VIRUSES PRODUCED FROM COMPLEMENTARY-DNA OF VIRULENT AND AVIRULENT STRAINS OF SWINE VESICULAR DISEASE VIRUSES RETAIN THE IN-VIVO AND IN-VITRO CHARACTERISTICS OF THE PARENTAL STRAIN

A full-length cDNA copy of the genome of the pathogenic strain, J1'73, of swine vesicular disease virus (SVDV) was constructed and inserted into the plasmid pSVL to generate a recombinant plasmid pSVLSJ1. Infec tious virus was produced following transfection of cultured mammalian cells with the plasmid. The recovered virus had the same in vitro prop el-ties as the parental strain with regard to antigenicity, plaque siz e on IBRS-2 cells and single-step growth. Pigs were experimentally inf ected with the parental virus, J1'73 strain, and viruses recovered fro m cells transfected with the plasmids pSVLSJ1 and pSVLS00 [Inoue T, Ya maguchi S, Saeki T, Sekiguchi K, J Gen Virol 71: 1835-1838 (1990)] cor responding to the pathogenic (J1'73) and non-pathogenic (H/3'76) Japan ese strains of the SVDV, respectively. All pigs inoculated with the vi rus recovered from pSVLSJ1 produced clinical signs of similar severity to those inoculated with the parental J1'73 strain. In contrast, pigs inoculated with the virus recovered from pSVLS00 did not show any cli nical signs. Viruses recovered from cells transfected with either pSVL SJ1 or pSVLS00 therefore retained the in vitro characteristics and the in vivo pathogenicity of their respective parental strains.