Identification of a novel bovine copiparvovirus in pooled fetal bovine serum.

A novel parvovirus was identified as a cell culture contaminant by metagenomic analysis. Droplet digital PCR (ddPCR) was used to determine viral loads in the cell culture supernatant and further analysis, by ddPCR and DNA sequencing, demonstrated that fetal bovine serum (FBS) used during cell culture was the source of the parvovirus contamination. The FBS contained ~ 50,000 copies of the novel parvovirus DNA per ml of serum. The viral DNA was resistant to DNAse digestion. Near-full length sequence of the novel parvovirus was determined. Phylogenetic analysis demonstrated that virus belongs to the Copiparvovirus genus, being most closely related to bovine parvovirus 2 (BPV2) with 41% identity with the non-structural protein NS1 and 47% identity with the virus capsid protein of BPV2. A screen of individual and pooled bovine sera identified a closely related variant of the novel virus in a second serum pool. For classification purposes, the novel virus has been designated bovine copiparvovirus species 3 isolate JB9 (bocopivirus 3-JB9).