Differences in the hepatitis C virus genotypes in different countries

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.

Factors predictive of response to interferon-alpha therapy in hepatitis C virus type 1b infection

Interferon-alpha (IFN-alpha) has been used to treat hepatitis C Virus (HCV)-induced infection but has been effective in only about half of all patients. It is suggested that the different responses to IFN-alpha treatment in HCV infection may be influenced by HCV genotypes, HCV RNA titer at the beginning of IFN-alpha therapy, and the sequences of the interferon sensitivity determining region (ISDR). However, there have also been reports showing that these have no relation to an IFN-alpha effect. In a previous study, it was found that the nucleotide sequence variation in the hypervariable region (HVR) 1 of the HCV could predict the effect of IFN-alpha. In the present investigation, an attempt was made to determine the predictive factors of IFN-alpha therapy. Twenty-six patients with HCV infection were treated with IFN-alpha. Among these, 13 patients recovered after 3 to 6 months of IFN-alpha treatment, although the other 13 patients showed no response after 6 months of treatment with IFN-alpha. In order to determine the predictive factors of IFN-alpha therapy, the ALT levels, HCV genotypes, HCV serum titer, and the quasispecies of HVR 1 were compared between responders and non-responders. It is suggested that the variation in the HVR 1 and HCV serum titer can be used to predict the effect of IFN-alpha.

Outcome of liver disease in a large cohort of histologically proven chronic hepatitis C: influence of HCV genotype

OBJECTIVE

To assess the influence of hepatitis C virus (HCV) genotypes on the clinical outcome of liver disease, we analysed 2,307 patients.

RESULTS

The most frequently represented genotypes were 1b (40%) and 2 (28.1%). Patients with these genotypes had a median age higher than patients with other genotypes (P< 0.01). The overall survival of subjects with genotype 1b was poorer than the survival of patients with other genotypes (P< 0.01). Liver cirrhosis was found in 280 patients (12.1%), and type 1b was the most represented isolate among them (P< 0.01). Sixty-two patients (22%) developed hepatocellular carcinoma (HCC) during a follow-up of 1481.8 cumulative years (estimated crude incidence rate, 4.1 cases per 100 person-years for all cirrhotics; 5.9 cases for genotype 1a; 4.5 cases for genotype 1b; and 2.8 cases for genotypes non-1). Considering the whole population of 2,307 patients, only genotype 1b was associated significantly with both cirrhosis and the development of HCC. One hundred and nineteen cirrhotic patients underwent treatment with interferon in uncontrolled studies. Interferon therapy was associated with both better survival (P< 0.01) and a lower cumulative hazard for HCC (P< 0.01).

CONCLUSIONS

Genotype 1b was associated with a poorer prognosis, probably because it leads to cirrhosis and consequently to HCC development. However, our data did not confirm genotype 1b as an independent risk factor for HCC in liver cirrhosis, which plays a major role in carcinogenesis. Interferon should be considered as a useful strategy in cirrhosis for improvement of survival and reduction of HCC risk.

Genotype and viral load as prognostic indicators in the treatment of hepatitis C

Interferon-alpha (IFN-alpha), either alone or in combination with ribavirin, is the standard treatment for patients with hepatitis C. However, most patients do not achieve a sustained remission with this treatment regimen. A number of studies have demonstrated that genotype, baseline viral load and/or a decrease in viral load early after treatment induction are the major predictive factors for response to treatment with IFN. Patients with hepatitis C virus (HCV) genotype 1 are more resistant to treatment with IFN, whereas low viral load at baseline and a marked decline in the HCV RNA level during the first 2-12 weeks of IFN therapy are associated with enhanced treatment efficacy. These variables could potentially be used to develop treatment algorithms that tailor therapies for specific clinical situations. Continued development and refinement of such algorithms would facilitate both the selection of patients who are most likely to benefit from therapy and the development of optimal treatment regimens for different patient groups. Predictive factors will also enable clinicians to identify subsets of patients who are not expected to respond well to current treatment. The development of new delivery methods for IFN that produce sustained antiviral pressure may provide a means of treating these previously difficult-to-treat patient groups.

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

Assessment of hepatitis C virus RNA and genotype from 6807 patients with chronic hepatitis C in the United States

Hepatitis C virus (HCV) RNA status and HCV genotype have become important tools in the diagnosis and monitoring of therapy in chronic HCV infection. To establish a database with respect to HCV genotype and serum HCV RNA concentrations in chronic hepatitis C patients in the United States, we analysed 6807 chronic hepatitis C patients who had HCV RNA and HCV genotype tests conducted at a central laboratory. The HCV RNA concentration cut-off for the lower 25th percentile of this population (low titre) was 0.9 x 106 copies ml-1. The median HCV RNA concentration was 3.5 x 106 copies ml-1 and the cut-off for the upper 25th percentile (high titre) was 5 x 106 copies ml-1. Male patients had a median HCV RNA concentration of 3.9 x 106 copies ml-1, which was significantly higher than the median HCV RNA level for females (2.75 x 106 copies ml-1; P < 0.001). HCV genotype 1 was detected in 73% of patients; genotype 2 in 14%; genotype 3 in 8%; mixed genotype in 4%; and genotypes 4, 5 and 6 with a frequency of < 1%. Patients from the Northeast, Southeast and Midwest had significantly (P < 0.001) more infections with genotype 1 than patients from the Western and Southern regions. African-American patients were more likely to be infected with genotype 1 when compared with Caucasian, Hispanic or Asian Pacific Islanders (P < 0.001). Patients infected with HCV genotype 1 and mixed HCV genotypes had significantly higher serum HCV RNA concentrations when compared with HCV genotypes 2 and 3 (P < 0.001 for all comparisons).

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

Hepatitis C virus genotypes in hemophiliacs in the state of Minas Gerais, Brazil

BACKGROUND

Hepatitis C virus (HCV) is a positive-strand RNA virus composed of at least 10 genotypes and dozens of subtypes. Six major genotypes can be distinguished by restriction fragment length polymorphism (RFLP) analysis of the amplified 5' noncoding region (NCR) of the genome. The genotypes are unequally distributed throughout the world. Types 1 and 3 are most common in Europe and the United States. Although fewer studies have been performed in Brazil, the pattern seems to mirror that in the other areas. HCV infection is highly prevalent among hemophiliacs and is a major cause of chronic liver disease.

STUDY DESIGN AND METHODS

This study investigated a sample of the hemophiliac population in the state of Minas Gerais, Brazil, by RFLP analysis of the 5' NCR.

RESULTS

It was observed that 84.1 percent were of genotype 1 and 13.6 percent of genotype 3. Sequence analysis of nine isolates confirmed the RFLP results and determined that all of the type 1 isolates belonged to subtype 1a. Phylogenetic analysis by parsimony and distance revealed that lineages of genotypes 1, 2, and 3, and 4 could be separated. The isolates of type 3 from this study were distinct from published sequences, which possibly indicated their different geographical origin.

CONCLUSION

Although the frequency of genotypes observed (types 1 and 3) among hemophiliacs in the state of Minas Gerais was higher than that in the southern part of the country, these frequencies were not different from those in other groups of patients in Brazil and other countries studied. Further investigation is needed of the evidence that the type 3 isolates observed in these studies are significantly different from other isolates previously characterized by sequence analysis.

Fulminant hepatic failure in acute hepatitis C: increased risk in chronic carriers of hepatitis B virus

BACKGROUND/AIMS

The role of hepatitis C virus (HCV) in fulminant hepatitis remains controversial. This study was conducted to investigate the risk of fulminant hepatitis C in relation to HCV genotypes and concurrent infection of other viruses.

PATIENTS

109 HCV RNA positive patients from 334 consecutive cases hospitalised to a medical centre in northern Taiwan for overt acute viral hepatitis were prospectively evaluated.

METHODS

HCV RNA was detected by a combined reverse transcription-polymerase chain reaction assay. HCV genotypes were analysed using a genotype specific probe based assay in the 5' untranslated region.

RESULTS

39 patients tested positive for hepatitis B surface antigen but negative for IgM antibody to hepatitis B core antigen, indicating concurrent chronic hepatitis B virus (HBV) infection. Twelve patients were hepatitis G virus (HGV) RNA positive. Genotyping of HCV disclosed 1b in 93, 1b mixed with 2a/2c or 1b mixed with 2b in 11, and not classified in five. Serum titres of HCV RNA were <10(5) copies/ml in 77, 10(5)-10(7) copies/ml in 25, and >10(7) copies/ml in seven. Eleven patients (10.1%) had fulminant hepatitis as a complication. Development of fulminant hepatitis did not correlate with age and gender of the patients, concurrent HGV infection, HCV genotypes, or serum titre of HCV RNA. However, the incidence (95% confidence interval) of fulminant hepatitis in patients with underlying chronic HBV infection was 23. 1% (9.9 to 36.3%), which is significantly higher than in those without (2.9% (-1.0 to 6.8%)). In 39 patients with concurrent chronic HBV infection, the clinical and virological characteristics showed no significant difference between those with fulminant hepatitis and those without.

CONCLUSIONS

Acute hepatitis C in patients with concurrent chronic HBV infection is associated with a substantial risk of fulminant hepatitis.

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection

An association has been reported between mutations in the amino acid residues 2209-2248 of the nonstructural protein 5A (NS5A) gene (interferon-sensitivity determining region [ISDR]) and interferon efficacy in hepatitis C virus (HCV)-1b infection. This relationship was analyzed in chronic HCV-2 infection. Forty patients with HCV-2a and 35 with HCV-2b were treated with interferon alfa for 6 months with a total dose of 468 to 860 million units. Pretreatment NS5A sequences were determined by direct sequencing. A higher complete and sustained response rate was observed in HCV-2a than in HCV-2b (70% vs. 34%; P =.003). Serum HCV-RNA levels were lower in complete responders than nonresponders in HCV-2a (P =.049) and HCV-2b (P =. 02). The number of amino acid mutations was greater in complete responders than nonresponders in NS5A2193-2228 (the region corresponding to the ISDR of HCV-1b) alone (P =.049), or NS5A2163-2228 consisting of NS5A2193-2228 plus its upstream region (P =.02) in HCV-2a, but not in HCV-2b. A significant inverse correlation was observed between serum HCV-RNA levels and the number of amino acid mutations in NS5A2193-2228 (P =.003) or NS5A2163-2228 (P =.005) in HCV-2a. With multivariate analysis, the number of substitutions in NS5A was an independent predictor for complete response in HCV-2a (odds ratio: 6.4; P =.03). Interferon efficacy is associated with amino acid variations in the NS5A protein in HCV-2a infection.

Hepatitis C virus serotypes and sources of infection in patients with HCV-related chronic liver disease from one geographical area in southeast Italy

Hepatitis C virus serotypes and sources of infection in HCV-positive patients from a restricted geographical area were evaluated. HCV serotypes were determined by Murex serotyping assay. Of 192 samples, serotypes were detected in 189 (98.5%): type 1 proved to be the most common (53.1%), followed by types 2 (15.2%), 3 (6.2%), 6 (5.3%), 4 (3.6%) and 5 (1.6%). Intravenous drug users were significantly younger than the rest of the patients and infected mainly with HCV type 3. Transmission of HCV 3 has only been observed over the past 20 years; other types have been transmitted for up to 40 years. These results support the view that the prevalence of the infection by different HCV types in one restricted geographical area may be associated with the source and duration of infection.

A computer model of the spread of hepatitis C virus among injecting drug users

A number of behavioural and clinical parameters influence the transmission of an infectious agent through direct contact between two individuals. The behavioural parameters encountered in such situations are also likely to exhibit an enormous amount of variability. With the spread of hepatitis C among injecting drug users, the parameters associated with injecting behaviour play an important role in the modelling of the transmission process. Computer simulation modelling is an ideal approach to deal with a large number of parameters as well as high levels of variability without excessive simplification. The simulation model presented in this paper is tested on data from a cohort of injecting drug users and the results obtained are very encouraging from a public health perspective. The model clearly indicates that the rate at which HCV spreads through a population of injecting drug users is extremely sensitive to the interaction rate and to the probability of infection through a single contact with an infective. At the same time it shows that rate of spread is not very sensitive to initial prevalence, which is very encouraging from a public health perspective.

Cryoglobulinaemia and rheumatic manifestations in patients with hepatitis C virus infection

OBJECTIVES

To investigate the association of cryoglobulinaemia and rheumatic manifestations in Korean patients with hepatitis C virus (HCV) infection.

METHODS

Forty nine Korean patients with HCV infection were recruited. The prevalence, concentration, and type of cryoglobulin (by immunofixation), rheumatoid factor (RF), antinuclear antibody (ANA), and various rheumatological symptoms were investigated and HCV genotype was determined by polymerase chain reaction with genotype specific primer.

RESULTS

The prevalence of cryoglobulin was 59% in Korean HCV patients and the concentration of cryoglobulin was 9.8 (7.9) g/l (mean (SD)). The type of cryoglobulinaemia was identified in 23 (80%) of 29 HCV patients with cryoglobulinaemia and they were all type III. There were no differences in age, sex, history of operation and transfusion, proportion of liver cirrhosis between the patients with cryoglobulinaemia and those without cryoglobulinaemia. The frequencies of RF and ANA were 14% and 3.4% respectively in HCV patients with cryoglobulinaemia. There was no difference in HCV genotype between the patients with cryoglobulinaemia and those without cryoglobulinaemia. Clinical features of HCV patients were as follows: arthralgia/arthritis (35%), cutaneous manifestation (37%), Raynaud's phenomenon (8%), paresthesia (44%), dry eyes (22%), dry mouth (10%), oral ulcer (33%), and abdominal pain (14%). However, these rheumatological symptoms did not differ between the two groups.

CONCLUSION

Although the rheumatological symptoms were not different between HCV patients with and without cryoglobulinaemia, HCV patients showed various rheumatological manifestations. These result suggests that HCV infection could be included as one of the causes in patients with unexplained rheumatological symptoms.

HCV genotypes in Northern Italy: a survey of 1368 histologically proven chronic hepatitis C patients

BACKGROUND/AIMS

Hepatitis C virus (HCV) easily undergoes genomic changes, thus accounting for the presence of different genotypes, with different geographic distributions and different outcomes of chronic hepatitis. Type 1b is frequently found in advanced diseases; however, since this genotype is the most prevalent in older patients, the association with advanced age and severity of the disease is confounding. The aim of this study was to assess changes in the prevalence of HCV genotypes by surveying a large population of chronic hepatitis C patients in Northern Italy, and to assess if the high prevalence of genotype 1b in older patients with advanced diseases simply reflects the duration of HCV infection, rather than intrinsic biological properties of HCV.

METHODS

We studied 1368 HCV-RNA positive patients, with histologically proven chronic hepatitis. Drug addiction, blood transfusions and sporadically acquired infections represented the risk factors.

RESULTS

Genotype 1b, the most prevalent isolate, and genotype 2a were associated with older age, cirrhosis, sporadically-acquired infections and blood transfusion, while types 1a, 3a, and 4 were associated with younger age, chronic persistent hepatitis and drug addiction. Patients with a history of transfusions were divided into four groups depending on the period of transfusion. The prevalence of genotype 1b decreased with time. Type 3a appeared only after 1979.

CONCLUSION

The severity of chronic hepatitis C could be related more to the duration of the infection rather than to the intrinsic pathogenicity of HCV genotypes.

Genotyping HCV isolates from Italy by type-specific PCR assay in the core region

A revision of the polymerase chain reaction (PCR) core procedure was performed for genotyping hepatitis C virus (HCV) in 139 patients from Italy. This procedure, developed prior to the identification of new genotypes, may be inadequate in several geographical areas. We proposed a new typing mixture in which primers for types 2c and 4, that are reported to be circulating in Italy, were added and a primer for type 2b was substituted. Using the modified procedure, 139 HCV-positive patients were analysed. The HCV genotype was identified in 96.4% of the cases. We observed double infections and unclassified genotypes in 5 (3.6%) and 5 (3.6%) patients, respectively. The classification of isolates into genotypes and subtypes 2b, 2c and 4 was confirmed by sequence analysis. Furthermore, the efficiency and accuracy of the modified core procedure were evaluated by parallel testing of 107 out of 139 samples using the line probe assay, and demonstrated a 98.9% degree of concordance. The results demonstrated the specificity of the selected primers for type 2c, 2b and 4 and confirmed the circulation of types 2c and 4 in Italy. In conclusion, the proposed modified PCR procedure is the only primer-specific PCR genotyping method available for identification of the 2c and 4 genotypes reported to be circulated in Italy and other European countries.

Hepatitis C virus genotypes: epidemiological and clinical associations. Benelux Study Group on Treatment of Chronic Hepatitis C

In a cohort of 292 chronic hepatitis C patients living in the Benelux countries the relationship between viral genotype and geographical origin, route of transmission, clinical characteristics and severity of liver disease was analyzed. HCV-RNA isolates could be classified by the Line Probe Assay (LiPA) as 1a, 1b, 2, 3, 4 or 5 in 286 (98%) cases. Patients of European origin were predominantly infected with HCV subtype 1b (164/254, 65%, CI 58-70%), as were patients of Asian origin (7/13, 54%). Patients originating from Surinam (South America) had predominantly type 2 (9/10, 90%), whereas Africans were mainly infected with type 4 (7/9, 77%). Blood transfusion was the mode of transmission in 142 (50%) patients, intravenous drug abuse (IVDA) in 40 (14%), occupational needle accident or tattoo in 11 (4%); no obvious source of infection was found in 93 (33%). In patients infected by blood transfusion, subtype 1b was predominant (70%, CI 61-77%), whereas subtypes la and 3 were predominant in those infected by IVDA (25% and 45%, respectively, p<0.001). Cirrhosis was observed in 68 (24%) patients; in multivariate analysis, factors independently related to cirrhosis were: the duration of infection, age and prior hepatitis B. No significant relationship was found between the severity of fibrosis or liver inflammation and the HCV (sub)types. In summary, in this large cohort of patients in the Benelux countries the hepatitis C virus (sub)type present was clearly related to the country of origin and the route of transmission, but not to the severity of liver disease.

[Biology of hepatitis C viruses: clinical implications]

Infection by hepatitis C virus is characterized by a high rate of chronicity and low viremia. The virus has only been recently identified; it is a positively stranded RNA virus which shows homology in its genetic organisation with the pestiviruses and flaviviruses. There is not yet an efficient culture system available. Evidence indicates that the genetic variability of the HCV genome might have important clinical implications.

Durability of serological remission in chronic hepatitis C treated with interferon-alpha-2B

OBJECTIVE

We assessed the long-term effect of a course of interferon therapy on the biochemical and virological markers of Canadian patients with chronic hepatitis C.

METHODS

Thirty-six patients with chronic hepatitis C were treated with a median total dose of interferon-alpha-2B of 181.0 million U (range 109.0-384.0 million U) and were followed for a median of 37.2 months (range 12.0-94.2 months) after completing treatment. All patients received an initial 16 wk of interferon at a dose of 3 million U three times weekly; this was followed by either no further interferon or by 8 wk more at doses ranging from 1.5 to 10.0 million U three times weekly. Serum alanine aminotransferase (ALT) and hepatitis C virus (HCV) RNA levels were measured before interferon therapy, 6 months after treatment, and at the end of follow-up for each patient. HCV RNA was analyzed by branched DNA 1.0 assay and, if undetectable, by polymerase chain reaction. HCV genotyping was performed on serum samples.

RESULTS

Five (13.6%) of the 36 patients had a sustained treatment response, defined as normal ALT and undetectable viremia 6 months after treatment. All five patients remained in serological remission to the end of their follow-up, a median of 48.2 months (range 23.0-66.2 months) after interferon therapy. Responders were similar to nonresponders in age, gender, initial ALT and serum HCV RNA levels, pretreatment histology, and total dose of interferon received.

CONCLUSIONS

In patients with chronic hepatitis C, 13.6% had normal ALT and undetectable serum HCV RNA 6 months after finishing interferon therapy. These patients remained in serological remission to the end of their follow-up, 48.2 months after interferon therapy.

The prevalence of hepatitis C virus types in patients of the same geographic area, according to the source of infection and liver disease

BACKGROUND

The duration and stage of hepatitis C might be associated with the source of infection and hepatitis C virus (HCV) types.

OBJECTIVE

We studied the relationship among the different HCV types, source, duration, and stage of infection in 100 patients from the Apulia, southern Italy, selected from consecutive clinical records. They were 20 parenterally infected haemophiliacs with 10-20 years of disease history, but without cirrhosis; 20 patients (matched for sex, age and disease) and without known risk factor for parenteral infections; 60 patients with community acquired infection (ten with CAH and ten with cirrhosis with less than 20 years disease history; 20 with cirrhosis and hepatocellular carcinoma (HCC) and more than 20 years of liver disease and 20 matched cases with cirrhosis without HCC).

RESULTS

Type 1 and 2 HCVs had comparable prevalence in patients with long lasting and recent HCV infection, 56 and 64%, 26 and 30% respectively. HCV type 3 was found in 6.5-12% of the patients with recent HCV infection, but it was not detected in those with infection longer than 20 years. Type 1 b HCV was more frequently found in HCC patients (68% of cases) than in the other forms of liver disease. The opposite was observed for HCV types (2 and 3).

CONCLUSIONS

The prevalence of the different HCV types appears associated with the source and duration of the infection. The interesting association between HCV type 1 b and HCC prompts further studies in larger series of patients.

Mutations in the NS5A gene of hepatitis C virus in North American patients infected with HCV genotype 1a or 1b

Previous studies from Japan have described an association between a conserved sequence within the hepatitis C virus (HCV) genome and resistance to interferon (IFN) therapy for patients infected with HCV genotype 1b [Enomoto et al. (1995): Journal of Clinical Investigation 96: 224-230; Enomoto et al. (1996): New England Journal of Medicine 334:77-81]. The present study examines amino acid sequences surrounding the putative Interferon Sensitivity Determining Region (ISDR) of the NS5A gene of HCV in 21 North American patients with genotype 1a or 1b infection receiving recombinant IFN therapy. The ISDR consensus or intermediate pattern was observed in 13 of 14 NS5A clones from North American patients infected with genotype 1b. However, we found no evidence of the consensus ISDR sequence in any NS5A clones isolated from 15 patients with genotype 1a infection. In select cases, gel shift analysis showed no significant changes in the clonal frequency of the putative ISDR domain of HCV genotype 1a or 1b infected patients who were either nonresponsive to IFN therapy, or relapsed following withdrawal of IFN therapy. These results suggest that a conserved ISDR domain is neither associated with, nor responsible for, IFN resistance in North American patients infected with HCV genotype 1a, and demonstrate a need for further investigation into the reported association between ISDR consensus sequences and IFN resistance in genotype 1b clones.

Distribution of hepatitis C virus genotypes among blood donors in Taiwan

The aim of this study was to investigate the prevalence and distribution of hepatitis C virus (HCV) genotypes of blood donors in Taiwan. RNA was extracted from the serum of anti-hepatitis C virus-positive carriers and this was followed by reverse transcriptase-polymerase chain reaction (RT-PCR) using type-specific primers for the presence of HCV genotypes, 1a, 1b, 2a, 2b, 3a and 6a. Of the 604 anti-HCV-positive specimens, the PCR demonstrated that 93.0% (562/604) were positive for at least one HCV genotype. The remaining 42 specimens (7%) were HCV negative. Among the 562 HCV-positive specimens, 505 (89.8%) contained HCV 1a, 1b, 2a, 2b and 3a as the only genotype, with a prevalence of 0.4% (2/562), 60.1% (338/562), 15.5% (87/562), 11.9% (67/562), and 2.0% (11/562), respectively. No HCV genotype 6a was found. Thirty-seven specimens (6.6%) exhibited mixed infections with multiple HCV genotypes that included types 1b, 2a and 2b, while 20 (3.5%) HCV RNA-positive sera remained unclassified. These results confirm that the predominant HCV genotype in Taiwan is 1b. In addition, genotypes 1a and 3a can also be found in Taiwan at low frequency.

Different viral aetiology of hepatocellular carcinoma between two hepatitis B and C endemic townships in Taiwan

In Taiwan, we found two hepatitis B virus (HBV)- and hepatitis C virus (HCV)-endemic townships, Paisha and Tzukuan, with an anti-HCV prevalence of 19 and 37% in men, and 26 and 38% in women, respectively. The hepatitis B surface antigen (HBsAg)-positive rates were 25 and 18%, for men and women in Paisha, and 25 and 22% in Tzukuan, respectively. According to the national death certification database (1982 to 1991), the annual age-adjusted mortality rates per 100,000 population for liver cancer among men and women were 83.0 and 13.8, respectively, in Paisha, and 55.9 and 17.0 in Tzukuan compared with 30.9 and 9.1 in Taiwan as a whole. The male-to-female ratios were 6.0 in Paisha and 3.3 in Tzukuan. Aetiology of 11 cases of hepatocellular carcinoma (HCC) from Paisha and 14 cases from Tzukuan were analysed. All HCC cases from Paisha were HBsAg positive, while 13/14 HCC cases from Tzukuan were anti-HCV positive. The endemic duration of HCV in Tzukuan seemed long enough to induce HCC, but the HCV appeared to be a newly introduced infection in Paisha.

Virological characterization and liver histology in HCV positive subjects with normal and elevated ALT levels

We analyzed HCV genotype and RNA titer in 36 chronically infected subjects, 20 with persistently normal or near-normal alanine aminotransferase (ALT) activity and 16 with raised ALT activity. All subjects underwent liver biopsy and evaluation of the histological activity index (HAI) by both Knodell's and Ishak's scoring systems. Genotype 2 was detected in most subjects with normal ALT activity, whereas genotype 1 was more frequent among subjects with raised ALT activity. HCV-RNA titer was higher in subjects with increased ALT. Histological evidence of chronic hepatitis was documented in all cases, but higher scores for grading and for staging were associated with increased ALT activity. HCV genotype had no statistical relationship with RNA titer or with liver histology. In logistic regression analysis, viral genotype, RNA titer or with liver histological scores for grading and staging were correlated independently with the ALT profile. The evidence of chronic hepatitis in all subjects with persistently normal ALT activity suggests that healthy HCV carriage is a rare event.

Evaluation of two simplified methods for genotyping hepatitis C virus

A number of different approaches have been used for genotyping hepatitis C virus (HCV). Two simplified methods were evaluated, both of which used polymerase chain reaction (PCR) to amplify products from the 5' non-coding region of HCV: non-isotopic restriction fragment length polymorphism (RFLP) analysis and type-specific PCR. Sixty-four viraemic patients suffering from chronic HCV infection were studied using these two techniques; 25/64 samples were further tested with a commercial serotyping ELISA based on synthetic NS4 antigen (Murex, U.K.). The results of the three typing methods were generally in agreement with each other. When only the predominant genotype identified by each method was analysed, the 3 methods had 100% agreement. RFLP did not detect any mixed infections and it was unsuccessful in 16/64 (25%) samples. Both type-specific PCR and serotyping ELISA detected mixed infections. However, serotyping ELISA did not give typeable results in 7/25 (28%) samples, whereas type-specific PCR gave typeable results in all 64 samples. Type-specific PCR detected more mixed infections than serotyping ELISA. Direct sequencing of four PCR products with indeterminate RFLP confirmed changes in restriction enzyme recognition sites. The sequences also confirmed the validity of the predominant genotype in cases of apparent mixed infections. It is possible that some of these cases were artefacts as a result of quasispecies.

Hepatitis C virus replicative levels and efficiency of genotyping by specific PCR and antibody assay

We studied factors which influence the detection of hepatitis C virus genotypes by the group-specific PCR of the sequence within the core region gene and by the newly developed genotype-specific NS4 antibody assay. Genotyping was performed on 75 hepatitis C virus carriers in Japan, where patients with hepatitis C viremia are exclusively infected with genotype 1b, 2a, and 2b. PCR failed to identify genotypes in 8 (11%) patients, whereas 12 (16%) patients, including the 8 patients mentioned above, could not be genotyped by the serological assay. Serological genotypes showed almost complete agreement with those found by the PCR except that double infection was revealed in only two of the eight patients serologically judged to be coinfected with genotypes 1 and 2. In each assay, disease activity and levels of viremia assessed by a competitive reverse transcription PCR assay were significantly lower in patients infected with untypeable isolates than in those infected with typeable ones (P < 0.01). The PCR could identify the genotypes of isolates from all 64 patients with levels of viremia of > or = 10(6) copies/ml, and the genotype-specific antibody responses were found in 60 (94%) patients. In contrast, isolates from only 3 (27%) of 11 patients with low levels of viremia (< 10(6) copies/ml) could be genotyped by the PCR (P < 0.00001), and these patients showed the genotype-specific antibody responses (P < 0.00001). These findings suggest that low levels of hepatitis C virus replication may reduce the efficiency of genotyping by serological assay as well as by PCR.

Distribution of hepatitis C virus genotypes in German patients with chronic hepatitis C: correlation with clinical and virological parameters

BACKGROUND/AIMS

The hepatitis C virus genotypes have been shown to be differently distributed between distinct geographical areas and to be associated with different clinical presentations. In the present study we investigated the distribution of HCV genotypes in 379 German patients with chronic hepatitis C in relation to age, sex, route of infection, liver histology and viremia.

METHODS

Typing of HCV was done using restriction fragment length polymorphism analysis as well as a DNA enzyme immunoassay. HCV RNA concentrations were determined by quantitative polymerase chain reaction. Liver biopsies were performed in 187 patients and the histological activity was graded by the Knodell score.

RESULTS

Seventy percent were infected with genotype 1 (20% subtype 1a, 80% subtype 1b), 4% with genotype 2 and 26% with genotype 3 (all subtype 3a). Genotype 3a and 1a infection was significantly associated with intravenous drug abuse. In contrast, genotype 1 predominated in patients with post-transfusion hepatitis and infection of unknown origin. A changing relative prevalence of HCV genotypes in relation to age was also observed. Patients with genotype 3 infection showed significantly lower HCV RNA levels and a lower mean histological activity score as compared to patients with genotype 1 and genotype 2. However, using multivariate analysis, only age and mode of transmission but not histological activitiy score were shown to be independent variables.

CONCLUSIONS

Our study confirms previous reports from other countries that HCV variants can be classified into a relatively small number of discrete genotypes, and that the subtype 1b clearly predominates. However, we found evidence that there is a changing relative prevalence of HCV genotypes in relation to age, and that the mode of transmission is reflected in the predominance of certain genotypes.

Relation of hepatitis C virus genotypes to risk factors and hepatic disease in Spanish patients

OBJECTIVE: To ascertain the prevalence of hepatitis C virus (HCV) genotypes in Spain and their distribution by risk factors. METHODS: The study covered 216 patients with hepatitis C. Of these, 63 were intravenous drug users (IVDU), 44 had received transfusions, and 30 were hemodialyzed, and in 79 the risk factors were unknown. Antibodies against HCV were detected by second-generation enzyme immunoassay (EIA) and confirmed by immunoblot. HCV RNA presence was investigated by reverse transcription---polymerase chain reaction (RT-PCR), and a reverse hybridization test of the amplifications was used for the genotyping. RESULTS: The most frequently encountered genotypes were 1b (48.1%), 1a (21.3%) and 3a (11.1%). HCV genotypes 1a (42.8%) and 3a (20.6%) were the most prevalent genotypes in IVDU patients, while 1b was the most frequent in patients with unknown risk factors (62.0%), transfused patients (68.1%) and hemodialyzed patients (50.0%). Mixed infections were detected in nine cases (4.1%); three appeared in IVDU patients (4.7% of the total IVDUs), two in transfused patients (4.5%) and four (50%) in patients with unknown risk factors. No statistically significant differences were found in average ages of the IVDU patients with different genotypes. Non-IVDU patients having genotype 3a presented the lowest average age of all. No significant statistical differences were observed in alanine aminotransferase levels among patient groups with different genotypes (p>0.05 in all cases). Subtype 1b was present in six of the seven cases of cirrhosis (85.7%) and in nine of the 18 cases of active chronic hepatitis (50.0%).

Influence of viral genotype and level of viremia on the severity of liver injury and the response to interferon therapy in Spanish patients with chronic C infection

BACKGROUND

We wanted to investigate the influence of viral genotype on the severity of liver injury and response to interferon and whether the level of viremia differs in accordance with genotype, severity of liver disease, and response to interferon in patients with hepatitis C virus (HCV) infection.

METHODS

We studied 118 patients with HCV-related liver disease. HCV genotypes were determined with a line probe assay, and serum HCV RNA levels with a competitive reverse transcription polymerase chain reaction assay.

RESULTS

HCV type 1b was the most prevalent genotype (88%). It was present in 100% of cirrhotic patients, with or without hepatocellular carcinoma (HCC), but only in 78% of patients with chronic hepatitis (P < 0.001). The response to interferon was better in patients infected with non-1b HCV genotypes (P = 0.002). In a multivariate analysis non-1b HCV genotypes and a low hepatic fibrosis correlated with a favorable response to interferon. Among patients with chronic hepatitis those infected with HCV type 1b were older (P < 0.001), and age was the only independent factor associated with HCV type 1b. Viremia levels differed neither between genotypes nor in response to interferon and was significantly lower in patients with cirrhosis and HCC.

CONCLUSIONS

HCV 1b was associated with more severe liver disease and a worse response to interferon therapy. Non-1b genotypes and a lower liver fibrosis were the only independent predictors of a favorable response to interferon. Levels of HCV viremia differed neither among different genotypes nor in response to interferon and decreased with advanced liver disease.

Detection and typing of hepatitis C RNA in liver biopsies and its relation to histopathology

This paper describes the correlation of hepatitis C genotypes detected in liver tissue with histological grading (inflammatory activity) and staging (degree of fibrosis/cirrhosis). The viral genotype was analysed by type-specific polymerase chain reaction (PCR) and correlated with histology and age of patients. In 69 patients with chronic hepatitis C (HCV) infection, genotypes 1a and 1b were detected in 13 (18.8%) and 31 (44.9%) liver biopsies, respectively. Genotypes 2a and 2b were each detected once (1.5%) and 12 (17.4%) tissue samples showed a mixed infection with two genotypes. In 11 (15.9%) biopsies, no genotype could be established. The liver specimens were grouped according to the presence or absence of genotype 1b: group A consisted of specimens infected with genotypes 1a, 2a, and 2b (n = 16), Group B contained biopsies infected with genotype 1b (n = 42), and group C were biopsies with no detectable genotype (n = 11). Activity (grade) of chronic hepatitis was not different in these three groups. However, advanced fibrosis/cirrhosis was observed in 16 (38.1%) biopsies in group B (containing genotype 1b), compared with none in group A (P = 0.01). The mean age of patients in group B was significantly higher than that in group A (P = 0.038), and the mean age of patients with advanced fibrosis was higher than that of patients with low fibrosis scores within these two groups (P = 0.004). Stepwise logistic regression revealed an independent association of age and genotype 1b (group B) with advanced fibrosis/cirrhosis. These data indicate that patients infected with genotype 1b have an higher risk of developing cirrhosis than do patients with other genotypes.

Genotyping of hepatitis C virus isolates from Basque Country, Spain

The genotype of HCV was determined in 161 chronic HCV-infected patients. The patients were classified into three groups on the basis of the origin of the HCV infection: 50 patients had a history of intravenous drug use (IVDU) but no HIV infection; 41 patients had received blood transfusions, and 70 patients had no known exposure. The distribution of HCV genotypes was associated with the origin of infection and age of patients: genotype 1b was predominant among patients who had received blood transfusions and those without evidence of parenteral exposure (84.6% and 67.7%, respectively), whereas genotype 3a was present in 65.3% of IVDUs. Patients with genotype 1b were older than those with genotypes 1a or 3a: 50.3 +/- 12 vs. 34.1 +/- 9.9 and 31 +/- 5.4 years, respectively. These findings suggest that the pattern of HCV genotypes in our region is changing and that genotype 1b may be substituted by 3a as the dominant genotype in the future.

Hepatitis C virus and organ transplantation

Hepatitis C virus (HCV) is both the leading cause of cirrhosis and hepatic failure leading to liver transplantation and a cause of chronic hepatitis in approximately 10% of all transplant recipients. Beginning 5-10 years or more posttransplant, HCV causes progressive liver disease in a significant fraction of infected individuals and contributes to an increased incidence of opportunistic infection and hepatocellular carcinoma. The existence of multiple genotypes of HCV with differing biologic behaviors and the generation of antigenic diversity of the virus (quasispecies) during the course of infection, limit the capacity of the immune system to generate protective immunity. Antiviral therapy with interferon-alpha is effective in only a minority of transplant patients, and since allografts from HCV infected donors are quite efficient in transmitting the virus, great attention is paid to the appropriate use of organs from HCV-positive donors. At present, these organs should be particularly targeted for patients in emergent need of lifesaving heart, liver, or lung transplants. Issues requiring further investigation include the impact of viral superinfection on HCV-infected recipients of organs from HCV-infected donors and the use of such organs in seronegative patients who are older, diabetic, or highly sensitized, for whom quality of life issues may outweigh the long-term impact of HCV infection.

Genotype analysis of hepatitis C virus among blood donors and inmates in Metro Manila, The Philippines

Antibodies against hepatitis C virus (HCV) were detected in 18 (2.3%) of 800 sera from commercial blood donors and 23 (4.6%) of 502 sera from inmates in Metro Manila, the Philippines. The difference in the antibody prevalence between the two groups was statistically significant (P < 0.05). HCV RNA was detected in 14 (78%) of the 18 antibody-positive sera from blood donors and 19 (83%) of the 23 antibody-positive sera from inmates. Genotype analysis revealed that HCV-2a (7%). Among inmates, on the other hand, HCV-1a (68%) was most common, followed by HCV-1b (11%), HCV-2a (5%) and HCV-2b (5%). Overall, HCV-1a and HCV-1b appeared to be predominant among them. Thus, the genotype prevalence in the Philippines was distinct from those in other Southeast Asian countries such as Thailand, Vietnam and Indonesia, and also distinct from those in the Far East including Taiwan, Mainland China and Japan.

Nucleotide sequence variation in the hypervariable region of the hepatitis C virus in the sera of chronic hepatitis C patients undergoing controlled interferon-alpha therapy

Ten patients with hepatitis C virus (HCV) infection (experimental group) were treated with interferon-alpha (IF-alpha). Dosage was six million units per day for one week and then three times a week for another six months. Seven HCV-infected patients (control group) did not receive IF-alpha therapy. The hypervariable region (HVR) of HCV in the sera of patients was amplified by reverse transcription-polymerase chain reaction (RT-PCR), and the variation of amino acid sequence in this region was determined. Serum alanine aminotransferase (ALT) activities in five patients treated for six months with IF-alpha fell to the normal range, when HCV was not detected in the sera of three patients. The nucleotide sequence variation in HVR of HCV in the sera of five patients who responded well to the IF-alpha therapy was relatively less than that in another five patients who did not respond to IF-alpha therapy and those in the control patients. These results indicate that the effectiveness of IF-alpha therapy was related to the sequence variation of HVR of HCV. This may have resulted from the selection pressure by humoral antibodies directed to HVR of HCV. It is concluded that the higher rate of sequence variation in HVR of HCV was compatible with a lower degree of effectiveness of IF-alpha therapy.

Usefulness and limitation of phylogenetic analysis for hepatitis C virus core region: application to isolates from Egyptian and Yemeni patients

We report here the nucleotide sequences of the core region of HCV isolates from Egyptian and Yemeni patients and the method for classifying these HCV isolates by phylogenetic analysis. Sequence comparison suggested that the genotypes of these isolates were the same. Preliminary phylogenetic analysis of the HCV core region indicated that the genotypes of both isolates were 1c. However, an additional phylogenetic tree of the HCV core region constructed using a greater number of HCV isolates than that used in the preliminary analysis and on the basis of alignment of nucleotide sequences in an appropriate length indicated that the genotypes of these isolates were 4 and not 1c. For a more detailed analysis, the nucleotide sequences of the HCV E1 region as well as the core region for the same Yemeni patient were determined. A phylogenetic tree of the E1 region confirmed that the genotype of the HCV isolate from the Yemeni patient was 4. These data indicate that even when classifying HCV isolates using phylogenetic analysis, the misclassification would occur if care is not taken regarding the number and sequence lengths of the isolates included in the analysis.

Hepatitis C genotypes: current trends and future implications

OBJECTIVE

To review the geographic distribution and current understanding of hepatitis C virus (HCV) genotypes in regard to liver disease activity and response to treatment.

MATERIAL AND METHODS

We review the relevant medical literature and discuss our recent findings relative to chronic HCV infection and the importance of HCV genotypes.

RESULTS

HCV genotypes 1a and 1b are the most commonly found genotypes in patients with chronic HCV in the United States. Infection with HCV genotype 1b may be associated with more severe liver disease and may have a higher risk for the development of hepatocellular carcinoma. HCV genotype 2b seemed to be the most sensitive and HCV genotype 1b was the least sensitive to interferon therapy.

CONCLUSION

The identification of the infectious HCV genotype may be beneficial in clinical settings and may assist in the selection of patients who would benefit from interferon treatment.

Serotyping of hepatitis C virus in chronic type C hepatitis in Taiwan: correlation with genotypes

To evaluate the usefulness of a new serologic assay to group hepatitis C virus (HCV), genotypes identified by this serotyping method were compared to those identified by a polymerase chain reaction (PCR) assay with type-specific primers in 71 Taiwanese patients with chronic type C hepatitis. The group-specific antibodies against different HCV genotypes were detected by using an enzyme-linked immunosorbent assay (ELISA) based on group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region. Among 71 patients positive for current second-generation HCV antibodies, HCV RNA was detected in 55 patients by PCR with primers from the 5' untranslating region, and in 52 by genotype-specific PCR. In 49 (89%) of 55 viremic patients, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the patients showed a group opposite to that of HCV genotype. The positive rate of group-specific antibodies (69/71;97%) was even better than that of the PCR (55/71;78%). We conclude that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes, and will be useful in future epidemiologic studies, as well for clinical application.

Distribution of the different subtypes of hepatitis C virus in Japan and the effects of interferon: a nationwide survey

Interferon (IFN) is now commonly used for the treatment of type C hepatitis; however, its effects differ depending upon the subtype of hepatitis C virus (HCV) being treated. It has been recently confirmed in many studies in Japan that the effectiveness of IFN treatment is poor in patients having type 1b and better in patients having type 2a HCV. However, the effects of IFN treatment on other subtypes of HCV were not clear because of the small number of patients in each hospital. In the present study, the effects of IFN treatment in patients with other HCV subtypes were analysed from nationwide data collected in Japan using a standard questionnaire. From this questionnaire, local differences in the distribution of HCV subtypes in Japan were also analysed. A standard questionnaire, consisting of questions about the number of patients with chronic type C hepatitis with different HCV subtypes and the number of patients showing different responses to IFN treatment, was sent to over 40 study groups in Japan. Answers to the questionnaire concerning HCV subtypes and the effects of IFN treatment were obtained from 26 and 22 hospitals, respectively, throughout Japan. The incidence of HCV type 1b was highest in the Kinki area (south-central Japan). The incidence of type 1b HCV decreased in parallel with distance from this area. The mortality rates of hepatic cancer in different areas were significantly correlated with the incidence of HCV type 1b. The efficacy of IFN treatment was significantly better for both types 2a and 2b HCV than for type 1b HCV; the efficacy of IFN treatment was poor in the mixed type of 1b and 2a and tended to be better in type 1a. The efficacy of IFN treatment for other types of HCV was also better. These results indicate that there are local differences in the distribution of HCV subtypes in Japan and that these differences may be closely associated with the clinical features of HCV-related liver disease. The efficacy of IFN treatment was significantly poorer in patients with the 1b-related type HCV than in patients with other types of HCV.

Hepatitis C viral infection in thalassemic children: clinical and molecular studies

To determine and correlate the liver function profile, hepatitis C virus (HCV) genome, anti-HCV, genotypes, quantitation, and nucleotide sequence variability in polytransfused thalassemic children, 61 such children were studied prospectively for 4 y. Twenty-six had HCV infection. The average age, number of transfusions, and alanine aminotransferase (ALT) levels of the HCV-infected group were higher than those of the 35 children without HCV infection. None was infected after the initiation of anti-HCV screening in donor blood. Liver biopsies were performed in six HCV-infected and eight HCV-noninfected thalassemic children, and portal fibrosis was found more frequently in the HCV-infected group. Quantitation of HCV RNA was done by the competitive polymerase chain reaction method, and the titer was about 1 x 10(6) to 5 x 10(8) copies/mL. The titer did not change significantly over the 4-y follow-up period and did not correlate with ALT levels. Nineteen HCV-infected patients were genotyped; 15 were Okamoto/Simmonds type II/1b, two were type III/2a, and two were type IV/2b. The hypervariable region of the HCV genome (E2/NS1) was cloned and sequenced in two serum samples from one patient collected at a 2-y interval, as the ALT levels decreased. The variation rate was estimated to be 1.2-1.7 x 10(-2)/nucleotide/y. The results showed that, in polytransfused thalassemic children, 43% (26/61) contracted HCV. We conclude that HCV infection may cause elevated ALT levels and portal fibrosis of the liver, whereas the viral titer and genotypes do not parallel ALT levels.

Relationship between hepatocellular carcinoma and subtypes of hepatitis C virus: a nationwide analysis

Although hepatitis C virus (HCV) has now been classified into several subtypes, the clinical significance of HCV subtypes is not well known. Typing of HCV is now routinely performed in Japan. In the present study, HCV subtypes in hepatocellular carcinoma (HCC) patients were analysed from nationwide data collected in Japan using a standard questionnaire. Answers to the questionnaire concerning HCV subtypes in patients with chronic hepatitis (CH), liver cirrhosis (LC) and HCC were obtained from 14 hospitals. The prevalence of the 1b-related subtype, which includes the mixed subtype of 1b and 2a or 2b, in patients with LC and HCC in each hospital was higher than in patients with CH, with few exceptions. However, the differences were not statistically significant because of the small number of patients in each hospital. In summarized data from all 14 hospitals, the 1b-related subtype was found in 1370 of 1922 patients with CH (71.2%). In 356 LC and 426 HCC patients, the prevalence of the 1b-related subtype was 79.8 and 80.5%, respectively. The prevalence of the 1b-related subtype in patients with LC and HCC was significantly higher than in patients with CH. There was no significant difference between the prevalence of the 1b-related subtype in patients with HCC and LC. These results indicate that the oncogenic activity of subtype 1b, although not yet clearly characterized, may be stronger than subtypes 2a and 2b.

Mutations in the nonstructural protein 5A gene and response to interferon in patients with chronic hepatitis C virus 1b infection

BACKGROUND

A region associated with sensitivity to interferon has been identified in the nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) genotype 1b. The region spans amino acid residues 2209 to 2248 (NS5A2209-2248) of HCV-J, a strain of HCV-1b whose complete genomic sequence has been identified. We examined whether the NS5A2209-2248 sequence present before therapy could be used as a predictor of the response to interferon therapy in patients with chronic HCV-1b infection.

METHODS

We retrospectively analyzed 84 patients with chronic HCV-1b infection who had received interferon alfa (total dose, 516 million to 880 million units) for six months. Pretreatment serum samples were analyzed. The amino acid sequence of NS5A2209-2248 was determined by direct sequencing of the HCV genome amplified by the polymerase chain reaction (PCR) and was compared with the established sequence for HCV-J.

RESULTS

A complete response, as evidenced by the absence of HCV RNA in serum on nested reverse-transcription PCR for six months after therapy, did not occur in any of the 30 patients whose NS5A2209-2248 sequences were identical to that of HCV-J (wild type). Five of 38 patients (13 percent) with 1 to 3 changes in NS5A2209-2248 (intermediate type) had complete responses, as did all 16 patients with 4 to 11 amino acid substitutions (mutant type), indicating that the mutant type was significantly associated with a complete response (P < 0.001). Although baseline serum HCV RNA levels, as measured by a branched-chain DNA assay, were lower in patients with the mutant type of NS5A2209-2248 than in those with the other types (P < 0.001), multivariate analyses revealed that the number of amino acid substitutions in NS5A2209-2248 was the only variable associated with an independent effect on the outcome of interferon therapy (odds ratio, 5.3; 95 percent confidence interval, 1.6 to 18; P = 0.007).

CONCLUSIONS

In patients with chronic HCV-1b infection, there is a substantial correlation between responses to interferon and mutations in the NS5A gene.

Virology of hepatitis C virus

Hepatitis C virus (HCV) has been identified as the main causative agent of posttransfusion non-A, non-B hepatitis. Through recently developed diagnostic assays, routine serologic screening of blood donors has prevented most cases of posttransfusion hepatitis. The purpose of this paper is to comprehensively review current information regarding the virology of HCV. Recent findings on the genome organization, its relationship to other viruses, the replication of HCV ribonucleic acid, HCV translation, and HCV polyprotein expression and processing are discussed. Also reviewed are virus assembly and release, the variability of HCV and its classification into genotypes, the geographic distribution of HCV genotypes, and the biologic differences between HCV genotypes. The assays used in HCV genotyping are discussed in terms of reliability and consistency of results, and the molecular epidemiology of HCV infection is reviewed. These approaches to HCV epidemiology will prove valuable in documenting the spread of HCV in different risk groups, evaluating alternative (nonparenteral) routes of transmission, and in understanding more about the origins and evolution of HCV.

Significance of anti-hepatitis C virus core IgM antibodies in patients with chronic hepatitis C

Antihepatitis C virus (HCV) IgM antibodies were found in patients with both acute and chronic hepatitis C. The aims of the study were to determine the significance, in terms of liver disease and virological parameters, of anti-HCV core IgM antibodies in the serum of patients with chronic hepatitis C, and the possible relationship between the presence of these antibodies before treatment and biochemical and virological responses to interferon therapy. Sixty-one patients with chronic hepatitis C were studied. Tests for serum anti-HCV core IgM antibodies were carried out before treatment. The patients received 3 mega units of interferon alpha-2a subcutaneously thrice weekly for at least 3 months (6 months when alanine aminotransferase activity was normal at month 3). A biochemical response to interferon therapy was defined as normal alanine aminotransferase activity at the end of treatment (month 6: biochemical response) and 6 months later (month 12: sustained biochemical response). A sustained virological response was defined as serum HCV RNA negativity by a polymerase chain reaction-based detection method (PCR) in patients with normal alanine aminotransferase at month 12. Anti-HCV core IgM antibodies were detected in 28 of the 61 patients (46%). The prevalence of these antibodies was significantly higher in patients infected with HCV genotype 1 (including subtypes 1a and 1b) than in patients infected with other genotypes (including 2a and 3a) (57% vs. 17%; P < 0.01). No significant difference was found between IgM-positive and IgM-negative patients as regards the mean age, sex ratio, serum alanine aminotransferase and gamma-glutamyl transpeptidase activities, the prevalence of cirrhosis in liver biopsy specimens, detection of HCV RNA by PCR, and quantitation by branched DNA assay. At month 6 of interferon therapy, normal alanine aminotransferase activity was significantly more frequent in IgM-negative than in IgM-positive patients (52% vs. 21%, respectively; P < 0.02). At month 12, normal alanine aminotransferase activity and PCR negativity were significantly more frequent in IgM-negative than in IgM-positive patients (18% vs. 0%, P < 0.04). It is concluded that anti-HCV core IgM antibodies in serum are significantly more frequent in patients infected by HCV type 1 than by other types. This suggests that their overall prevalence in patients with chronic hepatitis C in industrialized countries, where HCV type 1 accounts for the majority of infections, would be of the order of 50%, that anti-HCV core IgM antibodies are not associated with characteristic features of liver disease, and that their presence before treatment is associated with a failure of interferon alpha therapy to clear the virus.

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).

Efficacy of combination therapy with interferon and azidothymidine in chronic type C hepatitis: a pilot study

The effects of interferon are seen in only a limited number of patients with hepatitis C virus (HCV) of the K1 type, indicating that a combination therapy with other antiviral drugs may be essential to obtain better results. In the present pilot study, the effects of combination therapy with interferon (IFN) and an antiviral drug azidothymidine (AZT) were analyzed. The combination therapy was conducted in 22 patients with chronic hepatitis C after obtaining their informed consent (combination group). Three or six million units of natural IFN alpha was administered daily for 3 weeks and then three times a week for 21 weeks. Combination therapy was initiated at the beginning of the 8th week of IFN treatment, 500 mg of AZT per day being given for 8 weeks. As a control, changes in HCV-RNA were also analyzed in patients treated with interferon alone (IFN-alone group). At the end of the treatment, blood was negative for HCV in 32.5% of the IFN-alone group and in 50.0% of the combination group, the difference not being significant. However, in patients with HCV-K1, HCV-negative rates were 14.2% in the IFN-alone group and 45.5% in the combination group, showing a significant difference. In patients with other HCV genotypes, HCV-negative rates did not different between the two groups. These results suggest that combination therapy with IFN and AZT may be an effective treatment for chronic type C hepatitis caused by the K1 type virus, although further studies on larger number of patients will be needed to obtain definite conclusions.