Construction and evaluation of recombinant rabies virus encoding three copies codon-optimized G genes as inactivated rabies vaccine in dogs and cats.

Rabies is a fatal zoonotic disease affecting various warm-blooded animals. The number of dogs and cats in China has surpassed 120 million, yet no domestic universal rabies vaccine for them. The glycoprotein (G) of the rabies virus (RABV) serves as the principal antigen for inducing virus-neutralizing antibodies (VNA). In this study, we constructed a recombinant RABV strain (designated SAD-tOG) carrying three copies of the codon-optimized G gene using reverse genetics. The SAD-tOG strain exhibited comparable growth kinetics to the parent strain in cell culture while demonstrating enhanced G protein expression. Mouse challenge experiments revealed significantly reduced pathogenicity and elevated immunogenicity in the recombinant strain. Subsequently, a safe and efficient water-based adjuvant was selected to prepare an inactivated rabies vaccine. In another experiment, the VNA titers of dogs and cats after vaccination were both greater than the WHO-recommended protective antibody titer of 0.5 IU/ml for 360 days. Comparative analysis showed these titers were higher than those induced by commercial vaccines currently used in China. These findings collectively indicate that the SAD-tOG strain represents a safer and more effective vaccine candidate for dog and cat rabies prevention.