A Host-Protein Component of Influenza Viruses

Abstract

EXPERIMENTS designed to unmask deeper antigenic components of influenza viruses by heat degradation of their type-specific surface antigens yielded evidence of relationship between virus types A and B based upon their possession of a common antigen. The antigen concerned was found to be almost indistinguishable from a component of the host tissues (chick embryo) in which the viruses were propagated, which at once aroused suspicion that it might be merely contaminant material adsorbed on the virus. The presence of an antigenic component in purified virus preparations of types A and B, which was also demonstrable in normal allantoic fluids, was first reported by Knight¹, who used a precipitation test with hyper-immune rabbit sera and viruses purified by differential centrifugation. It has been pointed out that reliance upon centrifugation for virus purification is open to the objection that centrifugation merely selects particle size and density, and it has been shown by Knight² himself that the normal allantoic fluid antigen is of similar size to the influenza viruses.