Marked sequence diversity in the putative envelope proteins of hepatitis C viruses.

The nucleotide sequences of cDNAs (414 base pairs) encoding parts of putative envelope proteins (gp35 and gp70) of 40 isolates of hepatitis C virus (HCV-J) derived from 30 independent plasma or liver specimens from Japanese patients (13 with chronic hepatitis, 14 with hepatocellular carcinoma and 3 hemophiliacs who had received imported clotting factors), were analyzed using the polymerase chain reaction. Approximately 29-38% of the nucleotide sequences of the HCV-J isolates examined differed from those of isolates from the United States (HCV-US). Furthermore, 12-24% and 8-17% sequence diversities were found within the isolates of HCV-J and HCV-US, respectively. The diversities of the amino acid sequences were the same or greater than those of the nucleotide sequences. We confirmed that two hypervariable regions (HVR1 and HVR2) were present in this amplified region, as described in our previous report (Hijikata et al., 1991a) and we found that the HVR1 regions of HCV-J and HCV-US were 27 and 21 amino acids in length, respectively, and began from the N-terminal amino acid of gp70. HVR2 was found in HCV-J, but not in HCV-US isolates, in which the corresponding region of the genome was conserved. During the analysis, plural HCV genomes were found in 6 of 30 specimens. These plural HCV genomes in a single specimen were concluded to be derived from the same HCV ancestor, because of their relative low sequence diversities (about 10% in their nucleotide sequences).(ABSTRACT TRUNCATED AT 250 WORDS)     

Augmentation of human immunodeficiency virus type 1 gene expression by tumor necrosis factor alpha

It is now well established that cytokines are involved in the regulation of gene expression from HIV-1 LTR. The present study provides evidence that TNF-alpha stimulates HIV-1 gene expression and that the enhancer sequence within the HIV-1 LTR is involved in the stimulation. These results support the idea that immunologic stimulation and infection may trigger the development of clinical AIDS in individuals latently infected with HIV-1.     

Complete nucleotide sequence of an infectious clone of human T-cell leukemia virus type II: an open reading frame for the protease gene.

The entire nucleotide sequence of an infectious clone of human T-cell leukemia virus type II provirus was determined. This provirus consists of 8952 nucleotides. In addition to long terminal repeats and gag, pol, env, and X, a protease gene that is responsible for processing the gag precursor protein was found. The protease gene is encoded in a different frame from gag and pol and was located between the gag and pol open reading frames. The 5' region of the protease gene overlaps the 3' gag region. Coding regions of the provirus show about 60% homology with those of human T-cell leukemia virus type I at the nucleotide level. The evolutionary relationship between human T-cell leukemia virus types I and II is discussed.     

Identification of new immunogenic peptides in conserved regions of hepatitis C virus (HCV) 1b with the potentiality to generate cytotoxic T lymphocytes in HCV1b+ HLA-A24+ patients

Aim: Hepatitis C virus (HCV) 1b is resistant to standard interferon therapy and has a high risk of developing into hepatocellular carcinoma at the late stage of infection. Therefore, new therapeutic modalities for HCV1b infection must be developed. One approach would be active specific immunotherapy with highly immunogenic HCV1b peptides. Methods: HCV1b-derived 44 synthetic peptides were selected based on their binding scores to HLA-A24. Peptide-specific IgG were measured by ELISA. Peptide-specific cytotoxic T-lymphocytes (CTLs) were induced in vitro by repeated peptide-stimulation. Results: We identified three novel candidate peptides of HCV1b proteins containing HLA-A24 binding motifs. Each of them had the ability to induce HLA-A24-restricted and peptide-specific CTL activity, and IgGs specific to each of them were detected in the plasma of HCV1b patients. Among these three peptides, a peptide NS5A 2132-2142 was recognized by both cellular and humoral immunities in the majority of blood samples of patients tested. More importantly, the peptide-stimulated peripheral blood mononuclear cells (PBMCs) showed cytotoxicity against cells cotransfected with NS5A and HLA-A2402 genes in an HLA-restricted manner. This is an additional report to our previous study. Conclusion: These findings may provide a new insight into the development of a peptide-based specific immunotherapy for HCV1b-infected patients.     

Latent hepatitis B virus infection in healthy individuals with antibodies to hepatitis B core antigen

Several recent reports have shown that hepatitis B virus (HBV) could be frequently transmitted to the recipients from donors who have antibodies to hepatitis B core antigen (anti-HBc) through liver transplantation. We provide here the molecular evidence of latent HBV infection accompanied with ongoing viral replication in the liver tissue of anti-HBc-positive healthy individuals. HBV DNA was detectable in 13 of 14 healthy donors who were positive for both anti-HBc and antibodies to hepatitis B surface antigen (anti-HBs), but in none of 3 who were positive for anti-HBs alone. The detected HBV genomes from these subjects included covalently closed circular DNA and pregenomic RNA, the replication intermediate of HBV. Notably, 5 of 7 cases tested were predominantly infected with wild type HBV strains without any mutations in the precore and core promoter regions under the presence of circulating antibody to hepatitis B e antigen. Interestingly, a predominant clone detected in one donor showed a 63-nucleotide deletion in the precore region including an encapsidation signal sequence. Our findings indicate that the majority of healthy individuals positive for anti-HBc, which had been assumed to denote a past history of transient HBV infection, were latently infected with the episomal form of HBV accompanied by ongoing viral replication and few nucleotide mutations in the precore and core regions.