Encephalitis Virus “Antibody” in Sera of Experimentally Infected Animals by Agglutination of Virus-Coated Cells

Abstract

Details of the technic involved in satisfactorily coating bacterial cells with encephalitis virus and the agglutination of such cells by the sera of encephalitis patients have been given in a previous report 1 wherein the test was designated as the bacterial agglutination (B.A.) method of detecting serum antibody. That encephalitis virus was actually adsorbed onto the bacteria was indicated by the infectivity of ‘coated’ cells for susceptible animals even after repeated washing to remove extraneous virus. The specific nature of the agglutination reaction with patients' serum was demonstrated by certain control tests wherein the reaction did not occur when non-coated cells or cells coated with normal mouse brain were used. Further, sera from cases of clinically recognized poliomyelitis were studied which did not agglutinate cells coated with encephalitis virus although they were capable of agglutinating in high titer poliomyelitis virus-coated cells. And further, a high specificity was indicated by the ability of mouse-brain containing encephalitis virus as well as bacterial cells coated with this material to remove the agglutinating factor from the sera of encephalitis patients; while on the other hand, normal mouse brain or bacterial cells coated with normal mouse brain failed to remove the factor.

The application of this method to the detection of ‘antibodies’ in the blood serum of monkeys and hamsters experimentally infected with the virus of St. Louis encephalitis is the basis of the present report.

In Table I are given the results of the application of this method to the sera of hamsters wherein it will be noted that positive B.A. tests have been observed as early as the second day following inoculation with the virus of St. Louis encephalitis. Since this agglutinating factor has not been observed in the serum of normal animals, we presume that the B.A. titer of 1:10 observed in the case of animal No. 11 is related to the inoculation of virus 2 days previously.