In vitro replication activity of Bovine Viral Diarrhea Virus in an epithelial cell line and in bovine peripheral blood mononuclear cells

The present study focused on the in vitro infection of Madin Darby Bovine Kidney (MDBK) cells and bovine peripheral blood mononuclear cells (PBMCs) from naïve animals with non-cytopathic (ncp, BVDV-1b NY-1) and cytopathic (cp, BVDV-1a NADL) strains. Infections with 0.1 and 1 multiplicity of infections (MOI) and incubation times of 18 and 36 hr were compared. Twelve BVDV naïve heifers were enrolled to collect PBMCs. The viral loads in MDBK cells and in PBMCs after in vitro infections were measured by Real-Time Polymerase Chain Reaction (PCR) assays. The highest viral loads were measured at 1 MOI and 36 hr post-infection in both the cell systems and the lowest at 0.1 MOI and 18 hr with the exception of the cp strain NADL in PBMCs, where the highest viral load was observed at 0.1 MOI and 36 hr. Viral load mean values were higher for the cp strain than the ncp one irrespectively of the extent of the infection period and MOI. The models of infection studied uncovered different replication activities respectively to the biotype of virus, the cell substrate and the lasting of infection. Replication tends to be higher in PBMCs, particularly at low MOIs and for the ncp strain.