# Secretory proteins of Cryptosporidium parvum

> **NIH NIH R21** · WASHINGTON UNIVERSITY · 2020 · $249,764

## Abstract

Summary
Cryptosporidium is a common causative agent of chronic diarrheal disease in
immunocompromised patients, such as those with HIV/AIDS, and in young children,
particularly in the developing world. The majority of human infections are caused by C.
parvum, which is often acquired from animals, and C. hominis, which is mainly
transmitted human-to-human. Cryptosporidium infection is primarily concentrated in the
small intestine, where the parasite resides within a specialized vacuole that sits atop an
intestinal epithelial cell, protruding into the lumen of the intestine. Although this vacuole
shows highly developed ultrastructural features, such as an actin-rich pedestal in the
host cell and a membranous feeder organelle within the parasite, very little is known
about the proteins that function at this host-pathogen interface.
 Progress in studying the biology of Cryptosporidium has been hampered by the lack
of small animal models and in vitro systems for long-term cultivation. Fortunately, the
latter barrier has recently been solved by the development of robust in vitro systems for
cultivation. In preliminary studies, we have shown that stem cell-derived cultures of
primary mouse Intestinal Epithelial Cells (mIECs) allow complete development and long-
term culture of C. parvum in vitro. In mIEC cultures, C. parvum undergoes both asexual
and sexual phases of development, culminating in production of oocysts. We have used
this system to develop a panel of monoclonal antibodies (mAb) that define novel
Cryptosporidium antigens expressed during intracellular development.
 In this discovery-focused project, we will explore several of these mAbs that
recognize antigens that localize to the feeder organelle in trophozoites or that are found
within apical secretory compartments. We will utilize these mAbs to immunoprecipitate
C. parvum antigens and perform mass spectrometry to identify the proteins they
recognize. We will leverage recent advances in CRISPR/Cas9 technology to epitope-
tag the genes encoding these antigens and generate transgenic parasite lines. Finally,
we will use these exemplary proteins for permissive biotin labeling to define the parasite
secretome and characterize proteins that are concentrated at the host-pathogen
interface. These exploratory studies will help define key C. parvum proteins that engage
host cell receptors during invasion or that interact with host cellular pathways during
intracellular development.

## Key facts

- **NIH application ID:** 9875646
- **Project number:** 1R21AI149309-01
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** L. David Sibley
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $249,764
- **Award type:** 1
- **Project period:** 2020-02-08 → 2022-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9875646

## Citation

> US National Institutes of Health, RePORTER application 9875646, Secretory proteins of Cryptosporidium parvum (1R21AI149309-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9875646. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*