Construction of recombinant OPIV3 virus vectoring bivalent Mycoplasma ovipneumoniae adhesins.

Mycoplasma ovipneumoniae (MO) and Ovine parainfluenza virus type 3 (OPIV3) are significant pathogens implicated in ovine respiratory diseases, which impose substantial threats to extensive sheep farming. However, no commercial bivalent vaccines targeting both pathogens are currently available. In this study, we constructed a recombinant live-attenuated OPIV3 using Red/ET recombination, inserting MO adhesion protein genes (P60, P113) between the N and P genes of the OPIV3 genome. The recombinant candidate rOPIV3-MO was successfully generated and inhibited growth kinetics similar to those of the parental OPIV3 TJ2022 strain. Immunization trials in sheep indicated that rOPIV3-MO displayed a favorable safety profile. Both rOPIV3-MO and OPIV3 TJ2022 inoculation induced specific and neutralizing antibodies, as well as T-cell receptor (TCR) rearrangements.