Toxoplasma gondii, a member of the Apicomplexa, is a ubiquitous parasite of mammals. The predilection of this protozoan for the central nervous system causing necrotizing encephalitis constitutes its major presentation in patients with HIV infection. Because it can be transmitted by food or water T. gondii is classified as a category B NIH priority pathogen. During initial infection the rapidly proliferating tachyzoite stage of T. gondii differentiates into the slowly replicating bradyzoite stage that remain latent within tissue cysts for the life of the host;however reactivation of this latent infection can result in disease such chorioretintiis or encephalitis. Several lines of evidence suggest that bradyzoite differentiation is stress mediated and that the cyst wall (a modified parasitophorous vacuole membrane) contains many stage specific proteins and glycoproteins. In the present proposal, studies will be focused on the characterization of the components of the cyst wall. The components of the cyst wall will be characterized using a combination of proteomic, immunologic and genetic approaches taking advantage of techniques we have developed for purification of the T. gondii cyst wall. We have already identified several cyst wall specific proteins that have mucin type domains. Other investigators have previously noted that o-glycosylation occurs in T. gondii and is probably involved in differentiation. We will, therefore, also examine the role of o-glycosylation and mucin type linkages in the development of the cyst wall using biochemical and genetic approaches. Overall these studies will both elucidate the composition of the cyst wall and the glycoproteome of T. gondii providing reagents and insights that should prove useful in understanding the biology and organization of this critical structure. Understanding this structure is important for the development of new strategies to eliminate latent infection and prevent reactivation toxoplasmosis.

Public Health Relevance

Toxoplasma gondii is a food and water borne pathogenic organism, an opportunistic infection in AIDS patients and a cause of congenital infection. The cyst wall is a key structure in the pathogenesis of this infection permitting transmission and reactivation. Investigations on the formation of this structure should help define new approaches to control of this pathogenic protozoan. Toxoplasma gondii is a parasite of humans that causes infections resulting in damage to the nervous system. This is due to its ability to form tissue cysts within host cells. The tissue cyst wall is critical for the survival of this organism and its ability to cause latent infection. Many studies, including those from our laboratory group, have suggested that glycoproteins are involved in this process and in the formation of the cyst wall. This proposal will characterize the composition of the cyst wall and its associated glycoproteins. .

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-AARR-K (02))
Program Officer
Mcgugan, Glen C
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Albert Einstein College of Medicine
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Weiss, Louis M; Coyle, Christina (2018) In memorium Herbert B. Tanowitz, MD, FIDSA, FACP, FRSTMH 6 September 1941 - 17 July 2018. Parasitol Res :
Tomita, Tadakimi; Ma, Yanfen; Weiss, Louis (2018) Characterization of a SRS13: a new cyst wall mucin-like domain containing protein. Parasitol Res :
Tu, Vincent; Yakubu, Rama; Weiss, Louis M (2018) Observations on bradyzoite biology. Microbes Infect 20:466-476
Yakubu, Rama R; Weiss, Louis M; Silmon de Monerri, Natalie C (2018) Post-translational modifications as key regulators of apicomplexan biology: insights from proteome-wide studies. Mol Microbiol 107:1-23
Tomita, Tadakimi; Sugi, Tatsuki; Yakubu, Rama et al. (2017) Making Home Sweet and Sturdy: Toxoplasma gondii ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity. MBio 8:
Murata, Yuho; Sugi, Tatsuki; Weiss, Louis M et al. (2017) Identification of compounds that suppress Toxoplasma gondii tachyzoites and bradyzoites. PLoS One 12:e0178203
Yakubu, Rama R; Silmon de Monerri, Natalie C; Nieves, Edward et al. (2017) Comparative Monomethylarginine Proteomics Suggests that Protein Arginine Methyltransferase 1 (PRMT1) is a Significant Contributor to Arginine Monomethylation in Toxoplasma gondii. Mol Cell Proteomics 16:567-580
Sugi, Tatsuki; Tu, Vincent; Ma, Yanfen et al. (2017) Toxoplasma gondii Requires Glycogen Phosphorylase for Balancing Amylopectin Storage and for Efficient Production of Brain Cysts. MBio 8:
McPhillie, Martin; Zhou, Ying; El Bissati, Kamal et al. (2016) New paradigms for understanding and step changes in treating active and chronic, persistent apicomplexan infections. Sci Rep 6:29179
Sugi, Tatsuki; Ma, Yan Fen; Tomita, Tadakimi et al. (2016) Toxoplasma gondii Cyclic AMP-Dependent Protein Kinase Subunit 3 Is Involved in the Switch from Tachyzoite to Bradyzoite Development. MBio 7:

Showing the most recent 10 out of 36 publications