RECOMBINATION OF INFLUENZA VIRUSES IN THE DE-EMBRYONATED EGG.

A modified technique for de-embryonation of fertile eggs is described which allows retention of the whole surface of the allantois for influenza virus growth. With the standard technique involving treatment of the cells with receptor destroying enzyme RDE, haemagglutinin and newly produced infective virus are liberated earlier than in the normal allantoic cavity. Recombination in the first infective cycle is only demonstrable if the dose of virus used is sufficient to ensure that a considerable proportion of cells will be infected with at least two virus particles. When the interval between the addition of the two viruses to the system is one hour or less, recombination can be demonstrated. It is not shown when the interval is two hours. With cells all initially infected and treated with RDE to minimize the likelihood of reinfection, virus liberation continues for a long period. The constitution of the virus liberated into the fluid at different periods is almost uniform in regard to the extent of anomalous neutralization, the relative apparent excess of one virus over the other, the degree of "incompleteness" of the virus and the types of virus isolated by allantoic inoculation at limiting infective dilutions. The ratio of the recombinants MEL and AVSE from M +/WS -- experiments is approximately 4-7:1. Discussion of the significance of this ratio in the light of the existence of double neutralization leads to the conclusion that the viruses concerned normally have a diploid constitution. [ABSTRACT FROM AUTHOR]