HUMORAL AND CELL-MEDIATED IMMUNE-RESPONSES OF BEEF AND DAIRY-CATTLE EXPERIMENTALLY INFESTED WITH PSOROPTES OVIS

Objective-To compare cellular and humoral immune responses of beef (Be lgian White and Blue [BWB]) and dairy (Friesian-Horstein [FH]) cattle to Psoroptes ovis infestation and to determine whether Psoroptes ovis infestation impaired immune responses to infectious bovine rhinotrache itis virus (IBR) vaccine or an immunogenic protein (keyhole-limpet hem ocyanin [KLH]). Animals-19 BWB and 6 FH 1-year-old calves. Procedure-2 trials were performed. In each trial, 7 (trial 1) or 6 (trial 2) BWB calves and 3 FH calves were experimentally infested with P ovis and 3 BWB carves were maintained as uninfested controls. Animals were inocul ated with KLH and IBR virus vaccine twice; 3 BWB carves in each trial were treated with ivermectin. Serum antibody responses to KLH, IBR vir us, and P ovis were measured by use of ELISA. A lymphocyte transformat ion assay was used to determine nonspecific responses to 3 mitogens an d specific lymphocyte reactivity to P ovis antigen. Results-In each tr ial, 3 BWB and 3 FH calves developed clinical signs of psoroptic mange and mites could be recovered. Infested and control animals developed similar antibody titers to KLH and IBR virus. Antibodies to P ovis wer e detected early in some infested calves, and this was correlated with a marked cell-mediated immune response. Lymphocyte responsiveness to the 3 mitogens was not significantly different among groups. Conclusio ns-In these calves, infestation with P ovis induced a marked humoral a nd cell-mediated immune response. Immunosuppression was not evident.