Parasitology
Host responses to sheep scab
Huntley, JF and Jones, D
This project seeks to understand the mechanisms of immunity to the sheep scab mite, Psoroptes ovis, with a view to develop effective vaccines based on sound scientific rationale. Sheep scab is a ubiquitous problem and is often present as a chronic sub-clinical condition. However, even the latter is sufficient to significantly compromise performance. The disease is characterised by a yellow scab on the skin surface, and is accompanied by restlessness, scratching, wool-loss, bleeding wounds and loss of condition. In particular, the disease appears to cause considerable distress, irritation and/or pain and is, therefore, of major welfare concern. Since the banning, but subsequent restricted, use of organophosphate dipping, the prevalence of this disease has escalated to become endemic in all areas of the UK. Control for sheep scab has relied almost exclusively on chemical drugs, but there is now increasing concern over their use due to the emergence and spread of parasite resistance, and to toxicity and environmental issues. Because of this, alternative methods of control for mite infection are urgently sought. Studies have shown that the primary lesion is due to an intense local inflammatory cell response indicative of a hypersensitivity reaction. This project will analyse these reactions further in order to identify those parasite factors, particularly allergens, responsible. These allergens are likely to be prime vaccine candidates, and further studies will evaluate whether they can be used in a vaccine strategy to control sheep scab.