Cryptosporidium Volunteer Study

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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)
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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
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ID50 in Antibody-negative Volunteers
Ref of method Reed and Muench, Am J Hyg 27493,
1938
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Clinical Outcome in Volunteers
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Dose Response Curves in Neonatal Mice
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Cryptosporidium Infection in HCT-8 Cells
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Infectivity in Human vs Neonatal Mice and HCT-8
Cells
r2 0.933
r2 0.548
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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.