The identification of potential new drug targets is important for the treatment of T. gondii. The PI has characterized cystein proteinase activity in tachyzoites of T. gondii, cloned a Toxoplasma cysteine proteinase gene and shown that potent new cystein proteinase inhibitors inhibit intracellular multiplication. The applicant will have access to the newest generation of cystein proteinase inhibitors as well as cores for expression of recombinant proteinases, computer modeling crystallography. They will test the hypothesis that cysteine proteinases play a critical role in the pathogenesis of toxoplasmosis and may be a novel drug target. Their first specific aim is to characterize the cysteine proteinases of T. gondii by expressing the recombinant enzyme comparing the recombinant and native enzymes identifying other potential cysteine proteinase genes and their gene products and producing specific antibody to the proteinase.
The second aim i s to evaluate the role of the proteinases in the pathogenesis of toxoplasmosis by localizing the proteinase within the parasite, evaluating the release of cystine proteinases and their role in peptide degradation and evaluating the effect of specific cysteine proteinase inhibitors on parasite survival and identify their site of action.
The third aim i s to determine the effect of blocking cysteine proteinases in vivo in mouse models of toxoplasmosis by blocking acute infection in mice with specific inhibitors and comparing the outcome of infection with parasites lacking the cys proteinase gene.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI041903-02
Application #
2887574
Study Section
AIDS and Related Research Study Section 5 (ARRE)
Program Officer
Laughon, Barbara E
Project Start
1998-08-01
Project End
2002-05-31
Budget Start
1999-06-01
Budget End
2000-05-31
Support Year
2
Fiscal Year
1999
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Pathology
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Huang, Robert; Que, Xuchu; Hirata, Ken et al. (2009) The cathepsin L of Toxoplasma gondii (TgCPL) and its endogenous macromolecular inhibitor, toxostatin. Mol Biochem Parasitol 164:86-94
Que, Xuchu; Ngo, Huan; Lawton, Jeffrey et al. (2002) The cathepsin B of Toxoplasma gondii, toxopain-1, is critical for parasite invasion and rhoptry protein processing. J Biol Chem 277:25791-7
Denney, C F; Eckmann, L; Reed, S L (1999) Chemokine secretion of human cells in response to Toxoplasma gondii infection. Infect Immun 67:1547-52