# Identifying The Machinery That Translocates Toxoplasma Effectors Into The Host Cell

> **NIH NIH R01** · STANFORD UNIVERSITY · 2020 · $545,281

## Abstract

Abstract
 The major pathogenic species of Apicomplexa are all intracellular eukaryotic
parasites that generally reproduce within a parasitophorous vacuole (PV) in infected host
cells. This niche presents both an opportunity and a challenge to the parasites growing
within – on the one hand, they are sequestered from some of the immune defenses that
might detect their presence but at the same time, the PV membrane (PVM) presents a
physical barrier to the export of protein effectors necessary to modulate host functions to
the parasite's advantage.
 The phylum Apicomplexa includes many important human and animal pathogens
including Plasmodium sp., the cause of human malaria, Cryptosporidium parvum, the
cause of debilitating diarrheal disease, and Toxoplasma gondii, the cause of serious
neurologic disease in the developing fetus and those who are immunocompromised
through cancer (e.g., lymphoma), transplantation or infections, such as HIV-AIDS. We
have recently determined that Toxoplasma tachyzoites have the ability to dramatically
and specifically up-regulate expression of the human oncogene, c-Myc, using an effector
released from dense granules, called GRA16. Using a genetic screen for mutants
defective in c-Myc up-regulation, we have also recently identified the first components of
the Toxoplasma machinery that translocates GRA16 and other dense granule effectors
across the PVM. These novel proteins have been dubbed MYR1, MYR2 and MYR3. The
goal of the work proposed here is to identify the complete or near complete
machinery involved in translocation of effectors across the PVM, determine the
host responses that are dependent on this machinery, and elucidate the
importance of these effectors in Toxoplasma pathogenesis. We will do this through
using a combination of biochemical and genetic approaches.
 Through this work, we will both unveil an important and novel piece of cell
biology and identify crucial parasite components for eventual chemotherapeutic targeting
and amelioration of the disease caused by this and related parasites.

## Key facts

- **NIH application ID:** 9987493
- **Project number:** 5R01AI129529-03
- **Recipient organization:** STANFORD UNIVERSITY
- **Principal Investigator:** John C Boothroyd
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $545,281
- **Award type:** 5
- **Project period:** 2018-08-09 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9987493

## Citation

> US National Institutes of Health, RePORTER application 9987493, Identifying The Machinery That Translocates Toxoplasma Effectors Into The Host Cell (5R01AI129529-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9987493. Licensed CC0.

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