Feline Syncytial Virus Spontaneously Detected in Feline Cell Cultures

Abstract

Two strains of a virus were detected in feline kidney and liver cell cultures derived from an apparently healthy kitten. They replicated in feline cells with vacuolation, and multinucleated giant cell and small plaque formation. They were principally cell-associated and required actively dividing cells for their replication. From their viral nucleic acid, they were presumed to be of RNA type. They were sensitive to ether, heat and acid. The smallest infective particle was determined to be between 100 and 130 nm in diameter by membrane filtration and electron microscopy. They had a buoyant density of 1.19 g/ml in sucrose. They were identified as feline syncytial virus (FSV) by their biological and physicochemical properties, and serologically by the serum-neutralization and microimmunodiffusion tests. In a decade from 1968 the incidence of FSV infection in cats was very low (3.8%) in the Tokyo area. FSV is, however, of particular importance for investigators and vaccine producers who use cats and feline cell cultures also in Japan.