# MECHANISMS OF E HISTOLYTICA ADHERENCE AND CYTOLYSIS

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 1989 · $192,276

## Abstract

The enteric protozoan Entamoeba histolytica causes disease
worldwide; parasite adherence and cytolytic events are crucial in
pathogenesis of invasive amebiasis.  Our objective is to define the
biochemical and molecular basis of amebic adherence and cytolytic
activities with application for development of a vaccine protective
against invasive amebiasis.  Parasite in vitro adherence, mediated
by a 170 Kdalton galactose/N-acetyl-D-galactosamine (Gal/GalNAc)
inhibitable surface lectin, initiates cytolysis of target cells.
Amebic cytolytic activity is stimulated by phorbol esters requires
amebic phospholipase A activity, an acid pH in endocytic vesicles-
lethal increase in target cell free intracellular Ca++ ((CA++)).
Candidates for a vaccine include the Gal/GalNAc lectin, cytolytic
parasite proteins, and major amebic antigens.  The specific aims
and methods of this proposal are: (1) to determine the in vivo
vaccine efficacy of purified Gal/GalNAc lectin in gerbil! models
of intestinal colonization and liver abscess; (2) to describe
protein kinase C (PKC) mediated regulation and stimulation of
cytolytic activity by determining pborbol esterinduced PKC cytosol-
membrane translocation and protein substrate phosphorylation; (3)
to characterize the cytotoxicity of the purified Gal/GalNAc lectin,
including lectin binding, effects on (Ca++), and uptake by the
target cell; (4) to determine the mechanism of target cell death,
including the role of Ca++ DNA degradation, phorpholipases,
proteases, and membrane "pores"; 5) to characterize amebic proteins
which participate in cytolytic activity (Cyt proteins) by
mutagenesis and selection of histolytica clones deficient in
cytolytic activity (Cyt-), comparison of Cyt- to Cyt+ amoebae by
two-dimensional gel electrophoresis and immunoblotting to identify
Cyt+ proteins altered in Cyt- mutants, partial amino acid
sequencing of such proteins providing information for synthesis of
oligonucleotide probes to screen E. bistolytica Cyt+ cDNA and
genomic libraries, and determining function(s) of Cyt proteins by
sequence analysis of full length DNA cloned from the genomic
library and effects of anti-Cyt antibodies on amebic cytolytic
activity; and (6) to determine the immunogenicity and vaccine
efficacy of Cyt proteins and the major amebic antigens recognized
by human immune sera by immunization of gerbils with purified B-
galactosidase fusion proteins.  This research will expand our
knowledge of E.     histolytica and contribute to eliminating it
as a cause of human disease.

## Key facts

- **NIH application ID:** 3128238
- **Project number:** 2R01AI018841-07A1
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **SAM.gov UEI:** JJG6HU8PA4S5
- **Principal Investigator:** Jonathan Ravdin
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1989
- **Award amount:** $192,276
- **Award type:** 2
- **Project period:** 1982-07-01 → 1990-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3128238

## Citation

> US National Institutes of Health, RePORTER application 3128238, MECHANISMS OF E HISTOLYTICA ADHERENCE AND CYTOLYSIS (2R01AI018841-07A1). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3128238. Licensed CC0.

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