Immunological relationships between Salmonella flagella and their potential application for salmonellae detection by immunoassay.

Native flagella of ten Salmonella serotypes were shown to possess serotype-specific antigenic determinants as well as a multiple of common antigenic determinants, which varied in concentration. Each common antigenic determinant was shared by certain, but not all, serotypes. This has been demonstrated from agglutination and radioimmunometric assay (RIMA) results, using ten antisera raised in rabbits against purified polymeric flagellins from ten Salmonella serotypes as immunogens. The minimum detectable populations of salmonellae, as determined by RIMA varied considerably, due to variation in concentrations (and possibly types) of common antigenic determinants. However, the results demonstrated the feasibility of utilizing RIMA for the qualitative detection of salmonellae, using a mixture of only the ten antisera and 125I-labelled protein A as a general tracer. In this way, 77 different salmonellae were detected in less than 8 h after culturing in selective broth. The RIMA developed was specific for salmonellae and showed no cross-reactions with high populations of other members within the family Enterobacteriaceae.