Bovine Respiratory Syncytial Virus (BRSV)
BRSV was named for its characteristic cytopathic effect, the formation in infected tissue of syncytial cells, giant multinuclear cells formed by the fusion of several cells. BRSV has a predilection for the lower respiratory tract, where it can cause varying degrees of pneumonia by itself. Secondary bacterial infections, frequently involving Mannheimia (Pasteurella) haemolytica, causes disease of greater severity or death. Transmission is via respiratory aerosols or from direct contact with infected cattle.