Plaque Formation by Sendai Virus of Parainfluenza Virus Group, Type 1 on Monkey, Calf Kidney and Chick Embryo Cell Monolayers

Abstract

Cynomolgus monkey kidney cells were found to be a highly sensitive medium for plaque formation of Sendai virus and provided a practical method for the infectivity assay of the virus. The method gave reproducible titers and was as sensitive as the egg inoculation method and was simple enough to be used routinely. Sendai virus formed no recognizable plaques on chick embryo cell monolayers. However, the incorporation of a small amount of trypsin into the overlay medium induced plaques. This method gave comparable titers to those obtained on monkey kidney monolayers. Sendai virus formed plaques on calf kidney cell monolayers, but difficulties in the application of the method to infectivity assay arose from the fact that the plaques formed in calf kidney cells were small and not homogeneous in size and were not clearly defined.