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Cryptosporidium Volunteer Study. Laboratory staff: Blue Johnson Han Dang Constance Wang Michael Coletta Sonia Baker Danny Nguyen Marilyn Marshall. Investigators: Cynthia Chappell, PhD Pablo Okhuysen, MD Herbert DuPont, MD. UCRC Nursing staff: Madeline Jewell, RN Julie Rice, RN
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Cryptosporidium Volunteer Study Laboratory staff: Blue Johnson Han Dang Constance Wang Michael Coletta Sonia Baker Danny Nguyen Marilyn Marshall Investigators: Cynthia Chappell, PhD Pablo Okhuysen, MD Herbert DuPont, MD UCRC Nursing staff: Madeline Jewell, RN Julie Rice, RN Nai-Hui Chiu , RN Isolates: Charles Sterling, PhD (Iowa) Karen Snowden, DVM (TAMU) Joseph Crabb, PhD (UCP)
Preparation of Challenge Dose Passaged in calf and purified Shipped to Houston in potassium dichromate Tested for adventitious agents (viruses, bacteria) Adjusted for appropriate number Delivered via gelatin capsule
ID50 in Antibody-negative Volunteers Ref of method: Reed and Muench, Am J Hyg 27:493, 1938
Dose Response Curves in Neonatal Mice
Infectivity in Human vs Neonatal Mice and HCT-8 Cells r2 = 0.933 r2 = 0.548
Conclusions • C. parvum oocysts vary widely in infectivity, even within the same genotype • HCT-8, a human enterocyte cell line, shows a higher correlation with human genotype 2 infectivity than does the neonatal mouse model. • HCT-8 also has the advantage of supporting genotype 1 replication.