Propagation of group II avian adenoviruses in turkey and chicken leukocytes

An avirulent hemorrhagic enteritis virus isolate (HEV-A) as well as a virulent one (HEV-V), both belonging to the group II avian adenoviruses, were successfully propagated in turkey leukocyte cell cultures. HEV antigens were detected as early as 12 hr after infection of the cells, using HEV-specific monoclonal antibodies in a fluorescent antibody test, and virus particles were observed by electron microscopy in the nuclei of infected cells at 18 to 24 hr after infection. Electron microscopy revealed the presence of HEV in the nuclei of nonadherent cells, as well as in adherent cells. The nonadherent infected cells had the characteristics of immature mononuclear leukocytes, whereas the adherent cells had monocyte-macrophage characteristics. HEV produced in turkey leukocytes was mostly cell-associated, particularly with the nonadherent cells. HEV-A could be serially passed in turkey blood leukocyte cultures at least seven times. Various methods employed to culture virus indicated that cells grown in spinner cultures were superior to cells grown in stationary cultures. In contrast to the successful infection of HEV in turkey leukocytes, the infection of chicken leukocytes with either HEV or splenomegaly virus of chickens, or turkey leukocytes with splenomegaly virus, was poor.