Virological characteristics of HCV infection in Japanese haemophiliacs

It has been found that almost all haemophiliacs treated with pooled concentrates of clotting factor VIII or IX before 1985/6 have been infected with hepatitis C virus (HCV). In order to clarify the characteristics of HCV infection in Japanese haemophiliacs, we investigated the HCV genotype and HCV-RNA level in 80 patients with haemophilia who had been confirmed to be positive by a second-generation HCV antibody test. HCV-RNA was detected in 60 (75.0%) individuals and various HCV genotypes were found. Although 80% (48/60) of the patients had genotype 1b, the frequency of each genotype was quite different from that in HCV-infected non haemophiliac Japanese. Particularly, multiple HCV genotypes were observed in 27 (46.7%) patients. The mean (± SD) level of HCV-RNA was 5.3 × 10⁵ ±  1.1 × 10⁶ copies mL⁻¹. The viral load in patients with genotype 2a was significantly less common than those with genotype 1a ( P = 0.0007), genotype 1b ( P = 0.0009) and combined genotype 1a/1b ( P = 0.0019). In patients co-infected with human immunodeficiency virus (HIV), the HCV-RNA level was significantly higher ( P = 0.05) than in those without co-infection. However, there was no significant difference ( P = 0.25) in the HCV-RNA level with HCV/HIV co-infection among the 40 patients with group 1 genotypes. We conclude that this biased distribution of HCV genotypes in Japanese haemophiliacs reflects their specific mode of HCV infection. Moreover, these results suggest that super-infection with HIV does not greatly influence the HCV load in patients with no marked immunological deterioration.     

Hepatic iron contents and response to interferon-α in patients with chronic hepatitis C

Recent reports have shown that response to interferon treatment is influenced by hepatic iron contents in patients with chronic hepatitis C. In those reports, however, hepatitis C virus (HCV) genotypes and serum HCV-RNA levels were not examined. The aim of the present study was to investigate whether hepatic iron contents influence the response to interferon in patients with chronic hepatitis C and whether HCV genotypes and serum HCV-RNA levels play a role in this relationship. Among 65 patients with chronic hepatitis C, hepatic iron contents were significantly high in patients with a history of excess drinking of alcohol (more than 80 g/day) compared to those without, and significantly low in female patients before menopause. Having excluded these patients, hepatic iron contents were significantly higher in patients with genotype 1b infection than those with genotype 2a and 2b infection. There was no significant correlation between hepatic iron contents and plasma HCV-RNA levels. Among the patients with genotype 1b infection, hepatic iron contents were significantly lower in the responders to interferon than those in the nonresponders (429 ± 100 vs 875 ± 110 µg/g liver,P<0.05). From these results, it is concluded that response to interferon is mainly influenced by HCV genotypes, while hepatic iron contents may play an important role in response to interferon in patients with genotype 1b infection.     

Response to interferon in chronic hepatitis C due to mixed genotype infection

We examined the response to interferon (IFN) in patients with chronic hepatitis C (CHC) due to two different genotypes of hepatitis C virus (HCV) infection. Among 64 CHC patients studied, one (2%) had HCV-RNA genotype I, 36 (56%) had genotype II, 19 (30%) had genotype III, 2 (3%) had genotype IV and 6 (9%) had both genotypes II and III. There was no significant difference in age, sex, history of blood transfusion and liver histology among patients with genotypes II, III and II + III. The HCV-RNA titre of genotype II patients was significantly higher than that of genotype III patients (P < 0.05). However, there was no significant difference in the HCV-RNA titre between genotype II + III and the other groups. The complete response rate achieved with IFN therapy was significantly higher in genotype III patients (74%) than in genotype II patients (17%; P < 0.01). Of the six patients with genotype II + III, a complete response to IFN was only achieved by two patients (33%), both of whom had a low HCV-RNA titre (≦ 10^4,5 copies/mL) and HCV serotype 2. The remaining four patients had HCV serotype 1 and three of the patients had a high HCV-RNA titre (≧ 10⁵ copies/mL). The HCV genotype III was lost in two patients after IFN therapy. These data suggest that HCV-RNA titre and HCV serotype are important factors for predicting the efficacy of IFN therapy in patients with mixed genotype infection and show direct evidence of higher susceptibility towards CHC of patients with genotype III than genotype II.     

The prevalence of hepatitis B virus and hepatitis C virus infection among patients with chronic liver disease in South India.

OBJECTIVE: Determining the identity of hepatitis C virus (HCV) genotypes in liver disease has key implications for ascertaining the duration of antiviral therapy and disease prognosis. We investigated the presence of various genotypes of HCV among 69 chronic liver diseased (CLD) patients with chronic HCV infection. METHODS: Sixty-nine consecutive subjects with underlying chronic hepatitis (n=28), cirrhosis (n=35), and hepatocellular carcinoma (n=6), diagnosed by clinical, biochemical, and histological means, were studied. Hepatitis B virus (HBV) and HCV diagnostic markers were used. HCV-RNA was extracted from sera of HCV-infected subjects and subsequently the HCV genotypes were determined using a commercial line probe assay (Inno-LiPA HCV II). RESULTS: Of the 69 CLD cases screened for possible markers of HBV and HCV infection, 39 (57%) were positive for HBV and 30 (43%) were HCV infected. The overall HCV-RNA positivity was 77% (23/30). Of these, the majority were genotype 1b (13/23, 57%), followed by 1a (6/23, 26%), mixed genotypes 3 and 4(3/23, 13%), and mixed pattern of 1a, 1b, and 4 (1/23, 4.3%). The genotype 1b infected subjects demonstrated significantly elevated transaminase (ALT) levels (p<0.05) as compared with the other non-1b HCV genotypes. CONCLUSIONS: The predominance of HCV genotype 1b among CLD patients could pose a major challenge for the efficient management of HCV disease and the development of effective therapeutic interventions in peninsular India.     

Hepatitis C virus genotypes in Australia

The relative distribution of Australian hepatitis C virus (HCV) genotypes was determined for 500 isolates. Genotyping was performed using a commercial reverse phase hybridization assay after amplification of the 5' untranslated region of HCV by the polymerase chain reaction. Australian isolates comprised, predominantly, genotype 1 (55%) and genotype 3 (38%) with genotype 2 accounting for only 7%. Genotype 3a was the most common subtype. When the major risk groups of injecting drug users or transfusion-acquired hepatitis C were compared, there was a significantly higher incidence of genotype 1b in the transfusion-acquired group ( P < 0.03). When the age of the patients was analysed, genotype 3a was more prevalent in the 21–40-year age group than the 41–60-year age group ( P <0.05). There was no significant difference in genotype distribution between males and females. HCV genotypes 1, 2 and 3 are most often found in developed countries but the relatively high prevalence of genotype 3a in Australia is unusual.     

Effect of mutation in the hepatitis C virus nonstructural 5B region on HCV replication

Background We have reported that the presence of a mutation at the hepatitis C virus (HCV) nonstructural protein 5B (NS5B), defined as a change in amino acids at sites specific for a different reported genotype, was related to complete response (CR) to interferon (IFN) therapy in patients with chronic hepatitis C (CHC) with genotype 1b. The present study assessed the impact of the NS5B mutation on the replication of HCV in these patients.Methods Genotype-specific mutations of HCV NS5B were determined by direct sequencing. We measured HCV-RNA titers in serum by real-time detected polymerase chain reaction (PCR), and serum HCV core protein levels (as a marker of HCV-RNA replication) were measured using an enzyme immunoassay in patients with CHC genotype 1b. RNA-dependent RNA polymerase (RdRp) activity was measured by Behrens method in liver cirrhosis patients infected with HCV (n = 13) and in those infected with hepatitis B virus (HBV; n = 2).Results The titers of HCV-RNA (n = 44) and the levels of HCV core protein (n = 41) were significantly lower in patients with the HCV genotype 1b mutant compared with wild-type HCV (P < 0.05). RdRp activity in liver tissue did not show any correlation with the HCV NS5B mutation.Conclusions HCV NS5B genotype-specific mutations in HCV genotype 1b may influence HCV replication.     

Genetic diversity of HCV among various high risk populations (IDAs,thalassemia, hemophilia,HD patients) in Iran

ObjectiveTo determine the patterns of distribution of HCV genotypes among high risk population in north of Iran.MethodsA cross-sectional study was conducted on 135 HCV RNA-positive high risk individuals including thalassemia, hemophilia, patients under hemodialysis and intravenous drug addicts. HCV genotypes were determined based on amplification with type-specific primers methods.ResultsAmong the 187 anti-HCV positive samples, only 135 (72.2%) gave HCV-RNA positvity. Over all, the most identified HCV type was genotype 3a (51.1%) followed by 1a (27.4%), 1b (8.2%). Sixteen (11.9%) out of 135 HCV RNA-positive participants have infected with more than one genotype or subtypes as follow; 1a/1b in 11 (8.2%), 2/3a in 3 (2.2%), and 1a/1b/3a in 2 (1.5%). Stratification of participants revealed that HCV subtype 3a was more prominent in thalassemia, hemophilia and HD patients but 1a and 1b were frequent in intravenous drug addicts.ConclusionsThis study is the first report on HCV genotypes among Iranian subjects with different exposure categories resided in Mazandaran, where genotype 3a was found to be the most frequent genotype in thalassemia, hemophilia, and hemodialysis patients but not in IDAs. Since the addiction age is decreasing in Iran and a lot of addicts are IDAs, it might change the subtype pattern of HCV in general population.     

Genotyping of hepatitis C virus (HCV) in infected patients from Northeast Mexico

Information about HCV genotypes in infected patients from different regions of Mexico is limited. Objective: To determine the prevalence of HCV genotypes in a group of HCV infected patients who attended a third level Hospital in Northeast of Mexico. Methods: Genotyping analysis was performed using the InnoLiPA-HCV genotype assay in 147 patients (65 males and 82 females, mean age 44 ± 12 years) with positive anti-HCV antibodies and detectable HCV-RNA levels. Results: Infected individuals were more likely to be female (56%). Histological data showed that 63% of the patients had chronic hepatitis, while the remainder presented cirrhosis (37%). The most frequent HCV genotype was 1 (73%). We found the following distribution: genotype 1 (2.7%), 1a (28.6%), 1b (37.4%), 1a/1b (4.1%), 2a (1.4%), 2b (8.8%), 2c (0.7%), 2a/2c (2.7%), 3 (2%), 3a (10.2%), 4 (0.7%) and 4c (0.7%). The most frequent associated risk factor was blood transfusion (72.5%). Conclusion: Prevalence of HCV genotypes in the Northeast of Mexico is similar to those reported previously in other Mexican regions and the most frequent risk factor continues being blood transfusion.     

Risk factors for HCV infection in two haemodialysis units in the Netherlands

Background: In order to assess risk factors for HCV infection during haemodialysis, all patients receiving haemodialysis for more than 6 months in two separate units in the Netherlands were studied retrospectively.Methods: Antibodies to HCV, HCV-RNA and HCV genotypes were determined. Risk factors were identified by analysis of an extensive collection of clinical data.Results: In unit A, 8 out of 75 (11%) patients and in unit B 4 out of 122 (3%) patients had antibodies to HCV. Eleven out of the 12 anti-HCV-positive patients had detectable HCV-RNA. Genotyping showed the presence of 4 different genotypes in unit A (1, 1a, 2b, and 3a). Three patients in unit B were infected with the same genotype (1b), where one of these patients was also infected with genotype 1a. One patient in unit B did not have detectable HCV-RNA. The risk of acquiring a HCV infection in unit A was associated with the number of blood transfusions. However, in unit B this risk was associated with the duration of dialysis. Other factors such as the number of surgical procedures were not associated with HCV infection.Conclusions: Blood transfusions and the dialysis process itself are important and independent risk factors for HCV transmission in dialysis patients. Surgical events do not appear to be important risk factors. However, relative risks may vary considerably between different dialysis centres.     

Clinical significance of serum auto-antibodies in Chinese patients with chronic hepatitis C: Negative role of serum viral titre and genotype

Positive serum anti-nuclear antibody (ANA) and anti-smooth muscle antibody (SMA) have been reported in 10–66% of patients with chronic hepatitis C virus (HCV) infection from Western countries. However, the mechanism involved in this immunological disorder is still unknown. This study was carried out to evaluate the prevalence and clinical significance of positive serum auto-antibodies in Chinese patients with chronic hepatitis C and to assess the role of serum HCV-RNA titre and HCV genotype in the presence of serum auto-antibodies. Serum ANA, SMA and anti-mitochondrial antibody (AMA) were measured in 122 patients with chronic hepatitis C. Clinical, biochemical and virological data (serum HCV-RNA titre and HCV genotype) were compared between patients with and without serum auto-antibodies. Fifty-eight (48%) patients were associated with positive serum autoantibodies: 42 (34%) positive for ANA, six (5%) positive for SMA, nine (7%) positive for both ANA and SMA and one (1%) positive for AMA. Clinical parameters (age, sex, blood transfusion history), liver biochemical tests, the presence of cryoglobulinaemia or cirrhosis, and the response to interferon treatment were not significantly different between patients with and without positive serum auto-antibodies. Serum HCV-RNA levels and HCV genotypes were also not significantly different between the two groups. Logistic regression analysis showed that none of the previously mentioned parameters were significant predictors to associate with serum auto-antibodies in chronic hepatitis C. We concluded that 48% of Chinese patients with chronic hepatitis C were associated with positive serum auto-antibodies. Hepatitis C virus genotypes and serum HCV-RNA levels were not correlated to the presence of serum auto-antibodies. The clinical significance and actual pathogenesis of this phenomenon remain to be clarified.     

Hepatitis C virus clearance is prominent in women in an endemic area

BACKGROUND: The clinical and virological backgrounds of cases with previous hepatitis C virus (HCV) infection (positive for HCV antibody (anti-HCV) and HCV-RNA negative) in an HCV endemic area were examined to identify factors related to the clearance of HCV. METHODS: The study population comprised 3117 inhabitants, 1037 male and 2080 female, from an HCV endemic area. Hepatitis C virus antibody was detected by a passive haemagglutination test. The HCV-RNA and the HCV genotype were detected by using the polymerase chain reaction method. The HCV serotype was determined by enzyme immunoassay by using the peptides of the core region. RESULTS: Twenty-two per cent of the inhabitants were positive for anti-HCV, with males and the elderly having a significantly higher antibody titre (P < 0.01) than youths and females. Hepatitis C virus-RNA was detected in 78% of the HCV antibody-positive cases. The rate of HCV-RNA positivity was significantly higher in males than in females (P < 0.01). No relationship was found between HCV-RNA positivity and age. The HCV genotype 1b was the predominant genotype among the HCV-RNA-positive cases. Mixed genotypes (1b + 2a) were observed in 12% of cases, primarily in elderly males and females. In cases with previous HCV infection, serotype 1 was the most common serotype, and there appeared to be no relationship between the distribution of HCV serotypes and age and gender. There was a female predominance with regard to previous HCV infection, but not to being HCV carriers (P < 0.01). CONCLUSIONS: Gender, not HCV genotype, is the primary factor influencing HCV clearance.     

Diversity of hepatitis C virus genotypes among intravenous heroin users in Taiwan

IntroductionLimited information is available about genotypes of hepatitis C virus (HCV) in intravenous heroin users in Taiwan. The purpose of this study was to examine the concordance of the detection of antibody to HCV and HCV-RNA and to determine the distribution of HCV genotypes in male intravenous heroin users.MethodsThis was a cross-sectional study. The study population included 274 intravenous heroin drug users newly sentenced in a male prison in central Taiwan from November 2004 to February 2005, whose antibodies to HCV were positive, and antibodies to human immunodeficiency virus were negative. The mean age was 33.9 years (standard deviation, 7.8). The molecular diagnosis used to identify HCV-RNA was PCR.ResultsAmong 274 subjects, 214 subjects were found to contain HCV-RNA. Positive predictive value of HCV infection using antibody to HCV as an indicator was 78.1%. Among 214 subjects, HCV genotype 2a was the most predominant (58.9%, n = 126), followed by 1a (17.3%, n = 37), 1b (14.5%, n = 31), 2b (8.9%, n = 19) and 1a + 2b (0.4%, n = 1). Age-specific analysis also showed genotype 2a was the most prominent genotype among the 4 age groups, with the highest prevalence in groups aged 20 to 29 years and 30 to 39 years (53.3% and 67.6%, respectively).ConclusionsThe concordance of antibody to HCV and HCV-RNA is remarkable in selected high-risk groups. HCV genotype 2a is the most prevalent in male intravenous heroin users in central Taiwan, especially in aged 20 to 29 years and aged 30 to 39 years.     

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, 3×10³ respectively; patient 2, chronic active hepatitis (CAH) 2a, type III, 6×10⁴; patient 3, CAH2a, type IV, 2×10⁵; patient 4, CAH2b, type I, 2×10⁷; patient 5, CAH2b, type II, 8×10⁴; patient 6, CAH2b, type III, 7×10⁶; and patient 7, CAH2b, type IV, 1×10⁷. 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.     

Phylogenetic tree-based epidemiological analysis of hepatitis C virus transmission in a region of Japan with a high prevalence of infection

Local clustering of hepatitis C virus (HCV) infection has been demonstrated in various regions in Japan. HCV genotypes have now been compared between infected individuals from districts of Saga prefecture with either a high (H district) or low (L district) prevalence of HCV-seropositivity. The prevalence of HCV genotype 1b was significantly higher (P<0.001) in the H district (45/50; 90%) than in the L district (19/36; 52.8%). A phylogenetic tree was constructed based on the genomic sequences of viral isolates from 20 patients infected with genotype 1b in the H district. Almost all these HCV strains clustered in the same regions of the tree. With regard to risk factors for HCV transmission, the percentage of patients with a history of surgery was significantly higher in the H district than in the L district (58 versus 33.3%; P<0.05). Of 20 patients infected with similar strains of HCV in the H district, 16 (80%) had at least one parenteral risk factor associated with medical care. These results indicate an increased transmission of similar strains of HCV in the H district as a result of nosocomial infection.     

Peginterferon alfa-2b plus ribavirin for the treatment of chronic hepatitis C genotype 4

BACKGROUND: The hepatitis C virus (HCV) genotype is an important predictive parameter for the success of pegylated interferon plus ribavirin therapy. To date, most published therapeutic trials have enrolled patients infected mainly with HCV genotypes 1, 2, and 3. Data regarding the responsiveness of genotype 4, the predominant type of HCV in the Middle East, are very limited. OBJECTIVE: To assess the efficacy of peginterferon alfa-2b in combination with ribavirin for the treatment of chronic hepatitis caused by HCV genotype 4. METHODS: Sixty-six treatment-naive patients infected with HCV genotype 4 were enrolled in this open label, prospective study. Cohort characteristics included the following: 48 M/18 F, mean age 45 +/- 9 years, and mean weight 74 +/- 8 kg. All patients had raised alanine aminotransferase (ALT) and were compensated. The mean pretreatment HCV-RNA level was 4.2 x 10(6) copies/ml (8.4 x 10(5) iu/ml) and median was 2.15 x 10(6) copies/ml. Twenty patients (29%) exhibited cirrhosis or severe fibrosis on pretreatment liver biopsy specimens. Participants were to receive peginterferon alfa-2b, 1.5 mcg/kg/wk plus ribavirin 1,000-1,200 mg/day for 48 wk. Patients were followed up for 24 wk after completing therapy. End of treatment viral response and sustained viral response (SVR) were defined as the absence of HCV-RNA from serum (<100 copies/ml) at 48 wk of treatment and at the end of follow-up, respectively. Data were analyzed on an intention-to-treat basis. RESULTS: End of treatment and sustained virologic response were 77% and 68%, respectively. Among patients with pretreatment HCV-RNA > or =2 x 10(6) SVR was 55% compared with SVR of 86% among patients with HCV-RNA < 2 x 10(6) (p= 0.05). Patients with cirrhosis or severe fibrosis had significantly lower SVR rate compared to those with mild or no fibrosis (29 vs 84%; p < 0.0002). Three patients (4%) discontinued therapy because of severe flu-like symptoms. Four patients developed hypothyroidism. Dose reduction of ribavirin and peginterferon alfa-2b was necessary in 15% and 6% of the patients, respectively. CONCLUSION: Peginterferon alfa-2b in combination with ribavirin is effective in the treatment of HCV genotype 4. The treatment was well tolerated by most of the patients.     

Relationships between serum aminotransferase levels, liver histologies and virological status in patients with chronic hepatitis C in Taiwan

In patients with chronic hepatitis C, the relationships between serum alanine aminotransferase (ALT) levels, histological liver injury and serum hepatitis C virus (HCV) RNA titres remain controversial. To evaluate these relationships, 93 Chinese patients with histological diagnosis of chronic hepatitis C were enrolled for this study. Serum ALT levels, HCV-RNA titres and HCV genotypes were examined. The histology was evaluated according to a modified histological activity score based on the degree of periportal necro-inflammation, intralobular necro-inflammation, portal inflammation, total necro-inflammation and fibrosis. The mean serum ALT level was significantly higher in patients with severe intralobular necro-inflammation activity than in patients with mild or no activity (P= 0.013). However, scores of intralobular activity were only weakly correlated with serum ALT levels (r= 0.27) and could not be used to adequately predict ALT values. Serum ALT levels showed no significant correlation with the scores of portal inflammation, periportal necro-inflammation, total necro-inflammation and fibrosis. Also, there was no significant difference in the mean serum ALT level among different serum HCV-RNA levels and HCV genotypes. Serum HCV-RNA titres and genotypes showed no significant correlation with liver histology and serum HCV-RNA titres were only weakly correlated with the total necro-inflammatory score (r= 0.27). In conclusion, although serum ALT levels were higher in patients with more severe intralobular necro-inflammatory activity, the correlation was not strong enough to adequately predict ALT values. Serum HCV-RNA titres and genotypes also showed no significant correlation with serum ALT levels and liver histologies.     

Hepatitis C virus (HCV) genotypes in Spanish patients with HCV infection: relationship between HCV genotype 1b, cirrhosis and hepatocellular carcinoma

Background/Aims: The influence of the infecting virus genotype on the progression of the underlying liver disease in patients with chronic hepatitis C virus (HCV) infection remains controversial. The aim of this study was to investigate the prevalence of HCV genotypes in Spanish patients with chronic HCV infection and to elucidate the relationship between the infecting genotype and severity of the disease.Methods: A cross-sectional, retrospective analysis of frequency distribution of HCV genotypes was carried out in 414 Spanish patients with chronic HCV infection, including 243 patients with asymptomatic or minimally symptomatic chronic hepatitis, 112 patients with cirrhosis and hepatocellular carcinoma and 59 patients with decompensated cirrhosis. HCV genotype was determined by restriction fragment length polymorphisms of the 5′ non-coding region.Results: Infection with HCV genotype 1b was found in 72% of patients with chronic hepatitis and in more than 90% of patients with cirrhosis, with or without hepatocellular carcinoma. Older age, infection with genotype 1b and absence of overt parenteral exposure as a possible source of infection were associated with cirrhosis and hepatocellular carcinoma by univariate analysis and this association was confirmed by regression analysis.Conclusions: HCV genotype 1b is associated with advanced liver disease in our geographical area. However, this may be related to a cohort-effect caused by over-representation of genotype 1b in older patients with more advanced disease, because, in our country, this HCV genotype appeared earlier in time and is therefore associated with more prolonged periods of infection.     

Genotype,serum level of hepatitis C virus RNA and liver histology as predictors of response to interferon-α 2α therapy in Japanese patients with chronic hepatitis C

Abstract: To determine whether pretreatment HCV-RNA level, hepatitis C virus genotypes, alanine aminotransferase and histology correlate with subsequent response to interferon-α therapy or not, serum HCV-RNA levels and genotype were determined by branched DNA signal amplification assay and genotype-specific polymerase chain reaction in 43 patients with chronic active hepatitis C. Response to recombinant interferon-α 2α (504 million units in total) was defined as complete and sustained CR→SR, n=12), complete response followed by relapse (CR→Rel, n=17), and no response (NR, n=10), excluding dropouts (n=4). Patients who showed CR→SR had a lower HCV-RNA level (0.438 × 10⁶ eq/ml) compared to CR→Rel (2.452 × 10⁶ eq/ml, p=0.008) and NR (4.882 × 10⁶ eq/ml, p=0.009). A higher proportion of patients with CR→SR had type 2a HCV (67%) compared to the CR→Rel (28%) and the NR (0%). There was a trend for type 1b hepatitis C virus infection to have higher serum HCV-RNA levels. There was no correlation between pretreatment HCV-RNA level and alanine aminotransferase. However, no relation between pretreatment HCV-RNA level and liver histology was observed; a high proportion of patients with CAH2a showed CR→SR, compared to those with CAH2b (p=0.001). Moreover, the patients with CAH2b who had low level hepatitis C virus viremia did not show CR→SR. These data indicate that pre-treatment serum HCV-RNA levels, genotype and liver histology are good predictors of subsequent response to interferon-α therapy in Japanese patients with chronic hepatitis C virus infection.