Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey

Evaluation of complete genome sequences and sequences of individual gene products for the classification of hepatitis C viruses

Comparisons of genome and polyprotein sequences of hepatitis C virus (HCV) isolates world-wide has led to the identification of nine major genotypes and many subtypes. This classification is based on either complete genome/polyprotein sequences or sequence data from the 5' noncoding region, core, E1, NS3 or NS5B genes. The relative merit of different gene segments as taxonomic markers and the validity of the resulting assignments is not clear at this stage. To resolve the taxonomy of HCV genotypes and subtypes, we have compared the complete genome and polyprotein sequences of 19 HCV isolates available in the databases as well as sequences of individual genes and gene products of these isolates. Based on the correlation between sequence relationships and taxonomic assignments of other RNA viruses, we show that the nine major genotypes of HCV represent nine distinct virus species and their subtypes subspecies. Our sequence comparison of the 5' noncoding regions and the individual gene products suggests that E2, NS2, NS5B, E1, NS4A, NS4B and NS5A (in that order) are the most appropriate regions for the discrimination between species, subspecies and strains of HCV. The 5' noncoding, core and NS3 regions are less effective in distinguishing between species, subspecies and strains. Based on a comparison of the polymerase sequence identities of HCVs, pestiviruses and flaviviruses as well as the recent information on the size and morphology of HCV virions, we propose that HCVs, pestiviruses and flaviviruses should be classified into three separate families, named Hepciviridae, Pestiviridae and Flaviviridae, respectively rather than three genera of the Flaviviridae as currently classified. We also propose "Hepcivirus" as the genus name for HCVs.

Hepatitis C virus genotyping by means of 5'-UR/core line probe assays and molecular analysis of untypeable samples

To test the theoretical possibility of 5'-UR mistyping between hepatitis C virus subtypes 1a and 1b, we combined a 5'-UR/Core line probe assay (LiPA) with a nested PCR system and retested 183 sera, previously genotyped as type 1a or 1b and originating mainly from Western Europe. Eight percent of these were found to be wrongly subtyped. Based on this method, 3 additional subtypes of type 1 were discovered (1d-1f). Randomly selected European type 2 sera (n = 18) were tested with a similar type 2 5'-UR/Core LiPA. They were unexpectedly found to belong to subtype 2c in the majority of cases. Among serum samples originating from South-East Asia, several additional genotypes (7a, 7c, 7d, and 9a) were detected which had 5'-UR sequence motifs indistinguishable from genotype 1. Based on 13,203 pairwise comparisons in the 340-bp NS5B region, classification into types, subtypes, and isolates was obtained in 99.8% of all cases by using the phylogenetic border value of 0.328 for subtypes/types and 0.127 for isolates/subtypes; and evidence for a 10th major type of HCV was provided. Combination of all available HCV sequence data from the 447-bp Core/E1 region and the NS5B 340-bp and 222-bp regions provided evidence for the existence of 10 types, including 50 subtypes. Previously, extensive studies involving genotypes 1a, 1b, 2a, and 2b indicated the importance of HCV subtyping in interferon treatment and progression of chronic liver disease. The herein described expansion in the number of HCV types and subtypes should help improve diagnosis, treatment and possibly prophylaxis of hepatitis C liver disease.

Epitope mapping of the NS4 and NS5 gene products of hepatitis C virus and the use of a chimeric NS4-NS5 synthetic peptide for serodiagnosis

Specific domains of the NS4 and NS5 gene products of hepatitis C virus have been identified using hydrophilicity profiles for the prediction of potential immunogenic regions, and epitope scanning techniques. Peptides synthesised on the basis of such data show excellent reactivity in the ELISA format. Introduction of a glycine-glycine spacer between two peptides (NS4-12 and NS5-44) to give a single chimeric peptides does not appear to impair immunoreactivity. An ELISA based on the chimeric peptide and a Core-NS3 recombinant protein correctly diagnoses a cohort of haemodialysed patients, three commercial HCV panels and the sera of a negative control population.

Partial nucleotide sequencing of six subtype 2c hepatitis C viruses detected in Italy

The great majority of 121 hepatitis C virus (HCV) isolates obtained from 117 Italian patients with community-acquired infection could readily be typed by genotype-specific PCR. Subtype 1b was dominant (74 isolates); subtypes 2b, 2a, and 1a followed, with 19, 14, and 8 isolates, respectively. The six isolates that remained untyped by this method were classified as subtype 2c on the basis of sequence analysis of PCR amplicors obtained from the core and NS5 genes. These findings indicate that HCV subtype 2c has a relatively high prevalence in Italy. Sequencing the core region from positions 160 to 259 is sufficient to distinguish subtype 2c from other known HCV genotypes.

HCV genotypes in Swedish blood donors as correlated to epidemiology, liver disease and hepatitis C virus antibody profile

Sixty-two anti-HCV and HCV-RNA positive Swedish blood donors (44 men, 18 women; median age 34 years) were studied. HCV genotypes were correlated to parenteral risk factors, liver morphology, serum alanine aminotransferase (ALAT) levels and HCV antibody profile. Forty percent of the donors were infected with HCV genotype 1a, 10% with 1b, 21% with 2b, and 29% with 3a. Intravenous drug use (IVDU) was more common in donors with genotype 3a than in those with genotype 1a (p = 0.024), and prior blood transfusion more common in genotype 2b than in 3a (p = 0.012). Chronic active hepatitis with and without cirrhosis was found in 38% of donors infected with genotype 2b as compared to 8% of donors infected with 1a (p = 0.034). Forty percent of donors with genotype 1a had normal ALAT at the time of liver biopsy versus 11% with genotype 3a (p = 0.046). Antibodies to C33c and C22-3 were present in nearly all donors whereas reactivity to C100-3 and 5-1-1 was detected more often in donors with genotypes 1a and 1b as compared to donors with genotypes 2b and 3a. In conclusion, genotype 3a was correlated to IVDU or tattooing as parenteral risk factors for the acquisition of HCV infection, and genotype 2b to prior blood transfusion. Donors with genotypes 1a seemed to have less severe liver disease than those infected with genotypes 2b and 3a.

Genotypic variation, clinical and histological characteristics of chronic hepatitis C detected at blood donor screening

Since blood donor screening for the hepatitis C virus (HCV) began in 1991 a large number of seropositive subjects have been detected and several reports have suggested a high prevelance of liver disease. The aim of this study was to evaluate the severity of liver disease in HCV-positive blood donors in terms of the clinical, biochemical and histological abnormalities and to investigate the relationships between these features and the mode of transmission, duration of infection and viral genotype. We evaluated 54 consecutive blood donors who were positive for HCV both on serological testing and polymerase chain reaction. Twenty-three (43%) had a history of intravenous drug abuse and 17 (31%) had received blood transfusions. In only two (4%) was no risk factor identified. The mean duration of infection in those with a clear history of HCV exposure was 12 years. Eighty-three percent were HCV genotypes 1 or 3. All had abnormal liver biopsies with chronic hepatitis and several patients had periportal or portal-portal fibrous septa, but there was none with architectural distortion or cirrhosis. There was no correlation between severity of liver disease and duration of HCV infection, mode of transmission or viral genotype. In the majority of HCV carriers detected at donor screening there is a chronic hepatitis with bridging necrosis in one third, but the degree of fibrosis is minimal and cirrhosis was not present in our patients. The long period of infection of many patients suggests that irreversible liver injury does not necessarily develop at an early stage despite persistent infection.

Genomic characterization of hepatitis C virus isolates from Argentina

Thirty-three Argentinian patients infected with hepatitis C virus (HCV) were studied for viral genotyping. The patients included 10 hemophiliac and 4 polytransfused children and 19 adults: 3 polytransfused, 7 dialyzed and 9 sporadic cases. Core-based genotyping permitted the classification of 31 samples. Genotypes II, I and V were the most frequent: 21 (63.6%), 16 (48.4%) and 10 (30.3%) of the 33 patients, respectively. Only one polytransfused patient carried genotype IV. Genotype II was detected in 7 out of 9 sporadic cases. Thirteen patients (39.3%) were coinfected with two genotypes, and 2 others were coinfected with three genotypes. The remaining 2 samples which could not be typed were characterized following the restriction fragment length polymorphism (RFLP) method, and were classified as type 1. One of these had two consecutive transitional mutations in the 5' untranslated region (5' UTR).

Genotype distribution and comparison of the putative envelope region of hepatitis C virus from Korean patients

Comparative nucleotide sequence studies of the genomes of hepatitis C virus (HCV) revealed that there are at least 6 different genotypes of HCV. The prevalence of HCV genotypes among the patients with liver diseases in Korea was investigated using the polymerase chain reaction (PCR) for the NS5 region. In the 75 HCV RNA positive samples, two genotypes, type 1b and type 2a, were the major causative agents which accounted for 60% and 33% of infections respectively, while 7% could not be assigned a genotype by the methods used. The nucleotide sequences of cDNAs encoding the putative envelope proteins from 10 type 1b and 5 type 2a genotype samples were analyzed. Approximately 31-42% of the nucleotide sequences of type 1b samples examined differed from those of different genotypes. In the case of type 2a samples, 36-42% of the nucleotide sequences differed from those of different genotypes. The diversities of the amino acid sequences were the same or greater than those of the nucleotide sequences. Two hypervariable regions (HVR1 and HVR2) were recognized in both HCV genomes of genotypes 1b and 2a. However, the sequence divergence within the HVR2 region of genotype 2a was less than that of genotype 1b.

Host and viral features in chronic HCV infection: relevance to interferon responsiveness

Host and viral variables interact in determining the course and responsiveness to therapy of any viral infection. Presence of cirrhosis, serum levels of hepatitis C virus (HCV) RNA and the genotype of infecting virus are considered predictive of response to interferon (IFN) in chronic HCV infection. We evaluated these parameters in relation to IFN therapy in a cohort of anti-HCV-positive subjects with chronic hepatitis or cirrhosis. HCV RNA was detected by polymerase chain reaction (PCR) and by the branched DNA assay (bDNA), to quantify viraemia. HCV typing was performed by reverse-hybridization line probe assay. HCV RNA was detected in almost all anti-HCV-positive subjects with liver disease, PCR being more sensitive than bDNA. Hepatitis C viraemia was lowest in cirrhosis. Low pretreatment viraemia selected for those patients with chronic hepatitis obtaining a high rate of sustained response to IFN. The role of HCV type was less clearcut, due to the high prevalence in our population of type 1 (especially subtype 1b, accounting for 80% of cases). A trend towards a better response of non-1b genotypes was confirmed. This may be related to higher HCV RNA levels in type 1b-infected subjects. Cirrhosis remains however, independently from virological features, the strongest predictor of non-response to IFN.

Molecular epidemiology of hepatitis C virus infection among intravenous drug users

BACKGROUND/AIMS

The clinico-pathological features of hepatitis C virus infection in intravenous drug users are different from those found in other hepatitis C virus-infected patients. Our aim was to test whether specific viral variants circulate within this particular patient population.

METHODS

We studied the distribution of hepatitis C virus genotypes in 90 drug addicts and 484 controls, according to the method described by Okamoto.

RESULTS

Hepatitis C virus type 1a and 3a infections were more frequent among intravenous drug users than in 125 age-matched controls (48.8% and 21.1% vs 17.6% and 11.2%), accounting for the majority of infections in intravenous drug users. Analysis of hepatitis C virus genotypes according to age showed that, in the general population, hepatitis C virus types 1a and 3a were more prevalent among patients younger than 40 years of age than in older individuals (17.6% and 11.2% vs 1.4% and 0.6%).

CONCLUSIONS

These findings suggest that hepatitis C virus types 1a and 3a were recently introduced in Italy, presumably via needle-sharing among intravenous drug users, and from this reservoir they are extending to the general population, particularly among younger subjects.

Genotyping of hepatitis C virus in South Africa

The six major hepatitis C virus genotypes were investigated by using samples from 79 seropositive and PCR-positive blood donors from three different regions of South Africa as well as 9 patients with chronic renal failure, 19 with liver disease, and 23 with hemophilia. PCR products of the genome were typed by restriction fragment length polymorphic analysis by RsaI-HaeIII and MvaI-HinfI double digestion. Type 5 occurred in 40% of this population group; type 1 occurred in 33%; and types 2, 3, and 4 were found in 13.8, 7.7, and 2.3%, respectively.

Molecular epidemiology of an outbreak of infection with hepatitis C virus in recipients of anti-D immunoglobulin

In a retrospective investigation of possible transmission of hepatitis C virus (HCV) by anti-rhesus D immunoglobulin (anti-D) in 1977, we compared variants infecting anti-D recipients in Ireland of one of the implicated batches with those of epidemiologically unrelated HCV-infected individuals. All 100 of the recipients of the batch investigated to date were infected with a single genotype (type 1), consistent with a single-source outbreak, whereas a wider range of genotypes (1, 2, and 3) were found in anti-HCV positive individuals from Ireland infected by different routes. Nucleotide sequences from a 222 base fragment from the NS-5 region of the genome amplified from stored aliquots of the implicated batch closely matched those detected in anti-D recipients 17 years after the transmission event. This study shows the value of molecular epidemiological techniques for identifying distant sources of infection, and for the epidemiological investigation of the current distribution and transmission of HCV in different populations.

Influence of hepatitis C virus (HCV) genotypes on HCV recombinant immunoblot assay patterns

Ninety-six patients with chronic hepatitis C were studied. A second-generation recombinant immunoblot assay detected anti-NS4 antibodies significantly more often in patients infected by hepatitis C virus genotype 1 than in patients infected by other types. By a third-generation recombinant immunoblot assay, the prevalences of the four antibodies measured did not differ according to the hepatitis C virus genotype.

Genotype-dependent serologic reactivities in patients infected with hepatitis C virus in the United States

OBJECTIVE

To evaluate the serologic reactivities in patients infected with different hepatitis C virus (HCV) genotypes to four HCV proteins that are components of the second-generation recombinant immunoblot assay.

MATERIAL AND METHODS

Serum samples from 36 patients with chronic HCV infection were obtained. RNA was extracted by using chaotropic lysis and isopropanol precipitation. Reverse-transcriptase polymerase chain reaction of the NS-5 region was performed, followed by automated single-pass dideoxy sequencing of desalted amplification products. Classification of isolated HCV subtypes was based on Simmonds' system. All samples were tested for antibodies to proteins 5-1-1, C100-3, C33c, and C22-3 with the second-generation recombinant immunoblot assay.

RESULTS

Reactivity to protein 5-1-1 was significantly lower for patients with genotypes 2b and 3a than for those infected with HCV types 1a or 1b (P < 0.05). Antibody reactivity to the C100-3 protein was also reduced in patients infected with HCV types 2b and 3a.

CONCLUSION

These data indicate that the genotype-dependent differences in serologic reactivities are substantial among patients with chronic HCV infection.

Selection of more pathogenic hepatitis C virus genotype II during long-term follow-up of interferon-treated patients

The behavior of hepatitis C virus (HCV) infection with regards to type and number of HCV genotypes (tested with genotype-specific nested polymerase chain reaction) was evaluated in 60 patients with anti-HCV-positive chronic active hepatitis without cirrhosis [17 untreated and 43 subjects undergoing single or repeat courses of interferon (IFN) therapy] during a mean follow-up period of 76 +/- 18 months. In untreated patients (2 genotype I, 6 genotype II, 9 mixed infections) 4 out of 9 mixed infections selected for genotype II at the end of follow-up. Of the 43 treated patients 10 were long-term responders with histological remission, 6 were short-term responders, and 22 did not respond. Fifteen of the latter patients received another course of IFN therapy, and only 3 patients responded. Eight of the 10 responders had infection with a single genotype (4 gt I, 3 gt II, 3 gt III). After IFN therapy, all but 2 patients cleared the HCV infection. The responders to the second IFN course (1 gt I, 1 gt II, 1 gt III) remained viremic. Of the short-term responders, 2/6 patients had genotype II and 4 had a mixed infection (3 gt II +/- I and 1 gt II +/- III); gt III became prevalent in the latter in all but one patient. Of the nonresponders 18/24 had more than one genotype, 5 were genotype II at baseline and one had genotype I. At the end of the follow-up period 15/18 with mixed infection had selected for gt II (P < 0.01 vs. untreated patient).(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatitis C virus genotypes in French blood donors

The prevalence of different hepatitis C virus (HCV) genotypes in HCV infected individuals and the relation between the HCV genotypes and the source of the infection are controversial. The aim of this study was to determine the HCV genotypes in French blood donors. Fifty-one anti-HCV positive blood donors were studied with detectable serum HCV RNA by nested polymerase chain reaction (PCR) using primers derived from the 5' non-coding region. For genotyping HCV, we used a method based on analysis of the restriction fragment length polymorphisms (RFLP) after amplification by PCR of the HCV non-structural 5 (NS5) genome domain. Using this technique, the genotypes of 39 of the 51 blood donors (76%) were determined. Three previously described genotypes were found: 19 blood donors were infected by HCV genotype I (37%), 14 were infected by HCV genotype II (27%), 3 were infected by HCV genotype III (6%), and 3 were coinfected by two genotypes (6%). All three blood donors infected with two different genotypes were intravenous drug abusers. A past history of intravenous drug abuse was more frequent in blood donors with HCV genotype I. However, there was no difference in alanine transaminase (ALT) levels, histological lesions, and RIBA-2 patterns in blood donors infected with either HCV genotype I or HCV genotype II. These findings indicate that most HCV genotypes isolated from French blood donors belong to HCV genotype I and HCV genotype II, and that risk factors for HCV infection may differ for different genotypes of HCV.

High prevalence of a rare hepatitis C virus in patients treated in the same hemodialysis unit: evidence for nosocomial transmission of HCV

Hepatitis C virus (HCV) is a major cause of hepatitis among patients treated with maintenance hemodialysis. Blood transfusion appears to be the primary risk factor, but nosocomial transmission of HCV in the dialytic environment has been hypothesized. We addressed this issue by analyzing the individual variation of genomic sequences of HCV in 28 patients on chronic hemodialysis (HD) from the same department and 25 environmentally unrelated patients with HCV-related liver disease. Genome variations of HCV were studied by single strand conformation polymorphism (SSCP) analysis of polymerase chain reaction products obtained from the 5'-untranslated region of the viral genome and by sequence analysis. Six different SSCP patterns were identified in HD patients versus 16 in control patients. Among HD patients the three more frequent SSCP patterns accounted for 85% of observations, while in the control group each pattern was found in 4 to 12% of patients. The ability of SSCP to discriminate sequence variation was proven by sequence analysis which confirmed identity/diversity of sequences selected by SSCP. Moreover, sequence analysis permitted a recognition of the most frequent genome observed in HD patients as a type 4 HCV, which is considered to be rare in the Italian population. The relative homogeneity of HCV variants in HD patients treated in the same HD and the high prevalence in this unit of a rare viral variant support the possibility of a nosocomial transmission of HCV in the dialytic environment.

Serological reactivity and viral genotypes in hepatitis C virus infection

Patients infected with hepatitis C virus (HCV) were examined with four commercial HCV immunoblotting assays and for anti-GOR antibody to ascertain whether serological findings varied with the genotype of the infecting virus. The results indicate that patients infected with different HCV genotypes tend to show different immunoblotting profiles, mainly due to a low prevalence of antibodies to the viral region NS4 in patients infected with genotypes III and IV. Differences were more evident with second- than with third-generation assays. Patients infected with genotype IV exhibited a lower prevalence of anti-GOR antibody than patients infected with other genotypes.

Sequence variability of hepatitis C virus and its clinical relevance

Chronic type C hepatitis is a potentially serious disease that can lead to cirrhosis and hepatocellular carcinoma. This complex disease is caused by the hepatitis C virus (HCV), a positive sense, single-stranded RNA virus. HCV has been assigned to a separate genus within the Flaviviridae, and shares a close relationship to the pestiviruses. Nucleotide sequence variation has been observed in genomes amplified from serum of patients with HCV infection, and cloning of RNA amplified from patients infected with HCV has confirmed the heterogeneity of the agent responsible for post-transfusion and sporadic hepatitis C. The variability of HCV is structured in a way that immediately suggests a two tiered classification: this nomenclature comprises 'types' corresponding to the major branches in a phylogenetic tree of sequences from genomic or subgenomic regions of the genome, and 'subtypes', corresponding to the more closely related sequences within some of the major groups. This genotyping designation has provided an epidemiological tool for studying geographical differences in hepatitis C infection. Clearly discernible patterns of genotype distribution have been found in those countries that have been studied so far. In many European countries genotype distributions vary with the age of patients, reflecting rapid changes in genotype distribution with time within a single geographical area. Unfortunately we know very little about modes of transmission within different communities. There is considerable interest in the clinical significance of different HCV genotypes, and the intriguing question of whether these differences may affect the spectrum of the disease associated with hepatitis C. These data also have implications for diagnosis and treatment of acute and chronic hepatitis C. A uniform typing scheme and nomenclature will facilitate our understanding of the disease caused by this virus worldwide.

Discharge planning for the mentally disabled

Hepatitis C virus (HCV) is a major cause of chronic liver diseases including steatosis, cirrhosis and hepatocellular carcinoma. Currently, there is no vaccine available for prevention of HCV infection due to high degree of strain variation. The current treatment of care, Pegylated interferon α in combination with ribavirin is costly, has significant side effects and fails to cure about half of all infections. The development of in-vitro models such as HCV infection system, HCV sub-genomic replicon, HCV producing pseudoparticles (HCVpp) and infectious HCV virion provide an important tool to develop new antiviral drugs of different targets against HCV. These models also play an important role to study virus lifecycle such as virus entry, endocytosis, replication, release and HCV induced pathogenesis. This review summarizes the most important in-vitro models currently used to study future HCV research as well as drug design.