Recombinant adenovirus expressing pdhβ-pdhD fusion protein produces robust immune responses and partial protection against Mycoplasma Synoviae challenge in chickens.

Abstract

Mycoplasma synoviae (MS) stands as a pivotal pathogen, responsible for triggering arthritis and airsacculitis in both chickens and turkeys. Given the pressing need for safe and efficacious vaccine candidates, we engineered recombinant adenoviruses expressing a fusion antigen. This antigen consisted of the pyruvate dehydrogenase E1 subunit beta (pdh&#x3b2;) and dihydrolipoyl dehydrogenase (pdhD) of MS. We then systematically evaluated the immune effect and protective efficacy of these recombinant adenoviruses against MS challenge in a chicken model. Our results demonstrated the successful construction of recombinant adenoviruses rAd-pdh&#x3b2;, rAd-pdhD, and rAd-pdh&#x3b2;-pdhD. The pdh&#x3b2;, pdhD, and pdh&#x3b2;-pdhD proteins were efficiently expressed in cells infected with the respective recombinant adenoviruses. Animal experiments further revealed that vaccination with recombinant adenoviruses rAd-pdh&#x3b2;, rAd-pdhD, and rAd-pdh&#x3b2;-pdhD elicited significant specific humoral and cellular immune responses (P < 0.05). Notably, rAd-pdh&#x3b2;-pdhD exhibited superior immunogenicity compared to rAd-pdh&#x3b2; and rAd-pdhD. Moreover, all three recombinant adenovirus vaccine candidates conferred partial protection to chickens against MS challenge. They effectively alleviated MS-induced footpad and joint swelling, as well as inflammation. Among them, rAd-pdh&#x3b2;-pdhD demonstrated a better protective effect. In conclusion, vaccination with recombinant adenoviruses rAd-pdh&#x3b2;, rAd-pdhD, and rAd-pdh&#x3b2;-pdhD can evoke immune responses and provide partial protection against MS in chickens. In particular, rAd-pdh&#x3b2;-pdhD holds greater potential as a vaccine candidate against MS.