Survey of type 6 group variants of hepatitis C virus in Southeast Asia by using a core-based genotyping assay

Comparison of diagnostic performance among Abbott RealTime HCV Genotyping II, Abbott HCV Genotype plus RUO, and Roche Cobas HCV Genotyping assays for hepatitis C virus genotyping

Comparison of diagnostic accuracy for commercial hepatitis C virus (HCV) genotyping (Abbott RealTime HCV Genotyping II, Roche Cobas Genotyping) and investigational Abbott HCV Genotype plus RUO assays designed to discriminate genotype (GT)-1a, 1b or 6 in cases of ambiguous GT from the Abbott commercial assay remains limited. 743 HCV-viremic samples were subjected to analysis using Abbott and Roche commercial as well as Abbott HCV Genotype plus RUO assays. Next-generation sequencing (NGS) targeting core region was employed as the reference standard. Diagnostic accuracy was reported as the number of participants (percentages) along with 95% confidence intervals (CIs). Using NGS, 741 samples (99.7%) yielded valid genotyping results. The diagnostic accuracies were 97.6% (95% CI: 96.1%-98.5%) and 95.3% (95% CI: 93.4%-96.6%) using Abbott and Roche commercial assays (p = 0.0174). Abbott commercial assay accurately diagnosed HCV GT-6a and 6w, whereas Roche commercial assay accurately diagnosed HCV GT-6a. Both assays demonstrated low accuracies for HCV GT-6b, 6e, 6g, and 6n. Abbott HCV Genotype plus RUO assay discriminated 13 of the 14 samples (92.9%; 95% CI: 64.2%-99.6%) that yielded ambiguous GT. Both assays were capable of diagnosing mixed HCV infections when the minor genotype comprised >8.4% of the viral load. The diagnostic performance of commercial HCV genotyping assays is commendable. Abbott assay demonstrated superior performance compared to Roche assay in diagnosing HCV GT-6. Abbott HCV Genotype plus RUO assay aids in discriminating ambiguous GT. Both commercial assays are proficient in diagnosing mixed HCV infections at a cut-off viral load of 8.4% in minor genotype.

Epidemiology, clinical, and laboratory profile of patients with hepatitis C: A prospective, observational study from north-eastern India

Low and middle-income countries (LMICs) contribute to 80% of the global hepatitis C virus (HCV) infection burden. Intravenous drug use (IVDU) is not uncommon in Northeastern India, thus contributing to HCV. Its epidemiology, clinical, and laboratory profile were studied in a tertiary care centre in northeastern India.HCV patients (age >18) of either sex were prospectively assessed for demographic, virological, and genotype distributions. Most were male (M: F, 5.8:1) with a mean age of 37.1 ± 11.8 years. The most common risk factor was IVDU(77.69%), followed by concomitant alcohol use in 69.2%. Besides genotype 3 (59.2%), genotype 1 (26.1%) and genotype 6 were also common (14.6%). The demographics, liver disease severity, and biochemical parameters were similar across genotypes.

Challenges to Differentiate Hepatitis C Genotype 1 and 6: Results from A Field-Study in Cambodia

INTRODUCTION

We aim to report on results and challenges of different methods used for hepatitis C (HCV) genotyping in a Cambodian HCV/HIV coinfection project.

METHODS

Samples of 106 patients were available. HCV genotyping was initially (63 samples) done by the LightPower Taqman real-time PCR method (Viet A Corp.) and quality controlled using the Versant 2.0 line probe assay (Siemens Healthcare). Next, following interim quality control results, all 106 samples were (re)genotyped with Versant 2.0, complemented with 5'UTR/core sequencing for uninterpretable/incomplete Versant results.

RESULTS

Using Versant, 103 (97.2%) of the 106 HCV-coinfected patients had an interpretable genotype result: 1b (50.5%), 6 non-a/non-b (30.1%), 1a (6.8%), 6a or b (4.9%), 2 (3.9%), 1 (2.9%) and 3 (1.0%). For 16 samples that were interpreted as genotype 1 or 1b per Versant's current instructions, it could not be excluded that it concerned a genotype 6 infection as the core region line patterns on the Versant test strip were unavailable, inconclusive or atypical. Upon sequencing, seven of these were genotyped as 1b and nine as genotype 6. Combining Versant and sequencing results, a definitive genotype was assigned in 104 patients: 1b (44.2%), 6 non-a/non-b (39.4%), 1a (6.7%), 6a or b (4.8%), 2 (3.8%) and 3 (1.0%). Genotyping by LightPower and Versant was discordant for 23 (of 63) samples. The LightPower assay misclassified all genotype 6 non-a/non-b samples as genotype 1, which indicates that this assay is only using 5'UTR information.

CONCLUSIONS

HCV genotype 1b and genotype 6 non-a/non-b were most common. With Versant 2.0 (using 5'UTR and core information), genotype classification (1 or 6) remained inconclusive in 15% of samples. The locally available method (LightPower assay) failed to identify genotype 6 non-a/non-b, which highlights that methods using 5'UTR information only should not be used in Cambodia. Regional/national guidelines should be explicit about this.

TRIAL REGISTRATION

This study was performed as part of a larger cross-sectional study on the burden of hepatitis C coinfection in HIV patients in Cambodia (Clinical.trials.gov: HCV-Epi NCT02361541).

Dissection of two drug-targeted regions of Hepatitis C virus subtype 4a infecting Egyptian patients

Recently, treatment of HCV infection has been improved after the development of direct acting antivirals (DAAs) which target different viral proteins (NS3-4A, NS5A and NS5B). The activity and effectiveness of these DAAs are affected by the presence of resistance associated substitutions (RASs). This study aimed to characterize HCV genotypes circulating among Egyptian HCV patients, to dissect the full sequences of HCV NS3-4A and NS5B regions, and to characterize RASs associated with NS3-4A and NS5B inhibitors in HCV treatment-naïve patients. Genotyping of 80 HCV samples from treatment-naïve patients was done using restriction fragment length polymorphism and phylogenetic analysis based on some full NS5B sequences. Results showed the prevalence of HCV subtype 4a. Twenty four new full sequences of NS3-4A and NS5B regions of subtype 4a were deposited in the GenBank database. In general, the substitutions associated with NS3-4A-targeting drugs were absent predicting possible responsiveness of Egyptian HCV patients to these drugs. In addition, the absence of amino acid substitutions associated with resistance to Sofosbuvir may predict good response to treatment with Sofosbuvir. Some amino acid substitutions associated with resistance to different classes of non-nucleoside inhibitors were detected. Further investigations on treated Egyptian HCV patients may evaluate the effectiveness of the massively used drugs. Many predicted T-cell-binding epitopes in NS3-4A and NS5B regions were found to be highly conserved in the currently studied isolates; a finding that might be important for HCV vaccine development. We demonstrated potential NS3 epitopes that could be used in engineering T cells against HCV epitopes.

Efficacy and safety of direct-acting antiviral therapy for chronic hepatitis C genotype 6: A meta-analysis

BACKGROUND

Because of the heterogeneity of hepatitis C virus (HCV) distribution of different genotypes, large-scale clinical trials on direct-acting antiviral (DAA) mainly included patients with genotype 1 and genotype 3 infection. Data on the efficacy of direct-acting antiviral agents in patients with chronic genotype 6 HCV infection are limited.

METHODS

The PubMed, Embase, and the Cochrane Libraries were searched comprehensively. All published clinical trials assessing the efficacy of DAA therapy for patients with chronic genotype 6 HCV infection were included. Sustained virological response (SVR) and rapid virological response (RVR) were pooled. Additional meta-analyses were also performed to compare the efficacy of DAA therapy in HCV-6 versus HCV-1 or HCV-3 patients.

RESULTS

Seventeen studies met the inclusion criteria and were included in our meta-analysis. The pooled SVR of all single arms was 95% [95% confidence interval (CI): 0.90-0.97]. The pooled RVR of all single arms was 97% (95% CI: 0.95-0.99). The SVR and RVR were both similar between HCV-6 and HCV-1 or HCV-3. Adverse events were common but rarely caused treatment interruption.

CONCLUSION

Based on the available data, our results indicate that DAA treatment is effective and safe for patients with genotype 6 HCV infection, and the efficacy was similar compared to patients with genotype 1 HCV or genotype 3 HCV infection.

Systematic review: epidemiology and response to direct-acting antiviral therapy in genotype 6 chronic hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) genotype 6 (GT6) is predominantly encountered in Southeast Asia and data on GT6 response to direct-acting antiviral (DAA) therapy are relatively limited.

AIM

To review the epidemiology and virologic outcome of DAA regimens in HCV GT6 patients.

METHODS

Electronic literature search of PubMed, EMBASE, and The Cochrane Library databases were conducted.

RESULTS

Hepatitis C virus genotype 6 is the most genetically diverse, has a prevalence of 19.9%-95.6% in HCV infected patients in Southeast Asia and has been associated with a higher risk of HCC in those with cirrhosis. After an extensive literature review, a total of 20 studies were selected to assess study population and treatment outcomes (total of 938 GT6 patients were included); 12 were clinical trials and eight were observational studies. Sustained virologic response at week 12 (SVR 12) following glecaprevir/pibrentasvir (n = 4; 108 patients), ledipasvir/sofosbuvir (n = 8; 427 patients), sofosbuvir/velpatasvir with or without voxilaprevir (n = 5; 171 patients), sofosbuvir/daclatasvir (n = 3; 172 patients) and sofosbuvir with ribavirin (n = 3; 60 patients) was 98%-100%, 64%-100%, 100%, 88%-94% and 100%, respectively. Failure was mostly in those with cirrhosis and prior treatment experience. DAA therapy was well tolerated and with a serious adverse event rate of <5%.

CONCLUSIONS

Hepatitis C virus genotype 6 is genetically diverse and is highly prevalent in Asia. While SVR rates have been high, cirrhosis and prior treatment experience marginally compromise response to DAAs. Large scale and exclusive studies in HCV genotype 6 prevalent areas are needed, while the current evidence suggests that DAAs are highly effective and safe.

Current challenges and possible solutions to improve access to care and treatment for hepatitis C infection in Vietnam: a systematic review

Background

Hepatitis C infection is a major public health concern in low- and middle-income countries where an estimated 71.1 million individuals are living with chronic infection. The World Health Organization (WHO) has recently released new guidance for hepatitis C virus (HCV) treatment programs, which include improving the access to new direct-acting antiviral agents. In Vietnam, a highly populated middle-income country, the seroprevalence of HCV infection is approximately 4% and multiple genotypes co-circulate in the general population. Here we review what is currently known regarding the epidemiology of HCV in Vietnam and outline options for reducing the significant burden of morbidity and mortality in our setting.

Methods

We performed a systematic review of the currently available literature to evaluate what has been achieved to date with efforts to control HCV infection in Vietnam.

Results

This search retrieved few publications specific to Vietnam indicating a significant gap in baseline epidemiological and public health data. Key knowledge gaps identified included an understanding of the prevalence in specific high-risk groups, characterization of circulating HCV genotypes in the population and likely response to treatment, and the extent to which HCV treatment is available, accessed and utilized.

Conclusions

We conclude that there is an urgent need to perform up to date assessments of HCV disease burden in Vietnam, especially in high-risk groups, in whom incidence is high and cross infection with multiple genotypes is likely to be frequent. Coordinating renewed surveillance measures with forthcoming HCV treatment studies should initiate the traction required to achieve the WHO goal of eliminating HCV as a public health threat by 2030, at least in this region.

[Prevalence, risk factors and clinical characteristics in patients with genotype 6 chronic hepatitis C: a single institute experience]

BACKGROUND/AIMS

Hepatitis C genotypes 1 and 2 are widely distributed globally. In contrast, genotype 6 is found mainly in Southeast Asia, while genotype 6 is rare in Korea. This study aims to investigate the prevalence, risk factors and clinical characteristics of patients with genotype 6 chronic hepatitis C.

METHODS

We retrospectively identified 133 HCV-infected patients who underwent HCV genotype analysis between January 2012 and December 2012, and analyzed the prevalence, risk factors and clinical characteristics of patients diagnosed with genotype 6 chronic hepatitis C.

RESULTS

Among 133 patients, 53 patients (39.8%) were infected with genotype 1, 62 patients (46.6%) with genotype 2, 2 patients (1.5%) with genotype 3, 14 patients (10.5%) with genotype 6, and 2 patients (1.5%) with mixed genotypes (genotype 1 and 6). The risk factors associated with genotype 6 were acupuncture (n=4, 28.6%), intravenous drug use (n=3, 21.4%), tattoo (n=2, 14.3%), and transfusion (n=2, 14.3%). Of the 14 patients with genotype 6, 6 patients were treated with pegylated interferon and ribavirin. Five patients had reached the end of treatment. All patients reaching end of treatment for genotype 6 showed early virological response and sustained virological response.

CONCLUSIONS

The prevalence of genotype 6 is 10.5% and mixed infections of genotype 1 and 6 are 1.5% in patients with chronic hepatitis C. A major potential risk factor is intravenous drug use and the treatment response rate to pegylated interferon plus ribavirin is high in patients with genotype 6 chronic hepatitis C. Large scale multicenter studies are needed.

Comparison of Three Different Hepatitis C Virus Genotyping Methods: 5'NCR PCR-RFLP, Core Type-Specific PCR, and NS5b Sequencing in a Tertiary Care Hospital in South India

BACKGROUND

Based on genetic heterogeneity, hepatitis C virus (HCV) is classified into seven major genotypes and 64 subtypes. In spite of the sequence heterogeneity, all genotypes share an identical complement of colinear genes within the large open reading frame. The genetic interrelationships between these genes are consistent among genotypes. Due to this property, complete sequencing of the HCV genome is not required. HCV genotypes along with subtypes are critical for planning antiviral therapy. Certain genotypes are also associated with higher progression to liver cirrhosis.

METHODS

In this study, 100 blood samples were collected from individuals who came for routine HCV genotype identification. These samples were used for the comparison of two different genotyping methods (5'NCR PCR-RFLP and HCV core type-specific PCR) with NS5b sequencing.

RESULTS

Of the 100 samples genotyped using 5'NCR PCR-RFLP and HCV core type-specific PCR, 90% (κ = 0.913, P < 0.00) and 96% (κ = 0.794, P < 0.00) correlated with NS5b sequencing, respectively. Sixty percent and 75% of discordant samples by 5'NCR PCR-RFLP and HCV core type-specific PCR, respectively, belonged to genotype 6. All the HCV genotype 1 subtypes were classified accurately by both the methods.

CONCLUSION

This study shows that the 5'NCR-based PCR-RFLP and the HCV core type-specific PCR-based assays correctly identified HCV genotypes except genotype 6 from this region. Direct sequencing of the HCV core region was able to identify all the genotype 6 from this region and serves as an alternative to NS5b sequencing.

Sequencing Analysis of NS3/4A, NS5A, and NS5B Genes from Patients Infected with Hepatitis C Virus Genotypes 5 and 6

Direct-acting antivirals (DAAs) with activity against multiple genotypes of the hepatitis C virus (HCV) were recently developed and approved for standard-of-care treatment. However, sequencing assays to support HCV genotype 5 and 6 analysis are not widely available. Here, we describe the development of a sequencing assay for the NS3/4A, NS5A, and NS5B genes from HCV genotype 5 and 6 patient isolates. Genotype- and subtype-specific primers were designed to target NS3/4A, NS5A, and NS5B for cDNA synthesis and nested PCR amplification. Amplification was successfully performed for a panel of 32 plasma samples from HCV-infected genotype 5 and 6 patients with sequencing data obtained for all attempted samples. LiPA 2.0 (Versant HCV genotype 2.0) is a reverse hybridization line probe assay that is commonly used for genotyping HCV-infected patients enrolled in clinical studies. Using NS3/4A, NS5A, and NS5B consensus sequences, HCV subtypes were determined that were not available for the initial LiPA 2.0 result for genotype 6 samples. Samples amplified here included the following HCV subtypes: 5a, 6a, 6e, 6f, 6j, 6i, 6l, 6n, 6o, and 6p. The sequencing data generated allowed for the determination of the presence of variants at amino acid positions previously characterized as associated with resistance to DAAs. The simple and robust sequencing assay for genotypes 5 and 6 presented here may lead to a better understanding of HCV genetic diversity and prevalence of resistance-associated variants.

Analysis of HCV-6 isolates among Asian-born immigrants in North America reveals their high genetic diversity and a new subtype

We characterized full-length genomes for 15 HCV-6 isolates, all from Asian immigrants living in North America. Among these isolates, nine were novel variants showing >15% nucleotide differences from their nearest relatives, representing lineages distinct from known subtypes. The other six were classified into subtypes 6c, 6h, 6q, 6r, and 6s. The partial sequences were also determined for five additional HCV-6 isolates, three from the US and two from Canada. The latter two were assigned to new subtype 6xf as they were found to classify with two other isolates for which we recently reported their full-length genomes. We further analyzed partial Core-E1 sequences of 100 HCV-6 isolates sampled in North America, seven from the US and 93 from Canada and all from Asian immigrants except for four from Caucasians. These 100 isolates belonged to 20 assigned subtypes and 16 unclassified lineages showing great genetic diversity and enhanced significance to public health.

An expanded taxonomy of hepatitis C virus genotype 6: Characterization of 22 new full-length viral genomes

We characterized the full-length genomes of 22 hepatitis C virus genotype 6 (HCV-6) isolates: 10 from Vietnam (classified into subtypes 6e, 6h, 6p, 6r, 6s, and 6u), one from China (confirmed as a new subtype 6xd), and 11 from the Lao PDR (representing a new subtype 6xe plus eight novel variants). With these 22 new genomes, HCV-6 now has a diverse and extended taxonomic structure, comprised of 28 assigned subtypes (denoted 6a-6xe) and 27 unassigned lineages, all of which have been represented by full-length genomes. Our phylogenetic analyses also included many partially-sequenced novel variants of HCV-6 from Lao PDR. This revealed that Lao HCV isolates are genetically very diverse and are phylogenetically distributed in multiple lineages within genotype 6. Our results suggest that HCV-6 has been maintained in Laos, a landlocked country, since the common ancestor of genotype 6 and indicates historical dispersal of HCV-6 across Southeast Asia.

•

We characterized 22 full-length genomes of HCV-6.

•

They confirmed two new subtypes 6xd and 6xe plus eight novel variants.

•

We also reanalyzed many partially-sequenced novel HCV-6 variants from Lao PDR.

•

They are phylogenetically distributed across the whole of genotype 6.

•

They indicate historical dispersal of HCV-6 across Southeast Asia.

A novel nested reverse-transcriptase polymerase chain reaction method for rapid hepatitis C virus detection and genotyping

PURPOSE

Rapid and specific detection of viral nucleic acid is increasingly important in the diagnosis of infectious diseases. The objective was to develop a rapid, efficient process of nucleic acid based detection of hepatitis C virus (HCV) infection for its diagnosis and treatment follow-up.

MATERIALS AND METHODS

A two-step nested reverse-transcriptase polymerase chain reaction (RT-PCR) has been standardised on a sample set of 125 individuals from different liver clinics in Kolkata. The method utilises a novel fast nested RT-PCR for HCV detection and genotyping from HCV infected patient plasma with high processivity.

RESULTS

The overall time required from ribonucleic acid (RNA) isolation to nested PCR amplified product detection is reduced to 42% when compared with conventional nested RT-PCR amplification. The method is sensitive as conventional PCR and detected all HCV RNA positive samples. Sequencing, phylogenetic analysis of the PCR amplified product by this method showed concordant genotypes with conventional PCR.

CONCLUSION

Though being a two-step process, this method is fast, cost-efficient, reliable and feasible for regular HCV RNA screening and apt even in resource limited settings. This method could be translated to regular nucleic acid screening for other infectious diseases as regular PCR regimen.

Nine additional complete genome sequences of HCV genotype 6 from Vietnam including new subtypes 6xb and 6xc

We completely sequenced nine HCV-6 variants from Vietnam. They are grouped into six lineages beyond the 24 assigned subtypes, 6a-6xa, and 14 unclassified lineages that have been recently described with full-length genomes. Co-analysis with reference sequences in the NS5B region identified additional 22 such lineages, which made the total taxonomic number of HCV-6 increased to 66 that might be recognized at the subtype level. Because two of these six lineages revealed in this study each had >3 epidemiologically unlinked isolates identified, we proposed to assign them new subtypes 6xb and 6xc in following the eXtended format recently recommended in the expanded HCV nomenclature.

Efficacy and safety of pegylated interferon plus ribavirin therapy for chronic hepatitis C genotype 6: a meta-analysis

Background

Hepatitis C genotype 6 (HCV-6) is prevalent in Southeast Asia. Data on the efficacy of direct-acting antiviral agents in chronic HCV-6 patients is limited and pegylated interferon (Peg-IFN) plus ribavirin (RBV) combination therapy remains standard therapy for those patients.

Aim

Meta-analysis was performed to assess the efficacy and safety of Peg-IFN plus RBV combination therapy for chronic HCV-6 patients.

Methods

Relevant studies were found by database search through Medline, Embase, Web of Science and The Cochrane Library. All published clinical trials assessing the efficacy of Peg-IFN plus RBV combination therapy for chronic HCV-6 patients were included. Sustained virological response rate (SVR) was pooled. We performed additional meta-analyses to compare the SVR outcomes of 24 versus 48 weeks of treatment in four head-to-head trials. Another second meta-analysis was also conducted to compare the efficacy of combination Peg-IFN plus RBV therapy in HCV-6 versus HCV-1 patients.

Results

Thirteen studies met the inclusion criteria. The pooled SVR of all single arms was 75% (95% CI: 0.68–0.81). The SVR of 24 weeks treatment was significantly lower than that at 48 weeks, with a risk difference of −14% (95% CI: −0.25 to −0.02, p = 0.02). However, when restricted to the patients with rapid virological response (RVR), there was no significant effect on SVR between these two treatment groups, with a risk difference of −1% (95% CI: −0.1 to 0.07, p = 0.67). The SVR in HCV-6 patients was significantly higher than that in HCV-1 patients, with a relative risk of 1.35 (95% CI: 1.16–1.57, p<0.001). Side effects were common, but rarely caused treatment discontinuation.

Conclusions

The results of this meta-analysis suggest that Peg-IFN plus RBV is effective and safe for HCV-6 patients. Shortening treatment seems to be feasible in HCV-6 patients with RVR when tolerance to treatment is poor. However, this decision should be made cautiously.

Consensus Statement of HCV Task Force of the Indian National Association for Study of the Liver (INASL). Part II: INASL Recommendations for Management of HCV in India

The estimated prevalence of hepatitis C virus (HCV) infection in India is between 0.5 and 1.5% with hotspots showing much higher prevalence in some areas of northeast India, in some tribal populations and in certain parts of Punjab. Genotype 3 is the most prevalent type of infection. Recent years have seen development of a large number of new molecules that are revolutionizing the treatment of hepatitis C. Some of the new directly acting agents (DAAs) like sofosbuvir have been called game-changers because they offer the prospect of interferon-free regimens for the treatment of HCV infection. These new drugs have not yet been approved in India and their cost and availability is uncertain at present. Till these drugs become available at an affordable cost, the treatment that was standard of care for the whole world before these newer drugs were approved should continue to be recommended. For India, cheaper options, which are as effective as the standard-of-care (SOC) in carefully selected patients, are also explored to bring treatment within reach of poorer patients. It may be prudent to withhold treatment at present for selected patients with genotype 1 or 4 infection and low levels of fibrosis (F1 or F2), and for patients who are non-responders to initial therapy, interferon intolerant, those with decompensated liver disease, and patients in special populations such as stable patients after liver and kidney transplantation, HIV co-infected patients and those with cirrhosis of liver.

Hepatitis C virus genotypes circulating in patients with chronic hepatitis C in Thailand and their responses to combined PEG-IFN and RBV therapy

Different genotypes of hepatitis C virus (HCV) are circulating in different areas of the world. In Thailand, distribution of HCV genotypes has been investigated mostly in the central area while the information in other regions is limited. This study aimed to determine the HCV genotypes circulating in chronic hepatitis C patients in Chiang Mai, Thailand and to investigate the response of different HCV genotypes to pegylated interferon (PEG-IFN) and ribavirin (RBV) treatment. Patients infected chronically with HCV were treated with PEG-IFN/RBV based on the standard regimens for each HCV genotype and followed up the patients until the end of treatment and 6 months afterward. Out of 158 patients, three major HCV genotypes and eight subtypes were identified. Genotype 3 was the most predominant at 54.5%, followed by genotypes 1 (31%) and 6 (14.5%). Among subtypes, 3a was the most prevalent subtype (45%), followed by 1b (18.4%), 1a and 6f (each at 12.6%), 3b (9.5%), and 6a, 6i, 6n (each at 0.63%). Patients with genotype 3 showed higher rate of responding to the treatment at 80.2% compared to genotypes 1 (73.5%) and 6f (65%). Additionally, patients with genotype 6f showed higher rate of relapsing (25%) compared to genotypes 1 and 3 (14.3% and 16.3%, respectively). In conclusion, this study reported multiple HCV genotypes circulated in Thai patients and the response of different HCV genotypes to PEG-IFN/RBV treatment.

Epidemiology and treatment of hepatitis C genotypes 5 and 6

Chronic hepatitis C infection is a major global health problem. The WHO estimates the number of infected people worldwide to be approximately 170 million. The estimated number of hepatitis C virus (HCV)-infected people in Canada is approximately 250,000, with approximately 5000 Canadians newly infected each year. Based on the identification of genomic differences, HCV has been classified into six genotypes; genotype may influence the outcome of antiviral therapy. HCV genotypes 1, 2 and 3 are widely distributed throughout the world and have been the focus of the majority of epidemiological, natural course and treatment studies. Although HCV genotypes 5 and 6 are prevalent in certain geographical areas, they are studied less extensively. HCV genotypes 5 and 6 are uncommon in Canada and account for less than 5% of HCV-infected Canadians. However, immigration and travel can alter the epidemiology of these uncommon genotypes. The present article reviews and summarizes the available data regarding the epidemiology and treatment of HCV genotypes 5 and 6. Genotype 5 is endemic in the northern part of South Africa while genotype 6 is reported primarily in Asia. Available data show that 48 weeks of treatment with a combination of pegylated interferon and ribavirin lead to a higher sustained virological response compared with HCV genotypes 1 and 4. None of the approved direct-acting antiviral agents is currently recommended for the treatment of HCV genotypes 5 or 6.

Review article: the epidemiology and therapy of chronic hepatitis C genotypes 4, 5 and 6

BACKGROUND

The global burden of hepatitis C (HCV) infection is mostly found in Africa, the Middle East and Asia, where HCV genotypes 4, 5 and 6 are common. The literature on these genotypes is sparse and this synopsis will review characteristics of patients infected with these genotypes.

AIM

To review characteristics of patients infected with HCV genotypes 4, 5 and 6.

METHODS

PubMed search for 'hepatitis C' AND 'genotype 4', 'hepatitis C' AND 'genotype 5', and 'hepatitis C' AND 'genotype 6' was conducted and relevant articles were reviewed.

RESULTS

Intravenous drug use is generally responsible for HCV genotype 4 infection in developed countries, but unsafe medical practices cause most cases of HCV genotypes 4, 5 and 6 in endemic countries. The sustained virological response (SVR) rate for patients with HCV genotype 4 who receive pegylated interferon and ribavirin for 48 weeks ranges from 40% to 70% in various small studies. The SVR rate is in the 60-70% range for HCV genotype 5 and 70-80% range for HCV genotype 6 following 48 weeks with pegylated interferon and ribavirin. Preliminary data suggest that a shorter course of 24 weeks of pegylated interferon and ribavirin may be acceptable for HCV genotype 6, with an SVR rate of approximately 70%.

CONCLUSIONS

The current standard-of-care therapy for HCV genotypes 4, 5 and 6 is pegylated interferon and ribavirin for 48 weeks. A shorter course with 24 weeks of therapy may be considered for patients with genotype 6. Newer and much more effective therapies may be forthcoming in the next few years.

The Role of MicroRNA in Hepatitis C Virus Replication

Hepatitis C virus (HCV) infection is a major global health problem. There is no effective vaccine and the current treatment regimen with pegylated interferon α and ribavirin is associated with significant adverse events. Therefore, there is an urgent need to identify new antiviral targets for HCV therapy. In recent years, a growing number of microRNAs (miRNAs) have been reported to be able to regulate HCV replication and infection by interacting with the HCV genome directly or by regulating host innate immunity to build a nonspecific antiviral state within cells. In this review, we discuss HCV virology and standard of care followed by miRNA in general, and then give a brief overview of miRNAs involved in HCV infection and discuss their potential application as a therapeutic option for the treatment of HCV infection.

Molecular epidemiology and putative origin of hepatitis C virus in random volunteers from Argentina

AIM: To study the subtype prevalence and the phylogenetic relatedness of hepatitis C virus (HCV) sequences obtained from the Argentine general population, a large cohort of individuals was analyzed.

METHODS: Healthy Argentinian volunteers (n = 6251) from 12 provinces representing all geographical regions of the country were studied. All parents or legal guardians of individuals younger than 18 years provided informed written consent for participation. The corresponding written permission from all municipal authorities was obtained from each city or town where subjects were to be included. HCV RNA reverse transcription-polymerase chain reaction products were sequenced and phylogenetically analyzed. The 5’ untranslated region (5’UTR) was used for RNA detection and initial genotype classification. The NS5B polymerase region, encompassing nt 8262-8610, was used for subtyping.

RESULTS: An unexpectedly low prevalence of HCV infection in the general population (0.32%) was observed. Our data contrasted with previous studies that reported rates ranging from 1.5% to 2.5%, mainly performed in selected populations of blood donors or vulnerable groups. The latter values are in keeping with the prevalence reported by the 2007 Argentinian HCV Consensus (approximately 2%). HCV subtypes were distributed as follows: 1a (25%), 1b (25%), 2c (25%), 3a (5%), and 2j (5%). Two isolates ascribed either to genotype 1 (5%) or to genotype 3 (5%) by 5’UTR phylogenetic analysis could not be subtyped. Subtype 1a sequences comprised a highly homogeneous population and clustered with United States sequences. Genotype 1b sequences represented a heterogeneous population, suggesting that this genotype might have been introduced from different sources. Most subtype 2c sequences clustered close to the 2c reported from Italy and Southern France.

CONCLUSION: HCV has a low prevalence of 0.32% in the studied general population of Argentina. The pattern of HCV introduction and transmission in Argentina appears to be a consequence of multiple events and different for each subtype.

Distribution of hepatitis C virus genotypes among azerbaijani patients in capital city of iran-tehran

BACKGROUND

Determination of the Hepatitis C virus (HCV) genotype distributed in a particular area has an important role on public health throughout the world.

OBJECTIVES

The aim of this study was to determine the frequency of HCV genotypes in Azerbaijani patients.

PATIENTS AND METHODS

From March 2010 until March 2012, 235 Azerbaijani patients with established chronic hepatitis C, referred to Hospitals related to Iran University of Medical Sciences and Tehran Hepatitis Center, Clinical department of Baqiyatallah Research Center for Gastroeneterology and Liver Disease, were enrolled in this cross sectional study. About 5 mL of peripheral blood was collected from patients and after separation of plasma, viral RNA extracted. HCV-RNA were amplified by RT-nested PCR using primers from the 5´-UTR and genotyped by RFLP assay, and then HCV genotypes were confirmed using sequencing of cloned PCR products into pJET1.2/blunt cloning vector.

RESULTS

HCV genotyping of positive plasma samples demonstrated that predominant HCV subtype was noted for 1b (71.1%) followed by subtype 3a (17.0%), genotype 2 (6.8%), 1a (1.7%), and mixed infection (3.4%). The mean ± SD age of patients was 37.3 ± 11.8 (range: 2-63) years. Out of 235 patients, 139 (59.1%) were male. The frequency of HCV subtype 3a was higher in patients under 40 years old (3a: 18.1% vs. 15.0%), and subtype 3a was higher in male patients (3a: 18.7% vs. 14.6%).

CONCLUSIONS

The current study shows that the predominant HCV genotype among Azerbaijani patients with established chronic hepatitis C is subtype 1b (71.1%) followed by subtype 3a (17.0%).

Important factors in reliable determination of hepatitis C virus genotype by use of the 5' untranslated region

Accurate genotyping of hepatitis C virus (HCV) is important for determining the optimal regimen, dose, and duration of antiviral therapy for chronic HCV infection, as well as for estimating the response rate. The 5' untranslated region (UTR) of HCV RNA is used in commercial genotyping, but the probes and the lengths of the amplicons are proprietary and vary among the assays. In this study, factors involved in the reliable determination of HCV genotypes utilizing the 5' UTR were evaluated. Serum samples from four subjects with chronic HCV infection and disparate results on commercial genotyping and four controls were analyzed. HCV RNA was extracted from serum samples, and the 5' UTR and NS5B region were sequenced. Ten clones from each region were compared to prototype sequences and analyzed for genotype assignment using five programs. The results were compared to those from commercial assays. 5' UTR sequences were sequentially shortened from either the 5' end, the 3' end, or both ends, with genotyping of the resultant fragments. Sequences were obtained for the 5' UTR in all eight subjects and for the NS5B region in five subjects. The genotype assignments were identical between the two regions in the five subjects with complete sequencing. Genotyping by sequencing gave different results than those from the commercial assays in the four experimental samples but agreed in the four controls. Shortening of the sequences affected the results, and the results for sequences of <200 bases were inaccurate. Neither the Hamming distance nor the quasispecies affected the results. Sequencing of the HCV 5' UTR provided reliable genotyping results and resolved discrepancies identified in commercial assays, but genotyping by sequencing was highly dependent upon sequence length.

Eight novel hepatitis C virus genomes reveal the changing taxonomic structure of genotype 6

Analysis of partial hepatitis C virus sequences has revealed many novel genotype 6 variants that cannot be unambiguously classified, which obscure the distinctiveness of pre-existing subtypes. To explore this uncertainty, we obtained genomes of 98.0–98.8 % full-length for eight such variants (KM35, QC273, TV257, TV476, TV533, L349, QC271 and DH027) and characterized them using phylogenetic analyses and per cent nucleotide similarities. The former four are closely related phylogenetically to subtype 6k, TV533 and L349 to subtype 6l, QC271 to subtypes 6i and 6j, and DH027 to subtypes 6m and 6n. The former six defined a high-level grouping that comprised subtypes 6k and 6l, plus related strains. The threshold between intra- and inter-subtype diversity in this group was indistinct. We propose that similar results would be seen elsewhere if more intermediate variants like QC271 and DH027 were sampled.

Epidemiology, responses, and way forward: the silent epidemic of viral hepatitis and HIV coinfection in Vietnam

Viral hepatitis is a disease of great concern to public health that is now met by a favorable momentum to combat the global epidemic. This article is intended to highlight the importance of viral hepatitis in the Vietnam population as well in the group of people living with HIV/AIDS (PLWHA). We reviewed available data on epidemiology and response on hepatitis B virus (HBV) and hepatitis C virus (HCV) and HIV coinfection in Vietnam. The hepatitis B surface antigen (HBsAg) prevalence in the general population ranged from 5.7% to 24.7%. The anti-HCV prevalence ranged from 0.38% to 4.3% in the general population, while among people who inject drugs (PWIDs) it ranged from 31% to 97.2%. The HBV prevalence among PLWHA is similar to the general population, while HCV/HIV coinfection is concentrated in some groups. Anti-HCV prevalence among HIV-infected PWIDs can be as high as 98.5%. Developing policies for diagnosis and treatment of chronic HBV and HCV infections are critical priorities in order to prevent clinical progression to cirrhosis and liver cancer.

New insights into hepatitis C virus infection in the tribal-dominant part of Northeast India

Northeast India is known for the demographic heterogeneity of its tribal population, but there is no information about hepatitis C virus infection and associated risk factors. Anti-HCV was measured, HCV-RNA was detected based on the 5' UTR-core region, and genotyping was done by direct sequencing of the NS5b region. Antibodies to HCV were found in 13.7 % of the samples tested (96 out of 700), while HCV-RNA was positive in 73 % of the samples (70 out of 96) and in 5 out of 385 cases of occult HCV infection. Genotypes 1 to 4 were found respectively in 14.6, 7.3, 20, 30.8 %, and genotype 6 in 13.6 %, of the 75 HCV isolates. In acute viral hepatitis (AVH), the most prevalent genotype was 2a (28.6 %), while it was 4a (28 %) in chronic hepatitis C (CHC) and 29.4 % in cirrhosis. Males were more prone than females to HCV infection, and the highest numbers of cases of HCV infection were recorded in the age group of 40-49 years. The major risk factors were intravenous drug abuse (IVDU) (34.6 %), multiple sexual partners (20 %) and contact with professional barbers (38.6 %). The seroprevalence of HCV in Northeast India is higher than in the rest of India. This study highlights the fact that geographical variations occur with respect to HCV genotypes, which could influence the course and progress of different type of liver diseases seen in India.

A possible geographic origin of endemic hepatitis C virus 6a in Hong Kong: evidences for the association with Vietnamese immigration

Background

Hepatitis C virus (HCV) 6a accounts for 23.6% of all HCV infections of the general population and 58.5% of intravenous drug users in Hong Kong. However, the geographical origin of this highly predominant HCV subgenotype is largely unknown. This study explores a hypothesis for one possible transmission route of HCV 6a to Hong Kong.

Methods

NS5A sequences derived from 26 HCV 6a samples were chosen from a five year period (1999–2004) from epidemiologically unrelated patients from Hong Kong. Partial-NS5A sequences (513-bp from nt 6728 to 7240) were adopted for Bayesian coalescent analysis to reconstruct the evolutionary history of HCV infections in Hong Kong using the BEAST v1.3 program. A rooted phylogenetic tree was drawn for these sequences by alignment with reference Vietnamese sequences. Demographic data were accessed from “The Statistic Yearbooks of Hong Kong”.

Results

Bayesian coalescent analysis showed that the rapid increase in 6a infections, which had increased more than 90-fold in Hong Kong from 1986 to 1994 correlated to two peaks of Vietnamese immigration to Hong Kong from 1978 to 1997. The second peak, which occurred from 1987 through 1997, overlapped with the rapid increase of HCV 6a occurrence in Hong Kong. Phylogenetic analyses have further revealed that HCV 6a strains from Vietnam may be ancestral to Hong Kong counterparts.

Conclusions

The high predominance of HCV 6a infections in Hong Kong was possibly associated with Vietnamese immigration during 1987–1997.

NS4A protein as a marker of HCV history suggests that different HCV genotypes originally evolved from genotype 1b

BACKGROUND

The 9.6 kb long RNA genome of Hepatitis C virus (HCV) is under the control of RNA dependent RNA polymerase, an error-prone enzyme, for its transcription and replication. A high rate of mutation has been found to be associated with RNA viruses like HCV. Based on genetic variability, HCV has been classified into 6 different major genotypes and 11 different subtypes. However this classification system does not provide significant information about the origin of the virus, primarily due to high mutation rate at nucleotide level. HCV genome codes for a single polyprotein of about 3011 amino acids which is processed into structural and non-structural proteins inside host cell by viral and cellular proteases.

RESULTS

We have identified a conserved NS4A protein sequence for HCV genotype 3a reported from four different continents of the world i.e. Europe, America, Australia and Asia. We investigated 346 sequences and compared amino acid composition of NS4A protein of different HCV genotypes through Multiple Sequence Alignment and observed amino acid substitutions C22, V29, V30, V38, Q46 and Q47 in NS4A protein of genotype 1b. Furthermore, we observed C22 and V30 as more consistent members of NS4A protein of genotype 1a. Similarly Q46 and Q47 in genotype 5, V29, V30, Q46 and Q47 in genotype 4, C22, Q46 and Q47 in genotype 6, C22, V38, Q46 and Q47 in genotype 3 and C22 in genotype 2 as more consistent members of NS4A protein of these genotypes. So the different amino acids that were introduced as substitutions in NS4A protein of genotype 1 subtype 1b have been retained as consistent members of the NS4A protein of other known genotypes.

CONCLUSION

These observations indicate that NS4A protein of different HCV genotypes originally evolved from NS4A protein of genotype 1 subtype 1b, which in turn indicate that HCV genotype 1 subtype 1b established itself earlier in human population and all other known genotypes evolved later as a result of mutations in HCV genotype 1b. These results were further confirmed through phylogenetic analysis by constructing phylogenetic tree using NS4A protein as a phylogenetic marker.

Evolving epidemiology of hepatitis C virus

More than 20 years after the discovery of the hepatitis C virus (HCV), it is now well established that HCV is of global importance affecting all countries, leading to a major global health problem that requires widespread active interventions for its prevention and control. Chronic hepatitis C was linked to the development of cirrhosis and hepatocellular carcinoma in many areas of the world. Current epidemiological assessments have identified complex patterns with highly variable local prevalence rates between countries and within countries. HCV infection patterns have not significantly changed in most parts of the world since 1997, when first analyzed, partly due to the lack of new and more accurate data. The assessment of the national HCV prevalence and transmission modes should be completed to enable national authorities to prioritize preventive measures and to make the most appropriate use of available resources. The 'patchy' epidemiological situation in some areas will continue to complicate the task of the establishment of global, regional and national base line data. The present assessment finds a global prevalence of 2.35%, affecting 160 million chronically infected individuals. There is an urgent need for more accurate Information on the costs and burden of HCV to society. Twenty-one year after the discovery of HCV, the assessment is far from being complete and little progress has been made in the past 10 years in many countries. In some countries significant increases have been reported and this may also apply to countries were insufficient data exist. A safe and efficient vaccine against HCV is urgently needed.

New trends of HCV infection in China revealed by genetic analysis of viral sequences determined from first-time volunteer blood donors

Recently, we studied hepatitis C virus (HCV) sera-prevalence among 559 890 first-time volunteer blood donors in China. From randomly selected 450 anti-HCV positive donors, we detected HCV RNA in 270 donors. In this study, we amplified HCV E1 and/or NS5B sequences from 236 of these donors followed by DNA sequencing and phylogenetic analysis. The results indicate new trends of HCV infection in China. The HCV genotype distribution differed according to the donors' region of origin. Among donors from Guangdong province, we detected subtypes 6a, 1b, 3a, 3b, 2a, and 1a at frequencies of 49.7%, 31.0%, 7.6%, 5.5%, 4.1%, and 2.1%, respectively. Among donors from outside Guangdong, we detected 1b, 2a, 6a, 3b, 3a, 6e, and 6n at frequencies 57.1%, 13.2%, 11.0%, 9.9%, 4.4%, 2.2%, and 2.2%, respectively. Although we found no significant differences among regions in age or gender, subtype 6a was more common (P < 0.001) in donors from Guangdong than those from elsewhere, whilst subtypes 1b (P < 0.02) and 2a (P < 0.001) were more frequent outside Guangdong. Disregarding origins, the male/female ratio was higher for subtype 6a-infected donors (P < 0.05) than for subtype 1b donors, whilst the mean age of subtype 2a donors was 8-10 years older (P < 0.05) than that for all other subtypes. Detailed phylogenetic analysis of our sequence data provides further insight into the transmission of HCV within China, and between China and other countries. The predominance of HCV 6a among blood donors in Guangdong is striking and mandates studies into risk factors for its acquisition.

Natural history of chronic hepatitis C: genotype 1 versus genotype 6

BACKGROUND & AIMS

Data on the natural history of chronic hepatitis C virus (HCV) genotype 6 is lacking.

METHODS

We compared the natural history of 138 HCV genotype 1 patients (median age: 50) with 78 HCV genotype 6 patients (median age: 46.5). Baseline demographic data including gender, route of transmission, liver biochemistry, HCV RNA levels, and serial alanine aminotransferase (ALT) levels were compared. The rate of development of complications and mortality were also analyzed.

RESULTS

A total of 71.7% and 8.7% of genotype 1 patients were infected through blood transfusion and intravenous drug addiction, respectively, compared with 56.4% and 28.2% for genotype 6 patients, respectively (p<0.05). There were no differences in the baseline liver biochemistry in terms of ALT, albumin, bilirubin, alpha-fetoprotein (AFP), and HCV RNA levels between the two groups. Comparison of the proportion of normal and abnormal ALT levels between the two groups showed no statistical difference (p=0.121). There was also no statistical difference in the cumulative rate of development of cirrhotic complications and hepatocellular carcinoma (p=0.358) and mortality (p=0.649) between the two groups.

CONCLUSIONS

HCV genotype 1 patients were largely infected through blood transfusion, while a statistically larger proportion of genotype 6 patients were infected through intravenous drug injection. Both genotypes have comparable liver biochemistry, HCV viral load, and similar rates of development of cirrhotic complications and mortality.

Genotype diversity of hepatitis C virus (HCV) in HCV-associated liver disease patients in Indonesia

BACKGROUND

Hepatitis C virus (HCV) genotype distribution in Indonesia has been reported. However, the identification of HCV genotype was based on 5'-UTR or NS5B sequence.

AIMS

This study was aimed to observe HCV core sequence variation among HCV-associated liver disease patients in Jakarta, and to analyse the HCV genotype diversity based on the core sequence.

METHODS

Sixty-eight chronic hepatitis (CH), 48 liver cirrhosis (LC) and 34 hepatocellular carcinoma (HCC) were included in this study. HCV core variation was analysed by direct sequencing.

RESULTS

Alignment of HCV core sequences demonstrated that the core sequence was relatively varied among the genotype. Indeed, 237 bases of the core sequence could classify the HCV subtype; however, 236 bases failed to differentiate several subtypes. Based on 237 bases of the core sequences, the HCV strains were classified into genotypes 1 (subtypes 1a, 1b and 1c), 2 (subtypes 2a, 2e and 2f) and 3 (subtypes 3a and 3k). The HCV 1b (47.3%) was the most prevalent, followed by subtypes 1c (18.7%), 3k (10.7%), 2a (10.0%), 1a (6.7%), 2e (5.3%), 2f (0.7%) and 3a (0.7%). HCV 1b was the most common in all patients, and the prevalence increased with the severity of liver disease (36.8% in CH, 54.2% in LC and 58.8% in HCC). These results were similar to a previous report based on NS5B sequence analysis.

CONCLUSION

Hepatitis C virus core sequence (237 bases) could identify the HCV subtype and the prevalence of HCV subtype based on core sequence was similar to those based on the NS5B region.

An overview about hepatitis C: a devastating virus

Hepatitis C (HCV) is the disease that has affected around 200 million people globally. HCV is a life threatening human pathogen, not only because of its high prevalence and worldwide burden but also because of the potentially serious complications of persistent HCV infection. Chronicity of the disease leads to cirrhosis, hepatocellular carcinoma and end-stage liver disease. HCV positive hepatocytes vary between less than 5% and up to 100%, indicating the high rate of replication of viral RNA. HCV has a very high mutational rate that enables it to escape the immune system. Viral diversity has two levels; the genotypes and Quasiaspecies. Major HCV genotypes constitute genotype 1, 2, 3, 4, 5 and 6 while more than 50 subtypes are known. All HCV genotypes have their particular patterns of geographical distribution and a slight drift in viral population has been observed in some parts of the globe.

Geographic distribution of hepatitis C virus genotype 6 subtypes in Thailand

The nucleotide sequence of hepatitis C virus (HCV) genotype 6 found mostly in south China and south-east Asia, displays profound genetic diversity. The aim of this study to determine the genetic variability of HCV genotype 6 (HCV-6) in Thailand and locate the subtype distribution of genotype 6 in various geographic areas. Four hundred nineteen anti-HCV positive serum samples were collected from patients residing in - the central part of the country. HCV RNA positive samples based on reverse transcriptase- polymerase chain reaction (RT-PCR) of the 5'UTR were amplified with primers specific for the core and NS5B regions. Nucleotide sequences of both regions were analyzed for the genotype by phylogenetic analysis. To determine geographic distribution of HCV-6 subtypes, a search of the international database on subtype distribution in the respective countries was conducted. Among 375 HCV RNA positive samples, 71 had HCV-6 based on phylogenetic analysis of partial core and NS5B regions. The subtype distribution in order of predominance was 6f (56%), 6n (22%), 6i (11%), 6j (10%), and 6e (1%). Among the 13 countries with different subtypes of HCV-6, most sequences have been reported from Vietnam. Subtype 6f was found exclusively in Thailand where five distinct HCV-6 subtypes are circulating. HCV-6, which is endemic in south China and south-east Asia, displays profound genetic diversity and may have evolved over a considerable period of time.

Nomenclature and numbering of the hepatitis C virus

International standardization and coordination of the nomenclature of variants of hepatitis C virus (HCV) is increasingly needed as more is discovered about the scale of HCV-related liver disease and important biological and antigenic differences that exist between variants. Consistency in numbering is also increasingly required for functional and clinical studies of HCV. For example, an unambiguous method for referring to amino acid substitutions at specific positions in NS3 and NS5B coding sequences associated with resistance to specific HCV inhibitors is essential in the investigation of antiviral treatment. Inconsistent and inaccurate numbering of locations in DNA and protein sequences is becoming a problem in the HCV scientific literature.A group of experts in the field of HCV genetic variability, and those involved in development of HCV sequence databases, the Hepatitis Virus Database (Japan), euHCVdb (France), and the Los Alamos National Laboratory (United States), convened to reexamine the status of HCV genotype nomenclature, resolve conflicting genotype or subtype names among described variants of HCV, and draw up revised criteria for the assignment of new genotypes as they are discovered in the future. They also discussed how HCV sequence databases could introduce and facilitate a standardized numbering system for HCV nucleotides, proteins, and epitopes.A comprehensive listing of all currently classified variants of HCV incorporates a number of agreed genotype and subtype name reassignments to create consistency in nomenclature. A consensus proposal was drawn up for the classification of new variants into genotypes and subtypes, which recognizes and incorporates new knowledge of HCV genetic diversity and epidemiology. The proposed numbering system was adapted from the Los Alamos HIV database, with elements from the hepatitis B virus numbering system. The system comprises both nucleotides and amino acid sequences and epitopes, and uses the full-length genome sequence of isolate H77 (accession number AF009606) as a reference. It includes a method for numbering insertions and deletions relative to this reference sequence.

Identification of hepatitis C virus genotype 6 in Korean patients by analysis of 5' untranslated region using a matrix assisted laser desorption/ionization time of flight-based assay, restriction fragment mass polymorphism

Previous surveys of the prevalence of hepatitis C virus (HCV) in Korea have identified types 1 and 2, but little has been said of other genotypes and viral subtypes. In this study, HCV genotypes in Korea were investigated using Restriction Fragment Mass Polymorphism (RFMP) assay, a sensitive and specific method for genotyping based on MALDI-TOF mass spectrometry. A total of 1,043 independent serum samples from HCV-infected patients were analyzed. Of interest, 15 subjects (1.4%) were determined to contain HCV genotype 6 and 46 subjects (4.4%) contained mixed genotypes with the most prevalent genotypes being HCV 1b and 2a/c (45.0% and 35.4%, respectively). The 15 subjects with HCV genotype 6 comprised eight cases of subtype 6c, including one case of mixed infection with 1b, three cases of HCV 6a, and six cases of unassigned subtypes. Sequencing corroborated the identity of genotype 6 from 13 subjects, while the line probe assay (LiPA) mis-identified them as genotype 1b. The majority (7/9) of the genotype 6 patients enrolled for interferon/ribavirin therapy, achieved a sustained virologic response. The ability of the RFMP assay to differentiate various HCV genotypes should enable better analysis of the relationship between HCV genotype and disease prognosis.

Cutting the gordian knot-development and biological relevance of hepatitis C virus cell culture systems

Worldwide approximately 180 million people are chronically infected with hepatitis C virus (HCV). HCV isolates exhibit extensive genetic heterogeneity and have been grouped in six genotypes and various subtypes. Additionally, several naturally occurring intergenotypic recombinants have been described. Research on the viral life cycle, efficient therapeutics, and a vaccine has been hampered by the absence of suitable cell culture systems. The first system permitting studies of the full viral life cycle was intrahepatic transfection of RNA transcripts of HCV consensus complementary DNA (cDNA) clones into chimpanzees. However, such full-length clones were not infectious in vitro. The development of the replicon system and HCV pseudo-particles allowed in vitro studies of certain aspects of the viral life cycle, RNA replication, and viral entry, respectively. Identification of the genotype 2 isolate JFH1, which for unknown reasons showed an exceptional replication capability and resulted in formation of infectious viral particles in the human hepatoma cell line Huh7, led in 2005 to the development of the first full viral life cycle in vitro systems. JFH1-based systems now enable in vitro studies of the function of viral proteins, their interaction with each other and host proteins, new antivirals, and neutralizing antibodies in the context of the full viral life cycle. However, several challenges remain, including development of cell culture systems for all major HCV genotypes and identification of other susceptible cell lines.

The unique HCV genotype distribution and the discovery of a novel subtype 6u among IDUs co-infected with HIV-1 in Yunnan, China

The Yunnan province is the epicenter of HIV-1 epidemics in China and a center for drug trafficking to the other parts of the world. In six prefectures of this province, a total of 132 IDUs were recruited to determine the sero-prevalence of HCV and HIV-1 and the positive rates were 93.94% and 68.18%, respectively (P<0.001). Co-infection with HCV and HIV-1 was found among 89 IDUs, of whom several HCV fragments were amplified and sequenced. Sequences of the HCV 5'NCR-C and NS5B region were determined from 82 IDUs. Phylogenetic analyses showed consistent genotyping among 80 IDUs. Among them HCV genotypes 1a, 1b, 3a, 3b, 6a, 6n, and a tentatively assigned novel 6u subtype were found in 1 (1.25%), 16 (20%), 19 (23.75%), 24 (30%), 4 (5%), 9 (11.25%) and 7 (8.75%) individuals, respectively. In two IDUs, genotyping results were discordant, suggesting mixed HCV infections or recombination. The proportion of patients with HCV 1b tended to decrease from the north to south and from the east to west in this province. Genotype 3 and 6 strains were more frequent in the southern prefectures. The novel subtype 6u strains were only detected in Dehong which borders Myanmar. Our findings showed a unique pattern of HCV genotype distribution, which is similar to that in the southeastern Asian countries but distinct from that among the general population in China. Routes of drug trafficking and the resulting high prevalence of HIV-1 infection may have contributed to this pattern of HCV genotype distribution.

A set of reference sequences for the hepatitis C genotypes 4d, 4f, and 4k covering the full open reading frame

Infection with genotype 4 of the Hepatitis C virus is common in Africa and the Mediterranean area, but has also been found at increasing frequencies in injection drug users in Europe and North America. Full length viral sequences to characterize viral diversity and structure have recently become available mostly for subtype 4a, and studies in Egypt and Saudi Arabia, where high proportions of subtype 4a infected patients exist, have begun to establish optimized treatment regimens. However knowledge about other subtype variants of genotype 4 present in less developed African states is lacking. In this study the full coding region from so far poorly characterized variants of HCV genotype 4 was amplified and sequenced using a long range PCR technique. Sequences were analyzed with respect to phylogenetic relationship, possible recombination and prominent sequence characteristics compared to other known HCV strains. We present for the first time two full-length sequences from the HCV genotype 4k, in addition to five strains from HCV genotypes 4d and 4f. Reference sequences for accurate HCV genotyping are required for optimized treatment, and a better knowledge of the global viral sequence diversity is needed to guide vaccines or new drugs effective in the world wide epidemic.

Cytokine levels of TGF-beta, IL-10, and sTNFalphaRII in type C chronic liver disease

Cytokines play a key role in regulation of immunity and inflammation. The aim of the study was to detect serum levels of TGF-beta, IL-10, and sTNFalphaRII in patients with type C chronic liver disease (CLD) and to correlate these with biochemical and histopathological parameters used to assess the severity of the disease. Blood samples were aseptically collected from 90 CLD patients. Cytokine levels were also followed up in 39 chronic hepatitis cases. Levels of the cytokines in 90 CLD patients were significantly higher than in controls. In the follow up patients, 12 were non-responders and the serum levels of cytokines were still elevated after therapy whereas in 27 responders cytokine levels were significantly reduced after therapy and correlated well with biochemical and histopathological parameters. It is inferred that cytokine levels reflect the level of inflammation in chronic hepatitis C virus (HCV) infection and can be used as indirect markers to assess the severity of liver disease.

Hepatitis C virus (HCV) genotyping by annealing reverse transcription-PCR products with genotype-specific capture probes

The genotype of the hepatitis C virus (HCV) strain infecting a given patient is an important predictive factor for the clinical outcome of chronic liver disease and its response to anti-viral therapeutic agents. We herein sought to develop a new easy, sensitive and accurate HCV genotyping method using annealing genotype-specific capture probes (AGSCP) in an automation-friendly 96-well plate format. The validation of our new AGSCP was performed using the Standard HCV Genotype Panel. We then used both our AGSCP and the commercially available INNO-LiPA assay to analyze the HCV genotypes from 111 Korean patients. Discordant results were analyzed by direct sequencing. AGSCP successfully genotyped the standard panel. The genotypes of 111 patient samples were also obtained successfully by AGSCP and INNO-LiPA. We observed a high concordance rate (93 matched samples, 83.8%) between the two assays. Sequencing analysis of the 18 discordant results revealed that the AGSCP had correctly identified 12 samples, whereas the INNO-LiPA had correctly identified only 6. These results collectively indicate that AGSCP assay is a convenient and sensitive method for large-scale genotyping, and it may be a promising tool for the determination of HCV and other genotypes in clinical settings.

Complete genomes of hepatitis C virus (HCV) subtypes 6c, 6l, 6o, 6p and 6q: completion of a full panel of genomes for HCV genotype 6

Five hepatitis C virus (HCV) complete genome sequences (Th846, 537796, QC227, QC216 and QC99) from a blood donor in Thailand and three Asian immigrants and one Caucasian in North America were determined. Phylogenetically, they represent the first complete genomes for subtypes 6c, 6l, 6o, 6p and 6q, respectively. Similarity analysis showed no evidence of inter- or intrasubtype recombination. Further analysis in conjunction with partial sequences from the Los Alamos HCV database led to the identification of other closely related isolates from south-eastern Asia or immigrants from that region. However, Th846 did not cluster with any reference sequence and is the sole isolate of subtype 6c reported so far. This study completes the full genome sequencing of all 17 assigned HCV genotype 6 subtypes (6a-6q). The utility of this panel of complete sequences for accurate detection and classification of infection, and for estimating the origin of this genotype of HCV, is discussed.

Complete genomes for hepatitis C virus subtypes 6f, 6i, 6j and 6m: viral genetic diversity among Thai blood donors and infected spouses

In this study, the first complete genome sequences for hepatitis C virus (HCV) subtypes 6f, 6i, 6j and 6m, obtained from infected blood donors in Chiang Mai, Thailand, are reported. Pairwise genome-wide nucleotide similarities between some of these isolates were higher than the 75-80% value used previously to define different HCV subtypes. To investigate further, the entire genomes of four prototype isolates, Th602 (6i), Th553 (6j), B4/92 (6m) and D86/93 (6n), were sequenced. Pairwise comparison of these sequences gave a similar range of nucleotide similarities, thereby providing new information for HCV subtype classification. In order to study the hypothesis of interspousal HCV transmission, four additional complete HCV genome sequences were obtained from two infected Thai blood donors and their spouses, C-0044 and C-0046 (6f), and C-0192 and C-0185 (6m). Pairwise comparison of the sequences revealed that C-0044 and C-0046 share a nucleotide similarity of 98.1%, whilst C-0185 and C-0192 have a similarity of 97.8%. Several other studies of partial HCV sequences of different genomic regions from HCV-infected couples have shown nucleotide similarities ranging from 96.3 to 100%. The similarities of the complete genome sequences from the two couples in the current study are consistent with HCV transmission between spouses.

Hepatitis C virus infection in dialysis patients

Hepatitis C virus (HCV) infection is a global health problem, common worldwide, leading to acute and chronic hepatitis and its consequences of hepatocirrhosis and hepatocellular carcinoma. Patients on hemodialysis belong to the high-risk group of HCV infection. The prevalence of HCV infection in dialysis patients ranges from 4% to more than 70% in some countries. The main reasons for such a high incidence of infections are a high prevalence of HCV infection in the general population, lack of standard infection precautions and effective vaccination, inadequate disinfection procedures of dialysis machines and other medical equipment, as well as spread of infection from patient to patient, especially in dialytic centers with a high percentage of infected patients. The diagnostic procedures useful in the evaluation of HCV infection are detection of anti-HCV antibodies, identification of HCV RNA, counts of virus copies, and identification of its genome. From the 6 major genotypes and multiple subtypes of the HCV, genotypes 1a and 1b are the most common in Europe and Japan, and 1b is responsible for more severe liver disease and aggressive course leading to liver fibrosis. Antiviral therapy of HCV+ dialysis patients with interferon-alpha (INF-alpha) gives slightly better results than in the general population, but is poorly tolerated and associated with side effects. Although ribavirin in not recommended for dialysis patients, the addition of small doses of this compound to pegylated INF is discussed, especially for patients in whom previous infection treatment failed.

Hepatitis C virus genotype distribution in Myanmar: Predominance of genotype 6 and existence of new genotype 6 subtype

AIM

This study was performed to determine the prevalence and distribution of hepatitis C virus (HCV) genotypes in Myanmar.

METHODS

A total of 1333 peripheral blood samples were collected from four different border cities of Myanmar. The anti-HCV antibody-positive serum samples were identified. HCV was genotyped by reverse transcriptase polymerase chain reaction, direct DNA sequencing and phylogenetic analysis on the partial core genome.

RESULTS

The overall prevalence of HCV infection was 11.6% (154/1333). Regionally, it was 13.5% (47/349) in the north-eastern city, 12.8% (64/501) in the north-western city, 4.2% (16/380) in the southern city and 26.2% (27/103) in the western city. HCV was genotyped in 145/154 (94.2%) samples. Genotype 6 was the most prevalent genotype in this study (71/145, 49%), followed by genotype 3 (57/145, 39.3%), genotype 1 (16/145, 11%), and genotype 2 (1/145, 0.7%). Genotype 6 was mostly found in the northern cities and genotype 3 in the southern and western cities of Myanmar. Multiple HCV genotypes/subtypes were successfully characterized as 1a, 1b, 2a, 3a, 3b, 6m, 6n, and a new 6 subtype. Among them, subtype 6n was the most predominant subtype (38.6%), followed by subtype 3b (29.7%), 3a (9.6%), 6m (9%), 1b (6.9%), 1a (4.1%), new 6 subtype (1.4%) and 2a (0.7%). Subtype 6n was more widely distributed in the northern cities whereas subtype 3b was more common in the western city. The newly discovered genotype 6 subtype was from the northern cities.

CONCLUSIONS

The results indicate there are regional differences of HCV genotype distribution in Myanmar. There is a distinct geographic variation from other South-East Asian countries in terms of the existence of the new genotype 6 subtype.

Improvement of hepatitis C virus (HCV) genotype determination with the new version of the INNO-LiPA HCV assay

Hepatitis C virus (HCV) isolates have been classified into six main genotypes. Genotyping methods, and especially the widely used line probe assay (LiPA), are frequently based on the 5'-untranslated region (5'UTR). However, this region is not appropriate for discriminating HCV strains at the subtype level and for distinguishing many genotype 6 samples from genotype 1. We investigated the capacity of a novel LiPA (Versant HCV Genotype 2.0 assay) based on the simultaneous detection of 5'UTR and Core regions for genotypes 1 and 6 to provide correct HCV genotypes (characterized with a phylogenetic analysis) in a set of HCV strains mainly encountered in Western countries. The improvement was assessed by comparing the results to those obtained with the previous version of the assay. Of the 135 tested samples, 64.7% were concordant for genotype group and subtype with sequencing reference results using the Versant HCV Genotype 2.0 assay versus 37.5% with the previous version. The yield was mainly related to a better characterization of genotype 1, since the accuracy, tested in 62 genotype 1 samples, increased from 45.2% with the first version to 96.8% with the new one. However, this new version necessitates a specific PCR and could no longer be used after 5'UTR PCR used for current HCV infection diagnosis. Moreover, the information provided by 5'UTR hybridization is not reliable for correctly identifying the diversity within genotypes 2 and 4. Thus, the Versant HCV Genotype 2.0 assay remains a useful tool for clinical practice when only the discrimination between major HCV genotypes is necessary.

Use of sequence analysis of the NS5B region for routine genotyping of hepatitis C virus with reference to C/E1 and 5' untranslated region sequences

Nucleotide sequence analysis of the NS5B region was performed to identify genotypes of 8,479 hepatitis C virus (HCV) RNA-positive patient samples collected in the Canadian province of Quebec. Genotypes could be determined for 97.3% of patients. Genotypes 1 to 6 were found in 59.4, 9.0, 25.7, 3.6, 0.6, and 1.8% of patients, respectively. Two isolates did not classify within the six genotypes. The subtype 1 distribution was 76.7% 1a, 22.6% 1b, and 0.7% others, while the subtype 2 distribution was 31.8% 2a, 47.6% 2b, 10.9% 2c, 4.1% 2i, and 5.6% others. Subtype 3a accounted for 99.1% of genotype 3 strains, while all genotype 5 samples were of subtype 5a. The subtype 4 distribution was 39.2% 4a, 15.4% 4k, 11.6% 4d, 10.2% 4r, and 23.6% others. The subtype 6 distribution was 40.4% 6e, 20.5% 6a, and 39.1% others. The 5' untranslated region (5'UTR) sequences of subtype 6e were indistinguishable from those of genotype 1. All samples that did not classify within the established subtypes were also sequenced in C/E1 and 5'UTR. C/E1 phylogenetic reconstructions were analogous to those of NS5B. The sequences identified in this study allowed the provisional assignments of subtypes 1j, 1k, 2m, 2r, 3i, 4q, 6q, 6r, and 6s. Sixty-four (0.8%) isolates classifying within genotypes 1 to 6 could not be assigned to one of the recognized subtypes. Our results show that genotyping of HCV by nucleotide sequence analysis of NS5B is efficient, allows the accurate discrimination of subtypes, and is an effective tool for studying the molecular epidemiology of HCV.

Molecular methods of hepatitis C genotyping

Hepatitis C virus is an RNA virus that is associated with chronic infection in the majority of people infected. Chronic infection with hepatitis C virus is the cause of significant morbidity and mortality worldwide and is associated with a large spectrum of liver disease including cirrhosis and hepatocellular carcinoma. End-stage liver disease due to chronic hepatitis C virus infection is currently the leading indication for liver transplantation in the USA. Hepatitis C virus genotyping of viral isolates circulating in the blood during chronic infection has become an important part of hepatitis C virus monitoring in chronically infected patients, and is useful as a prognostic indicator and to direct duration of therapy. This review will summarize information on hepatitis C genotyping, describe the limitations of current commercially available methods, give information on more recently developed methods, and provide a look to the future in terms of where advances in hepatitis C virus genotyping assays need to be made.

Hepatitis C virus infection and genotypes in Antananarivo, Madagascar

The prevalence of hepatitis C virus (HCV) genotypes in Madagascar is not well known. Serum samples were obtained from 2,169 individuals selected by random sampling in the population living in Antananarivo city. Using HCV antibody test (Monolisa anti-HCV Plus version 2), 36 (1.7%) of the 2,169 samples were positive. The presence of HCV RNA was determined by using reverse transcription polymerase chain reaction amplifying the 5'-untranslated region (UTR): HCV RNA was detected in 17 of the 36 HCV antibodies positive samples. The genotype was determined using BLAST tool with another 5'-UTR fragment. The phylogenetic analysis of the polymerase (NS5b) and envelope (E1/E2) fragment sequences showed a low level of diversity compared to the high diversity in other African countries: subtype 1b (nine cases, 52.9%) and genotype 2 (eight cases, 47.1%) including subtype 2b (six cases), subtype 2k (one case), and one unclassified subtype. BLAST search with the 5'-UTR fragment sequence of this unclassified subtype identified that strain as subtype 2a.