Monoclonal antibodies directed against unique and common determinants on the lipopolysaccharide molecule of Salmonella serogroups A, B, and D.

A panel of monoclonal antibodies (MAbs) directed against lipopolysaccharide (LPS) of Salmonella serogroups A, B, and D was generated. Nine most productive hybrid clones were selected from several fusions of mouse myeloma cells with splenocytes from BALB/c mice, immunized with the corresponding heat-killed bacteria. The MAbs were characterized by enzyme immunoassay, Western blot analysis, and dot-immunoblotting with LPS and whole bacteria of Salmonella serogroups A-E and some other representatives of the Enterobacteriaceae family. Seven MAbs were reactive with the sole Salmonella strain used as an immunogen; one MAb, SD:10D9H, reacted with the five major serogroups of Salmonella species (A, B, D, E1, and E2); and one MAb, SA:5D12A, reacted with Salmonella serogroups A-E and a rough strain of S. cholerae-suis. None of the MAbs reacted with LPS of E. coli 055:B5 or whole bacteria of E. coli K12, Klebsiella pneumoniae, or Proteus vulgaris. The typical ladder-like patterns of bands were observed after immunoblotting of MAbs against electrophoretically resolved LPS from Salmonella serogroups A-E, which thus confirmed their LPS-directed specificity. MAbs affinity constants were determined by noncompetitive enzyme immunoassay using serial dilutions of both LPS as antigen (coating the plate) and antibodies. On the base of the results obtained, the presumed epitopes for each of the MAbs were discussed. The usefulness of MAbs generated for diagnostic and protective purposes was declared.