Toxoplasma gondii is a major opportunistic pathogen that causes severe disease (toxoplasmosis) in congenitally infected babies and immunocompromised individuals such as those suffering from AIDS. Because it is an obligate intracellular parasite, T. gondii must invade a host cell to survive and replicate. Furthermore, T. gondii invasion is directly responsible for the pathology of toxoplasmosis, since subsequent intracellular replication and egress destroys the infected host cell. Thus, a better understanding of T. gondii invasion could lead to the development of treatments for toxoplasmosis based on inhibition of invasion. Our recent studies indicate that parasite secretion of organelles called micronemes is essential for T. gondii invasion. Thus, the long-term goal of this proposal is to elucidate the function of micronemal proteins in an effort to identify new potential targets for treating toxoplasmosis. We will begin by focusing on MIC2 because our studies suggest that this micronemal protein likely functions as an important adhesin for T. gondii invasion.
Specific Aim I will be to use RNA antisense inhibition to measure the importance of MIC2 for T. gondii invasion of host cells and gliding motility.
Specific Aim II will be to use deletion and site-specific mutagenesis to identify the sites on MIC2 that mediate cell adhesion.
Specific Aim III will be to identify host cell receptors recognized by MIC2. These studies will directly lead to a better understanding of the molecular mechanisms underlying T. gondii invasion of host cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI046675-05
Application #
6747300
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Program Officer
Rogers, Martin J
Project Start
2000-06-01
Project End
2005-05-31
Budget Start
2004-06-01
Budget End
2005-05-31
Support Year
5
Fiscal Year
2004
Total Cost
$286,125
Indirect Cost
Name
Johns Hopkins University
Department
Microbiology/Immun/Virology
Type
Schools of Public Health
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Di Cristina, Manlio; Carruthers, Vern B (2018) New and emerging uses of CRISPR/Cas9 to genetically manipulate apicomplexan parasites. Parasitology 145:1119-1126
Schultz, Aric J; Carruthers, Vern B (2018) Toxoplasma gondii LCAT Primarily Contributes to Tachyzoite Egress. mSphere 3:
Lunghi, Matteo; Spano, Furio; Magini, Alessandro et al. (2016) Alternative splicing mechanisms orchestrating post-transcriptional gene expression: intron retention and the intron-rich genome of apicomplexan parasites. Curr Genet 62:31-8
Sidik, Saima M; Huet, Diego; Ganesan, Suresh M et al. (2016) A Genome-wide CRISPR Screen in Toxoplasma Identifies Essential Apicomplexan Genes. Cell 166:1423-1435.e12
Bullen, Hayley E; Jia, Yonggen; Yamaryo-Botté, Yoshiki et al. (2016) Phosphatidic Acid-Mediated Signaling Regulates Microneme Secretion in Toxoplasma. Cell Host Microbe 19:349-60
Huynh, My-Hang; Carruthers, Vern B (2016) A Toxoplasma gondii Ortholog of Plasmodium GAMA Contributes to Parasite Attachment and Cell Invasion. mSphere 1:
Pszenny, Viviana; Ehrenman, Karen; Romano, Julia D et al. (2016) A Lipolytic Lecithin:Cholesterol Acyltransferase Secreted by Toxoplasma Facilitates Parasite Replication and Egress. J Biol Chem 291:3725-46
Huynh, My-Hang; Liu, Bing; Henry, Maud et al. (2015) Structural basis of Toxoplasma gondii MIC2-associated protein interaction with MIC2. J Biol Chem 290:1432-41
Carruthers, Vern B (2015) Parasites and their heterophagic appetite for disease. PLoS Pathog 11:e1004803
Roiko, Marijo S; Svezhova, Nadezhda; Carruthers, Vern B (2014) Acidification Activates Toxoplasma gondii Motility and Egress by Enhancing Protein Secretion and Cytolytic Activity. PLoS Pathog 10:e1004488

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