Enzymatic Enhancement of Infectivity of Reovirus

Abstract Spendlove, R. S. (California State Department of Public Health, Berkeley), and F. L. Schaffer. Enzymatic enhancement of infectivity of reovirus. J. Bacteriol. 89:597–602. 1965.—Enhancement of infectivity by chymotrypsin treatment has been demonstrated with all three types of reovirus, although not in all viral preparations. Enzyme treatment did not produce a simultaneous increase in the hemagglutinating activity of reovirus type 1 (the only type tested). The infectivity of reovirus type 1 (Lang strain) was increased by treatment with chymotrypsin, trypsin, papain, and a filtrate from a culture of a Pseudomonas sp. but not by treatment with pepsin. Sedimentation experiments showed that the property of enhanceability was closely associated with the virus particles themselves. Results of studies involving various sequential treatments with chymotrypsin, and with heat in the presence or absence of 2 m MgCl2, were compatible with the interpretation that inhibited virus is resistant to exposure to a temperature of 56 C in the absence of MgCl2, whereas activated virus is thermolabile. Activation of reovirus infectivity by heat in the presence of MgCl2 and by chymotrypsin was not additive.