THE QUANTITATIVE DETERMINATION OF INFLUENZA VIRUS AND ANTIBODIES BY MEANS OF RED CELL AGGLUTINATION

Abstract

This paper discusses expts. dealing with the correlation between the agglutinating capacity of virus suspensions and their infectivity for mice, and expts. directed toward correlating the agglutination-inhibiting power of various sera with their virus-neutralizing capacity. The agglutination titer for chicken red cells of freshly prepared or carefully stored suspensions of PR8 influenza virus, i.e., virus of maximum pathogenicity, was found to be proportional to the mouse lethal titer of the same prepns. The agglutination titer of infected allantoic fluid procured in a standard way is relatively constant, regardless of the influenza strain used and its pathogenicity for mice. The agglutination inhibition test, using ferret and human sera, gives qualitative data regarding influenza antibodies which are similar to the information obtained on the same sera by means of the virus neutralization test. There is a definite relationship between the agglutina- tion inhibition titer and the virus neutralization titer of a serum. The agglutination inhibition titer of immune ferret serum is inversely proportional to the amt. of virus used in the test.