Studies on the P-Q variation of influenza A2 viruses.

3) Heat stability of hemagglutinins is higher with Q virus than P virus. 4) Bovine red cell agglutinins are detectable only with Q virus but not with P virus. In this article, the fact that the activity of receptor destroying enzyme is higher with Q virus than when P virus was added as the fifth marker. In the second place, higher avidity of P virus than Q virus to immune sera was studied further in a critical manner. The result revealed the fact that in hemagglutination inhibition test with human convalescent sera, when human 0 red cells were used instead of chicken red cells, hemagglutinin inhibitory antibody was detectable even with Q virus as an antigen. Secondly, in the com plement fixation test with both viral antigens, there was no difference between P and Q in the avidity to fix the antibody contained in human convalescent sera. Thus the idea to assume P virus as the one in an indicator state of Q virus was proposed. In fact, KIO4 treatment of various Q viruses gave rise to the virus which was susceptible to human antibody and various inhibitors in hemagglutin ation inhibition test. Treatment of Q virus with formalin or urea did not change the characteristics of Q virus as KIO4 did. Trypsin treatment of both P and Q virus revealed the fact that they are both fairly resistant to this enzymatic action. Bovine red cell agglutinin found with Q virus was assumed to be the marker associated to the virus particle, as a whole. Because it was easily lost with ether treatment and was not detectable with the small hemagglutinins derived from Q virus.