Cutaneous hypersensitivity reactions against unfed tick larval extract of Rhipicephalus evertsi in South African Mutton Merino, Namaqua Afrikaner and Dorper sheep

Expression of cytokine genes at tick attachment and control sites of Namaqua Afrikaner, Dorper and South African Mutton Merino sheep

Cytokines are immune response components important in innate immunity and inflammatory response. They are harnessed as part of local immunological responses by animals to combat local infections and/or infestations. This study investigated expression of four selected cytokine genes, namely, interleukin 1 beta (IL-1β), chemokine C-C ligand 2 (CCL2), chemokine C-C ligand 26 (CCL26) and interleukin 8 (IL-8), at tick attachment and control sites in a South African indigenous sheep breed the Namaqua Afrikaner (NA) and two commercial breeds, the Dorper and South African Mutton Merino (SAMM). The NA was previously shown to be more resistant to infestation by ticks than the two commercial breeds. NA ewes expressed IL-1β more at tick attachment sites compared to Dorpers. The NA breed was also more likely to upregulate the expression of the CCL2, CCL26 and IL-8 genes at tick attachment sites compared to control sites than the other breeds. The results of this study gave an indication that cytokines are involved in immune responses to tick challenge and laid a foundation for further studies under controlled challenge conditions.