IMMUNOLOGICAL RESPONSIVENESS OF PEKIN DUCKS TO CORE ANTIGEN OF DUCK HEPATITIS-B VIRUS

Cellular immune responses to the HBc or HBe antigen of hepatitis B vir uses contribute to the pathogenesis of hepatitis B and to the eliminat ion of the virus. Insufficient cytotoxic immune reactions against the core antigen may be one major reason for viral persistence in the abse nce of severe clinical symptoms. We attempted to stop viral. persisten ce in the animal model of congenitally infected ducks by injection of recombinant DHBc particles, together with the strong immunostimulator Freund's adjuvant. However, the duck HBc antigen (DHBcAg)-treated duck s did not develop detectable liver disease, nor was the virus persiste nce affected. The congenitally infected ducks did not contain antibodi es against DHBcAg before injection despite continuous production of du ck hepatitis B virus, and developed only a weak transient antibody res ponse after injection of recombinant DHBcAg together with Freund's adj uvant. Noninfected ducks developed, in contrast, a strong antibody res ponse to the injected DHBcAg. We conclude that congenitally infected d ucks are immunotolerant to DHBcAg and cannot be cured by immunotherapy with exogenous recombinant DHBcAg.