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

'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.

Hepatitis C virus subtype diversity and transmission clusters characteristics among drug users in Zhuhai, South China

BACKGROUND

Hepatitis C virus (HCV) infection poses a major public health challenge globally, especially among injecting drug users. China has the world's largest burden of HCV infections. However, little is known about the characteristics of transmission networks among drug user populations. This study aims to investigate the molecular epidemiology and transmission characteristics of HCV infections among drug users in Zhuhai, a bustling port city connecting Mainland China and its Special Administrative Regions.

METHODS

Participants enrolled in this study were drug users incarcerated at Zhuhai's drug rehabilitation center in 2015. Their sociodemographic and behavioral information, including gender, promiscuity, drug use method, and so forth, was collected using a standardized questionnaire. Plasmas separated from venous blood were analyzed for HCV infection through ELISA and RT-PCR methods to detect anti-HCV antibodies and HCV RNA. The 5'UTR fragment of the HCV genome was amplified and further sequenced for subtype identifications and phylogenetic analysis. The phylogenetic tree was inferred using the Maximum Likelihood method based on the Tamura-Nei model, and the transmission cluster network was constructed using Cytoscape3.8.0 software with a threshold of 0.015. Binary logistic regression models were employed to assess the factors associated with HCV infection.

RESULTS

The overall prevalence of HCV infection among drug users was 44.37%, with approximately 19.69% appearing to clear the HCV virus successfully. Binary logistic regression analysis revealed that those aged over 40, engaging in injecting drug use, and being native residents were at heightened risk for HCV infection among drug user cohorts. The predominant HCV subtypes circulating among those drug users were 6a (60.26%), followed by 3b (16.7%), 3a (12.8%), 1b (6.41%) and 1a (3.85%), respectively. Molecular transmission network analysis unveiled the presence of six transmission clusters, with the largest propagation cluster consisting of 41 individuals infected with HCV subtype 6a. Furthermore, distinct transmission clusters involved eight individuals infected with subtype 3b and seven with subtype 3a were also observed.

CONCLUSION

The genetic transmission networks revealed a complex transmission pattern among drug users in Zhuhai, emphasizing the imperative for a targeted and effective intervention strategy to mitigate HCV dissemination. These insights are pivotal for shaping future national policies on HCV screening, treatment, and prevention in port cities.

Genetic history of hepatitis C virus genotype 6 in Taiwan

Unlike hepatitis C virus (HCV) genotype (GT) 6, which is widely circulated in Southeast Asia and South China, GT 6 was not reported in Taiwan until 2006. GT 1b and 2a, also known as global HCV subtypes, have been reported as major GTs circulating in Taiwan. Because of improvement in genotyping kits and sequencing techniques for the subtyping of HCV, an increasing number of GT 6 subtypes have been reported, especially subtype 6a among intravenous drug users with human immunodeficiency virus infection after an outbreak since 2003. Thus, HCV GT 6 infection is regarded to be closely associated with injection drug use. However, recently, we found an unexpectedly high GT 6 prevalence in the general population in Tainan, southern Taiwan. Most of these GT 6 samples belonged to a putative novel subtype closely related to 6g and 6w instead of 6a. Phylogenetic analyses indicated that this putative 6g-related novel subtype and 6w could be indigenous in southern Taiwan for centuries. Southern Taiwan could be the origin of HCV subtype 6w. This finding might change the perspective of HCV epidemiology in Taiwan.

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.

Treatment Response and Drug Resistance Profiling of Genotype 6 of Hepatitis C Virus in HCV/HIV Co-Infected Patients: A Pilot Study from INDIA

Hepatitis C Virus (HCV) genotype (GT) 6 demonstrates maximum genomic diversity out of all the known genotypes of HCV, attributable to its inherent intra-genotype and inter-genotype recombination property. This is the most common genotype seen in HCV/HIV co-infected cases. HIV/HCV co-infection is linked with increased genetic diversity in HCV structural genes. The detailed information on the distribution of HCV GT6, its subtypes, and resistance to currently available antiviral drugs is limited in the Indian subcontinent. Therefore, in this single-center retrospective cross-sectional study, we aimed to map the occurrence of HCV GT6, its subtypes and resistance-associated substitution (RAS), and its correlation with antiviral treatment response in HCV-infected patients. From a cohort of 2052 HCV-infected patients, the overall prevalence of GT6 was 2.5% (n = 53), with a maximum of 81.1% (n = 43) seen in HCV/HIV co-infected patients. Nine different subtypes, 6a, 6b, 6f, 6i, 6n, 6u, 6v, 6w, and 6xa, were detected in the Indian population for the first time, with a predominance of 6xa (41.5%), a rare subtype, followed by 6n (39.6%). The phylogenetic analysis by the neighbor-joining method revealed three prominent viral clades, 6v, 6n, and 6xa–6u. The baseline (before treatment initiation) plasma samples of all GT6-infected patients were retrieved from −80 °C and a part of the NS5a and NS5b region of the viral genome was analyzed for the presence of RAS. No RASs were seen in the NS5b region, while in two patients (3.7%) RASs were seen at baseline in the NS5a region of the virus. Sustained viral response (SVR) was attained in 81% (n = 43) of patients. No difference in GT6 subtype distribution or occurrence of RAS was seen between mono-infected HCV and HIV/HCV co-infected cases. Our study revealed that RAS at baseline did not influence the attainment of SVR and the currently available antiviral therapy is effective against GT6 mono-infected and HIV/HCV co-infected patients.

Prevalence of HCV genotypes and subtypes in Southeast Asia: A systematic review and meta-analysis

Known for its high genetic diversity and variation in genotypic presence in different regions of the world, hepatitis C virus (HCV) is estimated to infect about 71 million people globally. Selection of an appropriate therapeutic regimen largely depends on the identification of the genotype responsible for the infection. This systematic review and meta-analysis was conducted to provide a comprehensive view of HCV genotype and subtype distribution in Southeast Asia (SEA). The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). We searched five databases without year and language restrictions. Data from 90 eligible studies involving 15,089 genotypes and 9,646 subtypes representing 10 SEA countries were analyzed. The pooled estimates showed that genotype 1 (46.8%) [95% CI, 43.2–50.4; I² = 92.77%; p < 0.001] was the most dominant HCV genotype in the region, followed by genotype 3 (23.1%) [95% CI, 19.4–27.2; I² = 93.03%; p < 0.001], genotype 6 (16.5%) [95% CI, 13.8–19.6], genotype 2 (4.6%) [95% CI, 3.5–5.9], genotype 4 (1.1%) [95% CI, 0.7–1.5] and genotype 5 (0.8%) [95% CI, 0.4–1.3]. Philippines had the highest prevalence of genotypes 1 and 2. Genotype 6 became more prevalent after year 2000. Over 40 different subtypes were identified, with subtypes 1b (26.3%), 1a (21.3%), and 3a (14.3%) being the most prevalent of all the reported subtypes. Although on a global scale, genotype 6 is considered highly prevalent in SEA, evidence from this study reveals that it is the third most prevalent genotype within the region.

Development of a Method for Screening and Genotyping of HCV 1a, 1b, 2, 3, 4, and 6 Genotypes

The World Health Organization and the World Health Assembly recommended eradicating hepatitis as a public threat by 2030. The accurate genotyping of hepatitis C virus (HCV) is crucial to achieving this goal because it is vital for the selection of anti-HCV therapy required for complete cure of HCV infection. We report the development of a method for accurate genotyping of HCV 1a, 1b, 2, 3, 4, and 6 genotypes. The merits of the developed method for HCV genotyping include (i) requirement of a single polymerase chain reaction (PCR) primer set, (ii) room-temperature detection in 30 min after the PCR, (iii) no need of highly trained professionals, (iv) highly accurate HCV genotyping results afforded by highly specific DNA-DNA hybridization, and (v) probe sequences that can be used on other platforms.

Diversity of hepatitis C virus infection among HIV-infected people who inject drugs in India

The availability of generic direct acting antivirals (DAAs) for hepatitis C virus (HCV) treatment has prompted many low-and-middle-income countries to launch HCV elimination programs. Because the efficacy of some of these generic DAAs varies by HCV viral subtype, information on subtype distribution can contribute important information to these elimination programs. We conducted a cross-sectional serosurvey to characterize HCV subtype diversity among HIV positive people who inject drugs (PWID) across 14 cities in India. Of 801 HIV positive PWID sampled, 639 tested HCV antibody positive (78.9%). Among 105 samples sequenced, genotype 3 (58.1%) was the most commonly observed followed by genotype 1 (36.2%) and genotype 6 (5.7%). Of the genotype 3 infections, 65% were subtype 3a and 35% were subtype 3b. Of the genotype 1 infections, 94% were subtype 1a and 6% were subtype 1b. All genotype 6 samples were subtype 6n. There was some variability in genotype diversity depending on geographic region and PWID epidemic stage with greater diversity observed in older PWID epidemics. One sequence, HY018, did not cluster with any known reference sequences in phylogenetic analysis. Nearly 80% of HIV infected PWID across India are co-infected with HCV, and subtype prevalence and genetic diversity varied by region and PWID epidemic stage. HCV elimination programs in India will need to consider HCV subtype.

High sustained virologic response in genotypes 3 and 6 with generic NS5A inhibitor and sofosbuvir regimens in chronic HCV in myanmar

Exclusive HCV therapy clinical trials with genotype 6 patients in high prevalence areas have been sparse. We analysed the safety and efficacy of two generic, pangenotypic NS5A/NS5B combination oral DAA regimens, primarily in genotypes 3 and 6, in a real-world setting: (a) daclatasvir/sofosbuvir (DCV/SOF) ± ribavirin (RBV) and (b) Velpatasvir/sofosbuvir (VEL/SOF ± RBV). Between December 2015 and November 2017, data from 522 patients were analysed, 311 of whom were treated with DCV/SOF ± RBV for 12/24 weeks (genotype 3: n = 193, genotype 6: n = 89) and 211 were treated with VEL/SOF ± RBV for 12/24 weeks (genotype 3: n = 83, genotype 6: n = 77). Overall SVR rates were high for both DCV/SOF ± RBV (96.1%, n = 299/311) and VEL/SOF ± RBV (95.3%, n = 201/211), and there was a good adverse event profile. Treatment naïve status and inclusion of RBV (in advanced fibrosis/cirrhosis) were significant independent predictors of achieving SVR12, while type of DAA regimen was not predictive. In this large cohort of genotypes 3 (n = 276) and 6 (n = 166; n = 127 unique subtype of 6c-l), high SVR rates of 94.9% (n = 262/276) and 95.2% (n = 158/166), respectively, were noted. In conclusion, generic and pangenotypic DCV/SOF and VEL/SOF ± RBV regimens were highly effective and safe, in genotypes 3 and 6 chronic HCV in Myanmar. These efficacious pangenotypic regimens suggest that baseline genotype testing can be eliminated moving forward. While RBV may still be needed for those with advanced fibrosis/cirrhosis, in a global elimination strategy it would not be practical even if it does compromise SVR in a minority with difficult to treat characteristics.

Complicated HCV subtype expansion among drug users in Guangdong province, China

Guangdong Province is one of the most developed and populous provinces in southern China. The subtype situation of hepatitis C virus (HCV) in Guangdong remains unknown. The aim of this study was to investigate and estimate the HCV subtypes in drug users (DU) using a city-based sampling strategy to better understand the characteristics of HCV transmission in Guangdong. Archived plasma samples (n = 1074) from DU who were anti-HCV positive in 2014 were selected randomly from 20 cities in Guangdong Province. Subtypes were determined based on core and/or E1 sequences using phylogenetic analysis. The distributions of HCV subtypes in DU and different regions were analyzed. A total of 8 genotypes were identified. The three main HCV subtypes in DU in Guangdong were 6a (63.0%), 3a (15.2%), and 3b (11.8%). Significant differences were discovered among different registered residency and regions but not among genders, marital status, education level, or drug use patterns. HCV subtype 3b was significantly higher in Guangdong residents than in non-Guangdong residents. In contrast, HCV subtype 6a was significantly lower in Guangdong residents than in non-Guangdong residents. Subtype 1b in eastern Guangdong (eastern) was significantly lower, while 6a was significantly higher when compared with other regions. Subtype 3a in the Pearl River Delta (PRD) region was significantly higher, while 3b was significantly lower when compared with other regions. In western Guangdong, HCV subtype 3a was significantly lower when compared with other regions. Additionally, in northern Guangdong subtypes 1b and 3b were significantly higher, while 6a was significantly lower when compared with other regions. Our study revealed the diversity and distribution of HCV subtypes in DU in nearly all the cities in Guangdong. The results provide essential information that will allow the establishment of specific intervention strategies that may help prevent HCV transmission.

Identification of a New HCV Subtype 6xg Among Injection Drug Users in Kachin, Myanmar

Characterizing hepatitis C virus (HCV) genetic diversity not only allows us to trace its origin and evolutionary history, but also provides valuable insights into diagnosis, prevention and therapy of HCV infection. Although eight HCV genotypes and 86 subtypes have been classified, there are still some HCV variants that need to be assigned. The genotype 6 is the most diverse HCV genotype and mainly prevalent in Southeast Asia. In this study, we identified a new HCV subtype 6xg from injection drug users (IDUs) in Kachin, Myanmar. A distinctive feature of 6xg from other subtypes of the genotype 6 was a Lys insertion in NS5A gene, which changes the RRKR/K motif into RRKKR/K. Bayesian analyses showed that HCV 6xg originated during 1984–1988, and experienced a rapid population expansion during 2005–2009. We characterized HCV subtype profile among IDUs in this region, and detected six HCV subtypes, including 1a (12.0%), 3a (12.0%), 3b (24.0%), 6n (16.0%), 6xa (20.0%), and 6xg (12.0%). Importantly, we found that HCV subtype distribution in Kachin was very similar to that in Dehong prefecture of Yunnan, but very distinct from those in other regions of Myanmar and Yunnan, indicating that the China–Myanmar border region shared a unique HCV subtype pattern. The appearance of 6xg and the unique HCV subtype profile among IDUs in the China–Myanmar border region have significant epidemiological and public health implications.

Differential prevalence and geographic distribution of hepatitis C virus genotypes in acute and chronic hepatitis C patients in Vietnam

BACKGROUND

The highest burden of disease from hepatitis C virus (HCV) is found in Southeast Asia, but our understanding of the epidemiology of infection in many heavily burdened countries is still limited. In particular, there is relatively little data on acute HCV infection, the outcome of which can be influenced by both viral and host genetics which differ within the region. We studied HCV genotype and IL28B gene polymorphism in a cohort of acute HCV-infected patients in Southern Vietnam alongside two other cohorts of chronic HCV-infected patients to better understand the epidemiology of HCV infection locally and inform the development of programs for therapy with the increasing availability of directly acting antiviral therapy (DAAs).

METHODS

We analysed plasma samples from patients with acute and chronic HCV infection, including chronic HCV mono-infection and chronic Human Immunodeficiency Virus (HIV)-HCV coinfection, who enrolled in four epidemiological or clinical research studies. HCV infection was confirmed with RNA testing. The 5' UTR, core and NSB5 regions of HCV RNA positive samples were sequenced, and the genotype and subtype of the viral strains were determined. Host DNA from all HCV positive patients and age- and sex-matched non-HCV-infected control individuals were analysed for IL28B single nucleotide polymorphism (SNP) (rs12979860 and rs8099917). Geolocation of the patients were mapped using QGIS.

RESULTS

355 HCV antibody positive patients were analysed; 54.6% (194/355) and 46.4% (161/355) were acute and chronic infections, respectively. 50.4% (81/161) and 49.6.4% (80/161) of chronic infections had HCV mono-infection and HIV-HCV coinfection, respectively. 88.7% (315/355) and 10.1% (36/355) of the patients were from southern and central regions of Vietnam, respectively. 92.4% (328/355) of patients were HCV RNA positive, including 86.1% (167/194) acute and 100% (161/161) chronic infections. Genotype could be determined in 98.4% (322/328) patients. Genotypes 1 (56.5%; 182/322) and 6 (33.9%; 109/322) predominated. Genotype 1 including genotype 1a was significantly higher in HIV-HCV coinfected patients compared to acute HCV patients [43.8% (35/80) versus 20.5% (33/167)], (p = <0.001), while genotype 6 was significantly higher in chronic HCV mono-infected patients [(44.4% (36/81) versus 20.0% (16/80)] (p = < 0.004) compared to HIV-HCV coinfected patients. The prevalence of IL28B SNP (rs12979860) homozygous CC was 86.46% (83/96) in control individuals and was significantly higher in acutely-infected compared to chronically-infected patients [93.2 (82/88) versus 76.1% (35/46)] (p = < 0.005).

CONCLUSION

HCV genotype 6 is highly prevalent in Vietnam and the high prevalence in treatment naïve chronic HCV patients may results from poor spontaneous clearance of acute HCV infection with genotype 6.

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.

Strategy and Efficacy of Generic and Pan-genotypic Sofosbuvir/Velpatasvir in Chronic Hepatitis C Virus: A Myanmar Experience

BACKGROUND

In resource-constrained areas, generic direct-acting antivirals (DAAs) have considerably reduced the cost of hepatitis C virus (HCV) therapy while there remain significant costs related to the baseline and follow-up virologic assays.

AIM

The aim was to assess the efficacy and safety of HCV therapy in Myanmar with pan-genotypic generic DAA sofosbuvir/velpatasvir (SOF/VEL) and with and without the baseline genotype testing, while the duration of treatment and use of ribavirin (RBV) was dictated by cirrhosis and prior treatment failure.

METHODS

Between September 2016 and June 2017, data from the 359 participants who completed treatment with SOF/VEL (± RBV) for 12-24 weeks were analyzed. Two hundred one patients did not have the baseline HCV genotype tested.

RESULTS

Regimens included SOF/VEL for 12 weeks (n = 43), SOF/VEL/RBV for 12 weeks (n = 275), or SOF/VEL/RBV for 24 weeks (n = 41). The mean age was 52 years, 44% were men (n = 159), 41 (11.4%) had a history of previous DAA therapy, 7 (1.9%) had a history of hepatocellular carcinoma, and 55 (15.3%) had cirrhosis. Overall, the sustained viral response (SVR)12 rate was 98.6% (354/359) and with a good adverse event profile. SVR rates were similar to those with and without baseline genotype testing and also across all genotypes in those who had genotype tested.

CONCLUSIONS

In Myanmar, generic and pan-genotypic SOF/VEL ± RBV is a highly effective and safe treatment for HCV, regardless of the HCV genotype, and therefore, the requirement for the baseline genotype can be eliminated. Future strategies should include elimination of treatment and end of treatment HCV RNA testing to enhance treatment uptake and further reduce cost.

Profile of the VERSANT HCV genotype 2.0 assay

INTRODUCTION

Hepatitis C virus (HCV) is divided into 7 genotypes and 67 subtypes. HCV genotype studies reflect the viral transmission patterns as well as human migration routes. In a clinical setting, HCV genotype is a baseline predictor for the sustained virological response (SVR) in chronic hepatitis C patients treated with peginterferon or some direct acting antivirals (DAAs). The Versant HCV genotype 2.0 assay has been globally used for HCV genotyping over a decade. Areas covered: The assay is based on reverse hybridization principle. It is evolved from its former versions, and the accuracy and successful genotyping/subtyping rate are substantially improved. It shows an accuracy of 99-100% for genotypes 1-6. It can also reliably identify subtypes 1a and 1b. However, the assay does not allow a high resolution for many other subtypes. Reasons for indeterminate or inaccurate genotyping/subtyping results are discussed. Expert commentary: Genotyping helps to find the most efficacious and cost-effective treatment regimen. The rapid development of anti-HCV treatment regimens, however, is greatly simplifying laboratory tests. In the near future, the need for HCV genotyping and frequent serial on-treatment HCV RNA tests will decrease along with the wide use of the more potent and pan-genotypic DAA regimens.

Clinical Characteristics and Treatment Outcome of Peginterferon Plus Ribavirin in Patients Infected with Genotype 6 Hepatitis C Virus in Korea: A Multicenter Study

Background/Aims

Because of the limited geographic distribution, there have been insufficient data regarding hepatitis C virus (HCV) genotype 6 in Korea. This study aimed to investigate the clinical characteristics and available treatment outcomes of patients with genotype 6 HCV in Korea.

Methods

From 2004 to 2014, data were collected from Korean patients infected with genotype 6 HCV in eight hospitals.

Results

Thirty-two patients had genotype 6 HCV. The median age was 44 years, and 6c was the most common subtype. The baseline median alanine transaminase level was 88 (21 to 1,019) IU/mL, and the HCV RNA level was 1,405,000 (96,500 to 28,844,529) IU/mL. Twenty-five patients were treated with peginterferon (PEG-IFN) and ribavirin. Three follow-up losses occurred. Additionally, 13 patients attained a sustained virologic response (SVR), seven patients relapsed, and two patients exhibited a null response. The SVR rates were 40% and 75% for the 24- and more than 48-week treatments, respectively, and five of the six patients who achieved a rapid virologic response (RVR) attained a SVR.

Conclusions

Korean patients infected with genotype 6 HCV are relatively young, and 6c is the most common subtype. When treated with PEG-IFN and ribavirin, the SVR rate was 52%. Similar to other genotypes, a longer duration of treatment and attainment of RVR are important for SVR.

6 HCV Genotyping 9G test for HCV 1a, 1b, 2, 3, 4 and 6 (6a, 6f, 6i and 6n) with high accuracy

According to EASL guidelines and WHO recommendations, the accurate detection of HCV genotypes such as HCV 1a, HCV1b, HCV 2, HCV 3, HCV 4, and HCV 6 (6a, 6f, 6i, 6n) is crucial for the efficient treatment of hepatitis C. HCV Genotyping 9G test allows simultaneous genotyping of HCV 1a, 1b, 2, 3, 4, and 6 (6a, 6f, 6i, and 6n) in clinical samples in 30min. The performance of the test was evaluated by comparison with sequence analysis. Serum samples (n=152) from HCV-infected patients (n=110) and healthy individuals (n=42) were processed under blinded codes. The k coefficient (kappa) values indicated high agreement between the HCV Genotyping 9G test and sequencing. The sensitivity and specificity of the test were 99.1% and 99.7%, respectively. The results indicate that HCV Genotyping 9G test is rapid, reliable, sensitive, and accurate for screening and genotyping of HCV in the clinical specimens.

Hepatitis C virus infection

Hepatitis C virus (HCV) is a hepatotropic RNA virus that causes progressive liver damage, which might result in liver cirrhosis and hepatocellular carcinoma. Globally, between 64 and 103 million people are chronically infected. Major risk factors for this blood-borne virus infection are unsafe injection drug use and unsterile medical procedures (iatrogenic infections) in countries with high HCV prevalence. Diagnostic procedures include serum HCV antibody testing, HCV RNA measurement, viral genotype and subtype determination and, lately, assessment of resistance-associated substitutions. Various direct-acting antiviral agents (DAAs) have become available, which target three proteins involved in crucial steps of the HCV life cycle: the NS3/4A protease, the NS5A protein and the RNA-dependent RNA polymerase NS5B protein. Combination of two or three of these DAAs can cure (defined as a sustained virological response 12 weeks after treatment) HCV infection in >90% of patients, including populations that have been difficult to treat in the past. As long as a prophylactic vaccine is not available, the HCV pandemic has to be controlled by treatment-as-prevention strategies, effective screening programmes and global access to treatment.

Management of hepatitis C virus infection in the Asia-Pacific region: an update

The Asia-Pacific region has disparate hepatitis C virus (HCV) epidemiology, with prevalence ranging from 0·1% to 4·7%, and a unique genotype distribution. Genotype 1b dominates in east Asia, whereas in south Asia and southeast Asia genotype 3 dominates, and in Indochina (Vietnam, Cambodia, and Laos), genotype 6 is most common. Often, availability of all-oral direct-acting antivirals (DAAs) is delayed because of differing regulatory requirements. Ideally, for genotype 1 infections, sofosbuvir plus ledipasvir, sofosbuvir plus daclatasvir, or ombitasvir, paritaprevir, and ritonavir plus dasabuvir are suitable. Asunaprevir plus daclatasvir is appropriate for compensated genotype 1b HCV if baseline NS5A mutations are absent. For genotype 3 infections, sofosbuvir plus daclatasvir for 24 weeks or sofosbuvir, daclatasvir, and ribavirin for 12 weeks are the optimal oral therapies, particularly for patients with cirrhosis and those who are treatment experienced, whereas sofosbuvir, pegylated interferon, and ribavirin for 12 weeks is an alternative regimen. For genotype 6, sofosbuvir plus pegylated interferon and ribavirin, sofosbuvir plus ledipasvir, or sofosbuvir plus ribavirin for 12 weeks are all suitable. Pegylated interferon plus ribavirin has been replaced by sofosbuvir plus pegylated interferon and ribavirin, and all-oral therapies where available, but cost and affordability remain a major issue because of the absence of universal health coverage. Few patients have been treated because of multiple barriers to accessing care. HCV in the Asia-Pacific region is challenging because of the disparate epidemiology, poor access to all-oral therapy because of availability, cost, or regulatory licensing. Until these problems are addressed, the burden of disease is likely to remain high.

Hepatitis C virus therapy with peg-interferon and ribavirin in Myanmar: A resource-constrained country

AIM

To investigate peg-interferon (peg-IFN) and ribavirin (RBV) therapy in Myanmar and to predict sustained virologic response (SVR).

METHODS

This single-center, open-label, study was conducted in Myanmar between 2009 and 2014. A total of 288 patients infected with HCV genotypes 1, 2, 3 and 6 were treated with peg-IFN alpha-2a (180 μg/wk) or alpha-2b (50 to 100 μg as a weight-based dose) and RBV as a weight-based dose (15 mg/kg/d). Treatment duration was 48 wk for genotypes 1 and 6, 24 wk for genotype 2, and 24 or 48 wk for genotype 3 based on rapid virologic response (RVR). Those co-infected with hepatitis B received 48 wk of therapy.

RESULTS

Overall, SVR was achieved for 82% of patients and the therapy was well tolerated. All patients achieved SVR at equivalent rates regardless of HCV genotype (P = 0.314). Low fibrosis scores (P < 0.001), high baseline albumin levels (P = 0.028) and low baseline viral loads (P = 0.029) all independently predicted SVR. On the other hand, IL-28B TT and CC genotypes were not found to significantly predict SVR (P = 0.634; P = 0.618). Among those who completed treatment, the occurrence of RVR showed a > 96% positive predictive value for achieving SVR. Treatment duration did not significantly impact the likelihood of achieving SVR for patients infected with genotype 3 HCV (P = 0.371). The most common adverse events were fatigue (71%) and poor appetite (60%). Among patients with genotype 3 HCV, more patients in the 48-wk treatment group required erythropoietin than in the 24-wk treatment group (61.1% vs 49.2%).

CONCLUSION

SVR rates were high with peg-IFN and RBV therapy in Myanmar. Fibrosis scores, baseline albumin, HCV RNA levels and RVR independently predicted SVR.

6 HCV genotyping 9G test and its comparison with VERSANT HCV genotype 2.0 assay (LiPA) for the hepatitis C virus genotyping

In this article, we describe the 6 HCV Genotyping 9G test and its evaluation by using clinical samples and plasmid DNA standards. In tests with 981 plasmid DNA standards, the 6 HCV Genotyping 9G test showed higher than 92.5% sensitivity and 99.4% specificity. The 6 HCV Genotyping 9G test was compared with the VERSANT HCV Genotype 2.0 assay (LiPA 2.0) for detection and discrimination of HCV genotypes in clinical samples. The results of both tests were verified by genomic sequencing. The 6 HCV Genotyping 9G test demonstrated a 100% agreement with the sequencing results, which was higher than LiPA 2.0. These results indicate that the 6 HCV Genotyping 9G test can be a reliable, sensitive, and accurate diagnostic tool for the correct identification of HCV genotypes in clinical specimens. 6 HCV Genotyping 9G test can genotype six HCV types in 1 PCR in 30min after PCR amplification. The 6 HCV Genotyping 9G test, thus provide critical information to physicians and assist them to apply accurate drug regimen for the effective hepatitis C treatment.

HCV Diversity among Chinese and Burmese IDUs in Dehong, Yunnan, China

HCV transmission is closely associated with drug-trafficking routes in China. Dehong, a prefecture of Yunnan, is the important trade transfer station linking Southeast Asia and China, as well as the drug-trafficking channel linking “Golden triangle” and other regions of China and surrounding countries. In this study, we investigated the HCV genotype diversity among IDUs in Dehong based on 259 HCV positive samples from 118 Chinese and 141 Burmese IDUs. HCV genotypes were determined based on the phylogenies of C/E2 and NS5B genomic sequences. Six HCV subtypes, including 1a, 1b, 3a, 3b, 6n and 6u, were detected. Interestingly, 4 HCV sequences from Burmese IDUs did not cluster with any known HCV subtypes, but formed a well-supported independent clade in the phylogenetic trees of both C/E2 and NS5B, suggesting a potential new HCV subtype circulating in Dehong. Subtype 3b was the predominant subtype, followed by subtypes 6n and 6u. Comparison showed that Dehong had a unique pattern of HCV subtype distribution, obviously different from other regions of China. In particular, HCV subtypes 6u and the potential new HCV subtype had a relatively high prevalence in Dehong, but were rarely detected in other regions of China. There was no significant difference in HCV subtype distribution between Burmese and Chinese IDUs. Few HCV sequences from Burmese and Chinese IDUs clustered together to form transmission clusters. Furthermore, about half of HCV sequences from Burmese IDUs formed small transmission clusters, significantly higher than that from Chinese IDUs (p<0.01). These suggest that the Chinese and Burmese IDUs were relatively isolated from each other in injection drug use behavior and the Burmese IDUs might prefer to inject drugs themselves together. The unique genotype distribution and complex diversity of genotype 6 among IDUs may be associated with the special geographical position of Dehong.

Hepatitis C virus genotypes in Myanmar

Myanmar is adjacent to India, Bangladesh, Thailand, Laos and China. In Myanmar, the prevalence of hepatitis C virus (HCV) infection is 2%, and HCV infection accounts for 25% of hepatocellular carcinoma. In this study, we reviewed the prevalence of HCV genotypes in Myanmar. HCV genotypes 1, 3 and 6 were observed in volunteer blood donors in and around the Myanmar city of Yangon. Although there are several reports of HCV genotype 6 and its variants in Myanmar, the distribution of the HCV genotypes has not been well documented in areas other than Yangon. Previous studies showed that treatment with peginterferon and a weight-based dose of ribavirin for 24 or 48 wk could lead to an 80%-100% sustained virological response (SVR) rates in Myanmar. Current interferon-free treatments could lead to higher SVR rates (90%-95%) in patients infected with almost all HCV genotypes other than HCV genotype 3. In an era of heavy reliance on direct-acting antivirals against HCV, there is an increasing need to measure HCV genotypes, and this need will also increase specifically in Myanmar. Current available information of HCV genotypes were mostly from Yangon and other countries than Myanmar. The prevalence of HCV genotypes in Myanmar should be determined.

Distribution of hepatitis C virus genotypes in volunteer blood donors from Chengdu, China

Hepatitis C virus (HCV) is a significant pathogen of global concern. The virus is usually spread through blood contact, such as transfusion, hemodialysis and injection of illegal drugs. HCV genotypes have a geographic distribution in different areas. In this paper, we focus on the distribution of HCV genotypes from volunteer blood donors in Chengdu. The prevalence of genotypes was analyzed using phylogenetic analysis. Phylogenetic trees were constructed based on the HCV core and NS5B regions from 313 sequences. HCV sequences were classified into six subtypes, and HCV genotypes were determined with the following results: 1b in 283, 2a in 14, 3b in seven, 3a in three, 6a in five and 6u in one. Subtype 1b was the most common and accounted for approximately 90.41 % (283/313), and a virus of subtype 6u was isolated for the first time from the Chengdu area. Genotypes 4 and 5 were not detected.

Decreasing Hepatitis C Virus Infection in Thailand in the Past Decade: Evidence from the 2014 National Survey

Hepatitis C virus (HCV) infection affects ≥ 180 million individuals worldwide especially those living in developing countries. Recent advances in direct-acting therapeutics promise effective treatments for chronic HCV carriers, but only if the affected individuals are identified. Good treatment coverage therefore requires accurate epidemiological data on HCV infection. In 2014, we determined the current prevalence of HCV in Thailand to assess whether over the past decade the significant number of chronic carriers had changed. In total, 5964 serum samples from Thai residents between 6 months and 71 years of age were obtained from 7 provinces representing all 4 geographical regions of Thailand and screened for the anti-HCV antibody. Positive samples were further analyzed using RT-PCR, sequencing, and phylogenetic analysis to identify the prevailing HCV genotypes. We found that 56 (0.94%) samples tested positive for anti-HCV antibody (mean age = 36.6±17.6 years), while HCV RNA of the core and NS5B subgenomic regions was detected in 23 (41%) and 19 (34%) of the samples, respectively. The seropositive rates appeared to increase with age and peaked in individuals 41–50 years old. These results suggested that approximately 759,000 individuals are currently anti-HCV-positive and that 357,000 individuals have viremic HCV infection. These numbers represent a significant decline in the prevalence of HCV infection. Interestingly, the frequency of genotype 6 variants increased from 8.9% to 34.8%, while the prevalence of genotype 1b declined from 27% to 13%. These most recent comprehensive estimates of HCV burden in Thailand are valuable towards evidence-based treatment coverage for specific population groups, appropriate allocation of resources, and improvement in the national public health policy.

Genotypic distribution of hepatitis C virus in Thailand and Southeast Asia

The majority of hepatitis C virus (HCV) infection results in chronic infection, which can lead to liver cirrhosis and hepatocellular carcinoma. Global burden of hepatitis C virus (HCV) is estimated at 150 million individuals, or 3% of the world’s population. The distribution of the seven major genotypes of HCV varies with geographical regions. Since Asia has a high incidence of HCV, we assessed the distribution of HCV genotypes in Thailand and Southeast Asia. From 588 HCV-positive samples obtained throughout Thailand, we characterized the HCV 5’ untranslated region, Core, and NS5B regions by nested PCR. Nucleotide sequences obtained from both the Core and NS5B of these isolates were subjected to phylogenetic analysis, and genotypes were assigned using published reference genotypes. Results were compared to the epidemiological data of HCV genotypes identified within Southeast Asian. Among the HCV subtypes characterized in the Thai samples, subtype 3a was the most predominant (36.4%), followed by 1a (19.9%), 1b (12.6%), 3b (9.7%) and 2a (0.5%). While genotype 1 was prevalent throughout Thailand (27–36%), genotype 3 was more common in the south. Genotype 6 (20.9%) constituted subtype 6f (7.8%), 6n (7.7%), 6i (3.4%), 6j and 6m (0.7% each), 6c (0.3%), 6v and 6xa (0.2% each) and its prevalence was significantly lower in southern Thailand compared to the north and northeast (p = 0.027 and p = 0.030, respectively). Within Southeast Asia, high prevalence of genotype 6 occurred in northern countries such as Myanmar, Laos, and Vietnam, while genotype 3 was prevalent in Thailand and Malaysia. Island nations of Singapore, Indonesia and Philippines demonstrated prevalence of genotype 1. This study further provides regional HCV genotype information that may be useful in fostering sound public health policy and tracking future patterns of HCV spread.

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.

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

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

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

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They are phylogenetically distributed across the whole of genotype 6.

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

The genetic diversity and evolutionary history of hepatitis C virus in Vietnam

Vietnam has a unique history in association with foreign countries, which may have resulted in multiple introductions of the alien HCV strains to mix with those indigenous ones. In this study, we characterized the HCV sequences in Core-E1 and NS5B regions from 236 Vietnamese individuals. We identified multiple HCV lineages; 6a, 6 e, 6h, 6k, 6l, 6 o, 6p, and two novel variants may represent the indigenous strains; 1a was probably introduced from the US; 1b and 2a possibly originated in East Asia; while 2i, 2j, and 2m were likely brought by French explorers. We inferred the evolutionary history for four major subtypes: 1a, 1b, 6a, and 6 e. The obtained Bayesian Skyline Plots (BSPs) consistently showed the rapid HCV population growth from 1955 to 1963 until 1984 or after, corresponding to the era of the Vietnam War. We also estimated HCV growth rates and reconstructed phylogeographic trees for comparing subtypes 1a, 1b, and HCV-2.

Performance comparison of the versant HCV genotype 2.0 assay (LiPA) and the abbott realtime HCV genotype II assay for detecting hepatitis C virus genotype 6

The Versant HCV genotype 2.0 assay (line probe assay [LiPA] 2.0), based on reverse hybridization, and the Abbott Realtime HCV genotype II assay (Realtime II), based on genotype-specific real-time PCR, have been widely used to analyze hepatitis C virus (HCV) genotypes. However, their performances for detecting HCV genotype 6 infections have not been well studied. Here, we analyzed genotype 6 in 63 samples from the China HCV Genotyping Study that were originally identified as genotype 6 using the LiPA 2.0. The genotyping results were confirmed by nonstructural 5B (NS5B) or core sequence phylogenetic analysis. A total of 57 samples were confirmed to be genotype 6 (51 genotype 6a, 5 genotype 6n, and 1 genotype 6e). Four samples identified as a mixture of genotypes 6 and 4 by the LiPA 2.0 were confirmed to be genotype 3b. The remaining two samples classified as genotype 6 by the LiPA 2.0 were confirmed to be genotype 1b, which were intergenotypic recombinants and excluded from further comparison. In 57 genotype 6 samples detected using the Realtime II version 2.00 assay, 47 genotype 6a samples were identified as genotype 6, one 6e sample was misclassified as genotype 1, and four 6a and five 6n samples yielded indeterminate results. Nine nucleotide profiles in the 5' untranslated region affected the performances of both assays. Therefore, our analysis shows that both assays have limitations in identifying HCV genotype 6. The LiPA 2.0 cannot distinguish some 3b samples from genotype 6 samples. The Realtime II assay fails to identify some 6a and all non-6a subtypes, and it misclassifies genotype 6e as genotype 1.

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.

Epidemiological characteristics and genotype distribution of hepatitis C virus in Guangxi

AIM: To investigate the distribution characteristic of HCV genotypes in Guangxi, and to explore the correlations of ethnicity, gender, age, route of infection and HCV-RNA load with HCV genotypes.

METHODS: The NS5B region was amplified from 137 HCV-RNA positive serum samples and sequenced. The sequences obtained were compared with the sequences deposited in Genebank to construct a HCV NS5B phylogenetic tree.

RESULTS: The major genotype of HCV in Guangxi was 1b (58.4%), followed by 6a (12.4%), 3b (10.2%), 1a (7.3%), 2a (7.3%), and 3a (4.4%). There were no significant correlations between HCV genotype and ethnicity or gender (P > 0.05 for both). Significant correlations were found between HCV genotype and age, route of infection and HCV-RNA load (P < 0.05 for all).

CONCLUSION: Accurate HCV genotypes and subgenotypes can be obtained by establishing a phylogenetic tree of the HCV NS5B region. At least seven subgenotypes were detected in Guangxi and the main genotypes are 1b, 6a and 3b. Compared with previous reports, our results indicated that the prevalence of genotype 1b seems to decline, and the prevalence of 6a tends to increase gradually. Genotypes 3 and 6a were mainly found in young intravenous drug users. The distribution of HCV genotypes changes with the change in the route of infection.

Hepatitis C virus genotype 6: virology, epidemiology, genetic variation and clinical implication

Hepatitis C virus (HCV) is a serious public health problem affecting 170 million carriers worldwide. It is a leading cause of chronic hepatitis, cirrhosis, and liver cancer and is the primary cause for liver transplantation worldwide. HCV genotype 6 (HCV-6) is restricted to South China, South-East Asia, and it is also occasionally found in migrant patients from endemic countries. HCV-6 has considerable genetic diversity with 23 subtypes (a to w). Although direct sequencing followed by phylogenetic analysis is the gold standard for HCV-6 genotyping and subtyping, there are also now rapid genotyping tests available such as the reverse hybridization line probe assay (INNO-LiPA II; Innogenetics, Zwijnaarde, Belgium). HCV-6 patients present with similar clinical manifestations as patients infected with other genotypes. Based on current evidence, the optimal treatment duration of HCV-6 with pegylated interferon/ribavirin should be 48 wk, although a shortened treatment duration of 24 wk could be sufficient in patients with low pretreatment viral load who achieve rapid virological response. In addition, the development of direct-acting antiviral agents is ongoing, and they give high response rate when combined with standard therapy. Herein, we review the epidemiology, classification, diagnosis and treatment as it pertain to HCV-6.

Transmission dynamics of hepatitis C virus among intra venous drug users in the border state of Manipur, India

Intra venous drug users (IVDUs) are at high risk for hepatitis C virus (HCV) infection owing to their high rate of drug abuses. The north-eastern part of India has a high prevalence of IVDUs with Manipur being the worst hit state. The aim of the study was to document the molecular epidemiology, the patterns of HCV transmission, genomic variation and recombination events within HCV genome among IVDUs of Manipur, India. 91 anti-HCV sero-reactive blood samples were collected from IVDUs in Manipur. The samples were processed for RNA extraction, nested RT-PCR, sequencing and quantitative viral RNA estimation. Phylogeographic analysis of the sequenced core and NS5B regions of HCV genome was performed to determine the probable transmission route and recombinant HCV strains. 83 out of 91 anti-HCV seropositive samples were RNA positive (91.20%) based on 5'UTR of HCV genome by nested RT-PCR. Of the RNA positive samples, 73 paired partial core and NS5B gene were sequenced. Three major genotype and eight subtypes were detected while no recombinant strains were found. Individuals with genotype 1 had the mean viral load (5.94 ± 0.705 log10IU/ml) followed by genotype 3 (4.91 ± 0.49 log10IU/ml) and 6 (3.96 ± 0.32 log10IU/ml). The viral load was statistically significant among the male individuals at 4.822 ± 1.36 log10IU/ml compared to 4.767 ± 0.49 log10IU/ml for females (t=3.249, p<0.005). The phylogeographic results indicated 3b, 6h originated from Vietnam, 1a had Indian origin, 3a, 6k originated from southern China while 1b originated from Myanmar, respectively. The incidence of eight different subtypes in Manipur reflects the transmission of these strains from the "Golden Triangle" drug trafficking regions. Sequence analysis confirmed the transmission routes of HCV, which is linked to China and Vietnam for the newly emergent genotype 6 in north-eastern India.

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.

Hepatitis C virus genotype diversity among intravenous drug users in Yunnan Province, Southwestern China

Background

Recently, high proportions (15.6%–98.7%) of intravenous drug users (IDUs) in China were found to be positive for hepatitis C virus (HCV). Yunnan Province is located in southwestern China and borders one of the world's most important opium-producing regions, thus it is an important drug trafficking route to other regions of China.

Methodology/Principal Findings

Here, we assessed 100 HCV-positive plasma samples from IDUs who were enrolled through the Kunming Center for Disease Control and Prevention in 2012. HCV C/E1 fragments were PCR-amplified and sequenced. We identified eight HCV subtypes (1a, 1b, 3a, 3b, 6a, 6n, 6u and 6v), of which genotype 6 was most predominant (frequency, 47%) followed by genotypes 3 (41%) and 1 (12%). HCV subtypes 6n (30%) and 3b (29%) were most common and were identified in 59% of the IDUs. We compared HCV genotypes among IDUs in Yunnan Province with those from other regions and found that the distribution patterns of HCV genotypes in Yunnan Province were similar to those in southern China, but different from those in eastern China. However, the distribution patterns of HCV subtypes varied among Yunnan Province and southern China, despite the shared similar genotypes. A comparison of the current data with those previously reported showed that the frequency of HCV genotype 6 increased from 25% to 47% within 5 years, especially subtypes 6a (5% to 15%) and 6n (11.2% to 30%). In contrast, the frequencies of subtypes 3b and 1b decreased by almost 50% within 5 years.

Conclusion/Significance

Our results provided further information to support the assertion that drug trafficking routes influence HCV transmission patterns among IDUs in Yunnan Province. The frequency of HCV genotypes and subtypes changed rapidly among IDUs in Yunnan Province and subtypes 6a and 6n may have originated in Vietnam and Myanmar, respectively.

Molecular epidemiology and genetic history of hepatitis C virus subtype 3a infection in Thailand

OBJECTIVE

Among all hepatitis C virus (HCV) infections, subtype 3a is the most common genotype in Thailand. This study investigates the molecular epidemiology and epidemic history of HCV subtype 3a in Thailand.

METHODS

Three hundred and fifty-six serum samples were collected from HCV-infected Thai patients. The virus was isolated, after which the core and NS5B regions were sequenced. Subsequently, the HCV genotype was classified by phylogenetic analysis based on the core and NS5B regions. Molecular evolution analysis of HCV subtype 3a was estimated using BEAST (Bayesian Evolutionary Analysis by Sampling Trees) v.1.5.4.

RESULTS

Based on our phylogenetic analyses, subtype 3a (38.5%) was the most prevalent, followed by 1a (21%), 1b (13.8%), genotype 6 (19.9%) [comprised of subtypes 6e (0.3%), 6f (11%), 6i (1.9%), 6j (1.9%) and 6n (4.8%)] and 3b (5.6%). Our phylogenetic tree indicates the existence of a specific group of HCV subtype 3a strains in the Thai population. Molecular evolutionary analysis dated the most recent common ancestor of the Thai HCV subtype 3a strains as existing approximately 200 ago, and a Bayesian skyline plot showed that this particular strain spread to Thailand during the mid-1970s and early 1980s. This period overlaps with the Vietnam War (1955-1975) and the widespread use of injection stimulants introduced by the US Army during this time.

CONCLUSION

The estimated history of HCV subtype 3a infection in Thailand may help to predict the future burden of HCV-related diseases and facilitate better public health control and surveillance.

Prevalence of hepatitis C and B virus among patients infected with HIV: a cross-sectional analysis of a large HIV care programme in Myanmar

Co-infection with the hepatitis C virus (HCV) and/or hepatitis B virus (HBV) influences the morbidity and mortality of patients with HIV. A cross sectional analysis was of 11,032 HIV-infected patients enrolled in the Integrated HIV Care Program from May 2005 to April 2012 and Epi-info 3.5 was used to determine the serological prevalence of chronic hepatitis B and hepatitis C. The mean ± standard deviation age of patients was 36 ± 8.4 years (adult cohort) and 7 ± 3 years (paediatric cohort). The sero prevalence of hepatitis B surface antigen, hepatitis C (anti HCV antibodies) and triple infection are 8.7%, 5.3% and 0.35%, respectively. Men who have sex with men are at the highest risk of being co-infected with hepatitis B while intravenous drug users are at the highest risk of being co-infected with hepatitis C. It is important to screen for hepatitis B and C in HIV infected people in order to provide quality care for HIV patients with co-infection.

Systematic review: Asian patients with chronic hepatitis C infection

BACKGROUND

Chronic hepatitis C (CHC) infection is a risk factor for both the development of end-stage liver disease and hepatocellular carcinoma (HCC). Globally, approximately 170 million people are chronically infected with the hepatitis C virus (HCV), and the majority of these individuals come from the western Pacific and Southeast Asia regions (94.6 million persons combined). CHC is an understudied and underappreciated health problem in many Asian countries and in the US, where Asians represent one of the fastest growing groups of new Americans.

AIM

To perform a systematic review of the current literature on the epidemiology, diagnosis and screening, clinical characteristics and response to anti-viral therapy of Asians with CHC.

METHODS

Using a PubMed search of 'hepatitis C' and 'Asia,' 341 original manuscripts published in peer-reviewed journals were identified, and 99 were selected based on their relevance.

RESULTS

Many Asian CHC patients do not have easily identifiable risk factors and may be underdiagnosed. Rates of HCV infection in Asians on community screening in the US are unexpectedly high, and there is a high prevalence of HCV genotype 6 in Southeast Asia and Southern China. HCV-infected Asians tend to present at older age and may have higher risk of HCC; however, they respond better to anti-viral therapy than non-Asians across all HCV genotypes.

CONCLUSIONS

Given the high HCV endemicity in Asia, lack of identifiable risk factors and favourable treatment response rates in Asians, we advocate the screening for HCV infection of all Asians who come from areas where HCV prevalence is ≥2%.

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 randomized trial of 48 versus 24 weeks of combination pegylated interferon and ribavirin therapy in genotype 6 chronic hepatitis C

BACKGROUND & AIMS

Genotype 6 chronic hepatitis C (HCV) is encountered predominantly in Southeast Asia and data on optimal treatment strategy is limited. This study was aimed at assessing the rate and predictors of sustained virological response (SVR) in genotype 6 chronic HCV following 48 and 24 weeks of pegylated interferon and ribavirin therapy.

METHODS

This investigator-initiated, open-label randomized trial was conducted in Vietnam between 2008 and 2010. One hundred and five treatment-naïve HCV genotype 6 patients were randomized to either 48-week (N=70) or 24-week (N=35) duration of pegylated interferon (PEG-IFN) alfa-2a 180 mcg/week and ribavirin (RBV) 15mg/kg/day; 92 patients completed the study (63 in the 48-week and 29 in the 24-week group, respectively). Primary outcome was sustained virological response (SVR) as intention-to-treat analysis.

RESULTS

There was no statistical difference in SVR between 48-week and 24-week treated groups (71% vs. 60%, respectively; p=0.24). In the 48-week and 24-week treatment groups, 81% and 80% of cases achieved rapid virological response (RVR) (p=0.86), and 86% and 80% achieved complete early virological response (p=0.45). Among those patients with RVR, SVR was in 86% (48-weeks), and 75% (24-weeks) of cases, whereas following non-RVR, only 8% of cases had an SVR with 48-week treatment duration.

CONCLUSIONS

Overall, RVR was achieved in the majority of genotype 6 patients and, in those patients, similar and high rates of SVR were noted following 24-week and 48-week therapy. This observation, however, needs validation in a larger study to demonstrate non-inferiority of the shorter duration therapy. In non-RVR patients, even 48-week therapy achieved low SVR rates.

The effects of widespread methadone treatment on the molecular epidemiology of hepatitis C virus infection among injection drug users in Hong Kong

The distribution of HCV genotypes among injection drug users in Hong Kong was assessed in context of methadone treatment availability. Three time periods were defined by the year of initiating injection-on or before 1980, 1981-1994, and 1995-2006-with methadone becoming widely available since the second period. Of the 273 HCV RNA-positive cases, the most prevalent subtype was HCV 6a (52.4%), followed by HCV 1b (38.5%). The new variants of HCV subtypes 6e and 6h were detected. Both subtypes 1b and 6a were prevalent among older injectors, while subtype 3a was more common in young injectors and those initiating injection recently during the third time period. Age (P < 0.05) and recent injection frequency (P < 0.01) were independently associated with HCV 6a infection. Subtype 1b was predominant in the first period, whereas 6a was more common in the second and third. Subtype 1b sequences appeared to have originated at two positions on the phylogenetic tree, while 6a showed a more disperse distribution suggestive of multiple introductions. Phylogenetic analysis on the NS5B region did not reveal specific clustering of any subtype/genotype. Overall, there was no suggestion of outbreaks of HCV. The extensive use of methadone may have protected Hong Kong from the emergence of HCV clusters among injection drug users.

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

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

Systematic review: epidemiology of hepatitis C genotype 6 and its management

BACKGROUND

Hepatitis C virus (HCV) genotype 6 is common among patients from Southeast Asia and the surrounding regions, where HCV prevalence is also high. HCV genotype 6 has great genetic diversity and different response to antiviral therapy compared with the more commonly known genotype 1.

AIM

Our goal was to provide a systematic review of the current literature on the epidemiology, classification and treatment of HCV genotype 6.

METHODS

A search using PubMed for 'hepatitis C' AND 'genotype 6' produced a total of 47 articles, of which 33 articles were found to be relevant and included in this review. Additional articles were identified using the reference lists of these 33 primary articles.

RESULTS

The prevalence of HCV genotype 6 is estimated to be as high as 50% in some regions of Southeast Asia with demonstrated significance among intravenous drug users and thalassemia major patients. Although previous line probe assays may have misclassified HCV genotype 6 as genotype 1, newer line probe assays can more accurately and reliably determine HCV genotype. Patients infected with HCV genotype 6 respond better to interferon-based therapy compared with those infected with genotype 1, although patient baseline clinical characteristics and side effect profiles are similar between HCV genotype 6 and other HCV genotypes.

CONCLUSIONS

Future studies should seek to clarify issues regarding early predictors for treatment response in patients with HCV genotype 6, and the impact of ethnic and genotypic factors to treatment response in HCV genotype 6 patients.

Randomized controlled trial of pegylated interferon-alfa 2a and ribavirin in treatment-naive chronic hepatitis C genotype 6

Hepatitis C virus (HCV) genotype is an important criteria in determining duration of therapy and predictor of sustained virologic response (SVR) to pegylated interferon (PEG IFN) and ribavirin (RBV) therapy. Optimal duration of therapy for patients with HCV genotype 6 is not known. We conducted a multicenter, open-label randomized controlled trial of patients with HCV genotype 6 at five gastroenterology clinics in the western U.S. Patients were stratified by viral load and histologic stage and assigned to receive PEG IFN-α2a 180 μg subcutaneously weekly and weight-based oral RBV 800 to 1,200 mg daily for 24 or 48 weeks. Primary outcome measurement was SVR rate by intention-to-treat analysis. From February 2005 to October 2007 a total of 60 patients (age 51 ± 10 years, 47% male, log HCVRNA 6.3 ± 1.1 IU/mL) were enrolled: 27 patients to 24 weeks and 33 patients to 48 weeks of therapy. In the 24-week and 48-week groups, 96% and 97% achieved early virologic response (P = 0.90); 89% versus 94% achieved end of therapy virologic response (P = 0.48). SVR was achieved in 70% versus 79% of patients assigned to 24 weeks versus 48 weeks (P = 0.45). Rapid virologic response (RVR) was a significant predictor of SVR in the 48-week group and trending towards significance in the 24-week group: 82% and 83% of those with RVR achieved SVR versus 33% and 29% for the 24-week and 48-week groups, respectively (P = 0.07 and P = 0.02).

CONCLUSION

There was no significant difference in SVR rates in patients with HCV genotype 6 treated with PEG IFN-α2a and RBV for 24 versus 48 weeks.

Response to pegylated interferon and ribavirin in Asian American patients with chronic hepatitis C genotypes 1 vs 2/3 vs 6

Chronic hepatitis C is generally underappreciated in Asian Americans, and most pivotal studies were conducted in western countries and only included a small numbers of Asian patients. Our goal was to examine and compare treatment outcomes in these patients with genotypes 1 vs 2/3 vs 6. We performed a retrospective cohort study of 167 consecutive treatment-naïve Asian American patients treated with pegylated interferon (PEG IFN) plus ribavirin (RBV) at two community clinics in Northern California from 12/00 to 1/08. Primary outcome was sustained virological response rate by intention-to-treat analysis. The overall completion rate was 76%, and treatment adherence (completion of ≥ 75-80% PEG IFN + RBV dose for ≥ 75-80% of intended duration) was 74%. Significant depression was noted in only 4% of patients. Sustained virologic response in patients with genotype 6 treated for 48 weeks was similar to that seen in those with genotype 2/3 (74%vs 75%, P = 0.89) and significantly higher than those with genotype 1 (74%vs 49%, P = 0.016). On multivariate analysis inclusive of sex, age, body mass index (≤ 25 vs > 25) and viral load, only treatment adherence and genotype (2/3 and 6 treated for 48 weeks) were found to be significant predictors of sustained virologic response. We conclude that significant depression is rare in Asian American patients (4%). Patients with genotype 6 treated for 48 weeks appear to have a similar treatment response rate as patients with genotype 2/3 and a significantly higher response rate than those with genotype 1.

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.