MONOCLONAL-ANTIBODIES TO A 55-KILODALTON PROTEIN PRESENT IN DUCK LIVER INHIBIT INFECTION OF PRIMARY DUCK HEPATOCYTES WITH DUCK HEPATITIS-B VIRUS

As an approach to identifying hepatocyte receptors for the avian hepad navirus duck hepatitis B virus (DHBV), hybridomas were prepared from m ice immunized with permissive duck hepatocytes. Monoclonal antibodies (MAbs) were screened for the ability to inhibit binding of DHBV partic les to primary duck hepatocytes and to block infection. We identified two MAbs which partially blocked binding and caused marked inhibition of infection of primary duck hepatocytes with DHBV. Lack of cross-reac tivity with DHBV envelope proteins suggested that inhibition of infect ion was due to specific interaction between the antibodies and a host cell. surface molecule. Both MAbs immunoprecipitated a 55-kDa protein (p55) expressed in duck liver and several other duck tissues. p55 homo logs were also identified in other birds and mammals. We predict from our data that only a small proportion of total cellular p55 molecules are expressed at the surfaces of hepatocytes and that p55 is involved in some early step in the infectious pathway.