Cultivation of bovine adenovirus type 3 in tracheal organ cultures

Abstract

A growth curve study of the WBR-1 strain of bovine adenovirus type 3 (BAV-3) in bovine foetal tracheal organ cultures showed that the virus replicated at high titres, was mainly cell-associated and persisted in the cultures. The histopathological changes were characterized by the progressive swelling, rounding and shedding of the epithelial cells which often showed intranuclear inclusions. The indirect immunoperoxidase reaction demonstrated that the virus replicated only in the epithelial cells of the organ cultures. Ultrastructural studies demonstrated that BAV-3 induced three different types of nuclear inclusions in the epithelial cells. A network of highly electron-dense, finely granular material was interspersed with patches of granular material of low electron density in the centre of the infected nuclei. In some nuclei, there were also some small circular very dense bodies near the central inclusion. The virions were either dispersed or packed into crystals, and they were released into the cytoplasm through breaks in the nuclear membrane. These ultrastructural changes were comparable with those induced by other oncogenic adnoviruses.