The risk of transmission from sheep experimentally infected with BVDV-1c during the acute phase to BVDV naïve sheep

Bovine viral diarrhoea virus (BVDV) is an economically important disease of cattle known to cause immunosuppression and reproductive dysfunction in infected animals. Although predominantly a disease of cattle other ruminant species, such as sheep, have been shown to undergo infection with similar outcomes as those observed in cattle. The main source of BVDV transmission is known to be persistently infected (PI) animals which shed large quantities of virus through all secretions and excretions. However, it is believed that BVDV is able to persist within herds even after the removal of these PI animals. Although not proven, this persistence is thought to be due to the short period of viral excretion shown to occur in acutely infected animals. As a result the aim of this study was to determine if transmission of BVDV could occur between sheep undergoing an acute BVDV infection and sheep naïve to BVDV. Five wethers, experimentally infected with BVDV-1c, were co-mingled with five pestivirus naïve wethers for a period of seven weeks. Weekly blood samples were collected and tested for the presence of BVDV-specific antibodies and BVDV antigen. Acute infection was successful in the experimentally inoculated animals, with antibodies detected in all five wethers by Day 35 post inoculation. Transmission of BVDV-1c was not shown to occur between these acutely BVDV-1c infected wethers and the naïve wethers co-mingled with them.