Viral diseases of the respiratory tract of cats: isolation and properties of viruses tentatively classified as picornaviruses.

Abstract

SUMMARY Of 11 ether-resistant viruses isolated from cats with respiratory disease, 2 were partially characterized. The viruses were rapidly cytopathic for feline fetal kidney (ffk) cells, and under single-step growth conditions (multiplicity of infection, 25), maximal levels of intra- and extracellular virus were produced after 6 and 8 hours, at which times all cells in the monolayer were shrunken, rounded, and intensely basophilic and had pyknotic and karyolytic nuclei. The 2 viruses did not agglutinate chicken or guinea pig red blood cells. At pH 3, titer of the viruses decreased by 2 to 6 log10; at pH 4, a loss of up to 1 log10 infectivity occurred; and at pH 5, the viruses were stable. M..