The overall objective of this proposal is to study the host/pathogen interaction at mucosal surfaces and to[unreadable] develop prevention strategies that maximize protective mucosal immune responses to Cryptosporidium[unreadable] parvum (C. parvuni). We will develop and maintain a murine model for murine acquired immunodeficiency[unreadable] syndrome (MAIDS) which will be used to study the pathogenesis of C. parvum; a potential pathogen[unreadable] commonly associated with AIDS patients. To develop the MAIDS model, C57BL/6 female mice will be[unreadable] immunosuppressed by inoculation with LP-BM5; then challenged with C. parvum 3 months post-infection.[unreadable] Studies of experimentally induced cryptosporidiosis using this model, will serve as a relevant tool for[unreadable] evaluating various therapies for prevention of this opportunistic disease specifically in AIDS patients. Our[unreadable] previous studies have confirmed that mice infected with LP-BM5, develop persistent experimental[unreadable] cryptosporidiosis with high numbers of Oocysts shedding in the feces. Since the spread of AIDS is global and[unreadable] frequently associated with opportunistic infections including cryptosporidiosis, it is critical to control these[unreadable] diseases in AIDS patients to alleviate human suffering to minimize both soscial and economic impact on[unreadable] society. Our long range goal will be to develop effective prophylactic regimens for the control of[unreadable] Cryptosporidium infection, especially through nutritional, immunotherapeutic or chemotherapeutic[unreadable] interventions. As yet, no effective treatment for cryptosporidiosis has been reported. We will achieve the[unreadable] following specific aims during these studies: (a) elucidate the role of cellular gut immunity to C. parvum in[unreadable] this MAIDS model by determining the roles and phenotypic frequencies of intestinal intraepithelial (lEL's)[unreadable] and lamina propria (LPL) subpopulations (CD4+, CD8+, IgA+, IgG+ and IgM+) and cytokine (TNF-a, INF-y,[unreadable] IL-2, 4, 5 and 10) production post C. parvum challenge, (b) evalute the efficacy of Lactobacillus reuteri and[unreadable] acidophillus as probiotics for the control of cryptosporidiosis and (c) evalute the efficacy of probiotics and[unreadable] vaccines administered simultaneously for the control of cryptosporidiosis. Results obtained from these studies[unreadable] will be relevant in the development of new therapies for the control of cryptosporidiosis and other[unreadable] opportunistic diseases in immuncompromised individuals especially AIDS subjects.