Jang Han

Vertical transmission of hepatitis C virus

There is evidence that hepatitis C virus (HCV) may be vertically transmitted from infected mothers to their children. To test this hypothesis, we prospectively studied 10 pregnant women at high risk from parenterally or sexually transmitted diseases with the polymerase chain reaction. HCV RNA was found in 8 newborn babies delivered by women who were anti-HCV seropositive, and persisted for 2-19 months of follow-up. Anti-HCV detected in 7 infants cleared by 9 months and remained undetectable thereafter. Serum alanine aminotransferase was raised in 3 infants. The findings provide evidence of vertical transmission of HCV and suggest that perinatal infection may initiate a silent disease process or chronic carrier state.

Intrahepatic Genetic Inoculation of Hepatitis C Virus RNA Confers Cross-Protective Immunity

ABSTRACT Naturally occurring hepatitis C virus (HCV) infection has long been thought to induce a weak immunity which is insufficient to protect an individual from subsequent infections and has cast doubt on the ability to develop effective vaccines. A series of intrahepatic genetic inoculations (IHGI) with type 1a HCV RNA were performed in a chimpanzee to determine whether a form of genetic immunization might stimulate protective immunity. We demonstrate that the chimpanzee not only developed protective immunity to the homologous type 1a RNA after rechallenge by IHGI but was also protected from chronic HCV infection after sequential rechallenge with 100 50% chimpanzee infectious doses of a heterologous type 1a (H77) and 1b (HC-J4) whole-virus inoculum. These results offer encouragement to pursue the development of HCV vaccines.

Hepatitis C virus replication in 'autoimmune' chronic hepatitis.

Both high and low anti-hepatitis C virus antibody (anti-HCV) prevalence has been reported in autoimmune chronic active hepatitis. Therefore, we studied 15 consecutive HBsAg-negative, ELISA anti-HCV-positive, autoantibody-positive patients with biopsy proven chronic active hepatitis in order to confirm ELISA specificity by immunoblot test (RIBA-HCV), and to evaluate HCV replication by serum HCV-RNA. Nine patients were anti-nuclear, three type 1 anti-liver-kidney microsomal and three anti-smooth muscle antibody positive. None had associated autoimmune disease. All cases showed mild clinical disease and only moderate necroinflammatory activity. Response to prednisone was poor. RIBA-HCV confirmed ELISA results in all patients. HCV-RNA was found in the serum from 10 patients. Institution of alpha-interferon treatment in three steroid non-responsive patients was followed by prompt normalization of transaminases. Thus, a subgroup of autoantibody-positive chronic active hepatitis can be recognized as HCV-related and should be clinically and etiologically distinguished from autoimmune chronic active hepatitis. Trials of alpha-interferon treatment are worthwhile in this condition.

Induction of Broad CD4+ and CD8+ T-Cell Responses and Cross- Neutralizing Antibodies against Hepatitis C Virus by Vaccination with Th1-Adjuvanted Polypeptides Followed by Defective Alphaviral Particles Expressing Envelope Glycoproteins gpE1 and gpE2 and Nonstructural Proteins 3, 4, and 5

ABSTRACT Broad, multispecific CD4+ and CD8+ T-cell responses to the hepatitis C virus (HCV), as well as virus-cross-neutralizing antibodies, are associated with recovery from acute infection and may also be associated in chronic HCV patients with a favorable response to antiviral treatment. In order to recapitulate all of these responses in an ideal vaccine regimen, we have explored the use of recombinant HCV polypeptides combined with various Th1-type adjuvants and replication-defective alphaviral particles encoding HCV proteins in various prime/boost modalities in BALB/c mice. Defective chimeric alphaviral particles derived from the Sindbis and Venezuelan equine encephalitis viruses encoding either the HCV envelope glycoprotein gpE1/gpE2 heterodimer (E1E2) or nonstructural proteins 3, 4, and 5 (NS345) elicited strong CD8+ T-cell responses but low CD4+ T helper responses to these HCV gene products. In contrast, recombinant E1E2 glycoproteins adjuvanted with MF59 containing a CpG oligonucleotide elicited strong CD4+ T helper responses but no CD8+ T-cell responses. A recombinant NS345 polyprotein also stimulated strong CD4+ T helper responses but no CD8+ T-cell responses when adjuvanted with Iscomatrix containing CpG. Optimal elicitation of broad CD4+ and CD8+ T-cell responses to E1E2 and NS345 was obtained by first priming with Th1-adjuvanted proteins and then boosting with chimeric, defective alphaviruses expressing these HCV genes. In addition, this prime/boost regimen resulted in the induction of anti-E1E2 antibodies capable of cross-neutralizing heterologous HCV isolates in vitro. This vaccine formulation and regimen may therefore be optimal in humans for protection against this highly heterogeneous global pathogen.

The Hepatitis C Virus: Genetic Organization, Persistence, and Vaccine Strategies

The proteins encoded by the hepatitis C virus (HCV) positive-stranded RNA genome have been identified in mammalian cells transfected with cloned HCV cDNA. The putative nucleocapsid protein C, (20kDa) and envelope glycoproteins (El, 33kDa and E2, 70kDa) have been identified along with putative nonstructural proteins 2 (23kDa), 3 (70kDa), 4a (10kDa), 4b (27kDa), 5a (56kDa), and 5b (70kDa). These proteins are processed from a poly protein precursor through the combined action of host and viral encoded proteases. The immune response to HCV has been investigated in patients with chronic hepatitis. Essentially, all patients have circulating antibodies to the envelope glycoproteins, and HCV-specific cytotoxic lymphocytes have been isolated from many individuals. These preliminary data indicate that persistence of HCV is not simply due to the absence of an immune response. Purified recombinant E1 and E2 glycoproteins have been used to immunize seven chimpanzees. Following experimental challenge with homologous HCV-1, five animals were protected from both HCV infection and disease. Although infected, the course of disease may have been inhibited in the remaining two vaccinees. These data encourage the use of an HCV vaccine to prevent infection and the carrier state.

Application of Polymerase Chain Reaction to Hepatitis C Virus Research and Diagnostics

Rapid advances in virology during the 1980s were due, in part, to the development of powerful molecular biological technologies including lambda GT11 immunoscreening (Young and Davis, 1983) and the polymerase chain reaction (PCR) (Saiki et al. 1985). The hepatitis C virus (HCV), which was cloned using lambda GT11 immunoscreening, is the only virus which was discovered by cloning and characterizing the viral genome prior to biochemical isolation and/or visualization of the virus or viral antigens by microscopy. The application of PCR to HCV enabled researchers to overcome some of the technical limitations associated with the relatively low titers of HCV in blood or liver tissue and the absence of an in vitro tissue culture system for the cultivation of HCV. PCR based diagnostics, the rapid accumulation of HCV sequence information and the availability of cDNA/PCR generated cDNA clones for the expression of putative viral antigens has contributed greatly to our understanding of the structure and biology of HCV.