Detection and clinical features of hepatitis C virus type 6 infections in blood donors from Hong Kong

Construction and characterization of a new hepatitis C virus genotype 6a subgenomic replicon that is prone to render the sofosbuvir resistance

Hepatitis C virus (HCV) infection remains a challenge to human public health despite the development of highly effective direct-acting antivirals (DAAs). Sofosbuvir (SOF), a key component in most DAA-based anti-HCV cocktail regimens, is a potent viral RNA polymerase (NS5B) inhibitor with a high barrier to drug resistance. The serine-to-threonine mutation at NS5B 282 (S282T) confers the SOF resistance, but severely impairs viral replication in most HCV genotypes (GTs) and cannot be stably maintained after the termination of the SOF-based therapies. In this study, we first developed a new HCV GT-6a subgenomic replicon PR58D6. Next, we selected SOF-resistant PR58D6 variants by culturing the replicon cells in the presence of SOF. Interestingly, unlike many other HCV replicons which require additional mutations to compensate for the S282T-inducing fitness loss, S282T alone in PR58D6 is genetically stable and confers the SOF resistance without significantly impairing viral replication. Furthermore, we showed that amino acid residue at NS5B 74 (R74) and 556 (D556) which are conserved in GT 6a HCV contribute to efficient replication of PR58D6 containing S282T. Finally, we showed that the G556D mutation in NS5B could rescue the replication deficiency of the S282T in JFH1, a GT-2a replicon. In conclusion, we showed that a novel GT-6a HCV replicon may easily render SOF resistance, which may call for attention to potential drug resistance during DAA therapies of HCV GT-6a patients.

Achieving WHO target of HCV control in Hong Kong: challenges and strategies

With the introduction of effective directly acting antiviral agents (DAAs) therapy, control and elimination of hepatitis C virus (HCV) infection is becoming a feasible goal. In Hong Kong, HCV prevalence in general population is 0.3%-0.5% over the past decades. However, like other high-income areas/countries, high prevalence of HCV infection has been found in several population groups, such as people who inject drugs (PWID), patients undergoing dialysis, and human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/ AIDS) patients. Based on the epidemiological study using data retrieved from the Hong Kong HCV Registry from January 2005 to March 2017, the estimated territory-wide diagnosis rate and treatment rate of HCV infection were only 50.9% and 12.4%, respectively. Although these rates was comparable to many developed countries/areas, the performances remained substantially below 90% and 80%, the 2030 targets proposed by World Health Organization (WHO). In recognition of the challenges, the Hong Kong Government set up the Steering Committee on Prevention and Control of Viral Hepatitis (SCVH) which formulated the Hong Kong Viral Hepatitis Action Plan 2020-2024. The Action Plan adopts four key strategies, as described in the WHO framework for global action, namely, awareness, surveillance, prevention and treatment. With the effective implementation of the Action Plan, especially in targeted screening of high-risk populations and more generalized use of the highly efficacious DAAs for all diagnosed HCV subjects, the goals of reducing HCV transmission and HCV-related morbidity and mortality can be achieved in Hong Kong by 2030.

Use of glecaprevir/pibrentasvir in patients with chronic hepatitis C virus infection and severe renal impairment

Background/Aims

Data on treatment efficacy and safety of glecaprevir/pibrentasvir (GLE/PIB) for chronic hepatitis C virus (HCV) infection in Asian patients with severe renal impairment are limited. This study aimed to study the treatment and side effects of GLE/PIB in these patients infected with non-1 genotype (GT) HCV.

Methods

We prospectively recruited patients with Child’s A cirrhosis and eGFR <30 mL/min/1.73 m² in Hong Kong and Taiwan during 2017–2018 to receive GLE/PIB treatment.

Results

Twenty-one patients (GT2, n=7; GT3, n=6; and GT6, n=8) received GLE/PIB for 11.2±1.8 weeks. All except one were treatment-naïve. GLE/PIB was initiated in 16 patients while on dialysis (seven on peritoneal dialysis [PD] and nine on hemodialysis) and in five patients before dialysis. One patient died of PD-related peritonitis during treatment and two were lost to follow up. The SVR12 rate in the remaining 18 patients was 100%. All patients achieved undetectable levels at 4-, 12-, 24- and 48-week after treatment. Patients with deranged alanine aminotransferase showed normalization after 4 weeks and the response was sustained for 48 weeks. No significant adverse event was observed.

Conclusions

GLE/PIB treatment was associated with high efficacy and tolerability in HCV-infected patients with severe renal impairment.

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.

HCV Genotype 6a Escape From and Resistance to Velpatasvir, Pibrentasvir, and Sofosbuvir in Robust Infectious Cell Culture Models

BACKGROUND & AIMS

Chronic liver diseases caused by hepatitis C virus (HCV) genotype 6 are prevalent in Asia, and millions of people require treatment with direct-acting antiviral regimens, such as NS5A inhibitor velpatasvir combined with the NS5B polymerase inhibitor sofosbuvir. We developed infectious cell culture models of HCV genotype 6a infection to study the effects of these inhibitors and the development of resistance.

METHODS

The consensus sequences of strains HK2 (MG717925) and HK6a (MG717928), originating from serum of patients with chronic HCV infection, were determined by Sanger sequencing of genomes amplified by reverse-transcription polymerase chain reaction. In vitro noninfectious full-length clones of these 6a strains were subsequently adapted in Huh7.5 cells, primarily by using substitutions identified in JFH1-based Core-NS5A and Core-NS5B genotype 6a recombinants. We studied the efficacy of NS5A and NS5B inhibitors in concentration-response assays. We examined the effects of long-term culture of Huh7.5 cells incubated with velpatasvir and sofosbuvir singly or combined following infection with passaged full-length HK2 or HK6a recombinant viruses. Resistance-associated substitutions (RAS) were identified by Sanger and next-generation sequencing, and their effects on viral fitness and in drug susceptibility were determined in reverse-genetic experiments.

RESULTS

Adapted full-length HCV genotype 6a recombinants HK2cc and HK6acc had fast propagation kinetics and high infectivity titers. Compared with an HCV genotype 1a recombinant, HCV genotype 6a recombinants of strains HK2 and HK6a were equally sensitive to daclatasvir, elbasvir, velpatasvir, pibrentasvir, and sofosbuvir, but less sensitive to ledipasvir, ombitasvir, and dasabuvir. Long-term exposure of HCV genotype 6a-infected Huh7.5 cells with a combination of velpatasvir and sofosbuvir resulted in clearance of the virus, but the virus escaped the effects of single inhibitors via emergence of the RAS L31V in NS5A (conferring resistance to velpatasvir) and S282T in NS5B (conferring resistance to sofosbuvir). Engineered recombinant genotype 6a viruses with single RAS mediated resistance to velpatasvir or sofosbuvir. HCV genotype 6a viruses with RAS NS5A-L31V or NS5B-S282T were however, able to propagate and escape in Huh7.5 cells exposed to the combination of velpatasvir and sofosbuvir. Further, HCV genotype 6a with NS5A-L31V was able to propagate and escape in the presence of pibrentasvir with emergence of NS5A-L28S, conferring a high level of resistance to this inhibitor.

CONCLUSIONS

Strains of HCV genotype 6a isolated from patients can be adapted to propagate in cultured cells, permitting studies of the complete life cycle for this important genotype. The combination of velpatasvir and sofosbuvir is required to block propagation of original HCV genotype 6a, which quickly becomes resistant to single inhibitors via the rapid emergence and persistence of RAS. These features of HCV genotype 6a could compromise treatment.

Impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott RealTime HCV Genotype II assay for hepatitis C genotyping

The Abbott RealTime HCV Genotype II assay (Abbott-RT-HCV assay) is a real-time PCR based genotyping method for hepatitis C virus (HCV). This study measured the impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott-RT-HCV assay. 517 samples were genotyped using the Abbott-RT-HCV assay over a one-year period, 34 (6.6%) were identified as HCV genotype 1 without further subtype designation raising the possibility of inaccurate genotyping. These samples were subjected to confirmatory sequencing. 27 of these 34 (79%) samples were genotype 1b while five (15%) were genotype 6. One HCV isolate was an inter-genotypic 1a/4o recombinant. This is a novel natural HCV recombinant that has never been reported. Inter-genotypic recombination and probe cross-reactivity can affect the accuracy of the Abbott-RT-HCV assay, both of which have significant implications on antiviral regimen choice. Confirmatory sequencing of ambiguous results is crucial for accurate genotyping.

24 versus 48 Weeks of Peginterferon Plus Ribavirin in Hepatitis C Virus Genotype 6 Chronically Infected Patients with a Rapid Virological Response: A Non-Inferiority Randomized Controlled Trial

Objectives

The optimal treatment of hepatitis C virus (HCV) genotype 6 is unclear owing to its limited geographic distribution. Because of a high predictive value of rapid virological response (RVR) for sustained virological response (SVR), we conducted an open-label randomized controlled trial to compare 24- and 48-week peginterferon/ribavirin combination therapy for patients with HCV genotype 6 in Southern China who achieved an RVR.

Methods and Findings

Treatment-naive, non-cirrhotic patients with chronic hepatitis C genotype 6 were treated with pegylated interferon α-2a (180 μg/week) and ribavirin (800–1,200 mg, according to weight) for 4 weeks. Patients who achieved an RVR, which was defined as HCV RNA negativity at week 4 (<50 IU), were randomized to receive either an additional 20 or 44 weeks of treatment (24- and 48-week treatment groups, respectively). The primary outcome measure was SVR. From January 2011 to June 2014, 152(152/210, 72.4%) patients with HCV genotype 6a and RVR were randomized 1:1 to the 24- or 48-week treatment group. The SVR rates in the 24- and 48-week groups in the intention-to-treat analysis were 90.8% (69/76) and 88.2% (67/76), respectively; those in the per-protocol analysis were 95.7% (67/70) and 97.0% (64/66), respectively. More patients in the 48-week group had anemia (46.1% vs. 28.9%, P = 0.03), but other adverse events were comparable between the groups. The limitation of the present study was that only patients from Southern China were enrolled which may inhibit the extensive application of the findings.

Conclusion

Twenty-four weeks of peginterferon/ribavirin combination therapy was non-inferior to 48 weeks in patients with HCV genotype 6a in Southern China who achieved an RVR.

Trial Registration

ClinicalTrials.gov NCT01263860

The full-length genome sequences of nine HCV genotype 4 variants representing a new subtype 4s and eight unclassified lineages

We characterized the full-length genomes for nine novel variants of HCV genotype 4 (HCV-4), representing a new subtype 4s and eight unclassified lineages. They were obtained from patients who resided in Canada but all had origins in Africa. An extended maximum clade credibility (MCC) tree was reconstructed after the inclusion of 30 reference sequences. It differentiated 18 assigned subtypes and 10 unclassified lineages within HCV-4. Similar analysis of 102 partial NS5B sequences resulted in another MCC tree that revealed 22 assigned subtypes (4a-4t, 4w, and 4v) and 30 unclassified lineages at the subtype level. Our study shows that HCV-4 is taxonomically complex and it displays high genetic diversity to support an African origin.

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.

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%.

Chronic hepatitis C genotype 6 responds better to pegylated interferon and ribavirin combination therapy than genotype 1

BACKGROUND AND AIMS

Chronic hepatitis C genotype 6 is common in Hong Kong, especially among i.v. drug abusers. Responses of these patients to combination of pegylated interferon and ribavirin treatment were inconsistent and the numbers of patients involved in previous studies were small. We performed a retrospective study to compare the therapeutic responses of this regimen in patients infected with genotype 6 and genotype 1.

METHODS

Seventy patients with either genotype 6 or genotype 1 were recruited. Both groups received 800-1200 mg of ribavirin daily plus either 180 mg of pegylated alpha-interferon-2a or 1.5 mg/kg pegylated alpha-interferon-2b weekly for 48 weeks. Their responses to treatments were compared.

RESULTS

The early virological response to combination therapy of patients with genotype 6 was significantly better than that of genotype 1 (88.6% vs 74.3%, P = 0.03). Significant difference was also identified in the end of treatment response of the two genotypes (60% vs 81.4% for genotype 1 and 6, respectively; P = 0.005). The sustained virological response (SVR) to treatment in patients with genotype 6 was also significantly superior to that of patients with genotype 1 (75.7% vs 57.1%, P = 0.02). Multiple logistic regression analysis demonstrated that age of 55 years or less, genotypes of hepatitis C virus, liver biopsy staging and baseline hepatitis C virus RNA of 200,000 IU/mL or less were independent predictors for better SVR in this cohort.

CONCLUSION

Patients with chronic hepatitis C genotype 6 respond better to pegylated interferon and ribavirin combination treatment than patients with genotype 1.

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

Abstract Hepatitis C virus (HCV) genotypes 4, 5 and 6 represent >20% of all HCV cases worldwide. HCV-4 is mainly seen in Egypt, where it represents 90% of all HCV cases. Antischistosomal therapy was the main cause of contamination there, followed by procedures performed by informal providers and traditional healers such as dental care, wound treatment, circumcision, deliveries, excision and scarification. It is also highly prevalent in sub-Saharan Africa and in the Middle East. In Europe, its prevalence has recently increased particularly among intravenous drug users and in immigrants. HCV-5 is mainly found in South Africa, where it represents 40% of all HCV genotypes, but four pockets of HCV-5 were found in France, Spain, Syria and Belgium and sporadic cases were found elsewhere. The mode of transmission is mainly iatrogenic and transfusion. HCV-6 is found in Hong Kong, Vietnam, Thailand and Myanmar and also in American and Australian from Asian origin. The response to treatment in HCV-4 is intermediate between HCV-1 and HCV-2 and HCV-3. A sustained viral response is achieved in 43-70% with pegylated interferon and ribavirin. It is higher in Egyptians than Europeans and Africans and is negatively related to insulin resistance and to the severity of fibrosis. It increases to >80% with 24 weeks of therapy only if a rapid virological response is achieved. In HCV-5, a sustained virological response is achieved in >60% with 48 weeks of therapy. HCV-6 is also considered an easy-to-treat genotype, leading to a response in 60-85% of cases.

Genetic history of hepatitis C virus in East Asia

The hepatitis C virus (HCV), which currently infects an estimated 3% of people worldwide, has been present in some human populations for several centuries, notably HCV genotypes 1 and 2 in West Africa and genotype 6 in Southeast Asia. Here we use newly developed methods of sequence analysis to conduct the first comprehensive investigation of the epidemic and evolutionary history of HCV in Asia. Our analysis includes new HCV core (n = 16) and NS5B (n = 14) gene sequences, obtained from serum samples of jaundiced patients from Laos. These exceptionally diverse isolates were analyzed in conjunction with all available reference strains using phylogenetic and Bayesian coalescent methods. We performed statistical tests of phylogeographic structure and applied a recently developed "relaxed molecular clock" approach to HCV for the first time, which indicated an unexpectedly high degree of rate variation. Our results reveal a >1,000-year-long development of genotype 6 in Asia, characterized by substantial phylogeographic structure and two distinct phases of epidemic history, before and during the 20th century. We conclude that HCV lineages representing preexisting and spatially restricted strains were involved in multiple, independent local epidemics during the 20th century. Our analysis explains the generation and maintenance of HCV diversity in Asia and could provide a template for further investigations of HCV spread in other regions.

Chronic hepatitis C virus genotype 6 infection: response to pegylated interferon and ribavirin

BACKGROUND

To date, no study has evaluated pegylated interferon for the treatment of chronic infection with hepatitis C virus (HCV) genotype 6. We aimed to determine the efficacy of pegylated interferon plus ribavirin for treating infection with genotype 6 versus genotype 1.

METHODS

Forty-two patients chronically infected with HCV (for genotype 1, n = 21; for genotype 6, n = 21) were treated with pegylated interferon alpha-2a (n = 20) or alpha-2b (n = 22) combined with oral ribavirin for 48 weeks.

RESULTS

There was no difference between genotypes 1 and 6 in the rates of early virological response (76% vs. 81%; P > .05) and end-of-treatment response (71% vs. 81%; ). Patients infected with genotype 6 had a higher rate of sustained virological response (SVR) than did patients infected with genotype 1 (86% vs. 52%; P = .019). The overall adverse-effects profile was similar in both genotype groups. There was no significant difference in the rate of SVR between patients receiving pegylated interferon alpha-2a and those receiving alpha-2b. Multivariate analysis showed that genotype was the only significant factor associated with SVR (P = .039).

CONCLUSIONS

Treatment with pegylated interferon and ribavirin for 48 weeks resulted in a significantly higher rate of SVR in patients infected with genotype 6 than in those infected with genotype 1. Further studies are required to determine whether lower dosages and 24 weeks of therapy may be sufficient for the treatment of genotype 6 infection.

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.

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.

Hepatitis C virus genotype distribution among intravenous drug user and the general population in Hong Kong

This study describes the distribution of hepatitis C genotypes among 106 intravenous drug users and 949 non-drug users in Hong Kong. Genotypes were identified by multiplex RT-PCR targeting the core region of viral genome. The accuracy of this typing system in identifying genotypes 1b and 6a was assessed by phylogenetic analysis. The distribution of hepatitis C virus (HCV) genotypes amongst non-drug users was 63.6% for genotype 1b, 23.6% for 6a, 4.5% for 1a, 3.9% for 3a, and 3.1% for 2a; whereas amongst the intravenous drug users, it was 58.5% for genotype 6a, 33.0% for 1b, 5.7% for 3a, 0.9% for 1a, and 0.9% for 2a. The proportion of genotype 6a was significantly higher (P < 0.001), whereas that for genotype 1b was significantly lower (P = 0.001) for the intravenous drug user group. Multivariate analysis revealed significant independent associations for the distribution of HCV genotypes 1b and 6a with age, sex, and intravenous drug user status. The co-circulation of a common (1b) and a rare (6a) HCV genotype in Hong Kong provides a unique opportunity for future studies to compare their transmission efficiency, clinical course, and response to treatment.

Viral hepatitis C in Hong Kong

OBJECTIVE

Hepatitis C virus (HCV) infection can lead to serious liver disease. Its medico-socio-economic burden on society can be immense. This study investigates the epidemiology of HCV infection in Hong Kong.

METHODS

Data from the Department of Health, relevant publications from Medline search and data from two acute hospitals were reviewed.

RESULTS

The prevalence of anti-HCV among voluntary blood donors is stable, remaining at approximately 0.035-0.099% over the past 10 years, and is higher in the older age group. Among the high-risk groups, the anti-HCV prevalence is as follows: (1) hospital patients 0.8%, (2) intravenous drug users 46.0%, (3) patients infected with HIV 7.9%, (4) children with transfusion-dependent hematologic disease 16.3%, (5) patients on continuous ambulatory peritoneal dialysis 1.8%, patients on hemodialysis 16.4%, recipients of kidney transplants 6.2% and (6) patients with hepatocellular carcinoma 7.3%. Among blood donors, 58.8% were infected with HCV genotype 1b and 27.0% with genotype 6a. Genotype 6a is particularly common among intravenous drug users.

CONCLUSION

Hong Kong has a low prevalence of HCV infection. Patients are mostly infected through transfusion with blood or products prior to the introduction of anti-HCV screening to the blood transfusion service. Illicit drug use constitutes another significant risk. Since 1997, there has been a great increase in population movement between China and Hong Kong which might affect the epidemiology of HCV infection.

Response to combined interferon and ribavirin is better in patients infected with hepatitis C virus genotype 6 than genotype 1 in Hong Kong

Data on the treatment efficacy of interferon (IFN)-alpha and ribavirin in patients with chronic hepatitis infected with hepatitis C virus (HCV) of genotype 6 are lacking. A study has been reported from Hong Kong which compared the treatment efficacy of IFN-alpha and ribavirin in the treatment of chronic HCV infection with genotypes 1 and 6. Twenty-four patients with HCV genotype 1 and 16 patients with HCV genotype 6 were studied. The baseline demographic data including median age, gender ratio, alanine aminotransferase levels, bilirubin levels, HCV RNA levels and histological scores were comparable between the two groups of patients. All patients received IFN-alpha 5 million units three times per week and ribavirin (1,000 mg for those weighing </=75 kg and 1,200 mg for those weighing >75 kg) for 1 year. Patients infected with HCV genotype 6 achieved virological response significantly higher than those with HCV genotype 1 (67 vs. 33% at week 24, p = 0.02; 75 vs. 42% at the end of treatment, p = 0.05; 63 vs. 29% at 6 months after completion of treatment, p = 0.04). Histological improvement in inflammatory activity and fibrosis in the liver were observed in 25% and 25% of patients infected with HCV genotype 6 in contrast to only 13 and 8% in patients infected with HCV genotype 1; however, the differences were not statistically significant. In conclusion, patients with HCV genotype 6 gain a better response to combined treatment with IFN-alpha and ribavirin than those with HCV genotype 1 and achieve a significantly higher rate of sustained virological response.

Hepatitis C virus genotype distribution in China: predominance of closely related subtype 1b isolates and existence of new genotype 6 variants

To determine hepatitis C virus (HCV) genotype distribution in China, a total of 148 HCV RNA positive serum samples were collected from nine geographic areas and subjected to RT-PCR followed by direct DNA sequencing and phylogenetic analysis of the core, E1, and NS5B regions. HCV was genotyped in 139 (93.9%) samples. Among them subtype 1b was the most predominant [66% (92/139)] followed by 2a [14% (19/139)]. Of 92 subtype 1b isolates, 35 (38%) and 30 (33%) formed two clusters, designated groups A and B. Group A was prevalent throughout China, while group B was predominant in the central and southern regions. In three cities in the Pearl River Delta, subtype 6a replaced 2a as the second most predominant subtype, and in Kunming (southwest) multiple HCV genotypes/subtypes were present. New variants of HCV genotype 6 were discovered in three samples from Kunming and one in Guangzhou in the Pearl River Delta.

Molecular characterization of human immunodeficiency virus type 1 and hepatitis C virus in paid blood donors and injection drug users in china

China is facing a rapid upsurge in cases of human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) infection due to large numbers of paid blood donors (PBD), injection drug users (IDU), and sexual partners of infected individuals. In this report, a total of 236 HIV-1-positive blood samples were collected from PBD, IDU, and their sexual partners in the most severely affected provinces, such as Henan, Yunnan, Guangxi, and Xinjiang. PCR was used to amplify the p17 region of gag and the C2-V3 region of env of HIV-1 and the 5' noncoding region and a region of E1/E2 of HCV. Genetic characterization of viral sequences indicated that there are two major epidemics of HIV-1 and multiple HCV epidemics in China. The PBD and transfusion recipients in Henan harbored HIV-1 subtype B', which is similar to the virus found in Thailand, and HCV genotypes 1b and 2a, whereas the IDU in Yunnan, Guangxi, and Xinjiang carried HIV-1 circulating recombinant forms 07 and 08, which resemble those in India, and HCV genotypes 1b, 3a, and 3b. Our findings show that the epidemics of HIV-1 and HCV infection in China are the consequences of multiple introductions. The distinct distribution patterns of both the HIV-1 and HCV genotypes in the different high-risk groups are tightly linked to the mode of transmission rather than geographic proximity. These findings provide information relevant to antiviral therapy and vaccine development in China and should assist public health workers in implementing measures to reduce the further dissemination of these viruses in the world's most populous nation.

HCV serotypes in Brazilian patients

OBJECTIVE

To investigate the prevalence of the different types of hepatitis C virus (HCV) in a population of chronic HCV carriers using the Murex HCV serotyping 1-6 assay.

METHODS

All serum samples from these patients had a positive nested PCR HCV reaction. The sera were submitted to ELISA, modified, for the identification of antibodies against HCV serotypes 1, 2, 3, 4, 5 and 6 (Murex HCV serotyping 1-6 assay).

RESULTS

The viral serotype was identified in 166 (75.8%) of the 219 patients, 108 (65.11%) males and 58 (34.9%) females. Patient age ranged from 12 to 73 years, with a mean of 41.1 years. The form of acquisition of the disease most frequently reported was blood transfusion. The results showed a predominance of type 1 (70.0%), followed by type 3 (22.3%) and type 2 (4.2%).

CONCLUSION

Samples presenting low and very close optical density readings may lead to discrepant diagnoses concerning HCV serotypes and should be confirmed by genotyping. The serotyping can be useful in clinical practice and can be of help in establishing the prognosis of the disease, also favoring epidemiologic studies independently of the technology required for genotyping tests.

Hepatitis C virus infection and genotypes among human immunodeficiency virus high-risk groups in Cameroon

Parenteral transmission of HCV is well established but other possible routes such as heterosexual transmission are still questioned. The Central African region is characterised by a high HCV endemicity without any evidence on the route of transmission. The information on HCV genotypes that circulate in this area is also limited and controversial. HIV infection is very frequent in this region and mostly acquired via the heterosexual route. The aim of this work was to investigate the trend of HCV infection and genotypes among HIV high-risk groups from Cameroon. Four hundred eighty-two patients including 229 tuberculosis clinic attendants, 184 sexually transmitted disease clinic attendants, and 69 HIV clinical suspects from another clinic were enrolled. All plasma samples were screened for antibodies to HCV and HCV RNA. Genotypes were assigned by sequencing a 5'UTR amplified fragment. The overall prevalence of HCV markers was 11.6% and a significant increasing trend with respect to age was observed. A proportion of 64.1% (34/53) of HCV antibody positive samples was viraemic. HCV RNA was found in 3 samples that were indeterminate in RIBA 3.0. One was negative in the antibody screening test and the two others were weakly positive. The data on HCV genotypes revealed that genotype 1 was involved in 57% of viraemias, genotype 2 in 24%, while genotypes 4 and 5a accounted for 16 and 3%, respectively. In contrary to the predominance of genotype 4 reported in some African countries and even the neighbouring countries, these data demonstrate clearly that HCV infection in Cameroon is dominated by genotypes 1 and 2. No association was found between the HCV markers and the presence of HIV infection. It is concluded, therefore, that the heterosexual route plays a minor role in HCV transmission in this country.

The epidemic behavior of the hepatitis C virus

Hepatitis C virus (HCV) is a leading worldwide cause of liver disease. Here, we use a new model of HCV spread to investigate the epidemic behavior of the virus and to estimate its basic reproductive number from gene sequence data. We find significant differences in epidemic behavior among HCV subtypes and suggest that these differences are largely the result of subtype-specific transmission patterns. Our model builds a bridge between the disciplines of population genetics and mathematical epidemiology by using pathogen gene sequences to infer the population dynamic history of an infectious disease.

HCV infection in northeastern Brazil: unexpected high prevalence of genotype 3a and absence of African genotypes

The genomic diversity of HCV embraces 6 genotypes and at least 52 subtypes with clinical and epidemiological correlations. There is a paucity of studies assessing HCV genotypes and biomolecular epidemiology in Brazil. We studied genotype distribution and epidemiological aspects in 232 HCV carriers, 133 (57.9%) males and 99 (42.1%) females, followed in the liver disease referral unit in Salvador, BA, northeastern Brazil. All of them were anti-HCV positive by 3rd generation ELISA assay, and HCV-RNA positive by RT-PCR. Genotyping was performed by INNOLIPA. Assessment of risk factors for HCV infection showed that 93 (40%) had past blood transfusion, 14 (6%) intravenous drug use, 19 (8%) inhalation of cocaine, 28 (12%) tattooing, 15 (7%) were health care workers, 5 (2%) had reused disposable syringes, 5 (2%) had multiple risk factors and in 53 (23%) no risk factor was determined. Genotype 1a was observed in 75 (32%), 1b in 72 (31%), 3a in 61 (26%), 2ab in 14 (6%); 5 (2.5%) had mixed genotypes and 5 (2.5%) were undetermined. Patients with genotype 1 had a higher mean age (P < 0.05) and no particular risk factors were associated with a specific genotype. Genotype 1 largely predominates in northeast Brazil followed by genotype 3 which, in this population, does not seem to be related to intravenous drug abuse, in contrast to some European studies. Although 80% of the Salvador population comprises African-Brazilians, no African genotype was identified, which may mean that HCV was introduced into this region via European immigration. This study demonstrated some peculiarities of HCV epidemiology in Brazil and strongly suggests that HCV introduction to this region was probably related to European immigration.

Antiviral therapy for hepatitis B and C in Asians

The clinical features and treatment of chronic hepatitis C in Chinese patients are the same as in Caucasian patients except that 27% of Chinese chronic hepatitis C patients have hepatitis C virus (HCV) genotype 6a. In contrast, Chinese patients with chronic hepatitis B (CHB) differ from Caucasian patients because the Chinese patients are immunologically tolerant to hepatitis B virus (HBV), having acquired hepatitis B infection perinatally or in early childhood. In the treatment of CHB, the short-term aims of loss of hepatitis B virus early antigen (HBeAg) and HBV-DNA need to be reassessed. In 1296 Chinese CHB patients, 67.7% of those who developed complications of cirrhosis or hepatocellular carcinoma, were HBeAg-antibody positive. Longer follow up of patients is, therefore, required to assess the time efficacy of a treatment regimen. After long-term follow up (median 90 months) of 206 Chinese CHB patients treated with interferon alpha (IFN alpha) compared with 203 untreated subjects, IFN alpha conferred no benefit in cumulative HBeAg seroconversion or in HBV-DNA negativity as determined by polymerase chain reaction assays or in decreasing long-term complications of cirrhosis and hepatocellular carcinoma. Lamivudine is a novel nucleoside analogue. In a recent 1 year study in 358 Chinese CHB patients, lamivudine treatment was associated with substantial histological improvement (including a reduction in fibrosis), with HBV-DNA suppression and normalization of alanine aminotransferase levels. However, lamivudine may have to be given on a long-term basis, as withdrawal of lamivudine results in rebound of HBV-DNA to pretreatment levels. The long-term effects of lamivudine are currently being assessed.

High prevalence of hepatitis C virus genotype 6 among certain risk groups in Hong Kong

The genotype of hepatitis C virus (HCV) of 172 HCV-RNA positive serum specimens taken from patients with chronic liver diseases, thalassaemia major, chronic renal failure (CRF), haemophilia and intravenous drug abusers (IVDA) was determined by analysis of the amplified 5'UTR region by genotype-specific oligonucleotide probes and restriction fragment length polymorphism (RFLP). Six different genotypes and subtypes (1a, lb, 2, 3, 4 and 6) were found. Genotype lb was the predominant genotype among patients with chronic liver diseases (69.6%), followed by genotype 6 (18.8%), which was similar to that reported for blood donors in earlier studies. Pronounced differences in the distribution of genotypes were seen between the four risk groups. Patients with CRF had a similar distribution to those with chronic liver diseases, whilst the greatest diversity of genotypes was seen in patients with haemophilia, which was expected since they were given factor VIII manufactured overseas. Genotype 6 was particularly prominent in patients with thalassaemia major (50%) and IVDA (62.5%). It is possible that clonal spread of HCV genotype 6 has taken place among a closed subset of the population in Hong Kong through intravenous drug abuse.

The complete coding sequence of hepatitis C virus genotype 5a, the predominant genotype in South Africa

Hepatitis C virus (HCV) genotype 5a is the predominant genotype in southern Africa with a high prevalence amongst infected blood donors from areas in South Africa. We have determined the nucleotide sequence corresponding to the complete coding region of an HCV isolate, EUH1480, previously classified as genotype 5a, from an Edinburgh haemophiliac. The sequence contained a single open reading frame (ORF) coding for a polyprotein of 3014 amino acids. Comparison with the polyprotein sequences from other HCV genotypes, where the ORF varies from 3008 to 3037 amino acids, showed the observed variation in size was due to differences in lengths of the envelope 2 and the nonstructural 5A proteins. The sequence divergence of HCV genotype 5 ranged from 29.4% nucleotide differences (24.91% amino acid differences) compared with genotype 1c to 32.5% nucleotide differences (30.3% amino acid differences) compared with 2a. Phylogenetic analysis of the available full length nucleotide sequences showed EUH1480 to form a branch distinct from the other HCV types, confirming the classification of type 5a as a separate genotype.