The Effect of Inhibitors on the Hemagglutinating Activity of Polyoma Virus

Abstract

In efforts to obtain reproducible results in hemagglutination tests with polyoma virus it was found that the presence of inhibitors accounted for the extreme variations in titers observed from test to test with individual virus preparations. The inhibitors combine with the virus at 4°C but readily dissociate at 37°C. They were found in all animal sera and cultured cells tested as well as in guinea pig red cell suspensions. Attempts to remove the inhibitors from virus preparations by differential centrifugation or treatment with fluorocarbon, trypsin or RDE did not meet with full success. Slight degrees of inhibitory activity always remained in the treated materials, indicating that at least two inhibitory substances are involved. Because of the rapid dissociation of inhibitor from the virus particles at 37°C reproducible hemagglutinin titers were obtained merely by incubation of the test at 37°C for a few minutes prior to settling of the red cells at 4°C. In the competition for the virus on cooling of the mixtures the red cells apparently outrace the inhibitors.