Infectivity Assay of Reoviruses: Comparison of Immunofluorescent Cell Count and Plaque Methods

Abstract
Summary: A method of plaque assay for reoviruses using BS-C-1 and L929 cell lines has been described and evaluated by comparison with the immunofluorescent cell counting technique in four cell lines. Both procedures were found satisfactory for infectivity assay of nine strains of reoviruses which included representatives of the three antigenic types. Demonstration of maximal infectivity required prior treatment of viral suspensions with a proteolytic enzyme such as chymotrypsin. A variety of quantitative and qualitative differences was observed among the reoviruses tested in respect to plaque morphology, plating efficiency, response to enzyme treatment and infectivity for various cell types. These differences are discussed in terms of the function of the protease-sensitive reovirus inhibitor.