Novel antigenic proteins of Mycoplasma synoviae as potential vaccine candidates

Abstract

Mycoplasma synoviae (M. synoviae) is a serious avian pathogen causing severe economic losses to chicken and turkey producers worldwide. The currently available live attenuated vaccine and inactivated vaccine on the market elicit only limited protection. The aim of this study was to identify antigenic proteins of M. synoviae as potential subunit vaccine candidates. In immunoproteomics and reverse vaccinology analyses, a total 24 candidate antigens were picked out. Five candidate antigens were selected to evaluate immunogenicity and preliminary protection in a chicken model, including RS01790 (lipoprotein, putative sugar ABC transporter), BMP (BMP family ABC transporter substrate-binding protein), GrpE (nucleotide exchange factor), RS00900 (putative nuclease) and RS00275 (Uncharacterized protein). The results showed that the five antigens had good immunogenicity. They could be localized on the M. synoviae cell membrane and adhere to DF-1 cells using indirect immunofluorescence assay. They induced specific humoral and cellular immune responses. Vaccine efficacy was evaluated by observing weight gain, pathogen load, pathological changes. As a result, the vaccinated chickens revealed significantly higher body weight gain, with lower air sac lesion scores and tracheal mucosal thicknesses. The vaccinated chickens also showed lower M. synoviae loads in throat swabs than nonvaccinated chickens. The protective effect of BMP, GrpE and RS00900 vaccines is better than that of RS01790 and RS00275. In conclusion, our study demonstrates the potential of using subunit vaccine, providing new ideas for the development of M. synoviae vaccines. The vaccine candidates may contribute to the future development of therapeutic strategies to control the spread of M. synoviae worldwide.