African horse sickness (AHS) is a lethal vector-borne disease caused by African horse sickness virus (AHSV) and represents a major threat to equine health and the horse industry. In 2020, outbreaks of AHS caused by AHSV serotype 1 (AHSV-1) were reported in Thailand, increasing the risk of AHS introduction into China. Given the safety issues associated with currently available live attenuated AHS vaccines, the development of safer and more effective vaccination strategies is urgently needed. In this study, we constructed a recombinant fowlpox virus (rFPV) expressing the AHSV-1 VP2 protein as a candidate vaccine, designated rFPV-VP2. The recombinant virus was verified by PCR and Western blot analysis, which confirmed the successful expression of VP2. Preliminary immunization trials were conducted in both mice and horses, and immune responses were evaluated via an indirect enzyme-linked immunosorbent assay (iELISA) and immunofluorescence assay (IFA). The results revealed that VP2-specific antibodies were successfully induced in the serum of rFPV-VP2-immunized animals. Notably, serum from immunized horses showed specific reactivity with AHSV-1, confirming the induction of AHSV-1-specific immune responses. Therefore, these results demonstrate that rFPV-VP2 is a promising candidate vaccine for AHSV-1 and provide a scientific basis for the development of safer preventive strategies.

Keywords: African horse sickness virus; VP2; immunogenicity; recombinant fowlpox virus.