INFLUENZA : III. RAPID ALTERATIONS IN THE RESPIRATORY RATE OF EMBRYONATED EGGS APPARENTLY CAUSED BY INFLUENZA VIRUS TOXIN.

Allantoic fluid from embryonated eggs infected with influenza A virus contains a toxic agent which can be demonstrated and quantitatively measured by its rapid effect on oxygen consumption when it is introduced in new series of fertile eggs. The effects were measured 90 minutes after the injection of the infected fluid, and were seen following both intra-allantoic injection and injection into the yolk sac. This toxin, in concentrations resulting from the injection of 0.5 cc. or less of the infected fluid, has no effect on oxygen consumption. The injection of 0.75 to 2.0 cc. of the fluid strikingly increases the oxygen consumption of the fertile eggs, while the injection of 3.0 cc. markedly depresses respiration. A similar reversal and eventual loss of the effect of the toxin on respiration were noted when the concentration of toxin was progressively diminished by heat inactivation. The toxic agent is slowly inactivated by heating at 56 degrees C., but is effective long after infectivity and hemagglutinating ability have been destroyed. In this respect the agent differs from rickettsial and lymphogranuloma venereum virus toxins. The method described may be of value in studying the physiological effects of other toxic agents.