Evaluation of a multiple peptide assay for typing of antibodies to the hepatitis C virus: Relation to genomic typing by the polymerase chain reaction

A panel of 16 type-specific synthetic peptides corresponding to variable antigenic regions within the hepatitis C virus (HCV) core, nonstruc-tural 4 (NS4), and NS5 proteins was synthesised. The peptide panel was used to develop an enzyme immunoassay (EIA) for the detection of antibodies directed to HCV type 1 (genotypes I/1a and II/1 b), type 2 (genotypes III/2a and IV/2b), and type 3 (genotype V/3). The peptides corresponded to residues 68–81 of the HCV core (types 1,2, and 3), residues 1692–1705 and 1710–1728 of HCV NS4 (types 1 a, 1 b, 2a, 2b, and 3), and residues 2303–2319 of HCV NS5 (types 1a, 1b, 2a, and 2b). The 16-peptide panel was evaluated using human sera from 46 carriers of HCV, which were genotyped in parallel by the polymerase chain reaction (PCR) using primers specific for types I, II, III, IV, and V of HCV core. Of the 46 carriers, 14 (30%) were infected by HCV genotype I, 7 (15%) by genotype II, 16 (35%) by HCV genotype IV, and 6 (13%) by HCV of genotype V. Two carriers had double infections of types I and II, and the HCV strain of one carrier could not be genotyped. Using the serotyping system, 40 (89%) out of the 45 genotyped carriers were found to contain type-specific antibodies corresponding to the genotypes identified by PCR. In 5 of the 23 carriers infected by genotypes I and/or II, antibodies specific for HCV type 1 could not be detected, whereas all 16 carriers infected by genotype IV were serologically typed as type 2. Out of the six carriers infected by HCV of genotype V, all were found to have antibodies of serotype 3, but in most cases together with antibodies to NS5 type 1, indicating sequence homologies between types 1 and 3 of this NS5 region. In the one patient serum where the HCV strain could not be genotyped, a mixture of types 1, 2, and 3 antibodies were found. In conclusion, a serotyping system with a sensitivity and specificity of 89% was developed. It is confirmed that at least three distinct serotypes of antibodies to HCV exist. The major advantage of using four different antigenic regions is that we often obtain high absor-bance values which are easily interpreted, or multiple reactions which confirm each other. © 1995 Wiley-Liss, Inc.     

Cross-reactivity and clinical impact of the antibody response to hepatitis C virus second envelope glycoprotein (E2)

The genotype of hepatitis C virus (HCV) can profoundly affect the success of antiviral therapy for HCV infection. A possible contributing factor is a varied immune response elicited by infection with different HCV genotypes. In this study, full-length E2 proteins of HCV genotypes 1a, 1b, 2a, and 2b were used to determine the fraction of the humoral immune response to HCV E2 that is genotype specific. Greater than 90% of all infected individuals had serum antibodies to the four E2 proteins. Overall, individuals infected with genotype 1a or 1b were characterized by variable immune responses to HCV E2 with relatively high amounts of cross-reactivity with other E2 proteins. Individuals infected with genotype 2a or 2b exhibited a strong preferential reactivity to genotype 2a and 2b E2 proteins. Individuals with elevated titers to HCV E2 were more likely to be infected with genotype 2a and had a significantly lower median viral load. These findings indicate that the antibody response to HCV E2 is affected by the genotype of the virus and that induction of a strong humoral immune response to HCV E2 may contribute to a decreased viral load.     

Molecular epidemiology of hepatitis C infection in cyprus: Evidence of polyphyletic infection

The genetic diversity of the hepatitis C virus (HCV) in Cyprus is investigated for the first time in this study. Nucleotide sequence analysis of the CORE‐E1 and NS5B regions of the HCV genome was performed on blood plasma samples obtained from 77 HCV patients in Cyprus, collected during 2005–2008. The amplified products were sequenced and compared to reference HCV strains of known genotype and subtype in order to classify the isolates found in this study. Genotype could be determined for all strains, and subtype for all but four isolates. Phylogenetic analysis revealed that 51 patients were genotype 1, of which 38 were subtype 1b, 9 were 1a, and 1 was unclassified, one patient was genotype 2c, 13 were genotype 3a, nine were genotype 4, of which six were subtype 4a, and three were of unclassified subtype, one was genotype 5a, two patients seem to carry a possible 2k/1b recombinant strain, and no genotype 6 strains were found. This study demonstrated a genetic heterogeneity of HCV infection in Cyprus, with five of the six known HCV genotypes on the island, including unclassified isolates in genotypes 1 and 4, and also the apparent introduction of the 2k/1b recombinant strain in intravenous drug users. J. Med. Virol. 81:238–248, 2009. © 2008 Wiley‐Liss, Inc.     

A point mutation at Asn-534 that disrupts a conserved N-glycosylation motif of the E2 glycoprotein of hepatitis C virus markedly enhances the sensitivity to antibody neutralization

The molecular basis of antibody neutralization against hepatitis C virus (HCV) is poorly understood. The E2 glycoprotein of HCV is critically involved in viral infectivity through specific binding to the principal virus receptor component CD81, and is targeted by anti‐HCV neutralizing antibodies. A previous study showed that a mutation at position 534 (N534H) within the sixth N‐glycosylation motif of E2 of the J6/JFH1 strain of HCV genotype 2a (HCV‐2a) was responsible for more efficient access of E2 to CD81 so that the mutant virus could infect the target cells more efficiently. The purpose of this study was to analyze the sensitivity of the parental J6/JFH1, its cell culture‐adapted variant P‐47 possessing 10 amino acid mutations and recombinant viruses with the adaptive mutations to neutralization by anti‐HCV antibodies in sera of HCV‐infected patients. The J6/JFH1 virus was neutralized by antibodies in sera of patients infected with HCV‐2a and ‐1b, with mean 50% neutralization titers being 1:670 and 1:200, respectively (P < 0.00001). On the other hand, the P‐47 variant showed 50‐ to 200‐times higher sensitivity to antibody neutralization than the parental J6/JFH1 without genotype specificity. The N534H mutation, and another one at position 416 (T416A) near the first N‐glycosylation motif to a lesser extent, were shown to be responsible for the enhanced sensitivity to antibody neutralization. The present results suggest that the residues 534, and 416 to a lesser extent, of the E2 glycoprotein are critically involved in the HCV infectivity and antibody neutralization. J. Med. Virol. 84:229–234, 2012. © 2011 Wiley Periodicals, Inc.     

Hepatitis C virus infection among dialysis patients in Tunisia: incidence and molecular evidence for nosocomial transmission

In order to study the incidence of hepatitis C virus (HCV) infection in Tunisian haemodialysis patients and detect its nosocomial transmission, 395 patients were enrolled in a prospective study (November 2001-2003). HCV serological and virological status was determined initially using, respectively a third generation ELISA and an RT-PCR qualitative assay. The genotype of the HCV isolates was determined by sequencing NS5B region. The issue of nosocomial transmission was addressed by sequencing the HVR-1 region of the E2 gene. About 20% of the patients had anti-HCV antibodies and HCV-RNA was detected in 73% of the anti-HCV positive patients. Two cases of de novo HCV infection were identified in two dialysis centers, during virological follow-up of patients susceptible to HCV infection. The incidence of de novo HCV infection was 0.5%. Determining the genotypes in the first center disclosed that all HCV-positive patients were infected with genotype 1b; sequencing of the HVR-1 region of the E2 gene provided strong evidence that the isolate from the newly infected patient and another infected dialysis patient were closely related, confirming nosocomial contamination. The investigation of the second center is pending. Besides, one patient with negative HCV serology had detectable HCV-RNA at the beginning of the study. This case had HCV genotype 1b, two other infected dialysis patients in the same unit had HCV genotypes 4k and 3a; thus precluding nosocomial transmission. Thanks to molecular and phylogenetic methods, one case of nosocomial HCV transmission in haemodialysis was confirmed. Epidemiological investigation suggested nosocomial transmission via the medical and/or nursing staff.     

Structural features of envelope proteins on hepatitis C virus-like particles as determined by anti-envelope monoclonal antibodies and CD81 binding

The envelope glycoprotein E2 of hepatitis C virus (HCV) is a major component of the viral envelope. Knowledge of its topologic features and antigenic determinants in virions is crucial in understanding the viral binding sites to cellular receptor(s) and the induction of neutralizing antibodies. The lack of a robust cell culture system for virus propagation has hampered the characterization of E2 presented on the virion. Here we report the structural features of hepatitis C virus-like particles (HCV-LPs) of the 1a and 1b genotypes as determined by various mouse and human monoclonal anti-envelope antibodies. Our results show that the E2 protein of HCV-LPs reacts with human monoclonal antibodies recognizing conformational determinants. Monoclonal antibodies (mAbs) specific for the hypervariable region 1 (HVR-1) sequence reacted strongly with HCV-LPs, suggesting that the HVR-1 is exposed on the viral surface. Several mAbs recognized both HCV-LPs with equally high affinity, indicating that the corresponding epitopes [amino acids (aa) 192-217 of E1 and aa 412-423, aa 522-531, and aa 640-653 of E2] are conserved in both genotypes and exposed on the surface of the HCV-LP. The E2 and E1/E2 dimers of 1a bound strongly to the recombinant large extracellular loop (LEL) of CD81 (CD81-LEL) of human and African green monkey, while the HCV-LP of 1a bound weakly to human CD81-LEL. E1/E2 dimers and the HCV-LPs of 1b did not bind CD81-LEL, consistent with the notion that CD81 recognition by E2 is strain-specific and does not correlate with permissiveness of infection. A model of the topology and exposed antigenic determinants of the envelope proteins of HCV is proposed.     

Isolation and characterization of human monoclonal antibodies against hepatitis C virus envelope glycoproteins

The isolation and characterization of human monoclonal antibodies (humAbs) against the hepatitis C Virus (HCV) glycoproteins E1 and E2 are described. B-cells from blood donors with anti-HCV were transformed with Epstein-Barr virus. The supernatants of the resulting lymphoblastoid clones were screened by ELISA with an extract of cells infected with a recombinant vaccinia virus RMPA95 expressing the envelope proteins E1 and E2 of an HCV genotype 1a virus (H strain). Positive clones were fused to the heteromyeloma cell line K6H6/B5. Fifteen heterohybridoma cell lines have been established. The specificity of the isolated humAbs was determined both by ELISA and Western blot assays. Several recombinant extracts expressing either the E1 or E2 protein or truncated forms were used in an attempt to map the epitopes on the viral glycoproteins. Some of the humAbs were used successfully for immunofluorescence investigation of transfected cells. Seven specific anti-E2 humAbs, which react with the envelope protein 2 of genotype 1a and 1b isolates, were characterized. J. Med. Virol. 55:28–34, 1998. © 1998 Wiley-Liss, Inc.     

A prime-boost strategy using virus-like particles pseudotyped for HCV proteins triggers broadly neutralizing antibodies in macaques

Chronic hepatitis C virus (HCV) infection, with its cohort of life-threatening complications, affects more than 200 million persons worldwide and has a prevalence of more than 10% in certain countries. Preventive and therapeutic vaccines against HCV are thus much needed. Neutralizing antibodies (NAbs) are the foundation for successful disease prevention for most established vaccines. However, for viruses that cause chronic infection such as HIV or HCV, induction of broad NAbs from recombinant vaccines has remained elusive. We developed a vaccine platform specifically aimed at inducing NAbs based on pseudotyped virus-like particles (VLPs) made with retroviral Gag. We report that VLPs pseudotyped with E2 and/or E1 HCV envelope glycoproteins induced high-titer anti-E2 and/or anti-E1 antibodies, as well as NAbs, in both mouse and macaque. The NAbs, which were raised against HCV 1a, cross-neutralized the five other genotypes tested (1b, 2a, 2b, 4, and 5). Thus, the described VLP platform, which can be pseudotyped with a vast array of virus envelope glycoproteins, represents a new approach to viral vaccine development.     

Identification of rare hepatitis C virus genotype 5a among Indian population

In Indian population, hepatitis C virus (HCV) genotypes 1 and 3 are prevalent and predominant with the highest frequency. However, other genotypes are seldom reported, and among them the HCV genotype 5a is exceptionally rare. The presented case had no history for either blood transfusion or using any type of IV drugs and never traveled to any other country. He was serologically positive with HCV antibodies and HCV RNA. 5′UTR-specific amplification and sequencing of infected viral genome confirmed that he had been infected with HCV genotype 5a which is not closely related to other common prevalent genotypes like 1a, 1b, 3a, and 3b in India. Patient’s wife and children tested negative for anti-HCV and HCV-RNA. This unique case report could be attributed to circulation of HCV genotype 5a from other geographic area at very low frequency in India as determined by phylogenetic analysis and nucleic acid-sequencing methods.     

Hepatitis C virus genotypes in 1,504 patients in Slovenia, 1993–2007

In order to identify the main routes of hepatitis C (HCV) transmission and to determine the HCV genotype distribution and its dynamics during a 15‐year period in Slovenia, HCV genotypes were detected using the INNO‐LiPA HCV II (Innogenetics) test for serum samples obtained from 1,504 patients representing 72.6% of all patients with chronic hepatitis C diagnosed from 1993 to 2007. HCV genotype 1 was predominant (56%), followed by genotypes 3, 2, and 4, with a prevalence of 37.8%, 5%, and 1.2%, respectively. HCV genotypes 5 and 6 were not detected in any patient. Patients infected with HCV genotype 3 were significantly younger (mean age 28.9 ± 8.5 years) than those infected with genotype 1 (mean age 38.9 ± 14.8 years; P < 0.0001) and those infected with HCV genotype 2 (mean age 50.3 ± 18.2 years; P < 0.0001). Intravenous drug use was identified as the most frequent possible HCV transmission route (34.3%), followed by medical‐related transmission such as transfusion of HCV‐contaminated blood or blood products, and hemodialysis (12.5%). Being an intravenous drug user was found to be strongly associated with HCV genotype 3 (OR, 3.71 [95% CI, 2.97–4.65]; P < 0.0001) and reporting infection by transfusion of blood or blood products was found to be strongly associated with HCV genotype 1 (OR, 3.28 [95% CI, 2.18–4.95]; P < 0.0001). During the 15‐year period, the proportion of genotype 3 increased substantially, reflecting the fact that the HCV epidemic in Slovenia is driven mostly by intravenous drug use. J. Med. Virol. 81:634–639, 2009 © 2009 Wiley‐Liss, Inc.     

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.     

Artificial NS4 mosaic antigen of hepatitis C virus.

An artificial antigen composed of 17 small antigenic regions derived from the NS4-protein of hepatitis C virus (HCV) genotypes 1 through 5 was designed and constructed. Eleven antigenic regions were derived from the 5-1-1 region, and 6 others were derived from the C-terminus of the NS4-protein of different genotypes. The gene encoding for this artificial antigen was assembled from synthetic oligonucleotides by a new approach designated as restriction enzyme-assisted ligation (REAL). The full-length synthetic gene was expressed in Escherichia coli as a fusion protein with glutathione S-transferase. By the use of site-specific antibodies raised against synthetic peptides, it was shown that all regions for which sequence-specific antibodies were obtained were accessible to antibody binding. The diagnostic relevance of the NS4 artificial antigen was demonstrated by testing this antigen with 4 HCV seroconversion panels and a panel of previously tested and stored serum specimens. The artificial antigen was found to specifically detect anti-NS4 antibodies in a number of specimens that were previously found to be anti-NS4 negative. Furthermore, this antigen detected anti-NS4 activity earlier in 2 of 4 seroconversion panels than did the antigen used in a commercially available supplemental assay. Equally important is the observation that the artificial NS4 antigen demonstrated equivalent anti-NS4 immunoreactivity with serum specimens obtained from patients infected with different HCV genotypes, whereas the NS4 recombinant protein derived from genotype 1, used in the commercial supplemental test, was less immunoreactive with serum specimens containing HCV genotypes 2, 3, and 4. Collectively, these data support the significant diagnostic potential of the NS4 mosaic antigen. The strategy employed in this study may be applied to the design and construction of other artificial antigens with improved diagnostically pertinent properties. J. Med. Virol. 59:437-450 1999.     

Expression of human CD81 in transgenic mice does not confer susceptibility to hepatitis C virus infection

We previously demonstrated that hepatitis C virus (HCV) binds to human CD81 through the E2 glycoprotein. Therefore, expression of the human CD81 molecule in transgenic mice was expected to provide a new tool to study HCV infection in vivo, as the chimpanzee is the only species currently available as a laboratory animal model that can be infected with HCV. We produced transgenic mice expressing the human CD81 protein in a wide variety of tissues. We confirmed binding of recombinant E2 glycoprotein to the liver tissue as well as to thymocytes and splenic lymphocytes in the transgenic mice. We inoculated chimpanzee plasma infected with HCV into these animals. None of these transgenic animals showed evidence of viral replication. Furthermore, human CD81 transgenic mice that lack expression of endogenous mouse CD81 were also resistant to HCV infection. We conclude that expression of human CD81 alone is insufficient to confer susceptibility to HCV infection in the mouse. The presence of additional possible factors for HCV infection is discussed.     

Evaluation of a new assay for hepatitis C virus genotyping and viral load determination in patients with chronic hepatitis C

A new method for hepatitis C virus (HCV) genotyping that analyzes products generated with the HCV Amplicor Monitor Test has been developed. One hundred and sixty-two Japanese patients with chronic hepatitis C, including 59 patients with hemophilia, were tested for HCV genotypes and viral loads with this new test, and the results were compared with those of a genotyping assay that involved direct sequencing of the E1 region. HCV genotypes and viral loads were also compared between patients with and without hemophilia. There were no discrepancies between the two methods in determining genotypes 2a, 2b, and 3a. However, two patients infected with 1a were mistyped as 1b with the new assay. One patient not classified by this assay was genotype 4. Genotypes found in patients without hemophilia were 1b, 2a, and 2b. Genotypes 1a, 3a, and 4, which were minor variants in Japan, were detected only in patients with hemophilia. In addition, J type, which is a subtype of 1b that originated in Japan, was found at low frequency in hemophiliacs. Thus, the HCV genotypes in patients with hemophilia are likely to be of foreign origin. Overall, this new assay was accurate except for genotype 1a and 4, and allowed simultaneous assessment of genotype and viral load.     

Genotype dependence of peptide-based immunoassays for the detection of HCV core antibodies

Detection of hepatitis C virus (HCV) antibodies is partially influenced by the genotype of the infecting isolate. Immunoassays using genotype-1a-derived recombinants or peptides results in diminished reactivity among individuals infected with heterologous genotypes. We examined the magnitude of this effect on detection of core antibodies by using genotype-1a-derived core peptide immunoassays to test 254 HCV anti-core-positive individuals infected with genotypes 1-4 or 6. Peptides corresponding to amino acids 1-18, 10-24, and 11-28 reacted with 60%, 89%, and 85% of all samples, respectively. Peptide 1-18 detected 78% of individuals infected with genotype-1 or 2 but only 43% of those infected with genotypes 3, 4, or 6. Genotype-dependent reactivity was also observed for peptides 10-24 and 11-28. The use of a 34-mer peptide (encompassing amino acids 10-43) within the immunodominant region detected antibodies in 100% of specimens, thereby eliminating the genotype-dependent antibody detection observed with shorter peptides. Sequence differences between peptides and core of the infecting isolate did not entirely account for the genotype-dependent reactivity since some individuals displayed reactivity to peptides containing up to seven amino acid differences relative to the sequence of the infecting isolate, while others with identical core sequences had little or no reactivity. Thus, HCV core sequence divergence accounts for only a portion of the differential core antibody detectability observed when non-type-specific peptides are used. Differences in immune response between individuals infected with identical isolates also plays a significant role in core antibody detection using short peptides.     

Hepatitis C virus nonstructural 3 protein: recombinant NS3 protein of the Thai isolates as an antigen in a diagnostic assay

Nonstructural 3 (NS3) protein of hepatitis C virus (HCV) is one of the antigens commonly used in diagnostic assays for antibody to hepatitis C virus. However, immune response to the NS3 protein from one genotype may not cross-react with that from other genotypes. In the development of an anti-HCV assay, the NS3 genes from genotypes 1 and 3 commonly found in Thailand were amplified and cloned into a bacterial expression system. These recombinant NS3 proteins were immunogenic and reacted with plasma samples of Thai patients infected with various HCV genotypes. Interestingly, the NS3 proteins from the Thai genotypes could react with 3 plasma samples from HCV infected Thai blood donors, which could not bind to the NS3.1 protein in the commercial HCV immunoblot kit using antigen from HCV genotype 1. This finding supports our prior observation that the appropriate HCV antigens used in a diagnostic assay should be derived from the virus genotypes commonly found in that geographical region.     

Detection of human respiratory syncytial virus genotype specific antibody responses in infants

Infection and reinfection of infants with human respiratory syncytial virus (HRSV) occur despite the presence of serum anti-viral glycoprotein antibodies similar to those, which afford protection in animal models of infection. Antigenic variation of the viral glycoproteins between different genotypes of the virus which co-circulate in the population may contribute to the ability of the virus to escape from antibody-mediated protection. In this study, we have investigated whether human infants infected with HRSV produced antibody responses recognising the antigenic differences between different contemporary genotypes of virus. Acute and convalescent sera from 26 infants were analysed for antibody responses to the glycoproteins of the virus isolated from their respiratory tract and to representative viruses of homologous and heterologous genotypes. All infants developed antibodies with similar reactivity for viruses of all contemporary isolates and genotypes when measured in an immunofluorescence assay against unfixed virus infected cells. However, when antibody responses to the individual glycoproteins were measured in a surace plasmon resonance (SPR) assay, although all infants developed genotype cross-reactive antibodies to the F glycoprotein, anti-G antibodies were detectable in only half of the infants and in all cases these were genotype specific. Possession of no or only genotype specific antibodies to the G glycoprotein may contribute to the susceptibility of infants to reinfection. In both assays, reactivity of anti-glycoprotein antibodies with the sub-group A archetypal strain, A2, was markedly lower than with any contemporary virus tested indicating that this strain alone is unsuitable for accurate assessment of infant antibody responses. .     

不同感染途径慢性丙型肝炎患者HCV基因型分布的差异

目的 探讨丙型肝炎病毒(HCV)基因型在中国部分城市输血与非输血途径感染者之间的分布。方法 对来自中国南北地区9个城市的慢性HCV肝炎患者的血清，用5′非编码区酶切分型方法进行HCV基因分型，分析HCV基因型在不同地区和感染途径之间的分布差异。结果 在219例慢性HCV肝炎血清中，有214例(97．7％)检测出HCV基因型，其中197例为单基因型HCV感染，主要的HCV流行株为1b(76．64％)和2a(18．22％)，并有5．14％的患者感染基因3b型，且首次在中国检测出4a型。HCV在中国南北地区城市的分布差异无显著意义，但输血感染者和非输血感染者之间的HCV基因型分布差异有显著意义，输血感染者中，93．88％为单基因型HCV感染，1b占76．87％，高于非输血途径感染患者中单基因型HCV感染百分率(86．57％)和1b的感染百分率(58．21％)，非输血感染者中的混合HCV基因型比例(13．43％)高于输血感染者(6．12％)。结论 中国南北部分地区的HCV基因型分布差异无显著意义，但经输血感染和非输血感染的慢性丙型肝炎患者之间的HCV基因型分布差异有显著意义。     

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. © 1995 Wiley-Liss, inc.