Production of Plaques with Influenza Viruses

Abstract

THE demonstration of the production of plaques, that is, necrotic foci, in tissue culture with the viruses of Eastern equine encephalomyelitis¹, Western equine encephalomyelitis², Newcastle disease², vaccinia³, and poliomyelitis⁴, offers additional quantitative applications to the study of these viruses. A necessary condition for the development of a plaque in tissue culture has been shown to be a destructive activity of the virus on the tissue employed. With the demonstration of a highly destructive effect of the WSE strain of influenza A virus on various chick embryonic tissues (9-day chorio-allantoic membrane, and 14-day lung and liver in roller tube cultures, unpublished results), experiments were undertaken to show production of plaques with this virus. Using the technique of Noyes³, plaques averaging 0.5 mm. in diameter were obtained in five days on chick embryonic layer tissue cultures with a high dilution of the allantoic fluids used. Attention was then directed to a less heterogeneous source of tissue, chick embryo lung. Plaque formation was shown to occur readily with this tissue not only with the WSE strain of influenza A virus, but also with the other influenza virus strains tested.