Evaluation of recombinant outer membrane protein C based indirect enzyme-linked immunoassay for the detection of Salmonella antibodies in poultry

AIM To evaluate the efficacy of recombinant outer membrane proteinC (rOmpC) based enzyme-linked immunoassay (ELISA) for the diagnosis of salmonellosis in poultry. MATERIALS AND METHODS Three antigens were prepared, and the indirect ELISA was standardized using the antigens and the antiserum raised in chicken against Omp and rOmpC. Sera were collected from a total of 255 apparently healthy field chickens and screened for the presence of Salmonella antibodies by this ELISA. RESULTS The sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of Omp revealed major polypeptides at 36, 42 and 52 kDa, and the rOmpC was evident by a single protein band of 43 kDa. The Omp and rOmpC antigen revealed an optimum concentration of 78 and 156 ng, respectively, in the assay, while the whole cell antigen gave an optimum reaction at a concentration of 10(6) organisms/ml. The test was found to be specific as it did not react with any of the antisera of seven other organisms. The developed ELISA detected Salmonella antibodies from 22 (8.62%) samples with rOmpC antigen, while 24 (9.41%) samples gave a positive reaction with both Omp and whole cell antigens. CONCLUSION We suggest rOmpC based indirect ELISA as a suitable screening tool for serological monitoring of poultry flocks.