Abstract: The aim of this study was to isolate virus from bovine viral diarrhea virus (BVDV) positive sample of the piglet and to study BVDV originating from pigs. BVDV positive samples from the piglet were inoculated in MDBK cells and a pig BVDV strain (SD0803) was obtained. In the study, cell culture, direct immunofluorescence assay, PCR amplification of 5′UTR，electron microscopy and TCID50 were performed, moreover，bioinformatics software were used to analyze the characteristics of molecular evolution. The results showed that the virus strain hadn’t caused cytopathic effect (CPE) until the 13th passage on MDBK cell. SD0803 infected cells showed strong fluorescent signal. DNA fragment of 307 bp and 428 bp were amplified by PCR from 5′UTR and Npro of SD0803. Under electron microscopy, virus particles were near round and enveloped with size of 50 nm in diameter. Virus titer of SD0803 was 10-6.5 TCID50·0.2 mL-1. The homology comparison and phylogenetic analysis of 5′UTR and Npro between SD0803 and representative BVDV isolates showed that SD0803 belongs to BVDV1. However, SD0803 had an obvious distance from the subtypes of BVDV1 and formed a separate group according to the phylogenetic relationship and this showed that the isolate might be a new subtype of BVDV1. So a pig originated BVDV SD0803 was successfully isolated and identified, and belongs to NCP BVDV1 and maybe a probably new subtype of BVDV1.

Key words: Bovine viral diarrhea virus, phylogenetic analysis, isolation and identification