Genetic heterogeneity of porcine and ruminant pestiviruses mainly isolatedin Japan

The genetic variability of porcine and ruminant pestiviruses was studied by comparative nucleotide sequence analysis of 73 isolates (42 porcine and 31 ruminant), including 65 Japanese isolates (35 porcine and 30 ruminant), Th e 5'-untranslated region (UTR) amplified by reverse transcriptase-polymeras e chain reaction (RT-PCR) was determined by direct sequencing and phylogene tic analysis was performed from the nucleotide sequence data. Most porcine isolates were divided into two major subgroups, classical swine fever virus (CSFV) subgroup 1 (CSFV-1, represented by Brecia strain) and subgroup 2 (C SFV-2, represented by Alfort strain). However, the Japanese Kanagawa/74, Ok inawa/86, Okinawa/86-2 and Thai CBR/93 strains were the most distinct varia nts and these were assigned to another new disparate subgroup, CSFV-3 (repr esented by p97 strain). Most ruminant isolates were classified as the bovin e viral diarrhoea virus (BVDV) genotype-I (BVDV-I) and subdivided into two subgroups, BVDV-Ia (represented by the NADL strain) and Ib (represented by the Osloss strain). Two bovine isolates (MS-1 and SY-89) and a contaminatin g strain (V/FLL) from an ovine cell line were classified as BVDV genotype-I I (BVDV-II) on genetic characteristics. These data suggested that the detec tion and phylogenetic analysis of 5'-UTRs are useful for the rapid characte rization of field isolates. (C) 1999 Elsevier Science B.V. All rights reser ved.