Differences in the hepatitis C virus genotypes in different countries

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.

Interferon treatment of chronic hepatitis C in patients with hemophilia or von Willebrand's disease in Japan

Seven patients with chronic hepatitis C, six hemophiliacs and a patient with von Willebrand's disease, were treated with interferon-alpha (IFN-alpha). Either 9 MU of recombinant IFN-alpha 2a or 3 MU of lymphoblastoid alpha-IFN was administered daily for 2 weeks and then three times a week for 22 weeks. Liver histology, hepatitis C virus (HCV) genotypes, and HCV-RNA levels in sera were investigated in all of the patients before IFN therapy was instituted. Liver histology was classified by the European classification. HCV genotyping conformed to the so-called Okamoto's classification. HCV-RNA levels in sera were quantitated by competitive polymerase chain reaction, using mutant RNA. Liver histology, HCV genotype, and serum HCV-RNA level (copies/ml) in each patient were: patient 1, chronic persistent hepatitis, type II, 3 x 10(3) respectively; patient 2, chronic active hepatitis (CAH) 2a, type III, 6 x 10(4); patient 3, CAH2a, type IV, 2 x 10(5); patient 4, CAH2b, type I, 2 x 10(7); patient 5, CAH2b, type II, 8 x 10(4); patient 6, CAH2b, type III, 7 x 10(6); and patient 7, CAH2b, type IV, 1 x 10(7). Sustained elimination of HCV was achieved in patient 3 and temporary elimination was achieved in patients 1 and 2. The other patients showed persistent HCV-RNA positivity in sera both during and after IFN treatment. Poor responsiveness to IFN was observed in patients with relatively progressive liver histology and high levels of HCV viremia.

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.

Hepatitis C virus type I(1a) in northern China

Twenty-four patients with hepatitis C virus (HCV) antibody from the Chinese North Western province of Jilin were further analysed by the immunoblot assay-2 (RIBA-2), reverse transcription-polymerase chain reaction (RT-PCR) for serum HCV RNA detection, and direct sequence-genotyping. Good concordance was found between the original second generation HCV antibody ELISA, RIBA-2, and serum HCV RNA. The occurrence of genotype I (1a), a genotype not previously reported in China, is described in 5(20.8%) of 24 cases, in association with genotypes II(1b) and III(2a) which were found in 16(66.7%) and 3(12.5%) of 24 cases, respectively. Imported blood products were unlikely to be the source of infection with genotype I (1a) but could not be definitively ruled out.

Genotype distribution in Nagoya and new genotype (genotype 3a) in Japanese patients with hepatitis C virus

We evaluated hepatitis C virus (HCV) genotype distribution among Japanese patients in the city of Nagoya and the possible existence of any other genotype not determined by Okamoto's method. Eighty-five of 93 (91.4%) anti-HCV-positive patients had detectable HCV RNA. The genotype of the HCV isolate was determined in 84 of 85 (98.8%) of these HCV RNA-positive patients by Okamoto's method but determination was not possible in one (1.2%). Genotype 1b was detected in 58 of the 85 patients (68.2%), genotype 2a in 20 (23.5%), genotype 2b in 3 (3.5%), and genotype 1b + 2a in 3 (3.5%). In the remaining 1 patient in whom the genotype could not be determined, we determined the nucleotide sequence of the core region in HCV RNA extracted from this patient and evaluated it by molecular evolutionary analysis. This HCV isolate was then classified as genotype 3a. These results suggest that genotype 3a is rare among Japanese patients with HCV; thus, when classifying Japanese isolates, we should take more care because genotype 3a is not determined by current typing systems.

Hepatitis C genotypes in haemophilic patients treated with alpha-interferon

The effect of alpha-interferon on the hepatitis C genotypes was examined in 25 anti-HCV-positive haemophilic patients. The rate of multiple HCV genotypes in patients who are likely to have mixed infections was also studied. Pretreatment results showed that 3/25 (12%) patients had a change in genotypes, whereas posttreatment this rose to 10/25 (40%). Seven of 10 (70%) patients who showed a change in genotype had a clinical response to alpha-interferon. Six of 25 (24%) patients showed a complete clinical response to alpha-interferon, and the majority of these were either type 2 or 3. This study supports previous evidence that type 1 is less likely to respond to alpha-interferon, and that alpha-interferon may alter the concentrations of the various circulating genotypes present in multiply-infected patients. There are many difficulties in studying hepatitis C in haemophilic patients due to the sequence heterogeneity within each individual, and this study has shown that no ideal method exists as yet for looking at HCV genotypes in multiply-infected individuals.

Clinical characteristics and antibody profiles of chronic hepatitis C patients: relation to hepatitis C virus genotypes

Genotyping of 179 consecutive Japanese chronic hepatitis C patients was carried out based on the variation in the hepatitis C virus (HCV) core gene. The results were correlated with clinical features and antibody responses toward specific HCV proteins deduced from the nucleotide sequence of genotype I/1a. Genotypes II/1b, III/2a, and IV/2b were identified in 138 (77%), 24 (13%), and 12 (7%) patients, respectively. Five patients had double infections. Genotype dependence was observed only for antibody response toward the NS4 (5-1-1) protein, which was infrequent in genotype III/2a patients (33%) compared with genotype II/1b (81%; P < 0.01) and genotype IV/2b (75%; P < 0.05). Following interferon-alpha therapy, sustained amniotransferase normalisation was achieved by 89% (eight of nine) patients without antibody to the 5-1-1 protein and 33% (17 of 51) with it (P < 0.01). These findings indicate that absence of antibody response to the 5-1-1 protein is frequent in genotype III/2a HCV carriers and may serve to predict responses to interferon therapy.

Hepatitis C virus genotypes in Belgian hemophiliacs

Hemophiliacs who have been exposed to unheated and/or dry heated pooled clotting factor concentrates are at a high risk of chronic hepatitis C. Serum HCV-RNA was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) technique in 58 hemophiliacs positive for anti-HCV antibodies, HCV-RNA was detected in 55 patients. Based on the results of PCR positivity, HCV genotyping was carried out using genotype specific probes and the dot blot hybridization assay: 2 patients were found to be infected with type 1a (3.6%), 31 patients with type 1b (56.4%), 8 patients with type 2 (14.6%), 6 patients with type 3 (10.9%), 1 patient with type 4, and 7 patients with double infection (12.7%). As compared to a control group of 105 nonhemophilia patients with chronic hepatitis C, HCV genotype 1b was found predominant in both groups. However, double infection with two HCV types as well as a relatively high prevalence of infection with type 2 and type 3 were found in hemophiliacs.

Current status of the molecular genetics of hepatitis C virus and its utilization in the diagnosis of infection

BACKGROUND

Since the discovery of hepatitis C virus (HCV) as a major cause of non-A non-B hepatitis, advances have been made in our understanding of the molecular biology of HCV and its relatedness to the flaviviruses and pestiviruses. The use of molecular techniques to construct an antibody assay has enabled the accumulation of information concerning the natural history and pathogenesis of HCV infection.

OBJECTIVES

The objective was to review the literature to March 1994 on the structure, function and genetics of HCV and to correlate these findings with approaches to diagnosis that have contributed to our understanding of HCV infections.

STUDY DESIGN

We reviewed the virological and medical literature from 1988 to March of 1994 with a focus on the stated objectives.

RESULTS

Although the structure of HCV has been well-defined, our knowledge of the function of all the genes of HCV is incomplete. Structural core and envelope proteins as well as enzymes have been described. The 5' end of the polypeptide is most conserved. Genotyping of isolates varies according to the part of the gene examined. Several genotypes exist and tend to predominate in global populations. Antibodies to the various proteins can be measured by EIA assays and positive specimens often require confirmatory testing. Uniquely sensitive nucleic acid detection systems for RNA amplified by PCR have enabled a better understanding of the natural history, epidemiology and responses to treatment.

CONCLUSIONS

Well-designed studies for the detection of nucleic acid, antibodies and antigens using a variety of viral gene products will provide even more information about HCV infections and help lead to treatment and prevention.

Subtyping of hepatitis C virus isolates by a line probe assay using hybridization

A reverse hybridization test (Inno-LiPA HCV; Innogenetics, N.V., Zwijnaarde, Belgium) was used for typing hepatitis C virus. All 38 samples, typed by PCR with primers from core and NS5 genes, were also genotyped by this test. Of the samples, 33 (87%) had the same subtypes by both assays. The correlations between PCR and Inno-LiPA for individual types were 77% for type I (1a), 90% for type II (1b), 100% for type III (2a), 100% for type IV (2b), and 100% for type V (3a). One of the type III (2a) samples also reacted with type I (1a) probes in the Inno-LiPA test.

Nucleotide sequence of the core region of hepatitis C virus in Pakistan and Bangladesh and the geographic characterisation of hepatitis C virus in south Asia

A large number of complete and partial hepatitis C virus (HCV) sequences have been reported and classified into several genotypes, although none have been reported from South Asia. We have determined and evaluated partial sequences in the core region of HCV obtained from patients with chronic hepatitis in Pakistan and Bangladesh. Nucleotide sequences from these viruses show significant homology with the Japanese HCV-TR isolate (91.7%-97.9%) and low homology with other Japanese, American, and UK isolates including HCV-1, HC-J4, HC-J6, HC-J8, and E-b1 (79.3%-86.2%). The homologies of their deduced amino acids sequence with HCV-1, HC-J4, HC-J6, HC-J8, E-b1, and HCV-TR were 84.3%-89.8%, 85.0-87.9%, 84.1%-86.9%, 84.3%-87.0%, 90.2%-93.1%, and 89.8%-93.5%, respectively. These results suggest that our clones might be classified into the same genotype as HCV-TR. Further analysis using molecular evolutionary methods strongly supported the classification of these sequences with the HCV-TR genotype. Moreover, we could not detect any isolates which were closely related to our clones or HCV-TR in countries outside the South Asian area. These data further support the association of HCV genotypes with distinct geographic regions.

Genotypes of hepatitis C virus in chronic liver disease in Taiwan

The genotypes of hepatitis C virus (HCV) infection in 81 patients with liver cirrhosis (LC) or hepatocellular carcinoma (HCC) were investigated by the polymerase chain reaction using type-specific primers. All the patients were positive for HCV RNA in the serum. Forty-two patients had LC with HCC, while the remaining 39 patients had LC without HCC. Genotype II was detected in 47 samples (58.0%), type III in 6 samples (7.4%), and type IV in 4 (6.2%). No evidence of genotype I was found. Mixed infection was detected in 11 samples (13.6%). The prevalence of genotype II in LC with HCC patients (69.0%) was significantly higher (P < 0.05) than in the LC without HCC patients (46.2%). It is concluded that genotype II is the most predominant type in patients with LC or HCC in Taiwan, and is found more frequently in patients who had LC with HCC than in those who had LC alone.

Hepatitis C virus infection in patients with chronic liver disease or chronic renal failure and blood donors in Thailand

Hepatitis C virus (HCV) RNA and genotypes, as well as markers of hepatitis B virus infection, were surveyed in 171 patients with chronic liver disease, 276 patients with chronic renal failure, and 961 blood donors in Thailand. HCV RNA was detected in 30 (23%) of 128 patients with non-alcoholic chronic liver disease and hepatitis B surface antigen (HBsAg) in 60 (47%), and both HCV RNA and HBsAg in 3; the cause of liver disease was not established in 41 (32%) patients. HCV RNA was detected in 44 (20%) of 221 patients on maintenance hemodialysis or with kidney transplantation, but in none of 55 patients on peritoneal dialysis. Antibodies to synthetic HCV core peptides were detected in 39 (4.1%) of sera from 961 blood donors, and HCV RNA was detected in 8 (0.8%). Of the 90 HCV RNA samples from patients and donors, genotype V prevailed (46%) followed by II (22%), I (14%), III (3%), and VI (2%); genotypes were not classifiable into any of I-VI in the remaining 10%. There were six sera which contained HCV RNA, but were without antibody to HCV detectable by the second-generation enzyme immunoassay. HCV RNA titers were high in four patients with kidney transplantation, but low in one patient with chronic liver disease and one patient on maintenance hemodialysis. HCV RNA at high titer (> or = 10(4)/ml) was not classifiable in one patient. These results indicate HCV of novel genotypes in Thailand, seronegative HCV infection in patients with kidney transplantation, and a low risk of HCV infection in patients treated by peritoneal dialysis.

Genotype distribution of hepatitis C virus infection in Taiwan

To investigate the prevalence of genotype distribution of hepatitis C virus (HCV) infection in Taiwan, genotypes were identified in 122 (36 anti-HCV-positive blood donors, 44 anti-HCV-positive aborigines, 28 hemodialysis patients, and 14 patients with chronic liver diseases) of 280 subjects, using polymerase chain reaction by Okamoto's type-specific primer method. Type II was the dominant (66.7%) type among anti-HCV-positive blood donors, followed by type III and type IV with the same percentages (16.7%), while none of type I was detected. The prevalence of genotype distribution were 75.0%, 81.1%, and 64.3% for type II, 4.6%, 17.9%, and 21.4% for type III, 13.6%, 0%, and 7.1% for type IV, for the aborigines, hemodialysis, and chronic liver diseases groups, respectively. Four subjects revealed mixed infections by two different genotypes: two cases of II and III; and each one case of II and IV, and III and IV. Diverse genotype distributions in two hemodialysis groups disclose the existence of obvious regional differences even within a region. The results reveal the highest prevalence of type II as in Japan. However, there is a higher prevalence rate of type IV than in Japan.

Distribution of viral genotypes in Italy determined by hepatitis C virus typing by DNA immunoassay

The distribution of hepatitis C virus (HCV) genotypes in Italy was investigated by PCR amplification of the E1 region and hybridization with type I- and type II-specific nonisotopic probes. Positive PCR results were obtained for 65 of 72 patients (90.3%). Type I was detected in 13 of 72 patients (18%), type II was detected in 39 patients (54.2%), and a mixed type I-type II infection was detected in 7 patients (9.7%). Six amplification products not classified by this method shared a low level of homology with HCV types I and II. HCV type I was significantly associated with human immunodeficiency virus, whereas HCV type II was detected in older subjects who were negative for human immunodeficiency virus markers. These results indicate different epidemiological distributions of HCV types I and II in Italy.

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.

A clinicopathologic study of chronic non-A, non-B (type C) hepatitis in Taiwan: comparison between posttransfusion and sporadic patients

To elucidate the clinicopathological course and the role of hepatitis C virus in posttransfusion and sporadic chronic non-A, non-B hepatitis in Taiwan, we retrospectively studied 85 histologically confirmed patients with long-term follow up. Antibodies against hepatitis C virus (anti-HCV) by a second-generation assay were positive in 81% of the patients: 88% in the posttransfusion group and 76% in the sporadic group. Clinical manifestations were generally mild, and were noted in only half of the patients. During follow up, 33% (28 of 85 patients) had episodes of acute exacerbation of chronic liver disease and 24% (20 of 85) had normalized liver tests. Patients with normalized liver tests were usually anti-HCV negative (55% vs. 8%, p < 0.001). In 34 patients who had had blood transfusions, initial liver biopsies revealed chronic active hepatitis in 41%, active cirrhosis in 6%, and inactive cirrhosis in 9%. Follow-up biopsies in eight patients in this group showed histological progression in three after an average of 40.6 months. In the 51 sporadically infected patients, initial work-up revealed chronic active hepatitis in 37%, active cirrhosis in 4%, and inactive cirrhosis in 14%. Among the nine who underwent repeated biopsies, only one (11%) had progression. Patients above age 40 displayed more severe histologic activity than those below 40 (p < 0.005). Three patients, all with cirrhosis, died of hepatocellular carcinoma 7 to 12 years after follow up. Further genotyping study of hepatitis C virus in 28 patients showed that type II virus was most predominant in Taiwan and histologic severity was similar among patients infected with different genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Genotyping of Canadian hepatitis C virus isolates by PCR

We used PCR for hepatitis C virus (HCV) genotyping with type-specific primers from the core and NS5 genes. Type I was predominant in the general population (58% in blood donors) as well as in different risk groups, such as intravenous drug abusers (58%), blood transfusion recipients (64%), hemophiliacs (62%), and patients with HCV chronic liver disease (76%). Types II, III, and IV were less prevalent in Canada, being found in 10.92, 6.72, and 5.88% of the population, respectively. The type II core primer was not type specific and reacted with the majority of our type I HCV samples, suggesting a false-positive dual infection with two different genotypes (I and II). Digestion of these amplified type I and type II products with restriction endonuclease AccI proved to be very useful in the exclusion of false-positive dual type I and type II infections.

The role of hepatitis C virus in fulminant viral hepatitis in an area with endemic hepatitis A and B

BACKGROUND/AIMS

The role of hepatitis C virus in fulminant hepatitis remains controversial and needs further investigation. The aim of this study was to examine the role of hepatitis C virus in fulminant hepatitis in an area with endemic hepatitis A and B.

METHODS

Serological markers of hepatitis C virus were studied in 62 adults from Taiwan with fulminant viral hepatitis.

RESULTS

Of 62 patients, 5 (8.1%) were infected with acute type B hepatitis, 11 (17.7%) were infected with acute non-A, non-B hepatitis, and the remaining 46 (74.2%) were hepatitis B surface antigen (HBsAg) positive but immunoglobulin M (IgM) antibody to hepatitis B core antigen negative. Of the latter, 11 (23.9%) were IgM antibody to hepatitis D virus positive, 16 (34.8%) had high-titered serum hepatitis B virus DNA (> 1000 pg/mL) and were suspected to have hepatitis B virus reactivation, and the other 19 (41.3%) had no identified causes. Serum hepatitis C virus RNA was found in 5 (45.5%) of 11 patients with fulminant non-A, non-B hepatitis, 3 (27.3%) of 11 HBsAg carriers with delta superinfection, and 6 (31.6%) of 19 HBsAg carriers with fulminant hepatitis of undetermined cause.

CONCLUSIONS

Nearly half of fulminant non-A, non-B hepatitis and about 20% of HBsAg carriers with superimposed fulminant hepatitis in Taiwan could be attributed to hepatitis C virus infection.

Detection of Divergent Hepatitis C Virus Envelope Sequences

The nucleotide sequences of the putative envelope region (E1) and the junction between the E1 and envelope 2/nonstructural 1 (E2/NS1) region of the hepatitis C virus (HCV) genome are divergent among different genotypes. To characterize them, we introduced a set of nested primers that are conserved among four different genotypes (types I-IV) of HCV for polymerase chain reaction (PCR) amplification. The amplified products include the variable full-length E1 region, and the 5' end of the E2/NS1 region, the so-called hypervariable region-1 (HVR-1). Of 53 patients with histologically confirmed chronic liver disease and HCV viremia, type II virus was the most dominant strain as detected by the PCR genotyping method and the envelope region could be amplified in more than half of them irrespective of their genotypes. The specificity was confirmed by subsequent nucleotide sequence analysis. The positivity of envelope region PCR was not correlated with histologic diagnosis and hepatitis activities in these patients. Our results suggest that the nested primers can amplify the variable E1 and hypervariable 5' end of E2/NS1 of the HCV genome with moderate efficiency, and thus will be useful in future studies of HCV infections. Copyright 1994 S. Karger AG, Basel

Analysis of hepatitis C virus genome in patients with autoimmune hepatitis type 2

BACKGROUND/AIMS

Hepatitis C virus (HCV) RNA is detectable in a proportion of patients with autoimmune hepatitis type 2, which is characterized by liver-kidney microsomal antibodies (LKM). Therefore, the genotype and sequence of HCV were studied in these patients.

METHODS

Sera from 43 LKM-positive and anti-HCV-positive patients (15 from Germany and 28 from Italy) and 82 LKM-negative and anti-HCV-positive patients (57 from Germany and 25 from Italy) were examined.

RESULTS

Genotyping revealed that the rate of genotype III HCV according to Okamoto's classification in patients with LKM antibody-positive autoimmune hepatitis type 2 was higher than in LKM-negative patients (22.0% vs. 2.4%; P < 0.05). This was because of an increase of genotype III in our patients from Italy. No HCV mutations were found that show a closer sequence homology to cytochrome P450IID6, the major LKM-1 antigen. Deletions in the envelope and nonstructural region 5 were found.

CONCLUSIONS

Because a specific HCV sequence is not associated with the induction of LKM-1 autoantibodies, future research must focus on host factors and possibly additional environmental factors.

Posttransfusion hepatitis C virus infection in children

Hepatitis C virus (HCV) infection was investigated retrospectively and prospectively in children who had open heart surgery. The retrospective study included 196 patients who had open heart surgery 2 to 6 years before enrollment and were regularly followed. Antibody to HCV was detected in eight cases, and seven of these eight patients had viremia caused by HCV infection. The other patient's anti-HCV titer gradually decreased and HCV ribonucleic acid was absent throughout the course. Four of these eight had persistent viral replication without clinical evidence of hepatitis; the other three had viremia and chronic hepatitis. The HCV infection rate in the retrospective study group was about 4%. The HCV was of genotype 2 in five cases and of genotype 3 in two cases. The clinical outcome was not related to sex, age, amount of transfusion, or HCV genotype. For the prospective study, we enrolled 94 patients. Of the 56 enrolled after the initiation of anti-HCV screening in the blood bank, none was infected by HCV. Of the 94 patients, 38 were enrolled before screening; 4 had abnormal liver function 1 to 3 months after operation, and 2 were infected with HCV. One patient had an acute but resolving course; the other had persistent anti-HCV and HCV viremia, although the liver function test results returned to the normal range. The HCV in both cases belonged to genotype 2. We conclude that in Taiwan the seroconversion rate of HCV in children who underwent open heart surgery was 4% to 5%. Anti-HCV screening in donor blood significantly decreased the incidence of posttransfusion hepatitis C.

Factors predictive of response to interferon-alpha therapy in hepatitis C virus infection

To determine the patient-dependent and virus-related factors that may predict sustained response to interferon-alpha therapy, we prospectively evaluated 60 consecutive patients with chronic hepatitis C who received a standardized treatment schedule of interferon-alpha. Twenty-eight patients achieved a long-term sustained remission, 14 patients had temporary responses during treatment but relapsed after completing it and 14 patients did not respond. Four patients dropped out because of severe side effects and were excluded from evaluation of efficacy. Twenty-one variables were chosen as possible predictors of sustained response and were analyzed by means of multivariate analysis. Variables related to the hepatitis C virus included genotype and concentration in serum before treatment. The former was determined by means of the polymerase chain reaction with genotype-specific primers for genotypes PT, K1, K2a and K2b, which were deduced from nonstructural region 5 of the hepatitis C virus genome. The latter was measured with a competitive polymerase chain reaction technique. Three variables were statistically significant (p < 0.05) on univariate analysis: viral genotype, pretreatment level of viremia and Knodell's fibrosis score. In multivariate analysis viral genotype and Knodell's fibrosis score were correlated independently with a sustained response (p < 0.05 for both). Incidence of sustained response was 40% and 91% in patients with genotypes K1 and K2a, respectively. We conclude that with the treatment schedule used, viral genotype was the most useful predictor of a sustained response to treatment with interferon-alpha.

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

The frequency of infection with the six classified major genotypes of hepatitis C virus (HCV) was investigated in 447 infected volunteer blood donors from the following nine countries: Scotland, Finland, The Netherlands, Hungary, Australia, Egypt, Japan, Hong Kong, and Taiwan. Viral sequences in plasma from blood donors infected with HCV were amplified in the 5'-noncoding region and were typed by restriction fragment length polymorphism analysis. Electrophoresis of DNA fragments produced by cleavage with HaeIII-RsaI and ScrFI-HinfI allowed HCV types 1 (or 5), 2, 3, 4, and 6 to be identified. Further analysis with MvaI-HinfI allowed sequences of the type 5 genotype to be distinguished from sequences of the type 1 genotype. Types 1, 2, and 3 accounted for almost all infections in donors from Scotland, Finland, The Netherlands, and Australia. Types 2 and 3 were not found in the eastern European country (Hungary), where all but one of the donors were infected with type 1. Donors from Japan and Taiwan were infected only with type 1 or 2, while types 1, 2, and 6 were found in those from Hong Kong. HCV infection among Egyptians was almost always by type 4. Donors infected with HCV type 1 showed broad serological reactivity with all four antigens of the second generation Chiron RIBA-2 assay (Chiron Corporation, Emeryville, Calif.), while infection with divergent HCV genotypes elicited antibodies mainly reactive to c22-3 and c33c. Reactivities with antibodies 5-1-1 and c100-3 were infrequent and were generally weak, irrespective of the geographical origin of the donor. Because the envelope region of HCV is even more variable than the NS-4 region, it is likely that vaccines based on these proteins need to be multivalent and perhaps specifically adapted for different geographical regions.

Problem hepatitis viruses: the mutants

Genetic variations in the known human hepatitis viruses are probably the result (a) of high viral replication rates and poor or absent proofreading ability intrinsic to RNA viruses (HAV, HCV, HDV, HEV) and (b) to a DNA virus (HBV) that uses a reverse-transcription mechanism for genomic replication. Nucleotide substitutions, deletions, duplications, insertions, and rearrangements resulting in amino acid changes may have no consequences, may impair replication, change host susceptibility, or may lead to escape from immune attack. Genetic diversity has been identified in each of the known hepatitis viruses. The importance of mutant viruses in pathogenicity, immunity, natural history, clinical outcomes, vaccine production, and responsiveness to treatment has emerged as an area for intensive study.

Prevalence of hepatitis C virus genotypes in Italy

Hepatitis C viruses (HCV) present in 110 Italian patients were characterized by genotype-specific PCRs. Among the 65 cases of community-acquired hepatitis, HCV genotype II was dominant (60%), followed by genotypes IV (15%), III (11%), and I (3%). Among the 45 hemophilia-associated cases, the distribution of the four HCV genotypes was markedly different: genotype I was the most prevalent (61%), followed by genotypes II (25%), III (4%), and IV (2%). Double infections were observed in eight patients. Two HCV remained unclassified. For the 45 community-acquired cases from which a liver biopsy was available, genotype II was associated with more severe liver damage than the other types.