Study of Infectivity and Hemagglutination of Influenza Virus in Deembryonated Eggs

Abstract

Deembryonated eggs were inoculated with different dilutions of influenza virus. It was observed that in the presence of high concentrations of virus little or no evidence of multiplication in terms of infectious titer was demonstrable while the hemagglutinin titers showed a consistent rise apparently independent of the amount of active virus present. More dilute inocula induced a concomitant rise in titer of infectivity and hemagglutination. A technique of washing was used to study the development of the hemagglutinin produced by concentrated inocula and some of its properties were examined. The hemagglutinin is apparently formed in the membrane. It is able to interfere with the multiplication of active virus in eggs and mice but incapable of self-propagation, its appearance depending upon the presence of large amounts of active virus. It has a shorter lag phase than fully active virus from which it is indistinguishable in hemagglutination-inhibition tests. On intracerebral inoculation into mice it has a low toxicity. This hemagglutinin is considered an “incomplete” or “immature” form of virus.