An adenovirus-vectored vaccine based on the N protein of feline coronavirus elicit robust protective immune responses

Feline coronavirus (FCoV) is an unsegmented, single-stranded RNA virus belonging to the Alphacoronavirus genus. It can cause fatal feline infectious peritonitis (FIP) in cats of any ages. Currently, there are no effective prevention and control measures to against FCoV. In this study, we developed a recombinant adenovirus vaccine, AD5-N, based on the nucleocapsid(N) protein of FCoV. The immunogenicity of AD5-N was evaluated through intramuscular immunization in 6-week-old Balb/c mice and 9–12 months old cats. Compared to the control group, AD5-N specifically induced a significant increase in IgG and SIgA levels in the vaccinated mice. Furthermore, AD5-N not only effectively promoted strong cellular immune responses in cats but also induced high levels of specific SIgA, effectively helping cats resist FCoV infection. Our findings suggest that adenovirus vector vaccines based on the N gene have the potential to become candidate vaccines for the prevention and control of FCoV infection.