Identification of Mycoplasma synoviae immunogenic surface proteins and their potential use as antigens in the enzyme-linked immunosorbent assay.

Specific immunogenic proteins of Mycoplasma synoviae (MS) strain WVU-1853 were purified and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by Western transfer using anti-MS, anti-M. gallisepticum, and non-immune chicken sera. A cluster of prominent immunoreactive proteins with molecular masses from 46 to 52 kDa (p46-52) and less reactive single proteins of approximately 22 and 92 kDa were shown to partition into the detergent phase of Triton X-114 MS lysates, suggesting that these amphiphilic polypeptides are integral membrane proteins. Monoclonal antibodies, produced by immunizing mice with MS whole cell proteins and shown to bind species-specific determinants, reacted strongly with p46-52 and less intensely with the 22-kDa protein, but they did not react with the 92-kDa protein. A protein fraction extracted from the Triton X-114 detergent phase and further purified by ion-exchange chromatography was found to be highly enriched in p46-52 and was used as antigen in a prototype enzyme-linked immunosorbent assay (ELISA) to detect MS antibodies. Seventy serum samples were taken variously from specific-pathogen-free chickens experimentally infected with MS or MG and from commercial broiler breeder chickens vaccinated for MS and MG. All samples were tested by both rapid serum agglutination and a prototype ELISA described herein; the two tests were strongly correlated (r = 0.776). The results indicate that the ELISA antigen used--the immunodominant cell surface proteins in the p46-52 cluster--appears to be a good candidate for use in the development of improved rapid diagnostics of MS infections in birds.