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

Award Number: R21AI175730
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 07/03/2023
PERIOD OF PERFORMANCE END DATE: 06/30/2026

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Identification and characterization of early encystation genes in the human parasite Entamoeba histolytica - 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 colonization and continue to propagate disease through spread of infectious cysts.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2025 ( Subtotal = $0 )
2025	2024	CLEMSON UNIVERSITY	201 SIKES HALL	CLEMSON	SC	29634	PICKENS	USA	Allergy and Infectious Diseases Research	000	2	6/24/2025	NON-COMPETING CONTINUATION	$0
														Subtotal = $0

Issue Date FY: 2024 ( Subtotal = $185,838 )
2024	2024	CLEMSON UNIVERSITY	201 SIKES HALL	CLEMSON	SC	29634	PICKENS	USA	Allergy and Infectious Diseases Research	000	2	7/5/2024	NON-COMPETING CONTINUATION	$185,838
														Subtotal = $185,838

Issue Date FY: 2023 ( Subtotal = $224,191 )
2023	2023	CLEMSON UNIVERSITY	201 SIKES HALL	CLEMSON	SC	29634	PICKENS	USA	Allergy and Infectious Diseases Research	000	1	7/3/2023	NEW	$224,191
														Subtotal = $224,191

Grand Total All Awards = $410,029

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

Award Number: R21AI175730

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 07/03/2023

PERIOD OF PERFORMANCE END DATE: 06/30/2026

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