Canine parvovirus empty capsids produced by expression in a baculovirus vector: use in analysis of viral properties and immunization of dogs

1 James A. Baker Institute, New York State College of Veterinary Medicine, Cornell University, Ithaca, New York 14853 2 Boyce Thompson Institute, Cornell University, Ithaca, New York 14853, U.S.A. and 3 Duphar B.V., C. J. Van Houtenlaan 36, 1381 CP Weesp, The Netherlands The VP-2 genes of canine parvovirus (CPV) and a recombinant consisting of CPV and feline panleukopenia virus (FPV) sequences were cloned into baculovirus expression vectors, fused to the baculovirus polyhedrin promoter. Recombinant baculoviruses were prepared and the properties of the parvovirus proteins expressed in insect cells examined. The proteins produced were the same size as the authentic CPV VP-2 protein, and were produced late after infection; the quantity of proteins recovered from the insect cell cultures was similar to those produced in CPV infections. Parvovirus particles formed had the haemagglutination (HA), sedimentation and buoyant density properties of authentic CPV capsids. Both the CPV capsids and the CPV-FPV recombinant capsids from the baculovirus system expressed the same epitopes as those seen in the viable parvoviruses when tested with a panel of anti-parvovirus monoclonal antibodies. Lysates of recombinant baculovirus-infected cells were inoculated into dogs, giving rise to serum neutralizing and HA-inhibiting antibodies, and the immunized dogs were protected from clinical disease upon challenge with a virulent isolate of the most recent antigenic type of CPV. Present address: Veterinary Research Institute, Al. Partyzantów 57, 24-100 Pulawy, Poland. > Present address: Virogenetics Corporation, 465 Jordan Road, Troy, New York 12180, U.S.A. Present address: Department of Entomology, University of Massachusetts, Amherst, Massachusetts 01003, U.S.A. Received 23 July 1991; accepted 21 October 1991.