Identification of novel immunogenic Mycoplasma ovipneumoniae proteins recognized by sera from domestic and bighorn sheep.

Domestic and bighorn sheep can both be infected by the bacterium Mycoplasma (Mesomycoplasma) ovipneumoniae. Disease presentation differs between these hosts, with bighorn sheep experiencing more severe outcomes; however, both species mount a humoral immune response following infection. This serological response has yet to be fully characterized; however, study of other species of Mycoplasma has demonstrated that disease severity can vary depending on the presence of antibodies, suggesting an important role of antibody production in disease manifestation. In the present study, a domestic sheep flock historically positive for M. ovipneumoniae was sampled to examine the relationship between the detection of the Mycoplasma in the nasal cavity and circulating antibodies. Our results revealed that animals harboring multiple M. ovipneumoniae strains exhibited more complex antigen banding patterns during immunocapillary reaction. Identification of candidate proteins driving the humoral response in domestic and bighorn sheep predominantly revealed adhesin and proteins containing domain of unknown function. These findings will enable future studies to elucidate the roles of these proteins in M. ovipneumoniae pathogenesis.