Genomic and serological diversity of bovine viral diarrhea virus in Japan

Genomic properties of 62 field isolates of bovine viral diarrhea virus (BVD V) collected fi-om 1974 to 1999 in Japan were investigated. The 5' untransl ated region (UTR) was amplified by reverse transcriptase polymerase chain r eaction (RT-PCR) and the 244 to 247 base nucleotide sequences were determin ed. Serological properties were also characterized by the cross-neutralizat ion test using antisera against the representative strain of the classified genotype. Using phylogenetic tree analysis, BVDV 1 was subdivided into two major clusters, BVDV-1a (29 isolates) and BVDV-1b (27 isolates). In group 1a, 3 differed from the other viruses, and were classified in a branch assi gned as 1a'. However, 4 isolates (So CP/75, 190 CP, 190 NCP and KS86-1-NCP) could not be assigned to group 1a or 1b. In comparison with the published sequence data, KS86-1-NCP, 190 CP and 190 NCP were similar to the Southern Africa isolates that have recently been proposed as BVDV 1c. The 5' UTR seq uence of So CP/75 was unique among those of BVDV 1, suggesting that the iso late should be classified into a new genotype. Only 2 out of 62 isolates co llected in 1989 and 1990 were identified as BVDV 2. The results of the cros s-neutralization test strongly supported these data, suggesting a close cor relation between the 5' UTR sequence and the antigenicity of BVDV.