Effects of age and viral determinants on chronicity as an outcome of experimental woodchuck hepatitis virus infection

Authors

  • Paul J. Cote Ph.D.,

    Corresponding author
    1. Division of Molecular Virology and Immunology, Department of Microbiology and Immunology, Georgetown University Medical Center, Rockville, MD
    • Division of Molecular Virology and Immunology, Georgetown University Medical Center, 5640 Fishers Lane, Rockville, MD 20852. fax: 301-881-0810
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  • Brent E. Korba,

    1. Division of Molecular Virology and Immunology, Department of Microbiology and Immunology, Georgetown University Medical Center, Rockville, MD
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  • Roger H. Miller,

    1. Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
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  • James R. Jacob,

    1. Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Betty H. Baldwin,

    1. Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • William E. Hornbuckle,

    1. Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • Robert H. Purcell,

    1. Hepatitis Viruses Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
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  • Bud C. Tennant,

    1. Department of Clinical Sciences, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY
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  • John L. Gerin

    1. Division of Molecular Virology and Immunology, Department of Microbiology and Immunology, Georgetown University Medical Center, Rockville, MD
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Abstract

Acute hepadnavirus infections either resolve or progress to chronicity. Factors that influence chronicity as an outcome of hepatitis B virus (HBV) infection in humans can be studied experimentally in the woodchuck model. Accordingly, several woodchuck hepatitis virus (WHV) inocula were characterized. Representative inocula had high titers of infectious virus (approximately 107.7-109.5 woodchuck 50% infectious doses per milliliter [WID50% /mL] by subcutaneous inoculation), with 1 WID50% ranging between 21 and 357 physical virion particles. WHV7P1 (standard high dose, 5 × 106WID50%) produced a 72% chronicity rate (i.e., percent chronic of total infected) in neonatal woodchucks (1-3 days old). Comparable doses of WHV8P1 resulted in a lower chronicity rate in neonates (34% chronic) indicating that it represented a strain different from WHV7P1. Neonatal woodchucks were more susceptible to chronic infection by high doses of WHV7P1 (range, 65%-75% chronic) compared with 8-week-old weanlings (33% chronic) and adult woodchucks (0% chronic; i.e., all resolved). High doses of cloned wild-type viruses also induced high rates of chronicity in neonates (70%-80% chronic). Chronicity rates in neonates were decreased for low doses of WHV7P1 (500 WID50% , 9% chronic) and for high doses of a precore WHeAg-minus mutant WHV8 clone (17% chronic). Thus, both age and viral determinants can influence chronicity as an outcome of experimental WHV infection. Standardized inocula will enable the study of mechanisms that initiate and maintain chronic hepadnavirus infection and also provide a means for developing WHV carriers for therapeutic studies.

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