Hemagglutination by Col-MM-Virus

Abstract

Hemagglutination of sheep red blood cells by the Col-MM strain of the EMC virus was inhibited by polyvalent anions, the inhibitor titers (Hl-titers) of the different negative ions being roughly proportionate to their net electrical charge. Whereas the HI-titer of specific antibody was inversely proportionate to the amts. of virus, indicating a stoichiometric combination of virus and antibody, the Hl-titers of Na hexametaphosphate (6-valent anions) were only slightly influenced by the quantity of virus added. The order of mixing of the reactants was of great importance for the serum inhibition but without effect on the activity of hexametaphosphate. The strong hemagglutination-inhibiting effect of Na hexametaphosphate was not paralleled by any virus neutralizing activity. A standard serological Hi-test, based on the results of a study of the Col-MM virus hemagglutination, is described. Applied on 569 human sera, this method gave a high incidence (12.5%) of strongly positive hemagglutination-inhibition titers among 384 sera obtained from patients showing distinct involvement of the central nervous system. Weakly positive reactions were encountered in 14.3%. A control group, consisting of 146 sera collected from healthy humans showed only 0.7% strong and 11% weak reactions, while 39 sera from patients with various ailments but apparently free from neurotropic infections were negative throughout. Even strongly inhibiting human sera failed neutralize Col-MM virus in animal expts.