Development of an indirect ELISA based on a new specific lipoprotein LP53 for the detection of antibodies against Mycoplasma synoviae

Mycoplasma synoviae (MS) is considered to be one of the main mycoplasma pathogens of poultry, causing arthritis, airsacculitis, eggshell apex abnormalities and production drops in chickens and turkeys. Infection by MS usually results in considerable economic losses to the poultry industry worldwide. Therefore, it is essential to develop a highly sensitive and accurate diagnostic method in the livestock production. The MSLP53 was predicted as a highly conserved and specific membrane associated lipoprotein of MS by bioinformatics analysis. The His-tagged MSLP53 (rMSLP53) protein was expressed and purified using E. coli expression system, and was confirmed by Western blotting to react with each MS-positive serum, but not react with positive sera against other avian pathogens, suggesting that the rMSLP53 had strong immunoreactivity and specificity. An rMSLP53-based indirect ELISA was developed, compared to IDEXX kit with a pool of 277 chicken sera samples, and showed high sensitivity (85.54%), specificity (89.19%) and coincidence rate (87.00%) within these two methods. When detecting the sera from experimentally infected chickens, the newly established rMSLP53-ELISA had certain advantages over the IDEXX kit, that is, it could identify the serum 3–18 weeks after infection as MS-positive serum, while IDEXX kit could only identify the serum 3–12 weeks after infection as positive serum. The MSLP53 protein is a specific immunogenic lipoprotein of MS, which was confirmed to be a promising antigen target for the detection of serum antibodies of MS. A rMSLP53-based indirect ELISA assay was successfully established in this study, showed high sensitivity, specificity and consistency with the commercial IDEXX kit, and could recognize the serum as MS-positive in a longer period after MS infection than IDEXX kit. This newly established rMSLP53-ELISA may be used as an effective detection method for MS serological monitoring and epidemiological investigation.