Detection of cryptosporidium parvum by recombinant antibodies

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The protozoan parasite Cryptosporidium parvum is an important and widely distributed pathogen causing the enteric illness cryptosporidiosis. When infective C. parvum oocysts are swallowed, they excyst into sporozoites which become attached to intestinal epithelial cells. Here, the parasites multiply by various sexual and asexual stages, and oocysts are formed and passed with feces. Cryptosporidiosis is an acute but self-limiting illness in immuno-competent patients who typically present with diarrhea, nausea, vomiting, abdominal cramps and fever. Immuno-compromised persons experience a more severe and chronic infection, which may lead to death. There is currently no known protective vaccine or treatment for cryptosporidiosis. Water is a common vehicle for transmission of Cryptosporidium spp. Routes of transmission for human cryptosporidiosis include zoonotic, environmental and person-to-person contact via the fecal-oral route. For the water industry, low-level contamination should at least indicate the need for caution and enhanced control measures. Assessing the threat of waterborne Cryptosporidium is complicated by the dynamic life cycle of the parasite itself. Even if oocysts are found in drinking water, it is difficult to determine their source, viability and infectivity towards humans. To implement an action level for Cryptosporidium, sensitive methods for detection and quantitation of infective oocysts in drinking water must be researched and brought into common use. The long term objective of our Cryptosporidium research program is to develop improved methods for the effective detection of Cryptosporidium. In the short term (5-year funding period of this grant), we plan to focus on the development, assessment and improvement of recombinant antibodies (rAbs) for detecting the presence as well as the viability and infectivity of Cryptosporidium oocysts. We will do this by selecting for, and improving the binding properties of, rAbs against several oocyst and sporozoite surface proteins. We will then test the ability of the rAbs to detect the presence of infective and viable C. parvum oocysts in water samples. Effective and early detection of C. parvum can ultimately lead to the safeguarding of drinking water supplies.