Genetic characterizations of pestiviruses, mainly classical swine fever virus (CSFV) and bovine viral diarrhea virus (BVDV), were established by phylogenetic tree analysis based on the viral sequence heterogeneity. CSFV isolates were classified into three genogroups, CSFV-1, CSFV-2 and CSFV-3. BVDV isolates were also divided into BVDV-Ia, BVDV-Ib and BVDV-II. (Lab. of Immunology, Department of Exotic Diseases TEL +81-42-321-1441)