Alternative antigens reduce cross-reactions in an ELISA for the detection of Salmonella enteritidis in poultry.

Two alternative antigens for the use in detection of antibodies to salmonellas were investigated: firstly, lipopolysaccharide (LPS) from members of the D2 group, having antigens O: 9, 46, and flagella antigens. Whereas LPS from the D2 group did not discriminate sufficiently with control sera, flagella antigens reacted specifically with antibodies directed to serotype specific H antigens. When flagella antigens were used to screen sera from birds of commercial flocks, however, cross-reactivity between flagella antigens was observed. When both LPS and flagella antigens were used to screen sera from chickens infected with Salmonella enteritidis, the sera gave higher titres with flagella antigens during the early stages of infection, and titres with flagella antigens dropped earlier after infection had ended than titres with lipopolysaccharide.