Electron microscopy of a porcine adenovirus

SYNOPSISA virus isolated from the pig and showing characteristics of an adenovirus has been examined by electron microscopy in both the purified state and in tissue culture cells. The virus is icosahedral in shape, has 252 capsomeres per capsid, and is characteristic of the adenovirus group. Examination of infected cells shows that the virus is predominantly intranuclear but virus has also been demonstrated in the cytoplasm. The cellular relationships characterise the adenovirus as more likely to be a member of the sub‐group containing types 3, 4 and 7 than that containing type 5. The virus is closely associated with the chromatin of the nucleus, in which parallel densely staining fibres have been demonstrated. Other structures with a rectilinear profile have been observed which have dense cores, evidence of a helical component and loci resembling the spheroidal form of virus.The first report of the isolation from a pig of a virus resembling an adenovirus was made by Haig et al. (1946): the results of serological tests indicated that the virus possessed the adenovirus group antigen but there was no neutralisation against several of the commoner human adenoviruses; the cytopathic changes in tissue culture were of the type described for the sub‐group of human adenoviruses types 3, 4 and 7. This paper records an electron‐microscope study of the morphology of the virus, the changes in infected tissue‐culture cells and the micro‐ecology of the virus.