Feline panleukopenia (FPL), resulting from infection with the feline panleukopenia virus (FPLV), is an extremely contagious and life-threatening viral disease characterized by high infection and death rates. Immunization continues to be the most reliable measure for limiting the spread and severity of the disease. The viral capsid protein VP2 is the dominant antigen of FPLV and serves as the principal focus for the design of improved vaccines. Recently, virus-like particle (VLP) technology has gained attention as a next-generation vaccine platform due to its excellent immune-stimulating ability and favorable safety characteristics. In the present research, FPLV-VLPs were constructed using a baculovirus expression vector system (BEVS) to express the VP2 protein derived from a Chinese epidemic isolate (Ala91Ser, Ile101Thr) of FPLV. The assembled particles displayed increased antigen recognition and hemagglutination capacity, producing a hemagglutination titer of 1:216. After immunization, cats generated high anti-FPLV hemagglutination inhibition (HI) antibody titers (1:216) and exhibited complete (100%) resistance when challenged with a virulent Chinese field strain (Ala91Ser, Ile101Thr). These results suggest that FPLV-VLPs could serve as effective subunit vaccine candidates for protection against FPLV infection.
