Monoclonal antibodies raised to purified woodchuck hepatitis virus core antigen particles demonstrate X antigen reactivity

ABSTRACT The immunity elicited against nucleocapsid of hepatitis B virus (HBV) and closely related woodchuck hepatitis virus (WHV) has been shown to be important in resolution of hepatitis and protection from infection. Further, activity of gamma interferon (IFN-γ), which may directly inhibit hepadnavirus replication, promotes antiviral defense and favors T helper cell type 1 (Th1) response, which is seemingly a prerequisite of HBV clearance. In this study, to enhance induction of protective immunity against hepadnavirus, healthy woodchucks were immunized with a bicistronic DNA vaccine carrying WHV core (WHc) and woodchuck IFN-γ (wIFN-γ) gene sequences. Three groups, each group containing three animals, were injected once or twice with 0.5 mg, 0.9 mg, or 1.5 mg per dose of this vaccine. In addition, four animals received two injections of 0.6 mg or 1 mg WHc DNA alone. All animals were challenged with WHV. The results showed that four of nine animals injected with the bicistronic vaccine and one of four immunized with WHc DNA became protected from serologically evident infection and hepatitis. This protection was not linked to induction of WHc antigen-specific antibodies or T-cell proliferative response and was not associated with enhanced transcription of Th1 cytokines or 2′,5′-oligoadenylate synthetase. Strikingly, all animals protected from hepatitis became reactive for WHV DNA and carried low levels of replicating virus in hepatic and lymphoid tissues after challenge with WHV. This study shows that the bicistronic DNA vaccine encoding both hepadnavirus core antigen and IFN-γ was more effective in preventing hepatitis than that encoding virus core alone, but neither of them could mount sterile immunity against the virus or prevent establishment of occult infection.

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Persistence of isolated antibodies to woodchuck hepatitis virus core antigen is indicative of occult infection

Hepatology ◽

10.1002/hep.20419 ◽

2004 ◽

Vol 40 (5) ◽

pp. 1053-1061 ◽

Cited By ~ 24

Author(s):

Carla S. Coffin ◽

Tram N.Q. Pham ◽

Patricia M. Mulrooney ◽

Norma D. Churchill ◽

Tomasz I. Michalak

Keyword(s):

Hepatitis Virus ◽

Core Antigen ◽

Woodchuck Hepatitis Virus ◽

Occult Infection ◽

Virus Core

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Replication of Naturally Occurring Woodchuck Hepatitis Virus Deletion Mutants in Primary Hepatocyte Cultures and after Transmission to Naive Woodchucks

Journal of Virology ◽

10.1128/jvi.75.8.3811-3818.2001 ◽

2001 ◽

Vol 75 (8) ◽

pp. 3811-3818 ◽

Cited By ~ 10

Author(s):

Mengji Lu ◽

Gero Hilken ◽

Dongliang Yang ◽

Thekla Kemper ◽

Michael Roggendorf

Keyword(s):

Hepatitis Virus ◽

Viral Population ◽

Core Antigen ◽

Woodchuck Hepatitis Virus ◽

Deletion Mutants ◽

Wild Type ◽

Lymphoproliferative Response ◽

Hepatocyte Cultures ◽

Liver Tissues

ABSTRACT Woodchuck hepatitis virus (WHV) mutants with core internal deletions (CID) occur naturally in chronically WHV-infected woodchucks, as do hepatitis B virus mutants in humans. We studied the replication of WHV deletion mutants in primary woodchuck hepatocyte cultures and in vivo after transmission to naive woodchucks. By screening 14 wild-caught, chronically WHV-infected woodchucks, two woodchucks, WH69 and WH70, were found to harbor WHV CID mutants. Consistent with previous results, WHV CID mutants from both animals had deletions of variable lengths (90 to 135 bp) within the middle of the WHV core gene. In woodchuck WH69, WHV CID mutants represented a predominant fraction of the viral population in sera, normal liver tissues, and to a lesser extent, in liver tumor tissues. In primary hepatocytes of WH69, the replication of wild-type WHV and CID mutants was maintained at least for 7 days. Although WHV CID mutants were predominant in fractions of cellular WHV replicative intermediates, mutant covalently closed circular DNAs (cccDNAs) appeared to be a small part of cccDNA-enriched fractions. Analysis of cccDNA-enriched fractions from liver tissues of other woodchucks confirmed that mutant cccDNA represents only a small fraction of the total cccDNA pool. Four naive woodchucks were inoculated with sera from woodchuck WH69 or WH70 containing WHV CID mutants. All four woodchucks developed viremia after 3 to 4 weeks postinoculation (p.i.). They developed anti-WHV core antigen (WHcAg) antibody, lymphoproliferative response to WHcAg, and anti-WHV surface antigen. Only wild-type WHV, but no CID mutant, was found in sera from these woodchucks. The WHV CID mutant was also not identified in liver tissue from one woodchuck sacrificed in week 7 p.i. Three remaining woodchucks cleared WHV. Thus, the presence of WHV CID mutants in the inocula did not significantly change the course of acute self-limiting WHV infection. Our results indicate that the replication of WHV CID mutants might require some specific selective conditions. Further investigations on WHV CID mutants will allow us to have more insight into hepadnavirus replication.

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