Polypeptide analysis with monoclonal antibodies of A type inclusion bodies induced by cowpox virus

The antigen in A type inclusion bodies (ATIB) induced by cowpox virus (CPV) was examined by immunofluorescent staining with monoclonal antibodies and polypeptide analysis. In the immunofluorescence (IF) test, these monoclonal antibodies reacted only with cytoplasmic inclusion bodies in cells infected with CPV. The fluorescence became detectable in the cells 6-9 hours after infection with CPV. No fluorescence was detectable in cells infected with CPV in the presence of cytosine-I-beta-D-arabinofuranosyl-HCl (Ara C) or in cells infected with other poxviruses, such as vaccinia virus (VV) or Shope fibroma virus (SFV). On Western blotting and immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), only one component with a molecular weight of about 160,000 (160 K) was detected in CPV-infected cells. This 160 K polypeptide was first detectable 12 hours after infection of cells with CPV, and was not detectable in infected cells in the presence of Ara C. The 160 K polypeptide was not detected in cells infected with VV or SFV, or in virions purified from CPV-, VV- or SFV-infected cells.