THE SEROLOGICAL RELATIONSHIPS OF THE RICKETTSIAE OF EPIDEMIC AND MURINE TYPHUS

Abstract

The complement-fixing antibodies present in epidemic and murine typhus immune sera can be differentiated by quantitative absorption tests. The neutralizing antibodies that participate in the Giroud reaction can be differentiated by quantitative inhibition tests.Epidemic and murine typhus immune sera contain two kinds of complement-fixing antibodies and also two kinds of neutralizing antibodies. The antigens that react with these antibodies differ in specificity and thermal resistance. Cross reactions between epidemic and murine rickettsiae are due to the presence of similar heat stable antigens in the two types. Type specific sera may be obtained by absorbing immune serum with either (a) rickettsiae of heterologous type or (b) heated rickettsiae of homologous type. The specific antibodies react only with the heat labile antigens of the homologous type of rickettsiae.Mice may be actively immunized against the toxic factors of murine and epidemic rickettsiae. The immunity produced by small doses of vaccine is type specific and dependent on the presence of heat labile antigen in the vaccine.