Ultrastructural studies of the replication of fowl adenoviruses in primary cell cultures

The replication of four fowl adenovirus strains (FAV-1, strain Phelps; FAV-5, strains 340 and TR-22; and FAV-7, strain YR-36), in primary chick kidney cell cultures, is described. Differences were found in the distribution of virus particles and virus associated inclusions between viruses belonging to different cytopathology subgroups. Thus in cells infected with FAV-1 (Phelps) and FAV-5 (340) (i.e. subgroup 1) virus particles, as they increased in number, tended to become distributed peripherally, close to the nuclear membranes, with the virus associated inclusions in the centre of the nucleus. With FAV-5 (TR-22) and FAV-7 (YR-36) (i.e. subgroup 2) virus particles and associated inclusions became concentrated initially in the central nuclear area later increasing to fill the whole nucleus, with virus particles and inclusions completely intermixed. The virus-associated inclusions were found to be identical to those described in human adenovirus infected cells and the same nomenclature was adopted. Other inclusions found in infected nuclei, included tubular structures and inclusions composed of granular particles.