Phylogenetic comparison of classical swine fever virus in China

An N-terminal fragment of the E2 gene of classical swine fever (CSF) virus encoding major immunogenic sites was amplified by RT-PCR directly from 110 clinical specimens representing 109 epizootic sites during the last decade in China. Phylogenetic relationships between these viruses as well as 20 re ference strains were determined by comparison of their nucleotide sequences . A phylogenetic tree showed that 103 of the 110 field viruses (93.60%) wer e clustered within group 2 and subdivided into three subgroups, while the r emaining seven viruses (6.4%), along with two Chinese reference strains, Sh imen and HCLV (attenuated vaccine strain), were clustered into subgroup 1.1 within group 1. However, none of the Chinese CSF viruses were members of s ubgroup 1.2 (represented by reference strain Brescia). This is the first re port on the distribution of CSF virus genotypes in China. Results indicated that CSF viruses predominating in recent epizootics within China are genet ically divergent from the reference strain Shimen and the vaccine strain HC LV. (C) 2001 Elsevier Science B.V. All rights reserved.