Molecular Characteristics of Bovine Viral Diarrhea Virus Strain Isolated from Commercial Foetal Bovine Serum

Abstract

Bovine viral diarrhea virus (BVDV) is commonly detected in biological products such as vaccines and serum. In this study, we have detected BVDV in commercial foetal bovine serum. In order to determine whether the serum contained infectious virus or viral genes, we inoculated the serum sample into MDBK cells. After six passages, results of indirect immunofluorescence assay confirmed that the commercial foetal bovine serum was contaminated with an infectious strain of BVDV, designated as BI-2023. The complete genome sequence of this isolate was 12,273 nt. Subsequent sequence analysis revealed that the 5'UTR genes and the full genome of BI-2023 shared 98% and 94.74% nucleotideidentity, respectively, with the BVDV1b reference strain CC13B. This suggests that BI-2023 represents a new subtype within the BVDV1b lineage. Phylogenetic analysis of the 5'UTR and full genome sequences of BVDVs indicatedthat BI-2023 clusters closely with a known BVDV1blineage. These findings underscore the importance of screening commercial foetal bovine serum for adventitious viruses.