Canine immunoglobulin F(ab′)2 fragments protect cats against feline parvovirus virus infection

•Canine immunoglobulin F(ab′)2 fragments showed efficient neutralizing activity in vitro against FPV.•Canine immunoglobulin F(ab′)2 fragments had therapeutic and prophylactic effects in FPV infected cats.•F(ab′)2 fragment may be used as a prophylactic and therapeutic agent for diseases caused by FPV. Feline parvovirus virus (FPV) causes severe diarrhea and leukopenia in felines, and threatening the health of wild and domestic felines. Currently, specific drugs to treat FPV have not yet been developed. In this study, IgG was extracted from inactivated FPV-immunized dog sera. Canine F(ab′)2 fragments were obtained from pepsin-digested IgG and then purified by protein-G column chromatography. The results showed that canine immunoglobulin F(ab′)2 fragments showed efficient neutralizing activity in vitro against FPV and had therapeutic and prophylactic effects in FPV infected cats. The anti-FPV-specific F(ab′)2 fragment can significantly alleviate the clinical symptoms of FPV infected cats and reduce the viral loads of the intestinal tract. These results indicated that the F(ab′)2 fragment prepared from inactivated FPV-immunized felines may be used as a prophylactic and therapeutic agent for diseases caused by FPV.