Humoral and cell-mediated immune responses of beef and dairy cattle experimentally infested with Psoroptes ovis

To compare cellular and humoral immune responses of beef (Belgian White and Blue [BWB]) and dairy (Friesian-Holstein [FH]) cattle to Psoroptes ovis infestation and to determine whether P ovis infestation impaired immune responses to infectious bovine rhinotracheitis virus (IBR) vaccine or an immunogenic protein (keyhole-limpet hemocyanin [KLH]).

19 BWB and 6 FH 1-year-old calves.

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 calves were maintained as uninfested controls. Animals were inoculated with KLH and IBR virus vaccine twice; 3 BWB calves in each trial were treated with ivermectin. Serum antibody responses to KLH, IBR virus, and P ovis were measured by use of ELISA. A lymphocyte transformation assay was used to determine nonspecific responses to 3 mitogens and specific lymphocyte reactivity to P ovis antigen.

In each trial, 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 were 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.

In these calves, infestation with P ovis induced a marked humoral and cell-mediated immune response. Immunosuppression was not evident.