INFLUENZA VIRUS AND ITS MUCOPROTEIN SUBSTRATE IN THE CHORIOALLANTOIC MEMBRANE OF THE CHICK EMBRYO II. S~PwlsE INACTIVATION OF SUBSTRATE AND IZS RELATION TO zm~ MODE O~" VIRAL MULTIPLICATION BY R. WALTER SCHLESINGER*, M.D., AXe0 H. VALERIE KARR

Heat-stable inhibitors (HI) of hemagglutination by influenza viruses have been extracted from the chorioallantoic membrane (CAM) of chick embryos, and in the preceding paper (1) it was shown that their general characteristics resembled those of inhibitors isolated from other biological materials which have been identified as mucoprotein in nature. Inhibitory activity of CAM extracts against heat-inactivated influenza viruses was used as a measure of the allantoic cells' total supply of substrate susceptible to enzymatic breakdown by active virus or by receptor-destroying enzyme of Vibrio cholerae (RDE). In this paper, experiments are described in which fluctuations in the level of soluble substrate (HI) extracted from CAM infected with influenza viruses were related on a time scale to different phases in the infectious process, x