ARBOVIRUS HEMAGGLUTININ INHIBITORS IN NORMAL ANIMAL SERA

I. INHIBITORS IN SERA FROM VARIOUS ANIMAL SPECIES AND THE PRELIMINARY OBSERVATION OF PHYSICOCHEMICAL PROPERTIES

Abstract

In order to gain the information about the properties of arbovirus hemagglutinin inhibitors in animal sera, the experiments were performed with several strains of arboviruses (JE-Nakayama, JE-JaGAr 01, Getah, Haruna, Sindbis and Bunyamwera viruses).
These results are as follow:
1) Arbovirus HA inhibitors widely found in various animal sera. However, there were at least two different inhibitors in sera, and the viruses were not equally sensitive to these inhibitors.
2) There was a highly selective inhibitor in adult female chicken sera and it was not removed by the usual acetone extraction. This acetone-resistant or acetone-insoluble inhibitor can be removed by additional treatment of kaolin without reduction of antibodies.
3) Some of the group A arboviruses shared a specific inhibitor appeared to be activated by the treatment of the sera with 2-mercaptoethanol employed for destruction of IgM, and this inhibitor was also removed by additional treatment of kaolin.
4) By thin-layer chromatographic techniques, inhibitory activity to arboviruses were seen in both cholesterol and cholesterolester fractions in normal swine serum, and highly inhibitory activity to the JaGAr 01 virus was found in cholesterol fraction. The hemagglutinating activity of JaGAr 01 virus was also highly inhibited by pure dehydrocholesterol suspension than those of other viruses were, but those of all tested viruses were slightly inhibited by β-lipoprotein. Chloroform fraction extracted from egg yolk inhibited remarkably HA activity of all viruses and highest titers were obtained in tests with JE viruses.
5) Inhibition titers to JE viruses and Haruna-virus were dependent of serum cholesterol titers when tested with human sera.
6) It seemed to be sure that these inhibitors did not neutralize the virus in the plaque reduction test.