Serological response of patients suffering from primary and recrudescent typhus: comparison of complement fixation reaction, Weil-Felix test, microimmunofluorescence, and immunoblotting.

Microimmunofluorescence and Western immunoblotting were compared with the classical complement fixation reaction and the Weil-Felix test to study the serological responses of patients to Rickettsia prowazekii and both Proteus vulgaris OX19 and OX2 during primary and recrudescent typhus infections. The serological response to R. prowazekii was found to be similar during primary and recrudescent typhus, and all sera examined contained antibodies to the same R. prowazekii cell structures. Immunoglobulin G (IgG) and IgM were found to be the dominant anti-R. prowazekii immunoglobulins in all sera tested and were found to be directed against the 100-kDa protein and the lipopolysaccharide. IgA antibodies, when present, were mainly against the 100-kDa protein. For P. vulgaris, IgG antibodies recognized the proteins and lipopolysaccharides of both OX19 and OX2 serotypes; IgM antibodies were directed against the P. vulgaris OX2 lipopolysaccharide. In addition, donor blood sera, which were negative by microimmunofluorescence, were found to contain IgG immunoglobulins reacting with R. prowazekii protein antigens of 135, 60, and 47 kDa by western immunoblotting.