Immunogenicity evaluation of recombinant rabies virus-vectored multivalent vaccines expressing feline calicivirus VP1 and feline herpesvirus 1 gB/gD genes.

Feline calicivirus (FCV) and feline herpesvirus 1 (FHV-1) are major pathogens threatening feline health, and prophylactic immunity remains the primary preventive approach. To develop a safe and effective multivalent vaccine against the two viruses, two recombinant rabies virus (RABV) vaccines expressing the FCV VP1 and FHV-1 gB/gD genes were constructed. The exogenous genes showed stable inheritance following serial viral passages, and the recombinant RABVs exhibited growth kinetics comparable to the parental strain, with a delayed peak titer. After verifying the viral pathogenicity, the recombinant RABV vaccines elicited specific IgG antibodies against VP1, gB, and gD, as well as neutralizing antibodies against FCV, FHV-1, and RABV in mice. Immunized mice were also protected against lethal RABV challenge. In cats, the vaccines induced neutralizing antibodies against the three pathogens, and immunized cats showed milder clinical signs and less severe histopathological lesions following FHV-1 and FCV challenge. Collectively, these findings indicate that the two recombinant vaccines induce robust humoral immune responses against FCV, FHV-1, and RABV in both mice and cats and confer protection against viral challenges.