The Level of Lactic Dehydrogenase Activity as an Indicator of the Growth of Influenza Virus in the Embryonate Egg

The relation, between time and the levels of lactic dehydrogenase activity of chorioallantoic fluids from embryonate eggs infected with the PR8 strain of influenza virus were determined quantitatively. The mean values, based on 10 determinations for each time interval, followed a sigmoid curve, with the greatest rates of change occurring between 48 and 72 hours after the inoculation of virus. The activities of the fluids from infected eggs at the 72nd hour or later were approximately 18 times higher than those from non-infected eggs. Based on the data above, a qualitative test for the presence of infection with influenza virus was developed.