Center for
Global Health

Scholar

Languages: English (fluent), German (native), French (basic), Spanish (basic)

Bio statement

Boris Striepen, PhD grew up in Ruhrort, Germany, where the rivers Rhine and Ruhr meet in an industrial area once dominated by coal and steel. He studied biology at the Universities of Bonn and Marburg, conducting early research on liver flukes in Bonn and Nagana in Burkina Faso. He earned his PhD summa cum laude for work on parasite biochemistry with Ralph Schwarz and completed postdoctoral training with David Roos at Penn, studying parasite cell biology. He launched his independent laboratory at the Center for Tropical and Emerging Global Diseases at the University of Georgia in 2000, where he became a Distinguished Research Professor, before joining the University of Pennsylvania faculty in 2017.

Dr. Striepen’s research focuses on the cell and molecular biology of apicomplexan parasites, with a current emphasis on Cryptosporidium, a major cause of diarrheal disease and mortality in young children worldwide. Once recognized primarily as an AIDS-defining opportunistic infection, Cryptosporidium is now known to account for nearly half of all U.S. waterborne outbreaks and to cause stunting and long-term developmental impacts in children in low-resource settings. Despite its importance, no effective treatment or vaccine exists.

His lab has pioneered genetic manipulation of Cryptosporidium and developed natural mouse models, opening the field to sophisticated mechanistic studies. Current projects explore three key areas:

1. How the parasite invades and manipulates intestinal epithelial cells.

2. How the sexual stages of its lifecycle unfold.

3. How the host immune system recognizes and restricts infection, and how immunity develops with age.

The lab uses a broad range of modern tools including single-cell sequencing, live-cell and super-resolution microscopy, cryo-electron tomography, genetic engineering, organoids, and animal models. In addition to advancing fundamental biology, the team works with academic and industry collaborators to develop new drugs and vaccines against cryptosporidiosis.

Beyond research, Dr. Striepen is deeply committed to education and training. He has taught undergraduate and graduate courses, directed NIH training grants in parasitology, and served as faculty and director of the Biology of Parasitism summer research course at the Marine Biology Laboratory in Woods Hole, MA.

Recent global health projects

1. Cryptosporiosis — A new genetic handle on an important diseases​10.5% of global child mortality is due to diarrheal disease. Comprehensive epidemiology at the global scale recently revealed Cryptosporidium to be the most important diarrheal pathogen in small children after Rotavirus. Recently, we have developed robust molecular genetics for this important pathogen. Currently we lack effective treatment. We collaborate with several groups in academia and industry to change that. Cryptosporidium has a highly stripped down metabolism and steals most of the metabolites it needs from the host. It also interacts with the bacterial flora of the intestine and has acquired the genes for numerous bacterial enzymes by horizontal gene transfer. We use rigorous genetics to unravel this complex metabolism and to evaluate targets for treatment.
2. Host parasite interaction. Infants are highly susceptible to cryptosporidiosis. However, under constant exposure, children older that two rarely show infection and disease. Most likely they are protected by immunity. The mechanisms that govern host immunity and parasite immune evasion remain largely to be discovered. We have isolate a 'wild' mouse Crytposporidium and have developed a natural mouse model that results in self-limiting infection and protection in immunocompetent mice. We are using this new model to understand the immunology of Cryptosporidium infection and the important role that the microbiome and nutritional state of the host play. We are currently exploring ways to broaden our studies to involve clinical colleagues to contrast findings in the laboratory with those from patients in relevant settings.

Selected publications

Shaw, S., Li, X., Yasur, D., Zhou, T., Buenconsejo, G., Anderson, T.A., and Striepen, B. (2025) Genetic crosses reveal genomic loci responsible for virulence in Cryptosporidium parvum infection. Cell Reports 44:116315.

Walzer, K., Tandel, J., Byerly, J. H., Daniels, A.M., Gullicksrud, J. A., Whelan, E. C., Carro, S.D., Krespan, E., Beiting, D.P., and Striepen, B. (2024) Transcriptional control of the Cryptosporidium lifecycle. Nature 630: 174-180.

Shaw, S., Cohn, I. S., Baptista, R. P., Melillo, B., Agyabeng-Dadzie, F., Kissinger, J. C., and Striepen, B. (2024) Genetic crosses within and between species of Cryptosporidium. Proc. Natl. Acad. Sci. U.S.A. 121: e2313210120.

Gilbert, I., Vinayak, S., Striepen, B., Ujjini, M., Khalil, I.A., Van Voorhis, W.C. and the CTAG (2023) Safe and effective treatments are needed for cryptosporidiosis, a truly neglected tropical disease. BMJ Global Health 8: e012540.

Guérin, A., Strelau,K., Barylyuk, K., Berry, L., Wallbank, B., Crook, O.M., Lilley, K.S., Waller, R.F., and Striepen, B. (2023) Cryptosporidium uses multiple distinct secretory organelles to interact with and modify its host cell. Cell Host & Microbe 12:650-664.

English, E.D., Guerin, A, Tandel, J. and Striepen, B. (2022) Live imaging of the Cryptosporidium parvum lifecycle reveals direct development of male and female gametes from type I meronts. PLoS Biology 20: e3001604.

Dumaine, J.E., Sateriale, A., Gibson, A.R., Redy, A., Gullicksrud, J.A., Hunter, E., and Striepen, B. (2021) The enteric pathogen Cryptosporidium parvum exports proteins into the cytosol of the infected host cell. eLife. e70451.

Guérin, A., Roy, N.H., Kugler, E.M., Berry, L., Burkhardt, J.K., Shin, J.-B., and Striepen, B. (2021) A screen for Cryptosporidium rhoptry proteins identifies ROP1 as an effector targeting the host cytoskeletal modulator LMO7. Cell Host & Microbe 29: 1-14.

Sateriale, A., Gullicksrud, J.A., Engiles, J.B., McLeod, B., Kugler, E.M., Henao-Mejia, J., Zhou, T., Ring, A.M., Brodsky, I.E., J.C. Hunter, C.A., and Striepen, B. (2021) The intestinal parasite Cryptosporidium is controlled by an enterocyte intrinsic inflammasome that depends on NLRP6. Proc. Natl. Acad. Sci. U.S.A. 118: e2007807118.

Guérin, A., Roy, N.H., Kugler, E.M., Berry, L., Burkhardt, J.K., Shin, J.-B., and Striepen, B. (2021) A screen for
Cryptosporidium rhoptry proteins identifies ROP1 as an effector targeting the host cytoskeletal modulator LMO7. Cell
Host & Microbe 29: 1-14.

Guérin, A., and Striepen, B. (2020) The Biology of the intestinal intracellular parasite Cryptosporidium. Cell Host &
Microbe 28: 509-515.

Pawlowic, M., Somepalli, M., Sateriale, A., Herbert, G.T. Gibson, A.R., Cuny, G., Hedstrom, L., and Striepen, B. (2019)
Genetic ablation of purine salvage in Cryptosporidium parvum reveals nucleotide uptake from the host cell. Proc. Natl.
Acad. Sci. U.S.A. 116: 21160-21165.

Last Updated: 07 October 2025