Nonspecific suppressive effect of bovine herpesvirus type 1 on bovine leukocyte functions

The effect of bovine herpesvirus type 1 on the specific and nonspecific immune response of calves was examined. Animals with or without prior aerosol exposure to Pasteurella haemolytica serotype A1 were aerosol challenged with 10(8) PFU of virus. Blood and serum samples were taken before and after virus challenge for determining cell-mediated, humoral, and neutrophil responses. A significant depression of the blastogenic responses to phytohemagglutinin, P. haemolytica, and Pasteurella multocida and of neutrophil chemotactic response was observed 4 to 7 days after challenge. However, the antibacterial activity of neutrophils was not significantly affected by virus exposure. Anti-bovine herpesvirus type 1 antibody responses were detected 11 days postchallenge. A significant elevation of the anti-P. haemolytica antibody response (day 0 versus day +11) was detected in animals previously exposed to P. haemolytica.