Developing In Vitro Culture Systems for Cryptosporidium

L. David Sibley at Washington University School of Medicine in the U.S. is developing a long-term in vitro intestinal epithelial culture system for the intracellular parasite Cryptosporidium, which causes severe diarrheal disease in both humans and animals, and is refractory to many anti-parasitic drugs. Currently, Cryptosporidium can only be grown in infected calves or in short-term in vitro cultures, which cannot be used for the high-throughput chemical screens needed to identify new drugs. In Phase I, they optimized the in vitro culture of isolated intestinal stem cells from human and mouse biopsies, and identified factors to control their differentiation into primary epithelial monolayers, which can better support the growth of intestinal pathogens. This led to around a five-fold increase in the rate of asexual replication of Cryptosporidium, which was enough to successfully test a chemical growth inhibitor. In Phase II, they will further improve culture conditions to support longer-term in vitro growth of Cryptosporidium, which will then be tested for stability and infectivity. They will also develop antibodies against specific developmental stages to help identify culture conditions that enable the parasite to undergo a complete life cycle, which will be valuable for culturing and screening efforts.