Tatsunori Nakano

Hepatitis B virus genotype assignment using restriction fragment length polymorphism patterns.

Hepatitis B virus (HBV) is classified into genotypes A–F, which is important for clinical and etiological investigations. To establish a simple genotyping method, 68 full‐genomic sequences and 106 S gene sequences were analyzed by the molecular evolutionary method. HBV genotyping with the S gene sequence is consistent with genetic analysis using the full‐genomic sequence. After alignment of the S sequences, genotype specific regions are identified and digested by the restriction enzymes, HphI, NciI, AlwI, EarI, and NlaIV. This HBV genotyping system using restriction fragment length polymorphism (RFLP) was confirmed to be correct when the PCR products of the S gene in 23 isolates collected from various countries were digested with this method. A restriction site for EarI in genotype B was absent in spite of its presence in all the other genotypes and genotype C has no restriction site for AlwI. Only genotype E is digested with NciI, while only genotype F has a restriction site for HphI. Genotype A can be distinguished by a single restriction enzyme site for NlaIV, while genotype D digestion with this enzyme results in two products that migrates at 265 and 186 bp. This simple and accurate HBV genotyping system using RFLP is considered to be useful for research on HBV.

Peginterferon α-2b and ribavirin therapy in chronic hepatitis C genotype 4: impact of treatment duration and viral kinetics on sustained virological response

Background: The response rates and duration of peginterferon alpha (PEG-IFN-α) and ribavirin combination therapy in chronic hepatitis C genotype 4, the prevalent genotype in the Middle East and Africa, are poorly documented. Aims: To compare the efficacy and safety of 24, 36, or 48 weeks of PEG-IFN-α-2b and ribavirin therapy in chronic hepatitis C genotype 4. Methods: In this prospective, randomised, double blind study, 287 patients with chronic hepatitis C genotype 4 were randomly assigned to PEG-IFN-α-2b (1.5 μg/kg) once weekly plus daily ribavirin (1000–1200 mg) for 24 weeks (group A, n = 95), 36 weeks (group B, n = 96), or 48 weeks (group C, n = 96) and followed for 48 weeks after completion of treatment. Early viral kinetics and histopathological evaluation of pre- and post treatment liver biopsies were performed. The primary end point was viral clearance 48 weeks after completion of treatment. Results: Sustained virological response was achieved in 29%, 66%, and 69% of patients treated with PEG-IFN-α-2b and ribavirin for 24, 36, and 48 weeks, respectively, by intention to treat analysis. No statistically significant difference in sustained virological response rates was detected between 36 and 48 weeks of therapy (p = 0.3). Subjects with sustained virological response showed greater antiviral efficacy (ε) and rapid viral load decline from baseline to treatment week 4 compared with non-responders and improvement in liver histology. The incidence of adverse events was higher in the group treated for 48 weeks. Conclusion: PEG-IFN-α-2b and ribavirin for 36 or 48 weeks was more effective in the treatment of chronic hepatitis C genotype 4 than treatment for 24 weeks. Thirty six week therapy was well tolerated and produced sustained virological and histological response rates similar to the 48 week regimen.

Inhibition of the DNA-binding activity of NF-κB by gold compounds in vitro

Nuclear factor κB (NF‐κB) is a transcription factor that is critical for the inducible expression of multiple cellular and viral genes. DNA binding activity is essential for its function. Here, we report that gold compounds, especially aurothioglucose (AuTG), have a strong inhibitory effect on NF‐κB‐DNA binding. Our finding also reveals that Zn2+ is a necessary component of NF‐κB for its DNA binding activity and that gold ion can efficiently block NF‐κB‐DNA binding, presumably through oxidation of the cysteins associated with zinc. This redox mechanism may provide an explanation for the observed efficacy of gold compounds in the treatment of rheumatoid arthritis.

New genotypes of TT virus (TTV) and a genotyping assay based on restriction fragment length polymorphism

A phylogenetic analysis, using the open reading frame 1 sequence of 93 TT viruses (TTV) obtained from various geographical areas, indicated that the virus could be classified into six different genotypes including three hitherto unreported genotypes. The high reliability of the six clusters was confirmed by bootstrap analysis. On the basis of these sequence data, a new simple genotyping assay based on a restriction fragment length polymorphism of TTV was developed. Using the enzymes NdeI and PstI, followed by cleavage with NlaIII or MseI, it was possible to distinguish between the six TTV genotypes. This system will provide the framework for future detailed epidemiological and clinical investigations.

An updated analysis of hepatitis C virus genotypes and subtypes based on the complete coding region

The hepatitis C virus (HCV) genomic database is expanding rapidly.

Cellular Immune Responses in Seronegative Sexual Contacts of Acute Hepatitis C Patients

ABSTRACT Acute hepatitis C virus (HCV) is typically defined as new viremia and antibody seroconversion. Rates and immunologic correlates of hepatitis C clearance have therefore been based on clearance of viremia only in individuals who initially had an antibody response. We sought to characterize the immunological correlates of clearance in patients with acute hepatitis C and their sexual contacts. We prospectively determined CD4+ and CD8+ cytotoxic T-lymphocyte responses in index patients with acute HCV and their sexual contacts who developed acute infection, either with or without spontaneous clearance, as well as those contacts who never developed viremia. Responses were measured using proliferation and ELISpot assays for CD4+ and CD8+ responses. We demonstrate in this prospective study that cellular immune responses can develop in exposed but persistently aviremic and antibody-negative individuals as well as those individuals with spontaneous clearance of acute HCV. These findings lend further credence to the importance of cellular immune responses in recovery from HCV and suggest that low exposure to HCV may lead to development of HCV-specific immune responses without ongoing HCV replication. This finding has important implications for HCV vaccine and therapeutic development.

Viral gene sequences reveal the variable history of hepatitis C virus infection among countries

BACKGROUND The analysis of molecular phylogenies estimated from the gene sequences of sampled viruses can provide important insights into epidemiological processes. METHODS The demographic and migration histories of the prevalent hepatitis C virus (HCV) subtypes 1a and 1b were inferred from viral gene sequences sampled in 5 countries. Estimated viral phylogenies were analyzed by use of methods based on parsimony and coalescent theory. RESULTS The parsimony migration analysis suggested that the global subtype 1a and 1b epidemics are geographically structured, with asymmetrical movement of HCV strains among the sampled countries. The coalescent analysis indicated that subtype 1a infections in the United States, Brazil, and Indonesia began to increase exponentially during the 1940s and 1950s, whereas in Vietnam the increase began after the 1970s. In contrast, subtype 1b infections in these 4 countries and in Japan began to increase exponentially between 1880 and 1920, with a possible recent decrease in infection rates in Indonesia and Japan. In the United States, Brazil, and Vietnam, the epidemic growth rates for subtype 1a strains were higher than those for subtype 1b strains, whereas the growth rates were similar in Indonesia. CONCLUSIONS The estimated histories of migration and population growth indicated that patterns of HCV transmission differ among countries and viral subtypes.

Three different GB virus C/hepatitis G virus genotypes: Phylogenetic analysis and a genotyping assay based on restriction fragment length polymorphism

The 5′‐untranslated region (5′‐UTR) sequences of 33 GB virus C/hepatitis G virus (GBV‐C/HGV) obtained from different geographic areas were determined through reverse‐transcription polymerase chain reaction and dideoxy chain termination sequencing, the alignment of sequences, the estimation of the number of nucleotide substitution per site, and construction of phylogenetic trees. The 5′‐UTR of GBV‐HGV was found to be heterogeneous, with 70.9–99.5% homology. Three distinct phylogenetic branches were observed consistently in all phylogenetic trees. GBV‐C is the prototype for one, HGV for another, and there is a new branch which consisted of GBV‐C/HGV isolates from Asia. Genotype‐specific restriction sites for the restriction enzymes, ScrFI and BsmFI, were identified, and a simple restriction fragment polymorphism analysis was developed for genotyping. These data provide evidence that GBV‐C/HGV consists of three different genotypes. Our simple genotyping assay will also provide a tool for epidemiological studies of GBV‐C/HGV infection.

High prevalance of TT virus infection in Japanese patients with liver diseases and in blood donors

BACKGROUND/AIMS Although a novel DNA virus, TT virus (TTV), has been isolated from a patient with cryptogenic post-transfusion hepatitis, its pathogenic role remains unclear. To elucidate its prevalence and clinical impact in patients with liver diseases, the presence of TTV DNA was assessed in patients with liver diseases and blood donors (BDs) in Japan using two primer sets, one conventional and the other new and highly sensitive. METHODS We studied 261 samples, 72 with chronic hepatitis associated hepatitis C virus (HCV-CH), 57 with hepatocellular carcinoma associated HCV (HCV-HCC), 12 with HCC without either HCV or hepatitis B virus (NBNC-HCC), and 120 of BDs. RESULTS Using two primer sets, TTV DNA was detected in 68 (94.4%), 53 (93.0%), 12 (100%), and 98 (81.7%) HCV-CH, HCV-HCC, NBNC-HCC, and BDs, respectively. The prevalence was not significantly different between HCV-CH and HCV-HCC, or between HCV-HCC and NBNC-HCC. Comparison between patients with and without TTV revealed no significant differences in backgrounds or biochemical findings. Histopathological findings in patients with HCV-CH, and number, maximum diameter, and histological differentiation of HCC also did not demonstrate any relation to TTV infection. TTV strains can be divided into five groups using phylogenetic analysis, but no disease-specific group appears to exist. CONCLUSIONS Our data suggest that: 1) TTV is very prevalent among patients with liver diseases and even among BDs in Japan, 2) TTV infection does not impact on liver damage with HCV infection, and 3) TTV infection also does not affect the development or progression of HCC.

A new genotype of TT virus (TTV) infection among Colombian native Indians.

Serum TTV DNA was assayed in 140 native Indians and 40 members of the general population in Colombia to determine the prevalence of TT virus (TTV) infection among Colombian native Indians. Of the 140 native Indians, 23 (16.4%) were positive for TTV DNA, compared to 4 (10.0%) of 40 from the general population (P = not significant). The prevalence of TTV DNA among native Indians was much higher than that of HBsAg and anti‐HCV. Comparison of subjects with and without TTV DNA revealed no significant differences in all characteristics between the two groups. A phylogenetic tree, using the open reading frame 1 sequence (222 bp), indicated that the virus could be classified into four different genotypes, including three previously reported ones. The results show that TTV infection is common in Colombian native Indians without liver disease and also indicate the existence of a novel genotype of TTV. J. Med. Virol. 57:264–268, 1999.