Identification and characterization of immunogenic genes from genomic expression library of mycoplasma ovipneumoniae

Abstract

Mycoplasma ovipneumoniae is an important pathogen causing respiratory disease in sheep. At present, the immune-associated antigens of M. ovipneumoniae are still unknown, which significantly limits the development of new vaccines for M. ovipneumoniae. In order to identify and characterize the immune-associated antigen genes, genomic expression library of M. ovipneumoniae was constructed and identified, from which positive clones were recognized and screened by positive serum against M. ovipneumoniae. Sequence analysis showed that these 10 clones contained 5 different genes encoding P97-like protein, P102-like protein, Translation initiation factor (IF-1), Methionine aminopeptidase (MAP) and P56 membrane protein, respectively. Three proteins including IF-1, MAP and P97-like protein were expressed in E. coli and used to immunize lambs to verify their immunogenicity, respectively. Animal immunization test confirmed that the novel protein MAP displayed a strong immunogenicity, while the immunogenicity of P97-like protein and IF-1 were relatively weak. The identification of immunogenic protein MAP provided a potentially valuable antigen candidate for the development of serological diagnostic method and subunit vaccine against M. ovipneumoniae infection.