The antibody response to salmonellae in mice and humans studied by immunoblots and ELISA

The antibody response to salmonellae in mice and humans was studied by immunoblots and ELISA. Sera from mice infected with attenuated salmonellae (including an aroA live vaccine strain) recognized up to 45 different bands on immunoblots at the height of the response, including lipoprotein, OmpA protein, porins, a putative heat-shock protein and flagella. Adsorption of antisera with intact or sonicated smooth or rough salmonellae prior to immunoblotting showed that antibodies were directed against exposed, masked and intracellular antigens. Sera from H-2 congenic B10 mice which vary in their ability to clear salmonellae from the reticuloendothelial system (RES) showed a progressive increase in the intensity of the antibody response, which persisted longer in animals which failed to clear bacteria from the RES. The LPS response was much stronger in susceptible mice. Sera from 18 confirmed cases of human typhoid recognized similar antigens to mouse typhoid sera, with individual variations; there was no correlation between the immunoblot pattern and the titres of other serological tests for typhoid fever.