Bovine viral diarrhoea virus infection in bone marrow of experimentally infected calves.

Colostrum-deprived calves were inoculated with either a field isolate of bovine viral diarrhoea virus (BVDV) containing cytopathogenic (CP) and noncytopathogenic (NCP) biotypes or with only the NCP biotype. Paraffin wax-embedded sections of bone marrow from these calves, examined by means of an immunoperoxidase method, showed BVDV antigen in megakaryocytes and myeloid cells. Infection of such cells may play a role in the pathogenesis of thrombocytopenia, leucopenia and neutropenia, as reported in cattle infected with BVDV.