INFLUENZA llI. RAPID ALTERATIONS IN THE RESPIRATORY RArE OF EMBR¥ONATED EGGS APPARENTLY CAUSED BY INFLUENZA VIRUS TOXIN* BY DONALD GREIFF, Sc.D.,

Following the intra-allantoic injection of influenza A virus in embryonated eggs, a latent period of 4 to 6 hours has been observed, during which little or no active virus can be recovered from any of the embryonic fluids or tissues (1, 2). Microbial toxins probably exert their effect by altering cellular metabolism. Pappenheimer and Hendee have suggested that the diphtheria toxin, for example, m a y be a cytochrome b which interferes competitively with mammalian cytochrome b, and thus inhibits intracellular respiration (3). I t therefore seemed possible that the existence of an influenza virus toxin might be demonstrated, and its concentration measured, by studying the oxygen consumption of fertile eggs during the early par t of the latent period of virus multiplication. The method employed somewhat parallels that used for the demonstration of rickettsial toxins (4-7) in connection with which the initial assumption was made that any deaths occurring in mice shortly after rickettsial injection would be ascribable to toxins rather than rickettsial multiplication. The data to be presented here indicate that the allantoic fluid of fertile eggs infected with influenza virus contains a factor which when injected into a new series of eggs, profoundly modifies the respiration of the embryos. This toxic factor persists after infectivity has been destroyed by heating.