HCV genetic variability: from quasispecies evolution to genotype classification

'Unusual' HCV genotype subtypes: origin, distribution, sensitivity to direct-acting antiviral drugs and behaviour on antiviral treatment and retreatment

The high genetic diversity of hepatitis C virus (HCV) has led to the emergence of eight genotypes and a large number of subtypes in limited geographical areas. Currently approved pangenotypic DAA regimens have been designed and developed to be effective against the most common subtypes (1a, 1b, 2a, 2b, 2c, 3a, 4a, 5a and 6a). However, large populations living in Africa and Asia, or who have migrated from these regions to industrialised countries, are infected with 'unusual', non-epidemic HCV subtypes, including some that are inherently resistant to currently available direct-acting antiviral (DAA) drugs due to the presence of natural polymorphisms at resistance-associated substitution positions. In this review article, we describe the origin and subsequent global spread of HCV genotypes and subtypes, the current global distribution of common and unusual HCV subtypes, the polymorphisms naturally present in the genome sequences of unusual HCV subtypes that may confer inherently reduced susceptibility to DAA drugs and the available data on the response of unusual HCV subtypes to first-line HCV therapy and retreatment. We conclude that the problem of unusual HCV subtypes that are inherently resistant to DAAs and its threat to the global efforts to eliminate viral hepatitis are largely underestimated and warrant vigorous action.

Risk Factors Associated with Hepatitis C Subtypes and the Evolutionary History of Subtype 1a in Mexico

The Hepatitis C Virus (HCV), with its diverse genotypes and subtypes, has significantly impacted the health of millions of people worldwide. Analyzing the risk factors is essential to understanding the spread of the disease and developing appropriate prevention strategies. This study aimed to identify risk factors associated with HCV subtype transmission and calculate the emergence time of subtype 1a in Mexico. A cross-sectional study was conducted from January 2014 to December 2018, involving 260 HCV-infected adults. HCV infection was confirmed via Enzyme-Linked Immunosorbent Assay, and viral load was measured by real-time PCR. Genotyping/subtyping tools were the Line Probe Assay and Sanger sequencing of the non-structural region 5B (NS5B). The most frequent HCV subtype was 1a (58.5%), followed by subtypes 1b (19.2%), 3a (13.1%), 2b (5.4%), 2a/2c (2.7%), 2a (0.8%), and 4a (0.4%). Intravenous drug use and tattoos were significant risk factors for subtypes 1a and 3a, while hemodialysis and blood transfusion were linked with subtype 1b. For the evolutionary analysis, 73 high-quality DNA sequences of the HCV subtype 1a NS5B region were used, employing a Bayesian coalescent analysis approach. This analysis suggested that subtype 1a was introduced to Mexico in 1976, followed by a diversification event in the mid-1980s. An exponential increase in cases was observed from 1998 to 2006, stabilizing by 2014. In conclusion, this study found that HCV subtypes follow distinct transmission routes, emphasizing the need for targeted prevention strategies. Additionally, the findings provide valuable insights into the origin of HCV subtype 1a. By analyzing the history, risk factors, and dynamics of the HCV epidemic, we have identified these measures: limiting the harm of intravenous drug trafficking, enhancing medical training and infrastructure, and ensuring universal access to antiviral treatments. The successful implementation of these strategies could lead to an HCV-free future in Mexico.

Mechanisms and Consequences of Genetic Variation in Hepatitis C Virus (HCV)

Chronic infection with hepatitis C virus (HCV) is an important contributor to the global incidence of liver diseases, including liver cirrhosis and hepatocellular carcinoma. Although common for single-stranded RNA viruses, HCV displays a remarkable high level of genetic diversity, produced primarily by the error-prone viral polymerase and host immune pressure. The high genetic heterogeneity of HCV has led to the evolution of several distinct genotypes and subtypes, with important consequences for pathogenesis, and clinical outcomes. Genetic variability constitutes an evasion mechanism against immune suppression, allowing the virus to evolve epitope escape mutants that avoid immune recognition. Thus, heterogeneity and variability of the HCV genome represent a great hindrance for the development of vaccines against HCV. In addition, the high genetic plasticity of HCV allows the virus to rapidly develop antiviral resistance mutations, leading to treatment failure and potentially representing a major hindrance for the cure of chronic HCV patients. In this chapter, we will present the central role that genetic diversity has in the viral life cycle and epidemiology of HCV. Incorporation errors and recombination, both the result of HCV polymerase activity, represent the main mechanisms of HCV evolution. The molecular details of both mechanisms have been only partially clarified and will be presented in the following sections. Finally, we will discuss the major consequences of HCV genetic diversity, namely its capacity to rapidly evolve antiviral and immunological escape variants that represent an important limitation for clearance of acute HCV, for treatment of chronic hepatitis C and for broadly protective vaccines.

Detection, quantification and genotype distribution of HCV patients in Lahore, Pakistan by real-time PCR

BACKGROUND

Hepatitis C virus (HCV) is considered as "Viral Time Bomb" suggested by the World Health Organization and if it is not treated timely, it will lead towards cirrhosis and hepatocellular carcinoma (HCC).

OBJECTIVE

The purpose of the present research is to study possible risk factors, frequent genotypes of HCV and its association with different age groups.

METHODS

Suspected blood samples from HCV patients were collected from different hospitals of Lahore, Pakistan. Out of 1000 HCV suspected samples, 920 samples were found HCV positive detected by Anti-HCV ELISA, CobasR. kit. The quantification of HCV load was determined by HCV quantification kit and LINEAR ARRAY KIT (Roche) was used for genotype determination by Real-Time PCR (ABI). Statistical analysis was done by using Microsoft Excel.

RESULTS

Out of 920 subjects, 77 subjects (8.4%) were false positive and they were not detected by nested PCR. Three PCR positive samples were untypeable. Genotype 3 was predominant in Lahore which was 83.5%, whereas type 1 and 2 were 5.1% and 0.7% respectively. There were also mixed genotypes detected, 1 and 3 were 0.4%, 2 and 3 were 1.41% and 3 and 4 were 0.2% only. Male were more infected of HCV in the age <40 years and females >40years.

CONCLUSION

The major risk factor for HCV transmission is by use of unsterilized razors/blades. It is necessary to spread awareness among the general population of Pakistan about HCV transmission risk factors. Regular physical examination at least once a year is recommended, so that early detection of HCV could be done.

Hepatitis C virus (HCV) genotype 1 NS5A resistance-associated variants are associated with advanced liver fibrosis independently of HCV-transmission clusters

OBJECTIVES

The aim of the study was to characterize the differences in the frequencies of NS3 and NS5A resistance-associated variants (RAVs) among Polish therapy-naive genotype 1 (G1) hepatitis C virus (HCV)-monoinfected and human immunodeficiency virus (HIV)/HCV-coinfected patients including clustering patterns and association of RAV frequency with liver fibrosis.

METHODS

NS3/NS5A RAVs were identified by population sequencing in 387 directly acting antiviral treatment-naive G1-infected individuals (54 with genotype 1a (G1a) and 333 with genotype 1b (G1b)). Liver fibrosis was assessed based on histopathology or ultrasound elastography. Phylogenetic clusters were identified using maximum likelihood models. For statistics, chi-squared or two-sided Fisher's exact tests and multivariate logistic regression models were used, as appropriate.

RESULTS

NS3 RAVs were found in 33.33% (18/54) for G1a and 2.62% (8/297) for G1b whereas NS5A variants were present in 5.55% (3/54) G1a and 9.31% (31/333) G1b sequences. Variations in NS5A 31 and 93 codon positions were found only in G1b (4.2% (14/333) for L31I/F/M and 5.39% (17/333) for Y93H). NS5A RAVs were more frequent among patients with advanced liver fibrosis (17.17% (17/99) for F3-F4 versus 6.94% (17/245) for F0-F2; p 0.004) or liver cirrhosis (20.34% (12/59) for F4 versus 7.72% (22/285) for F0-F3; p 0.003). Liver cirrhosis (F4) was associated with higher odds ratio of the NS5A RAVs among HCV-infected patients (odds ratio 2.34, 95% CI 1.004-5.291; p 0.049). NS5A RAVs were less frequent among sequences forming clusters and pairs (5.16% (8/155) versus 11.21% (26/232); p 0.039).

CONCLUSIONS

Presence of NS5A RAVs correlated with progression of liver fibrosis and represents de novo selection of variants rather than transmission of drug resistance. Hence, the presence of NS5A RAVs may be a predictor for a long-lasting HCV infection.

Prevalence of hepatitis-C virus genotypes and potential transmission risks in Malakand Khyber Pakhtunkhwa, Pakistan

Background

Hepatitis C virus (HCV) is a leading cause of chronic liver disease and frequently progresses towards liver cirrhosis and Hepatocellular Carcinoma (HCC). This study aimed to determine the prevalence of HCV genotypes and their association with possible transmission risks in the general population of Malakand Division.

Methodology

Sum of 570 serum samples were collected during March 2011 to January 2012 from suspected patients visited to different hospitals of Malakand. The suspected sera were tested using qualitative PCR and were then subjected to molecular genotype specific assay. Quantitative PCR was also performed for determination of pre-treatment viral load in confirmed positive patients.

Results

Out of 570 serum samples 316 sera were seen positive while 254 sera were found negative using qualitative PCR. The positive samples were then subjected to genotyping assay out of 316, type-specific PCR fragments were seen in 271 sera while 45 samples were found untypable genotypes. Genotype 3a was seen as a predominant genotype (63.3%) with a standard error of ±2.7%. Cramer’s V statistic and Liklihood-Ratio statistical procedures are used to measure the strength and to test the association, respectively, between the dependent variable, genotype, and explanatory variables (e.g. gender, risk, age and area/districts). The dependent variable, genotype, is observed statistically significant association with variable risk factors. This implies that the genotype is highly dependent on how the patient was infected. In contrast, the other covariates, for example, gender, age, and district (area) no statistical significant association are observed. The association between gender-age indicates that the mean age of female was older by 10.5 ± 2.3 years with 95% confidence level using t-statistic.

Conclusion

It was concluded from the present study that the predominant genotype was 3a in the infected population of Malakand. This study also highlights the high prevalence rate of untypable genotypes which an important issue of health care setup in Malakand and create complications in therapy of infected patients. Major mode of HCV transmission is multiple uses and re-uses of needles/injections.

Trial registration

ISRCTN ISRCTN73824458. Registered: 28 September 2014

Hepatitis C virus in vitro replication is efficiently inhibited by acridone Fac4

Hepatitis C virus (HCV) affects about 170 million people worldwide. The current treatment has a high cost and variable response rates according to the virus genotype. Acridones, a group of compounds extracted from natural sources, showed potential antiviral actions against HCV. Thus, this study aimed to evaluate the effect of a panel of 14 synthetic acridones on the HCV life cycle. The compounds were screened using an Huh7.5 cell line stably harbouring the HCV genotype 2a subgenomic replicon SGR-Feo-JFH-1. Cells were incubated in the presence or absence of compounds for 72 h and cell viability and replication levels were assessed by MTT and luciferase assays, respectively. At a concentration of 5 µM the acridone Fac4 exhibited a >90 % inhibition of HCV replication with no effect on cell viability. The effects of Fac4 on virus replication, entry and release steps were evaluated in Huh7.5 cells infected with the JFH-1 isolate of HCV (HCVcc). Fac4 inhibited JFH-1 replication to approximately 70 %, while no effect was observed on virus entry. The antiviral activity of Fac4 was also observed on viral release, with almost 80 % of inhibition. No inhibitory effect was observed against genotype 3 replication. Fac4 was able to intercalate into dsRNA, however did not inhibit NS5B polymerase activity or translation driven by the HCV IRES. Although its mode of action is partly understood, Fac4 presents significant inhibition of HCV replication and can therefore be considered as a candidate for the development of a future anti-HCV treatment.

Design, Construction and Evaluation of 1a/JFH1 HCV Chimera by Replacing the Intergenotypic Variable Region

BACKGROUND

The E2 glycoprotein is an important encoded hepatitis C virus (HCV) protein that contains three different variable regions.

OBJECTIVES

The aim of the present study was to construct an HCV 1a/JFH1 chimeric virus by replacing the intergenotypic variable region (igVR) fragment of the highly variable region of the E2 gene of the Japanese Fulminant hepatitis genotype 2a JFH1 virus with a similar region of HCV genotype 1a. This chimera was produced as a model virus with the ability to be cultured. We analyzed the adapted virus and the variations of nucleic acids within it.

METHODS

Specific primers were designed for the igVR of HCV genotype 1a followed by the overlap-PCR method for the synthesis of the desired DNA fragment. The amplified igVR-1a chimera gene and pFL-J6/JFH were digested by KpnI and BsiWI restriction enzymes, and the fragment was ligated into pFL-J6/JFH. The recombinant vector was transformed into Escherichia coli JM109 strain competent cells. All clones were confirmed by colony PCR using specific primers, and the confirmed recombinant vector was sequenced. The recombinant vector was targeted for RNA synthesis by T7 RNA polymerase enzyme. RNA transfection was performed in the Huh7.5 cell line. Virus production in several passages and the evaluated viral load were studied using quantitative real-time PCR and ELISA methods. After 30 passages, the RNA virus was extracted and cloned in PCDNA3.1 vector, and was then sequenced.

RESULTS

Quantitative real-time PCR results showed 11,292,514 copies/mL of chimeric virus production in cell culture. The virus production was confirmed using ELISA, which showed a virus core production of 808.2 pg/mL. The results of cloning and sequencing showed that some of the nucleic acids in the chimera virus were changed, affecting the viral behavior in the cell culture.

CONCLUSIONS

Real-time PCR and ELISA showed high levels of production of 1a/JFH1 chimeric HCV in the Huh7.5 cell culture. The constructed virus can be used for future studies, including the development of new HCV drugs and vaccines.

Hepatitis C virus: Promising discoveries and new treatments

Despite advances in therapy, hepatitis C virus (HCV) infection remains an important global health issue. It is estimated that a significant part of the world population is chronically infected with the virus, and many of those affected may develop cirrhosis or liver cancer. The virus shows considerable variability, a characteristic that directly interferes with disease treatment. The response to treatment varies according to HCV genotype and subtype. The continuous generation of variants (quasispecies) allows the virus to escape control by antivirals. Historically, the combination of ribavirin and interferon therapy has represented the only treatment option for the disease. Currently, several new treatment options are emerging and are available to a large part of the affected population. In addition, the search for new substances with antiviral activity against HCV continues, promising future improvements in treatment. Researchers should consider the mutation capacity of the virus and the other variables that affect treatment success.

HCV dsRNA-Activated Macrophages Inhibit HCV Replication in Hepatocytes

BACKGROUND

Macrophages play critical roles in innate immune response in the liver. Whether macrophages participate in liver innate immunity against HCV replication is poorly understood.

OBJECTIVES

The aim of this study was to investigate the role of macrophages in liver innate immunity against HCV replication.

MATERIALS AND METHODS

Freshly isolated monocytes were purified from peripheral blood of healthy adult donors. Macrophages refer to 7-day-cultured monocytes in vitro. A hepatoma cell line (Huh7) was infected with HCV JFH-1 to generate in vitro HCV infectious system. RT-PCR was used to determine HCV RNA and mRNA levels of genes expression. ELISA was used to measure the protein level of interferon-α (IFN-α) and western blot was used to determine protein expression level of Toll-like receptor 3 (TLR3).

RESULTS

HCV dsRNA induced the expression of type I IFN (IFN-α/β) in monocyte-derived macrophages. HCV dsRNA also induced the expression of TLR3 and IFN regulatory factor-7 (IRF-7), the key regulators of the IFN signaling pathway. When HCV JFH-1-infected Huh7 cells were co-cultured with macrophages activated with HCV dsRNA or incubated in media conditioned with supernatant (SN) from HCV dsRNA-activated macrophages, HCV replication was significantly suppressed. This macrophage SN action on HCV inhibition was mediated through type I IFN, which was evidenced by the observation that antibody to type I IFN receptor could neutralize the macrophages-mediated anti-HCV effect. The role of type I IFN in macrophages-mediated anti-HCV activity is further supported by the observation that HCV dsRNA-activated macrophages SN treatment induced the expression of several IFN-stimulated genes (ISGs), ISG15, ISG56, OAS-1, OAS-2, MxA and Viperin in HCV-infected Huh7 cells.

CONCLUSIONS

Macrophages may play an important role in liver innate immunity against HCV replication through a type I IFN-dependent mechanism.

Hepatitis C virus genetic variability and evolution

Hepatitis C virus (HCV) has infected over 170 million people worldwide and creates a huge disease burden due to chronic, progressive liver disease. HCV is a single-stranded, positive sense, RNA virus, member of the Flaviviridae family. The high error rate of RNA-dependent RNA polymerase and the pressure exerted by the host immune system, has driven the evolution of HCV into 7 different genotypes and more than 67 subtypes. HCV evolves by means of different mechanisms of genetic variation. On the one hand, its high mutation rates generate the production of a large number of different but closely related viral variants during infection, usually referred to as a quasispecies. The great quasispecies variability of HCV has also therapeutic implications since the continuous generation and selection of resistant or fitter variants within the quasispecies spectrum might allow viruses to escape control by antiviral drugs. On the other hand HCV exploits recombination to ensure its survival. This enormous viral diversity together with some host factors has made it difficult to control viral dispersal. Current treatment options involve pegylated interferon-α and ribavirin as dual therapy or in combination with a direct-acting antiviral drug, depending on the country. Despite all the efforts put into antiviral therapy studies, eradication of the virus or the development of a preventive vaccine has been unsuccessful so far. This review focuses on current available data reported to date on the genetic mechanisms driving the molecular evolution of HCV populations and its relation with the antiviral therapies designed to control HCV infection.

The inhibitory effects of anacardic acid on hepatitis C virus life cycle

Hepatitis C virus (HCV) is a small positive-sense single-stranded RNA virus that causes severe liver diseases. Current anti-HCV therapies involving direct-acting antivirals have significantly enhanced efficacy in comparison to traditional interferon and ribavirin combination. However, further improvement is needed to eradicate HCV. Anacardic acid (AnA) is a phytochemical compound that can inhibit the activity of various cellular enzymes including histone acetyltransferases (HATs). In this study, we investigated the effects of AnA on different phases of HCV life cycle. Our data showed that AnA can inhibit HCV entry, replication, translation, and virion secretion in a dose-dependent manner with no measurable effects on cell viability. In addition, we showed that two HAT inhibitors and knocking down HAT (PCAF) by RNAi can reduce HCV replication, suggesting a mechanism of AnA’s inhibitory effects on HCV. Elucidation of the AnA-mediated inhibitory mechanism should facilitate the development of new drug candidates for HCV infection.

IFNL3 (IL28B) and IFNL4 polymorphisms are associated with treatment response in Thai patients infected with HCV genotype 1, but not with genotypes 3 and 6

Recent studies have shown an association between single nucleotide polymorphisms (SNPs) in the interferon lambda-3 (IFNL3 or IL-28B) and IFNL4 genes and treatment response to hepatitis C virus genotype 1 (HCV-1) infection. The importance of these SNPs for HCV genotype 3 (HCV-3), and particularly HCV genotype 6 (HCV-6), remains to be elucidated. We analyzed a cohort of 225 Thai individuals with chronic HCV infection treated with pegylated-interferon and ribavirin, of whom 69 (30.7%), 114 (50.7%) and 42 (18.6%) patients were infected with HCV-1, HCV-3, and HCV-6, respectively. DNA extracted from blood samples was analyzed for the SNPs rs12979860 and ss469415590. The distribution of CC, CT, and TT genotypes of rs12979860 was 189 (84%), 28 (12.4%) and 8 (3.6%), respectively, while the distribution of TT/TT, ΔG/TT, and ΔG/ΔG genotypes of ss469415590 was 192(85.3%), 28(12.5%), and 5(2.2%), respectively. Significantly lower frequencies of the favorable genotypes CC (for rs12979860) and TT/TT (for ss469415590) were found in the HCV-1 group in comparison with the other groups. The favorable genotypes were associated significantly with rapid and sustained virological response in the HCV-1 group. However, they were only associated with rapid virological response in the HCV-3 and HCV-6 groups. Furthermore, both SNPs were associated equally with the treatment outcome in the HCV-1 group. In contrast, the role of these SNPs in predicting treatment response was attenuated in the HCV-3 and HCV-6 groups. Thus, identification of these SNPs may be useful only in patients with refractory HCV-1 infection.

HCV E2 core structures and mAbs: something is still missing

The lack of structural information on hepatitis C virus (HCV) surface proteins has so far hampered the development of effective vaccines. Recently, two crystallographic structures have described the core portion (E2c) of E2 surface glycoprotein, the primary mediator of HCV entry. Despite the importance of these studies, the E2 overall structure is still unknown and, most importantly, several biochemical and functional studies are in disagreement with E2c structures. Here, the main literature will be discussed and an alternative disulfide bridge pattern will be proposed, based on unpublished human monoclonal antibody reactivity. A modeling strategy aiming at recapitulating the available structural and functional studies of E2 will also be proposed.

Early viral kinetics during hepatitis C virus genotype 6 treatment according to IL28B polymorphisms

AIM

To investigate the early viral kinetics and interleukin-28B (IL28B) polymorphisms of hepatitis C genotype 6 during pegylated interferon and ribavirin therapy.

METHODS

Sixty-five patients with chronic hepatitis C virus (HCV) infection treated with pegylated interferon and ribavirin (PEG-IFN/RBV) were included, of whom 15 (23.1%), 16 (24.6%) and 34 (52.3%) patients were infected with hepatitis C genotype 1 (HCV-1), genotype 3 (HCV-3) and genotype 6 (HCV-6), respectively. Serum HCV-RNA levels were measured frequently during the first 4-wk of therapy. DNA extracted from samples was analyzed for the IL28B single nucleotide polymorphism (SNP) rs12979860 by polymerase chain reaction and direct sequencing.

RESULTS

During the first 4-wk of therapy, the mean viral decline for patients with HCV-6 (5.55 ± 1.82 log₁₀IU/mL) was comparable to that of patients with HCV-3 (5.55 ± 1.82 log₁₀IU/mL vs 5.86 ± 1.02 log₁₀IU/mL, P = 0.44) and was significantly higher than patients with HCV-1 (5.55 ± 1.82 log₁₀IU/mL vs 4.23 ± 1.99 log₁₀IU/mL, P = 0.04). In the HCV-6 group, the first phase (days 0-2) viral decline was significantly higher in patients with the favorable rs12979860 CC than non-CC genotypes (2.46 ± 1.01 log₁₀IU/mL/wk vs 1.70 ± 0.67 log₁₀IU/mL, respectively, P = 0.045). A statistically insignificant decrease in the second-phase (days 7-28) decline was also found in patients with the CC genotype than those with the non-CC genotype, though not significantly different (1.24 ± 0.64 log₁₀IU/mL/wk vs 0.80 ± 0.65 log₁₀IU/mL/wk, respectively, P = 0.172). At baseline, the SNP genotype was an independent predictor of rapid virological response but not of sustained virological response.

CONCLUSION

The IL28B genotype was linked to an impact on early viral kinetics in response to PEG-IFN/RBV therapy in HCV-6 infected patients.

Comparison of quasispecies diversity of HCV between chronic hepatitis c and hepatocellular carcinoma by Ultradeep pyrosequencing

Backgrounds. Hepatitis C virus (HCV) exists as population of closely related genetic variants known as quasispecies. HCV quasispecies diversity is strongly influenced by host immune pressure on virus. Quasispecies diversity is expected to decline as host immune response to HCV decreases over natural course of progressing from chronic hepatitis C (CHC) to hepatocellular carcinoma (HCC). Methods. Ultradeep pyrosequencing (UDPS) was used to evaluate degree of quasispecies diversity in 49 patients infected with HCV including 26 with CHC and 23 with HCC. Whole structural protein of HCV genome was subjected to UDPS. Results. Shannon's indices for quasispecies diversity in HCV E1 were significantly lower in patients with HCC than in those with CHC. 14 amino acid positions differed significantly between two groups. Area under curve of ROC analysis for differentiating HCC from CHC was >0.8 for all of 14 amino acid positions. Conclusion. HCV quasispecies diversity as indicator of declining host immune functions was easily assessed by UDPS technology. Shannon's indices in 14 amino acid positions were found to differentiate between patients with CHC and those with HCC. Our data propose that degree of HCV quasispecies measured by UDPS might be useful to predict progression of HCC in chronic HCV patients.

Prevalence and associated clinical characteristics of hepatitis B, C, and HIV infections among injecting drug users in Korea

Injecting drug use is associated with an increased risk of blood-borne viral infections, such as hepatitis B and C viruses (HBV and HCV, respectively) and human immunodeficiency virus (HIV). However, their prevalence, virological characteristics, and associated factors are not clear among the injecting drug users in Korea. The aim of this study was to determine the prevalence of HBV, HCV, and HIV infection, as well as their virological and clinical characteristics of injecting drug users in South Korea. Between 2007 and 2010, 318 injecting drug users (89.3% male; mean ± age 41.9 ± 8.15 years) were participated. While HIV infection was not found, the seroprevalence of anti-HCV and HBV surface antigen (HBsAg) was 48.4% (n = 154) and 6.6% (n = 21), respectively. HBV/HCV co-infection was found in 4.1% (n = 13). Occult HBV infection was suggested in 5.0% (n = 16). Among the HCV genotypes, 1b (37.7%) and 2a/2c (35.7%) were mostly often detected. HCV RNA was detected in 98.1% (n = 151/154) and high-level viremia (HCV RNA level, ≥400,000 IU/ml) were observed in 59.6% (n = 90/151). In multiple logistic regression analysis, old age (OR 1.18 per year, 95% CI = 1.09-1.27) and ever-sharing injecting equipment (OR 4.17, 95% CI = 1.39-12.45) independently predicted HCV mono-infection. The prevalence of HBV and HCV infection were high but largely undiagnosed in the present sample of Korean injecting drug users. Strategic prevention, screening, and treatment are needed to reduce further transmission and morbidity.

MicroRNAs, hepatitis C virus, and HCV/HIV-1 co-infection: new insights in pathogenesis and therapy

MicroRNAs (miRNAs) can exert a profound effect on Hepatitis C virus (HCV) replication. The interaction of HCV with the highly liver-enriched miRNA, miR-122 represents one such unique example of viruses having evolved mechanism(s) to usurp the host miRNA machinery to support viral life cycle. Furthermore, HCV infection can also trigger changes in the cellular miRNA profile, which may ultimately contribute to the outcome of viral infection. Accumulating knowledge on HCV-host miRNA interactions has ultimately influenced the design of therapeutic interventions against chronic HCV infection. The importance of microRNA modulation in Human Immunodeficiency Virus (HIV-1) replication has been reported, albeit only in the context of HIV-1 mono-infection. The development of HCV infection is dramatically influenced during co-infection with HIV-1. Here, we review the current knowledge on miRNAs in HCV mono-infection. In addition, we discuss the potential role of some miRNAs, identified from the analyses of public data, in HCV/HIV-1 co-infection.

Mutations in different regions of the genome of hepatitis C virus genotype 1b and association with response to interferon therapy

The aim of this study was to investigate the association of mutations in the E2/NS1 [hypervariable regions 1 and 2 (HVR1 and HVR2)] and NS5A regions of the hepatitis C virus (HCV) genome and the effectiveness of interferon (IFN) therapy, and assess whether the degree of heterogeneity of HCV quasispecies predicts response to IFN treatment. Fourteen patients infected with HCV genotype 1b (HCV-1b) who were treated with pegylated IFN-α-2a and ribavirin for 24 weeks, were studied. E2/NS1 and NS5A gene segments were amplified by reverse-transcription polymerase chain reaction. HCV quasispecies heterogeneity in the E2/NS1 region was determined by cloning and sequencing. Mutations in the NS5A region were detected by direct sequencing. The heterogeneity of HCV quasispecies in the HVR1 was significantly greater in the non-responder group than in the responder group, but was not significant for HVR2 or NS5A. The correlation between mutations in IFN sensitivity-determining region (ISDR, NS5A2209-2248) and IFN sensitivity could not be supported. The degree of quasispecies heterogeneity in HVR1, but not in HVR2 and NS5A, may be predictive of response to IFN therapy. An ISDR may not apply to patients infected with HCV-1b.

Molecular study of HCV detection, genotypes and their routes of transmission in North West Frontier Province, Pakistan

OBJECTIVE

To determine hepatitis C virus (HCV) genotypes and explore the associated risk factors in chronic HCV patients.

METHODS

A total of 116 patients with chronic hepatitis C were subjected to polymerase chain reaction (PCR) based detection out of which 112 chronic HCV patients [53 male (47.32%), 59 female (52.68%); mean age (43.76±16.40) years; mean BMI (23.8±3.9) kg] were enrolled in this study. The frequency of 6 HCV genotypes and associated risk factors were evaluated from five districts of North West Frontier Province (NWFP).

RESULTS

Genotype 3 was the most prevalent in 73 samples (65.17%) followed by genotype 1 in 24 (21.42%) and genotype 2 in 13 (11.60%) samples. Genotype 3 had significantly high prevalence (P=0.000 2). The results showed that 48 (42.85%) samples were infected with HCV 3a; 25 (22.32%) with 3b; 14 (12.50%) with 1a; 10 (8.92%) with 1b; 11 (9.82%) with 2a; 2 (1.78%) with 2b; and 2 were untypable. The distribution of HCV genotypes in Mardan, Charsadda, Peshawar, Sawabi and Nowshehra districts was different. Use of unsterile equipment for medication, barbers and previous history of hospitalization were the main risk factors for HCV transmission.

CONCLUSIONS

Genotype 3a and 3b, 1a, 1b and 2a are the common genotypes in NWFP. Genotype 4, 5, and 6 can not be found in a single sample. The level of awareness about various modes of transmission of HCV among the population is found to be very low.

Response-guided therapy for patients with hepatitis C virus genotype 6 infection: a pilot study

The optimal duration of treatment with pegylated interferon (PEG-IFN) plus ribavirin (RBV) in patients with hepatitis C virus (HCV) genotype 6 is unknown. This study was aimed at determining treatment response on the basis of rapid virological response (RVR) of HCV genotype 6 in comparison with genotypes 1 and 3. Sixty-six treatment naïve patients were treated with PEG-IFN-α2a (180 μg/week) plus weight-based RBV (1000-1200 mg/day). Patients with genotype 1 n = 16) and genotype 3 (n = 16) were treated for a fixed duration of 48 and 24 weeks, respectively. Patients with genotype 6 (n = 34) who achieved RVR were treated for 24 weeks (response-guided therapy) and the remaining patients were treated for 48 weeks (standard therapy). The mean baseline HCV RNA levels were not statistically different between groups (6.4 ± 0.8, 6.0 ± 1.0 and 6.5 ± 0.8 Log(10) IU/mL for genotypes 1, 3 and 6, respectively). Patients with genotypes 1, 3 and 6 achieved RVR in 43.8%, 87.5% and 73.5% of cases, respectively. One patient with genotype 1 and 3 with genotype 6 were considered nonresponders and discontinued therapy. Sustained virological response (SVR) was achieved in 62.5%, 81.3% and 76.5% of patients with genotypes 1, 3 and 6, respectively. The SVR rate in patients with genotype 6 who underwent response-guided therapy was 88%. This pilot study suggested that the SVR rate of HCV genotype 6 was at an intermediate level between those of genotypes 3 and 1. Treatment with PEG-IFN plus RBV for 24 weeks may be sufficient for patients with genotype 6 who achieve RVR. Prospective randomized trials are required to evaluate this response-guided strategy in a larger number of patients with genotype 6.

Resistance analysis of the hepatitis C virus NS3 protease inhibitor asunaprevir

Asunaprevir (BMS-650032) is a potent hepatitis C virus (HCV) NS3 protease inhibitor demonstrating efficacy in alfa interferon-sparing, direct-acting antiviral dual-combination regimens (together with the NS5A replication complex inhibitor daclatasvir) in patients chronically infected with HCV genotype 1b. Here, we describe a comprehensive in vitro genotypic and phenotypic analysis of asunaprevir-associated resistance against genotypes 1a and 1b using HCV replicons and patient samples obtained from clinical studies of short-term asunaprevir monotherapy. During genotype 1a resistance selection using HCV replicons, the primary NS3 protease substitutions identified were R155K, D168G, and I170T, which conferred low- to moderate-level asunaprevir resistance (5- to 21-fold) in transient-transfection susceptibility assays. For genotype 1b, a higher level of asunaprevir-associated resistance was observed at the same selection pressures, ranging from 170- to 400-fold relative to the wild-type control. The primary NS3 protease substitutions identified occurred predominantly at amino acid residue D168 (D168A/G/H/V/Y) and were associated with high-level asunaprevir resistance (16- to 280-fold) and impaired replication capacity. In asunaprevir single-ascending-dose and 3-day multiple-ascending-dose studies in HCV genotype 1a- or 1b-infected patients, the predominant pre-existing NS3 baseline polymorphism was NS3-Q80K. This substitution impacted initial virologic response rates in a single-ascending-dose study, but its effects after multiple doses were more ambiguous. Interestingly, for patient NS3 protease sequences containing Q80 and those containing K80, susceptibilities to asunaprevir were comparable when tested in an enzyme assay. No resistance-associated variants emerged in these clinical studies that significantly impacted susceptibility to asunaprevir. Importantly, asunaprevir-resistant replicons remained susceptible to an NS5A replication complex inhibitor, consistent with a role for asunaprevir in combination therapies.

Both innate and adaptive immunity mediate protective immunity against hepatitis C virus infection in chimpanzees

Understanding the immunological correlates associated with protective immunity following hepatitis C virus (HCV) reexposure is a prerequisite for the design of effective HCV vaccines and immunotherapeutics. In this study we performed a comprehensive analysis of innate and adaptive immunity following HCV reexposure of two chimpanzees that had previously recovered from HCV-JFH1 infection. One of the chimpanzees, CH10274, became protected from active viremia by repeated challenges with homologous HCV-JFH1 and developed neutralizing antibodies, but was later infected with high-level viremia by a heterologous challenge with the HCV H77 virus that persisted for more than 1 year. The other chimpanzee, CH10273, was protected from a similar, heterologous H77 challenge without any evidence of neutralizing antibodies. Peripheral HCV-specific T-cell responses were present in both chimpanzees after challenges and, interestingly, the overall magnitude of response was lower in uninfected CH10273, which, however, exhibited a more robust CD8+ T-cell response. CH10273 showed higher hepatic expression of CD8 and CD56 (natural killer) markers than CH10274 did shortly after inoculation with H77. The heightened T-cell response was associated with an enhanced hepatic production of interferons (both type I and II) and interferon-stimulated genes (ISGs) in CH10273. Therefore, protection or clearance of HCV reinfection upon heterologous rechallenge depends on the activation of both intrahepatic innate and cellular immune responses. Furthermore, our results suggest that serum neutralizing antibodies may contribute to early control of viral replication and spread after homologous HCV rechallenges but may not be sufficient for a long-term protective immunity.

CONCLUSION

Our study shows that protective immunity against HCV reinfection is orchestrated by a complex network of innate and adaptive immune responses.

Hepatitis C virus RNA recombination in cell culture

BACKGROUND & AIMS

The Hepatitis C virus (HCV) exhibits large genetic diversity, both on a global scale and at the level of the infected individual. A major underlying mechanism of the observed sequence differences is error-prone virus replication by the viral RNA polymerase NS5B. In addition, based on phylogenetic comparisons of patient-derived HCV sequences, there is evidence of HCV recombination. However, to date little is known about the frequency by which recombination events occur in HCV and under what conditions recombination may become important in HCV evolution. We, therefore, aimed to set up an experimental model system that would allow us to analyze and to characterize recombination events during HCV replication.

METHODS

A neomycin-selectable, HCV replicon-based recombination detection system was established. HCV replicons were mutated within either the neomycin-phosphotransferase gene or the NS5B polymerase. Upon co-transfection of hepatic cells lines, recombination between the mutated sites is necessary to restore the selectable phenotype.

RESULTS

Recombinants were readily detected with frequencies correlating to the distance between the mutations. The recombinant frequency normalized to a crossover range of one nucleotide was around 4 × 10(-8).

CONCLUSIONS

An experimental system to select for HCV recombinants in cell culture was successfully established. It allowed deriving first estimates of recombinant frequencies. Based on these, recombination in HCV seems rare. However, due to the rapid virus turnover and the large number of HCV-infected liver cells in vivo, it is expected that recombination will be of biological importance when strong selection pressures are operative.

Genetic heterogeneity of hepatitis C virus in association with antiviral therapy determined by ultra-deep sequencing

Background and Aims

The hepatitis C virus (HCV) invariably shows wide heterogeneity in infected patients, referred to as a quasispecies population. Massive amounts of genetic information due to the abundance of HCV variants could be an obstacle to evaluate the viral genetic heterogeneity in detail.

Methods

Using a newly developed massive-parallel ultra-deep sequencing technique, we investigated the viral genetic heterogeneity in 27 chronic hepatitis C patients receiving peg-interferon (IFN) α2b plus ribavirin therapy.

Results

Ultra-deep sequencing determined a total of more than 10 million nucleotides of the HCV genome, corresponding to a mean of more than 1000 clones in each specimen, and unveiled extremely high genetic heterogeneity in the genotype 1b HCV population. There was no significant difference in the level of viral complexity between immediate virologic responders and non-responders at baseline (p = 0.39). Immediate virologic responders (n = 8) showed a significant reduction in the genetic complexity spanning all the viral genetic regions at the early phase of IFN administration (p = 0.037). In contrast, non-virologic responders (n = 8) showed no significant changes in the level of viral quasispecies (p = 0.12), indicating that very few viral clones are sensitive to IFN treatment. We also demonstrated that clones resistant to direct-acting antivirals for HCV, such as viral protease and polymerase inhibitors, preexist with various abundances in all 27 treatment-naïve patients, suggesting the risk of the development of drug resistance against these agents.

Conclusion

Use of the ultra-deep sequencing technology revealed massive genetic heterogeneity of HCV, which has important implications regarding the treatment response and outcome of antiviral therapy.

Emerging therapies for hepatitis C virus

IMPORTANCE OF THE FIELD

Currently, 170 million people worldwide are affected by the HCV. Chronic HCV infection is amongst the leading causes of chronic liver disease and its complications such as cirrhosis and hepatocellular carcinoma, making it the most common reason for liver transplantation. The current standard of treatment for HCV is pegylated IFN-α plus ribavirin. This treatment, when administered for the standard duration, allows sustained virological response (SVR) in ∼ 50% of patients infected with HCV and about 40% for HCV genotype 1, the most prevalent form of HCV in the US. SVR rates for populations with co-morbidities (patients with chronic renal disease) and certain ethnic backgrounds (African Americans and Hispanics) are lower. Given the high prevalence and relatively low cure rates of current antiviral therapy, the burden of HCV is enormous.

AREAS COVERED IN THIS REVIEW

Faced with this urgent and growing medical need, research into novel therapeutic compounds for the treatment of HCV is a rapidly growing industry. Several novel compounds are in advanced stages of clinical development, such as HCV protease inhibitors (particularly those against NS3-4A protease), HCV polymerase inhibitors (including both nucleoside and non-nucleoside analogs) and cyclophilin inhibitors.

WHAT THE READER WILL GAIN

HCV treatment has seen many advances in the last decade and the discovery process has been fraught with both successes and disappointments. Through a process of rigorous research, the current late stage novel HCV therapeutics seem to have overcome some of the obstacles met by their early predecessors and offer the promise of meeting the shortfalls of the current standard of treatment.

TAKE HOME MESSAGE

Data from clinical trials are encouraging and suggest that combination therapies of these novel agents may have the potential to shorten treatment duration and increase viral clearance when used in conjunction with pegylated IFN-α and ribavirin.