Effects of BHV-1 on PMN adhesion to bovine lung endothelial cells

Bovine herpes virus-1 (BHV-1) infection appears to decrease the rate of polymorphonuclear leukocyte (PMN) influx into the lung in response to the secondary invader, Pasteurella haemolytica. It was postulated that BHV-1 may affect the rate of cellular infiltration by altering the function of the endothelium, thereby preventing PMN movement across the blood-tissue barrier. Therefore, we decided to investigate the effect of BHV-1 on the ability of PMN to adhere to lung endothelial cells (LEC). LEC were isolated from fetal bovine fetal tissue and were shown to function in PMN adhesion assays. Furthermore, enhanced PMN adhesion was observed after exposure of LEC to recombinant bovine TNF-α (rBoTNF-α) for 4, 8, 12, and 24 h. LEC infected with BHV-1 were shown to be less responsive to rBoTNF-α. However, infection of LEC with BHV-1 at an mulitiplicity of infection (MOI) of 1.0 or 10 did not affect basal levels of PMN adhesion to these cells. Decreased PMN binding to BHV-1-infected LEC, simultaneously treated with rBoTNF-α, was observed at 10–12 h post-infection. The data suggest that BHV-1 may prevent cytokine-induced PMN infiltration of the lung through the modification of EC responses to cytokines.