Studies on the specificity of agglutinins against human erythrocytes modified by Newcastle disease virus.

The specificity of agglutinins in human sera against human erythrocytes modified by Newcastle disease virus (NDV-O agglutinins) was studied with agglutination and agglutination inhibition techniques. Virus grown in both embryonic eggs and tissue culture was used in the experiments. The findings were compatible with the existence of four specificities of agglutinins. In some sera, including those from subjects recently inoculated with vaccines prepared in eggs, the agglutinins were directed against a component of the allantoic fluid. In high-titred infectious mononucleosis (IM sera the agglutinins were directed against antigenic groupings present in the Vic strain but not the B1 strain of NDV, whereas in certain other sera they were directed against antigens present in both of them. Finally, in some sera the agglutinins probably reacted with a red cell antigen uncovered by the viral neuraminidase.