# Identification and characterization of early encystation genes in the human parasite Entamoeba histolytica

> **NIH NIH R21** · CLEMSON UNIVERSITY · 2024 · $185,838

## Abstract

PROJECT SUMMARY
 The inability of Entamoeba histolytica to form infectious cysts in the laboratory setting has greatly hindered
investigation of this crucial stage in the infection and disease cycle of this human pathogen that causes
amoebic dysentery in ~100 million people each year worldwide. Instead, scientists have been forced to rely on
studies with the distantly related reptile pathogen Entamoeba invadens. The long-term goal of our research
program is to determine how E. histolytica adapts to different environments it encounters during infection and
the disease process. In particular, we are interested in how E. histolytica adapts to the environment of the large
intestine in order to colonize there and spread disease by formation and dissemination of infectious cysts. We
have now established a reproducible system for encystation and excystation of E. histolytica in culture. This
major technological advance enables us to pursue an understanding of how E. histolytica senses and
responds to environmental cues that signal conversion from motile trophozoite to infectious cyst and back. As
part of our long-term goal, the overall objective of this proposal is to identify and characterize genes
responsible for initiation of encystation. The rationale for the proposed project is that understanding how E.
histolytica senses and responds to its environment through encystation will lead to a better understanding of
how this pathogen can survive and thrive as it encounters very diverse environments during different stages of
its infectious cycle. We will pursue two specific aims: (1) identify encystation initiation genes using RNAseq;
and (2) screen an overexpression library for genes involved in initiation of encystation in E. histolytica.
Candidate genes identified through these two approaches will be validated through analysis of gene silenced
and gene overexpression strains. We will evaluate these strains for their ability to encyst, excyst, and establish
standard trophozoite growth as well as their responses to other stresses such as heat, oxidative, and
nitrosative stress to determine whether any of the candidate genes play a general stress response role. As part
of the proposed research, we will optimize our encystation protocol and determine other environmental signals
that trigger more rapid encystation. The complementary RNAseq and library screening approaches should
allow us to identify genes required for the earliest stages of encystation prior to chitin cell wall formation as well
as regulatory genes. The significance of this research is that we can now begin to understand the interplay of
environmental signals that regulate encystation and how these signals are acted upon by E. histolytica. This
research will have an important impact on the field in that for the first time the processes involved in stage
conversion can be fully studied directly in the human pathogen to provide a better understanding of how E.
histolytica can thrive during ...

## Key facts

- **NIH application ID:** 10880541
- **Project number:** 5R21AI175730-02
- **Recipient organization:** CLEMSON UNIVERSITY
- **Principal Investigator:** CHERYL Jean INGRAM-SMITH
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $185,838
- **Award type:** 5
- **Project period:** 2023-07-03 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10880541

## Citation

> US National Institutes of Health, RePORTER application 10880541, Identification and characterization of early encystation genes in the human parasite Entamoeba histolytica (5R21AI175730-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10880541. Licensed CC0.

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