Sheep scab mite (Acari: Psoroptidae): General morphology and immunocytochemistry using serum from infested animals

The basic morphology of the digestive, reproductive, and nervous systems of the sheep scab mite, Psoroptes ovis Hering, was defined by light microscopy. An understanding of the structure of the digestive system of P. ovis is prerequisite to identification of target antigens in specific regions of the digestive tract using immunocytochemistry. Sera from a mite-infested animal and an animal with repeated mite infestations no longer able to maintain a population of P. ovis (acquired resistance) were used to determine antibody specificity to the mite digestive system, and these were compared with the sera from uninfested animals. Sera from naive animals with mite infestations and those animals with repeated infestations had antibodies that were specific against the digestive tract, whereas sera from uninfested control animals did not demonstrate any antibody specificity to mite antigens. Immunocytochemistry demonstrated that polyclonal antibodies to mite gut antigens were present in infested naive animals as well as in multiply infested animals, indicating that gut antigens have a possible role in host resistance.