotypes of HCV in a large population cohort of pregnant women.

Methods

Blood samples (947) were collected from pregnant women in the five main cities of the country. The prevalence was evaluated by two ELISA tests, and the circulating genotypes were characterized by sequencing and phylogenetic analysis.

Results

Twenty pregnant women (2.1%) were infected with HCV. The seroprevalence differed significantly by region (p = 0.004) and increased significantly with age (p = 0.05), being 1.3% at 14–20 years, 1.1% at 21–25 years, 1.9% at 26–30 years, 4.1% at 31–35 years and 6.0% at > 35 years. Sequencing in the 5'-UTR and NS5B regions showed that the circulating strains belonged to genotypes 4 (4e and 4c).

Conclusion

We found that the HCV seroprevalence in pregnant women in Gabon is almost as high as that in other African countries and increases with age. Furthermore, only genotype 4 (4e and 4c) was found. More extensive studies aiming to evaluate the prevalence and heterogeneity of HCV genotypes circulating in the general population of the country are needed.

Evaluation of Versant hepatitis C virus genotype assay (LiPA) 2.0

Hepatitis C virus (HCV) genotyping is a tool used to optimize antiviral treatment regimens. The newly developed Versant HCV genotype assay (LiPA) 2.0 uses sequence information from both the 5' untranslated region and the core region, allowing distinction between HCV genotype 1 and subtypes c to l of genotype 6 and between subtypes a and b of genotype 1. HCV-positive samples were genotyped manually using the Versant HCV genotype assay (LiPA) 2.0 system according to the manufacturer's instructions. For the comparison study, Versant HCV genotype assay (LiPA) 1.0 was used. In this study, 99.7% of the samples could be amplified, the genotype of 96.0% of samples could be determined, and the agreement with the reference method was 99.4% when a genotype was determined. The reproducibility study showed no significant differences in performance across sites (P = 0.43) or across lots (P = 0.88). In the comparison study, 13 samples that were uninterpretable or incorrectly genotyped with Versant HCV genotype assay (LiPA) 1.0 were correctly genotyped by Versant HCV genotype assay (LiPA) 2.0. Versant HCV genotype assay (LiPA) 2.0 is a sensitive, accurate, and reliable assay for HCV genotyping. The inclusion of the core region probes in Versant HCV genotype assay (LiPA) 2.0 results in a genotyping success rate higher than that of the current Versant HCV genotype assay (LiPA) 1.0.

Clinical and pathological characteristics and response to combination therapy of genotype 4 chronic hepatitis C patients: experience from a spanish center

This observational study evaluated the characteristics of genotype 4 chronic hepatitis C (CHC) patients and their response to combination therapy in Spain. 383 patients with CHC, 44 with genotype 4-HCV infection, were investigated. Nineteen genotype 4-HCV infected patients received IFNalpha-2b (3 MU three times weekly) plus ribavirin (1-1.2 g/day) and ten received Peg-IFNalpha-2b (1.5 microg/kg/week) plus ribavirin (1-1.2 g/day) for 12 months. A sustained virological response (SVR) was evaluated. Genotype 4-HCV was detected in 11.5% of patients, and was significantly associated with a higher proportion of infection through intravenous drug use (46% vs 11%; p<0.001), a higher alcohol intake (35% vs. 7%; p<0.001), higher proportion of anti-HBc positivity (41% vs. 22%; p<0.05), lower ALT (87+/-50 vs. 139+/-142 IU/L; p<0.001) and AST (53+/-30 vs. 85+/-126 IU/L; p<0.001) levels, lower viremia (4.1 +/- 7.7 (x 10(5)) vs . 7.3 +/- 9.8 IU(x 10(5) )/mL) p<0.05) and less fibrosis (stage 3-4 in 21% vs. 32%; p<0.06). Sixteen (55%) out of the 29 patients treated with combination therapy achieved a sustained virological response (SVR) while 10 (36%) were non-responders and 3 (9% relapsed. In conclusion, the lower stage of fibrosis, lower viremia and higher SVR rate than genotype 1 suggest a less aggressive pattern of diseased caused by this genotype.

Differences in viral kinetics between genotypes 1 and 3 of hepatitis C virus and between cirrhotic and non-cirrhotic patients during antiviral therapy

AIM: To evaluate the impact of hepatitis C virus (HCV) infection with genotype 1 or 3 and the presence or absence of liver cirrhosis (LC) in the early viral kinetics response to treatment.

METHODS: Naive patients (n = 46) treated with interferon-α (IFN-α) and ribavirin and followed up with frequent early HCV-RNA determinations were analysed. Patients were infected with genotype 1 (n = 28, 7 with LC) or 3 (n = 18, 5 with LC).

RESULTS: The first phase decline was larger in genotype 3 patients than in genotype 1 patients (1.72 vs 0.95 log IU/mL, P < 0.001). The second phase slope decline was also larger in genotype 3 patients than in genotype 1 patients (0.87 vs 0.15 log/wk, P < 0.001). Differences were found in both cirrhotic and non-cirrhotic patients. Genotype 1 cirrhotic patients had a slower 2^nd phase slope than non-cirrhotic patients (0.06 vs 0.18 log/wk, P < 0.02). None of genotype 1 cirrhotic patients had a 1^st phase decline larger than 1 log (non-cirrhotic patients: 55%, P < 0.02). A similar trend toward a slower 2^nd phase slope was observed in genotype 3 cirrhotic patients but the 1^st phase slope decline was not different. Sustained viral response was higher in genotype 3 patients than in genotype 1 patients (72% vs 14%, P < 0.001) and in genotype 1 non-cirrhotic patients than in genotype 1 cirrhotic patients (19% vs 0%). A second phase decline slower than 0.3 log/wk was predictive of non-response in all groups.

CONCLUSION: Genotype 3 has faster early viral decline than genotype 1. Cirrhosis correlates with a slower 2^nd phase decline and possibly with a lower 1^st phase slope decline in genotype 1 patients.

Review article: predicting response in hepatitis C virus therapy

The introduction of combination therapy with ribavirin and of pegylated interferons has improved treatment results in patients with chronic hepatitis C. However, overall rates of sustained virologic response following antiviral therapy of chronic hepatitis C still do not exceed 54-63%. Because of several virus- and patient-related factors, treatment is even less successful in some patient subpopulations. The major viral factors associated with impaired response are hepatitis C virus genotype 1 infection and a high viral load. Among patient-related factors cirrhosis is of special importance. Baseline predictive factors for sustained virologic response become less important for prediction of treatment outcome when quantifications of hepatitis C virus RNA during early therapy are taken into account. This article provides a summary of virus- and patient-related parameters, which are prognostic for response to antiviral therapy in chronic hepatitis C and focuses on the prediction of treatment response by quantification of hepatitis C virus RNA concentration during therapy.

The kinetics of hepatitis C virus

The kinetics of hepatitis C virus (HCV) RNA during the first weeks of interferon-based antiviral therapy can be analysed by specific mathematical models. Those models have been inspired by previous work on the kinetics of human immune deficiency virus (HIV) and hepatitis B virus (HBV) during antiviral therapy and are able to summarize important features of early response to antiviral therapy in patients chronically infected with HCV. Kinetic parameters of the underlying biological processes as viral clearance and infected cell loss as well as an efficiency factor of therapy on viral production can be obtained when fitting frequent quantifications of HCV RNA with such models. The main aims of analysing hepatitis C viral kinetics include the efficient comparison of different treatment regimens, prediction of virological response, and conclusions on antiviral mechanisms of therapy.

Kinetics of hepatitis C virus RNA load during pegylated interferon alpha-2a and ribavirin treatment in naïve genotype 1 patients

Background

Pegylated interferon given for 24 or 48 weeks constitutes the most effective initial therapy for the treatment of chronic hepatitis C. It has been shown that viral load at week 2 appears the best time for predicting response to treatment. The objectives of this study were to assess whether the hepatitis C virus (HCV) RNA viral decline is predictive of sustained virological response (SVR) and to determine the best time for predicting complete response in our cohort of naïve patients treated with pegylated interferon alpha-2a (Peg-IFN alpha-2a) and ribavirin.

Results

Twenty patients treated with Peg-IFN alpha-2a and ribavirin for 48 weeks were studied. Six months after the end of treatment, a SVR (negative HCV RNA measured by PCR six months after the end of therapy) was obtained in 9 patients. Samples were obtained before and at week 2, 4, 8, and 12. At the end of week 2, viral load decreased more than 1.39 log in 8 out of the 9 patients with SVR and in 1 out of the 11 other patients. When we considered the viral load reduction from baseline to each week of treatment, week 2 appeared to be the best point time for predicting SVR, with a sensitivity of 91% (95%CI: 59;99), a specificity of 89% (52;98), a positive predictive value of 91% (59;99) and a negative predictive value of 89% (57;98).

Conclusion

During treatment with Peg-IFN alpha-2a plus ribavirin in genotype 1 patients, when the main objective of the treatment is viral eradication, viral kinetics showed that week 2 appeared to be the best time point for predicting SVR. Our results must be further confirmed on a larger cohort.

Response of hepatitis C genotype-4 naïve patients to 24 weeks of Peg-interferon-alpha2b/ribavirin or induction-dose interferon-alpha2b/ribavirin/amantadine: a non-randomized controlled study

BACKGROUND AND AIM

Currently, pegylated interferon is the most effective therapy for hepatitis C but its cost is out of reach of most patients in the developing countries. The aim of this study was to assess the response rate of genotype-4 patients to 24 wks of peg-interferon-alpha2b (Peg-IFN-alpha2b) and ribavirin (RBV) or interferon-alpha2b (IFN-alpha2b) with RBV and amantadine (AMD) as an alternative option.

METHODS

In a controlled study, 180 biopsy-proven naïve chronic hepatitis C patients were allocated into three groups based on their financial affordability to any of the study regimens. Group I (control) comprised 40 patients who received Peg-IFN-alpha2b in a flat dose of 100 mug/wk (the dose available in Egypt) plus RBV 1,000-1,200 mg per day based on body weight for 48 wks. Group II comprised 70 patients who received the same regimen for 24 wks. Group III comprised 70 patients who received induction-dose triple therapy (IDTT) in the form of IFN-alpha2b 3 MU once daily for the first 4 wks then reduced to TIW for 20 wks plus RBV 1,000-1,200 mg per day based on body weight and AMD 100 mg twice daily for 24 wks. Six patients from group I, eight patients from group II, and four from group III discontinued the study either due to financial limitations and/or intolerable adverse effects of the drugs.

RESULTS

Intention-to-treat analysis revealed that sustained virological response (SVR) achieved in 22 (55.0%), 34 (48.6%), and 20 (28.6%) in groups I, II, and III, respectively. Adherence-to-treatment analysis (80/80/80) revealed that SVR achieved in 22 (64.7%), 34 (54.8%), and 20 (30.3%) in groups I, II, and III, respectively. In absence of eradication of hepatitis-C-virus-RNA at week 12, there was virtually no chance of achieving SVR. These data collectively may indicate that genotype 4 is "not difficult to treat" as previously reported.

CONCLUSION

Response of genotype-4 patients to 24 wks of Peg-IFN-alpha2b/RBV did not significantly differ from 48 wks, but was significantly higher than IDTT. Although SVR achieved by IDTT is less than Peg-IFN-alpha, yet it might provide a second option when the latter is not affordable. Early virological response should be used as a predictor to SVR to avoid unnecessary expenses in nonresponders patients.

Pegylated interferon and ribavirin therapy for chronic hepatitis C virus genotype 4 infection

Hepatitis C Virus (HCV) is classified into six genotypes. Genotype 4 is now spreading in Europe, especially among drug users, who are often infected with both HCV and the human immunodeficiency virus (HIV). Previous studies have shown that HCV-4 responds poorly to interferon. Pegylated interferon (peg-IFN) associated with ribavirin is now the most effective treatment for eradicating the virus. We have now studied the response of HCV-4 to peg-IFN and ribavirin and investigated the influence of HIV infection on anti-HCV therapy. Twenty-eight patients infected with HCV-4 were given peg-IFN plus ribavirin for 48 weeks. Patients infected with HCV alone tended to have a better initial response (66%) than patients infected with both HCV and HIV (30%, P = 0.06) and eradication was better (50%) than in doubly infected patients (15%, P = 0.06). After controlling for major factors influencing virus response, the virus response 12 weeks after the beginning of treatment in patients infected with HCV-4 (50%) was similar to that of patients infected with genotype 1 (53%) and lower than that of patients infected with genotypes 2 or 3 (82%, P < 0.05). The response 24 weeks after the end of therapy in patients infected with HCV-4 (32%) was similar to that of patients infected with HCV-1 (28%) and lower than that of patients with HCV-2 or HCV-3 (62% P < 0.05). These results indicate that HCV-4 patients should be considered to be difficult-to-treat.

Role of viral kinetics under HCV therapy in HIV/HCV-coinfected patients

Patients coinfected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) are less responsive to anti-HCV therapies and are at a higher risk of toxicity than HCV monoinfected patients. HCV viral kinetics is the basis for the study of response to interferon-based therapy and for predicting sustained virological response (SVR). A lack of early virological response (EVR; undetectable HCV RNA or a decrease of >/=2 log(10) from baseline) after 12 weeks of pegylated interferon (peg-IFN) plus ribavirin (RBV) is an equally reliable predictor of lack of SVR in HIV/HCV-coinfected patients and in the monoinfected HCV population. Early stopping rules are particularly important in coinfected HIV/HCV patients, considering their low chances of response in the more difficult-to-treat HCV genotypes 1 and 4 (<30%). Several factors have been involved in this low efficacy, including higher baseline HCV viraemia, slower viral kinetics decay under interferon pressure and a defective immune substratum. A better understanding of HCV viral kinetics under HCV therapy may be the basis for assaying different peg-IFN plus RBV schedules, such as induction or extending strategies, and may help physicians to make tailored decisions for the management of their patients.

Response to Interferon-Based Therapies in HIV-Infected Patients with Chronic Hepatitis C Due to Genotype 4

Background

The hepatitis C virus (HCV) genotype is the main predictor of response to interferon (IFN)-based therapies. HCV genotype 4 is spreading among European intravenous drug users, who are frequently coinfected with HIV. Information about treatment response in this subset of patients is scarce and conflicting results have been reported.

Methods

All HIV-infected patients treated for chronic hepatitis C at our institution with a minimum follow-up of 6 months after discontinuing therapy were retrospectively analysed. They had received one of three HCV treatment modalities: IFN monotherapy, IFN plus ribavirin (RBV) or pegylated interferon (PEG-IFN) plus RBV. Treatment responses were stratified according to HCV genotype.

Results

A total of 390 patients were analysed. Sustained virological response (SVR) to HCV therapy had been reached by 90 (23.1%): 22/119 (18.5%) with IFN monotherapy; 17/106 (16%) with IFN plus RBV; and 51/165 (30.9%) with PEG-IFN plus RBV. SVR was significantly higher among those with HCV genotypes 2 or 3 (40.4%; 61/151) than in patients with either HCV genotype 1 (11.2%; 22/197) or HCV genotype 4 (16.7%; 7/42) ( P<0.0001). In contrast, there were no significant differences in the response rate comparing HCV genotypes 1 and 4 ( P=0.53).

Conclusions

Response to IFN-based therapies in HIV-positive patients with hepatitis C due to HCV genotype 4 is poor, similar to that obtained for HCV genotype 1 and much lower than for HCV genotypes 2 and 3. Therefore, HIV-infected patients with hepatitis C due to genotype 4 should be considered as a particular subset of difficult-to-treat patients. New treatment strategies and drugs for these patients are eagerly awaited.

Persistence of hepatitis C virus in a white population: Associations with human leukocyte antigen class 1

The aim of this study was to define novel associations between human leukocyte antigen (HLA) class 1 alleles and persistence or clearance of the hepatitis C virus (HCV) in a white population. All individuals in the study were seropositive for anti-HCV antibodies. Viral status was determined by the Roche HCV Amplicor test. HLA-A, -B, -C allelic group profile was molecularly defined by reverse line probe hybridization. The strongest individual allelic group associations with persistent HCV infection were HLA A*11 (p = 0.044) and Cw*04 (p = 0.006). However, only the HLA C*04 association survived correction for multiple comparisons. Further analysis of alleles in linkage with HLA Cw*04 revealed that the haplotype HLA A*11, Cw*04 was present in 11 individuals, 10 of whom were viremic (p = 0.05). No gene dosage effect was observed. No association between HLA class 1 allelic groups and aviremia and virus load was evident in this white population. HLA B*44 is associated with low virus load in human immunodeficiency virus disease, but this association was not evident in this HCV-infected population. Novel HLA class 1 alleles associated with persistence of HCV have been identified.