Western blot analysis of the human serum response to Mycoplasma hominis.

Mycoplasma hominis is a human genital pathogen with importance in postpartum pregnancy complications (postpartum fever/endometritis). Previous research has suggested that serum antibody levels to M. hominis are important in predicting which groups of women are at risk. M. hominis strain PG21 was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots to determine which protein antigens would be good candidates for use in serologic tests. Western blots of strain PG21 were probed with acute and convalescent human sera from patients with culture-confirmed M. hominis infections, animal sera directed against strain PG21 and other M. hominis strains, and sera from patients with confirmed infections from other sexually transmitted diseases (STD). Western blot analysis showed that the prenatal (Groups I, II, III) and convalescent (Group IV) M. hominis human sera reacted with proteins with apparent MWs of 106, 67, 46, and 40 kilodaltons (kDa). Only the convalescent sera (Group IV) and the prenatal sera (Group III) reacted with proteins having apparent MWs of 58 and 50 kDa. Animal antisera directed against all strains of M. hominis examined showed that these proteins were reactive in all strains, and other STD human sera did not react with proteins in strain PG21 corresponding to the apparent MWs of 50 and 58 kDa. Preliminary evidence suggested that proteins with the apparent MWs of 50 and 58 kDa may be viable candidates for use in serologic tests for the detection of human anti-M. hominis antibodies and help to eliminate cross-reactivity observed with whole-cell lysates.