# TOXOPLASMA GONDII: ANTIGENIC CHARACTERIZATION & IMMUNITY

> **NIH NIH R01** · DARTMOUTH COLLEGE · 1989 · $150,333

## Abstract

Our objective is to understand the major stage specific antigens of
Toxoplasma gondii and their role in immunity.  The three stages to be
investigated are the tachyzoite (asexual invasive stage), bradyzoite
(chronic encysted stage) and the oocyst/sporozoite (feline excreted
postgametogenesis stage).  The first specific aim is to determine which
antigens of the tachyzoite elicit a humoral immune response.  Parasiticidal
monoclonal antibodies generated against tachyzoite antigens will be used to
purify antigens critical to protective humoral immunity and to select
monoclonal antibody resistant mutants.  Purified antigens will be used to
screen for congenital toxoplasmosis.  Minor antigenic differences among
different tachyzoite strains will be identified and their importance in
strain specific immunity will be assessed.  We will investigate by
molecular cloning the surface antigens of T. gondii that elicit a host
parasiticidal response.  These studies will explore the potential of
synthetic peptides representing these antigens in eliciting immunity to
toxoplasmosis.  In the absence of adequate cell mediated immunity
toxoplasmosis is a serious infection of immunosuppressed individuals,
especially victims of AIDS.  The tachyzoite antigens that elicit the
cellular response may differ from those that stimulate humoral immunity.
Specific antigens that induce in vitro T-cell proliferation will be
identified and the response frequency determined by limit dilution
analysis.  Proliferating lymphocytes will be assayed for cytotoxic
ability.  Supernatant from antigen primed T-cell cultures will be assayed
for parasite growth inhibitory factors such as gamma interferon or possibly
antigen specific lymphokines.  The third aim is to examine the stage
specific antigens of the bradyzoite.  These antigens will be identified and
characterized with monoclonal antibodies.  Once characterized these
antigens may be useful in evaluating the duration of infection in high risk
individuals such as pregnant women.  Parasite transformation from
tachyzoite to bradyzoite will be studied in vitro using a monoclonal
antibody model.  The fourth specific aim is to determine if stage specific
antigens elicit an IgA immune response.  IgA antibody in toxoplasmosis has
only been studied in a cursory manner.  The in vivo IgA antibody response
in serum and CSF to parasite antigens will be determined.  The secretory
IgA response in cats to stage specific parasite antigens will be evaluated
and the ability of purified antigens to elicit a protective response
assessed.

## Key facts

- **NIH application ID:** 3128944
- **Project number:** 5R01AI019613-07
- **Recipient organization:** DARTMOUTH COLLEGE
- **SAM.gov UEI:** EB8ASJBCFER9
- **Principal Investigator:** LLOYD H KASPER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1989
- **Award amount:** $150,333
- **Award type:** 5
- **Project period:** 1983-01-01 → 1990-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3128944

## Citation

> US National Institutes of Health, RePORTER application 3128944, TOXOPLASMA GONDII: ANTIGENIC CHARACTERIZATION & IMMUNITY (5R01AI019613-07). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3128944. Licensed CC0.

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