Parasitology
Mucosal immunity to gastrointestinal nematode parasites
Huntley, JF and Smith, WD
Gastrointestinal roundworm parasites are a major cause of ill-health, poor weight gain, and economic loss to the ruminant industry in the UK and globally. The most important and widespread nematode parasite of sheep in Britain is Teladorsagia circumcincta , which infects the lining of the stomach. Control has largely relied on chemical drugs, although there is increasing concern of parasite resistance to these and of drug residues in food and the environment. Because of this, alternative methods for worm control are urgently sought. Natural immune responses are able to limit worm burdens in older animals, although the mechanism which elicits this immunity remains unclear. In particular, the role of eosinophils has been of considerable debate, and the function of these will be examined in vivo and in vitro . Immune responses may be directed towards retarding worm growth, reducing egg output, or through the rapid ejection of incoming larvae. The latter aspect will be investigated by utilising an in vitro challenge model, which will be augmented by in vivo studies examining the local responses in gastric lymph after challenge. Nutrition has been previously shown to have a major effect on the development of immunity to gastrointestinal nematodes, and sheep on high or low nutritional planes will provide further information on the immune mechanism. Finally, the effective stimulation of the gastric local immune system will be investigated using a newly developed intra-nasal microparticulate delivery system, as a prelude to the development of a vaccine.