The neglected hepatitis C virus genotypes 4, 5 and 6: an international consensus report

IL28B polymorphism is associated with treatment response in patients with genotype 4 chronic hepatitis C

BACKGROUND & AIMS

Polymorphisms in the region of the interleukin (IL)28B gene have been associated with pegylated-interferon (PEG-IFN) and ribavirin treatment response mainly in genotype 1 HCV infections. However, there are few data on HCV genotype 4 (HCV-4) infection. We evaluated, in a unique well-characterized cohort of HCV-4 patients, the association of IL28B polymorphism with response to treatment or liver disease severity.

METHODS

This study included 164 HCV-4 patients from different ethnic groups (Egyptian, European, and Sub-Saharan African). Among these patients, 82 were studied for response and 160 for disease severity. Free DNA extracted from all the 164 patient's serum samples was analyzed by direct sequencing of the SNP rs12979860 of IL28B. Genetic and bio-clinical features from patients having sustained virological response (43 SVR patients) and from those who did not respond to treatment or had a relapse after the end of the treatment (39 NR patients) were compared. IL28B polymorphism was compared between the 78 patients with mild fibrosis (Metavir score F0-F1) and the 82 with advanced fibrosis (F2-F4).

RESULTS

Our data showed a better treatment response rate of the C allele of the IL28B gene SNP rs12979860 (p=0.0008). The response rates were 81.8%, 46.5%, and 29.4% for genotype CC, CT, and TT, respectively. No significant relationship was found between rs12979860 and the severity of the disease.

CONCLUSIONS

The SNP rs12979860 is strongly associated with SVR in patients infected with HCV-4, but not with liver disease severity. Analysis of IL28B genotype might be used to guide treatment for these patients.

ARF1 and GBF1 generate a PI4P-enriched environment supportive of hepatitis C virus replication

Cellular levels of phosphatidylinositol 4-phosphate (PI4P) have been shown to be upregulated during RNA replication of several viruses, including the HCV replicon model. However, whether PI4P is required in an infectious HCV model remains unknown. Moreover, it is not established whether the host transport machinery is sequestered by the generation of PI4P during HCV infection. Here we found that PI4P was enriched in HCV replication complexes when Huh7.5.1 cells were infected with JFH1. HCV replication was inhibited upon overexpression of the PI4P phosphatase Sac1. The PI4P kinase PI4KIIIβ was also found to be required for HCV replication. Moreover, the vesicular transport proteins ARF1 and GBF1 colocalized with PI4KIIIβ and were both required for HCV replication. During authentic HCV infection, PI4P plays an integral role in virus replication.

Interleukin-28B gene polymorphisms: a new beginning of personalized treatment of hepatitis C

It is well known that genetic diversity of individual hosts plays a significant role in the treatment of patients with chronic hepatitis C. From August 2009 to January 2010, four independent genome-wide association studies (GWAS) around the world have demonstrated that interleukin-28B (IL28B) gene polymorphisms are associated with antiviral treatment response to pegylated interferon and ribavirin combination therapy (PEG-IFN/RBV). Two single nucleotide polymorphisms (SNPs), rs8099917 and rs12979860, in the IL28B gene are most strongly associated with sustained virological response (SVR). This review aims to describe the association of IL28B genotypes with treatment response, natural clearance of HCV, molecular epidemiology of HCV infection and some drug side effects. Current observations give us a hint that the era of personalized therapy based on IL28B genotypes may come in the near future.

Antiviral therapy: why does it fail in HCV-related chronic hepatitis?

HCV infection is a very common cause of chronic viral hepatitis. It is a worldwide health problem with approximately 170 million persons infected and areas of high endemicity in which the percentage of the population infected reaches 30%. It is a progressive disease that can lead to complications such as severe liver fibrosis and cirrhosis, ascites, esophageal varices, gastrointestinal bleeding and, in 30-50% of patients with cirrhosis, hepatocellular carcinoma. Extrahepatic pathologies such as mixed cryoglobulinemia, non-Hodgkin lymphoma and membrano-proliferative glomerulonephritis have been associated with HCV infection. Effective treatment exists, and is based on IFN-α. Sustained disappearance of the virus (sustained virological response) radically changes the natural history of chronic hepatitis C, with reduced or no disease progression and complications. Interferon-based treatment has improved over the years owing to the association with ribavirin and subsequently with 'pegylation' of interferon molecules. The present standard of care results in a response rate of up to 80% in some subpopulations. Nevertheless, some patients do not respond to this therapy. Several factors predicting nonresponse to interferon therapy have been investigated since it became available. These factors include the characteristics of the virus and of the subject infected, and the therapy used. The aim of this article is to provide an overview of these factors, and insights into the newly recognized causes of nonresponse to help clinicians select the most appropriate therapy for HCV viral hepatitis.

Differential efficacy of protease inhibitors against HCV genotypes 2a, 3a, 5a, and 6a NS3/4A protease recombinant viruses

BACKGROUND & AIMS

The hepatitis C virus (HCV) genotype influences efficacy of interferon (IFN)-based therapy. HCV protease inhibitors are being licensed for treatment of genotype 1 infection. Because there are limited or no data on efficacy against HCV genotypes 2-7, we aimed at developing recombinant infectious cell culture systems expressing genotype-specific nonstructural (NS) protein 3 protease (NS3P).

METHODS

Viability of J6/JFH1-based recombinants with genotypes 1-7 NS3P/NS4A was evaluated in Huh7.5 human hepatoma cells. Adaptive mutations were identified in reverse genetic studies. Efficacy of lead compound linear protease inhibitors VX-950 (telaprevir) and SCH503034 (boceprevir) and macrocyclic inhibitors TMC435350, ITMN-191 (danoprevir), and MK-7009 (vaniprevir) was determined in high-throughput infection assays.

RESULTS

For genotype(isolate) 2a(J6), 3a(S52), 5a(SA13), and 6a(HK6a), we developed culture systems producing supernatant infectivity titers of 3.5-4.0 log₁₀ focus forming units/mL. Against 2a(J6), 5a(SA13), and 6a(HK6a), all inhibitors showed similar efficacy; macrocyclic inhibitors had ~10-fold greater potency than linear inhibitors. However, compared with 2a recombinant J6/JFH1, efficacy against 3a(S52) was 16- to 70-fold lower for macrocyclic inhibitors and 2- to 7-fold lower for linear inhibitors. Testing of additional genotype 2a and 3a isolates showed that these differences were genotype specific. The resistance of 3a isolates was similar to J6/JFH1 with engineered resistance mutations originally observed for genotype 1 patients. In contrast, we found similar efficacy of NS5A inhibitor BMS-790052 and interferon-alfa2.

CONCLUSIONS

Novel HCV culture systems with genotype specific NS3P/NS4A revealed similar efficacy of protease inhibitors against genotypes 2a, 5a, and 6a and comparatively low but varying efficacy against genotype 3a isolates. These systems will facilitate genotype-specific studies of HCV protease inhibitors and of viral resistance.

Hepatitis C virus genotypes in clinical specimens tested at a national reference testing laboratory in the United States

Hepatitis C virus (HCV) genotype (GT) distribution and frequency were studied among 22,407 unique specimens tested at a national reference testing laboratory. Subjects with HCV GT 3 were younger (P < 0.0001) than those with GT 1, 2, or 4, and the regional frequencies of HCV GT 2 and 3 ranged from 19.9% to 29.2%.

'Easy to treat' genotypes were not created equal: can rapid virological response (RVR) level the playing field?

Genotypes 2 and 3 (G2/G3) of hepatitis C virus have been lumped together as 'easy to treat'. As a result, guidelines recommend 24 weeks of peginterferon/ribavirin for both. However, a closer look at trials shows that these genotypes are not the same, with G2 infection proving more responsive to peginterferon. The data supporting this conclusion are presented along with possible explanations for the differences observed. Ultimately, decisions must be made about therapy. Rapid virological response (RVR) may be the best parameter predicting successful antiviral therapy. For patients with G2 infection who achieve an RVR, shortened courses of therapy are effective. In contrast, for G3 patients without an RVR, there may be benefit to extending therapy to 48 weeks; however, this requires confirmation in prospective studies. Using RVR to guide therapy may level the playing field between these 'easy to treat' genotypes.

Twenty-four weeks of pegylated interferon plus ribavirin effectively treat patients with HCV genotype 6a

The optimal duration of treatment and expected response rate for hepatitis C virus genotype (HCV-6)-infected patients have not been determined. Our aims were to determine the treatment outcome with pegylated interferon (PEG-IFN) plus ribavirin for HCV-6a-infected patients at Southwest Hospital and assess the association of the on-treatment virological response with the sustained virological response (SVR). Medical records were reviewed retrospectively. Twenty-two HCV-6a-infected patients were treated for 24 weeks, and 21 (95.5%) achieved an early virological response (EVR), 20 (90.9%) an end-of-treatment response (ETR) and 18 (81.8%) a SVR. However, only 18 of the 22 HCV-6a-infected patients were tested for serum HCV RNA level at week 4 of treatment and 15 (83.3%) achieved a rapid virological response (RVR). The rates of SVR, RVR, EVR and ETR in these patients were all similar to those in HCV-2/3 treated for 24 weeks and higher than those in HCV-1b-infected patients treated for 48 weeks. A lower relapse rate (10.0%) was seen in HCV-6a compared with HCV-2/3 (12.5%) or HCV-1b-infected patients (23.3%). The positive predictive values of RVR and EVR for HCV-6a were comparable with those for HCV-2/3-infected patients (86.7%vs 90.9%, P = 0.683 and 85.7%vs 86.8%, P = 0.904, respectively). Of the 3 HCV-6a-infected patients who did not achieve a RVR, 2 achieved an EVR and went on to achieve a SVR. The patient who did not achieve an EVR did not achieve a SVR. In summary, our results indicate that 24 weeks of PEG-IFN plus ribavirin can effectively treat patients with HCV-6a chronic infection.

Development and application of hepatitis C reporter viruses with genotype 1 to 7 core-nonstructural protein 2 (NS2) expressing fluorescent proteins or luciferase in modified JFH1 NS5A

To facilitate genotype-specific high-throughput studies of hepatitis C virus (HCV), we have developed reporter viruses using JFH1-based recombinants expressing core-nonstructural protein 2 (NS2) of genotype 1 to 7 prototype isolates. We introduced enhanced green fluorescent protein (EGFP) into NS5A domain III of the genotype 2a virus J6/JFH1 [2a(J6)]. During Huh7.5 cell culture adaptation, 2a(J6)-EGFP acquired a 40-amino-acid (aa) (Δ40) or 25-aa (Δ25) deletion in NS5A domain II, rescuing the impairment of viral assembly caused by the EGFP insertion. Δ40 conferred efficient growth characteristics to 2a(J6) tagged with EGFP, DsRed-Express2, mCherry, or Renilla luciferase (RLuc), yielding peak supernatant infectivity titers of 4 to 5 log(10) focus-forming units (FFU)/ml. 2a(J6) with Δ40 or Δ25 was fully viable in Huh7.5 cells. In human liver chimeric mice, 2a(J6)-EGFPΔ40 acquired various deletions in EGFP, while 2a(J6)Δ40 did not show an impaired viability. We further developed panels of JFH1-based genotype 1 to 7 core-NS2 recombinants expressing EGFP- or RLuc-NS5AΔ40 fusion proteins. In cell culture, the different EGFP recombinants showed growth characteristics comparable to those of the nontagged recombinants, with peak infectivity titers of 4 to 5 log(10) FFU/ml. RLuc recombinants showed slightly less efficient growth characteristics, with peak infectivity titers up to 10-fold lower. Overall, the EGFP and RLuc recombinants were genetically stable after one viral passage. The usefulness of these reporter viruses for high-throughput fluorescence- and luminescence-based studies of HCV-receptor interactions and serum-neutralizing antibodies was demonstrated. Finally, using RLuc viruses, we showed that the genotype-specific core-NS2 sequence did not influence the response to alfa-2b interferon (IFN-alfa-2b) and that genotype 1 to 7 viruses all responded to treatment with p7 ion channel inhibitors.

Management of hepatitis C virus genotype 4: recommendations of an international expert panel

HCV has been classified into no fewer than six major genotypes and a series of subtypes. Each HCV genotype is unique with respect to its nucleotide sequence, geographic distribution, and response to therapy. Genotypes 1, 2, and 3 are common throughout North America and Europe. HCV genotype 4 (HCV-4) is common in the Middle East and in Africa, where it is responsible for more than 80% of HCV infections. It has recently spread to several European countries. HCV-4 is considered a major cause of chronic hepatitis, cirrhosis, hepatocellular carcinoma, and liver transplantation in these regions. Although HCV-4 is the cause of approximately 20% of the 170 million cases of chronic hepatitis C in the world, it has not been the subject of widespread research. Therefore, this document, drafted by a panel of international experts, aimed to review current knowledge on the epidemiology, natural history, clinical, histological features, and treatment of HCV-4 infections.

Hepatitis C virus subtypes circulating among intravenous drug users in Lisbon, Portugal

Hepatitis C virus (HCV) infects 2-3% of the world population and intravenous drug consumption is the leading cause of transmission in industrialized countries. The unavailability of data on the molecular epidemiology of HCV infection in Portugal prompted the study of HCV subtypes circulating among intravenous drug users residing in the Lisbon metropolitan area and sampled about 10 years apart (1998-2000 and 2008-2009). Partial coding sequences for E1 and/or NS5B were obtained from 124 individuals with HCV viremia, both mono-infected and co-infected with HIV. Phylogenetic analysis showed that, for both time periods, the most prevalent subtypes were 1a and 3a, found, altogether, in 64.9% and 71.6% of the individuals, respectively for the first and the second sampling periods. However, genotype 4 viruses (subtypes 4a and 4d), introduced later, as inferred by comparison of intra-subtype genetic distances, were also relatively frequent even one decade ago (24.6%). This HCV subtype profile for Portuguese intravenous drug users is in agreement with those described for other southern European countries when in association with drug consumption. With the exception of subtype 1b, phylogenetic trees did not show clustering of the Portuguese sequences, but rather phylogenetic mixing of HCV sequences from different geographic origins, as described previously in other Western countries and suggestive of a large international transmission network. Consistent with the low recombination rates reported for HCV, only one sample revealed discordant subtypes for the two regions analyzed (4d in E1 and 4a in NS5B), representing a potential new recombinant that deserves further analysis.

A new standard of care for the treatment of chronic HCV infection

The introduction of direct acting antiviral agents (DAAs) will markedly change treatment options for individuals who have a chronic HCV infection. Within the next few months, licensing of two HCV protease inhibitors (boceprevir and telaprevir) for the treatment of patients with chronic hepatitis C as part of a triple therapy with PEG-IFN-α and ribavirin is anticipated in the USA, Europe and many other countries. Final results of pivotal phase III clinical trials in previously untreated and treatment-experienced patients with HCV genotype 1 infection were presented at the Annual Meeting of the American Association for the Study of the Liver 2010 held in Boston, MA, USA, and at the Annual Conference of the Asian Pacific Association for the Study of the Liver 2011, held in Bangkok, Thailand. This article summarizes the results of these phase III trials in consideration of accumulating data on important baseline and on-treatment predictive factors for treatment response, such as the host IL28B genotype and the rapid virologic response; the introduction of these new therapies into clinical practice is also covered. Furthermore, preliminary data on the combination of different classes of DAAs, such as HCV protease inhibitors and HCV polymerase inhibitors, without interferon α are discussed.

Genotype differences in susceptibility and resistance development of hepatitis C virus to protease inhibitors telaprevir (VX-950) and danoprevir (ITMN-191)

Protease inhibitors (PIs) have proven to be effective adjuncts to interferon/ribavirin treatment of hepatitis C virus (HCV) infections. Little clinical or in vitro data exists, however, on their effectiveness for nontype 1 genotypes that predominate in Europe, the Middle East, Africa, and most of Asia. NS3 protease and NS4A genes from genotypes 1-6 were inserted into the JFH clone to generate replication-competent intergenotype chimeras. Susceptibility to PIs was determined by replication and infectivity assays. To study resistance development, chimeras were cultured in subinhibitory concentrations of PIs and mutations phenotypically characterized. Marked differences in susceptibility of different genotypes to danoprevir (ITMN-191) and telaprevir (VX-950) were observed. Genotypes 1, 4, and 6 showed median inhibitory concentration (IC(50) ) values of 2-3 nM, >100-fold lower than genotypes 2/3/5 (250-750 nM). Telaprevir susceptibilities varied over a 4-fold range, with genotypes 1 and 2 being most susceptible and genotypes 4 and 5 most resistant. Culture of genotypes 1-6 in PIs induced numerous mutations in the NS3 protease domain, highly variable between genotypes. Introduction of danoprevir and BILN 2061-induced mutations into the original clones by site-directed mutagenesis (n = 29) all conferred resistant phenotypes, with particularly large increases (1-2 log greater IC(50) values) in the initially susceptible genotypes 1/4/6. Most introduced mutations and showed little or no effect on replicative fitness.

CONCLUSION

Major differences were found between genotypes in their susceptibility and resistance development to PIs. However, equal sensitivities of genotypes 1, 4, and 6 to danoprevir and a broader efficacy range of telaprevir between genotypes than initially conceptualized provide strong evidence that PIs might be effectively used beyond their genotype 1 target group.

Risk perception and priority setting for intervention among hepatitis C virus and environmental risks: a cross-sectional survey in the Cairo community

Background

Hepatitis C virus (HCV) recently emerged as a major public health hazard in Egypt. However, dramatic healthcare budget constraints limit access to the costly treatment. We assessed risk perception and priority setting for intervention among HCV, unsafe water, and outdoor air pollution in Cairo city.

Methods

A survey was conducted in the homes of a representative sample of household heads in Cairo city. Risk perception was assessed using the "psychometric paradigm" where health hazards are evaluated according to several attributes and then summarized by principal component analysis. Priority setting was assessed by individual ranking of interventions reducing health hazards by 50% over five years. The Condorcet method was used to aggregate individual rankings of the three interventions (main study) or two of three interventions (validation study). Explanatory factors of priority setting were explored in multivariate generalized logistic models.

Results

HCV was perceived as having the most severe consequences in terms of illness and out-of-pocket costs, while outdoor air pollution was perceived as the most uncontrollable risk. In the main study (n = 2,603), improved water supply received higher priority than both improved outdoor air quality (60.1%, P < .0001) and screening and treatment of chronic hepatitis C (66.3%, P < .0001), as confirmed in the validation study (n = 1,019). Higher education, report of HCV-related diseases in the household, and perception of HCV as the most severe risk were significantly associated to setting HCV treatment as the first priority.

Conclusions

The Cairo community prefers to further improving water supply as compared to improved outdoor air quality and screening and treatment of chronic hepatitis C.

Genetic history of hepatitis C virus in Venezuela: high diversity and long time of evolution of HCV genotype 2

BACKGROUND

The subtype diversity of the hepatitis C virus (HCV) genotypes is unknown in Venezuela.

METHODOLOGY/PRINCIPAL FINDINGS

Partial sequencing of the NS5B region was performed in 310 isolates circulating in patients from 1995 to 2007. In the samples collected between 2005 and 2007, HCV genotype 1 (G1) was the most common genotype (63%), composed as expected of mainly G1a and G1b. G2 was the second most common genotype (33%), being G2a almost absent and G2j the most frequent subtype. Sequence analysis of the core region confirmed the subtype assignment performed within the NS5b region in 63 isolates. The complete genome sequence of G2j was obtained. G2j has been described in France, Canada and Burkina Fasso, but it was not found in Martinique, where several subtypes of G2 circulate in the general population. Bayesian coalescence analysis indicated a most recent common ancestor (MRCA) of G2j around 1785, before the introduction of G1b (1869) and G1a (1922). While HCV G1a and G1b experienced a growth reduction since 1990, coincident with the time when blood testing was implemented in Venezuela, HCV G2j did not seem to reach growth equilibrium during this period.

CONCLUSIONS/SIGNIFICANCE

Assuming the introduction of G2j from Africa during the slave trade, the high frequency of G2j found in Venezuela could suggest: 1- the introduction of African ethnic groups different from the ones introduced to Martinique or 2- the occurrence of a founder effect. This study represents an in-depth analysis of the subtype diversity of HCV in Venezuela, which is still unexplored in the Americas and deserves further studies.

New antiviral therapies for chronic hepatitis C

Chronic hepatitis C is an important health issue worldwide. The current standard therapy is based on a combination of pegylated-interferon (pegIFN) and ribavirin (RBV), but this treatment leads to only ~50% sustained virological response (SVR) in patients with HCV genotype 1 and high viral loads, who were mostly null-responders or relapsers. Among HCV genotypes other than HCV genotype 1, especially HCV genotype 4 patients show only 40-70% SVR by this treatment. Although new drugs also depend on the combination of pegIFN and RBV, it appears that these drugs improve not only rapid virological response (RVR) but also early virological response, leading to SVR in these patients. In the near future, we predict higher SVR rates in chronic hepatitis C patients treated with these new drugs.