Submitted to: American Association of Veterinary Parasitologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/16/1999
Publication Date: N/A
Citation: Gasbarre, L.C. 1999. Immunity to gastrointestinal (gi) parasites: the journey from mice to cattle [abstract]. American Association of Veterinary Parasitologists Proceedings.
Technical Abstract: In the last few years there has been a tremendous increase in our understanding of how the immune system functions, and of the mechanisms of immunity to GI parasites in rodent host-parasite models. In spite of these advances, there are no practical means by which host immunity can be used to control GI parasite; leading to questions concerning the accuracy of rodent model systems in identifying immune effector mechanisms across mammalian species. We will examine two important GI parasites of cattle, Cryptosporidium parvum (Cp) and Ostertagia ostertagi (Oo), to see how well studies in mouse models reflect the situation in cattle. Studies of Cp in mice indicate that the induction of gamma- Interferon (g-IFN) is central to cure from infection; and a number of means to induce such responses have been tested. In cattle, g-IFN also seems to be important, however the means used to induce g-IFN responses in the gut of neonatal mice appear to be less effective in neonatal calves. The biology of Oo infections points out a very important facet of the adaptation of parasites to their hosts. Model systems indicate that immunity to GI nematodes is predicated on the elicitation of IL-4 and IL-13 gene expression, but the host does not become immune. This appears to be a result of the ability of Oo to escape the normally effective responses driven by IL-4/IL-I3. Instead the parasite may use the stereotypic response to protect itself from other less noticeable, but more effective, immune mechanisms. The most economically important parasites are those that have developed means to evade the highly effective polarized immune responses seen in mice. Care should be taken when extrapolating results from these model systems to agriculturally important species.