MECHANISM BASED DRUG SELECTION AND DESIGN FOR T GONDII

  • Ullman, Buddy, (PI)
  • Luft, Benjamin (PI)
  • Roos, David S. (PI)
  • Joiner, Keith (PI)

Project: Research project

Description

Alternative forms of therapy are needed to treat acute toxoplasma gondii
encephalitis and to prevent relapses after resolution of the event.
Protein synthesis inhibitors of the macrolide and lincosamide class have
activity against acute T. gondii infections in murine models and early
clinical data suggests that these drugs may be efficacious. The compounds
show limited and variable activity against T. gondii in vitro, however, and
the mechanism of action remains undefined. Efficacy of protein synthesis
inhibitors against T. gondii requires that the compounds reach the
ribosomal target site within the intracellular parasite, bind to the
parasite ribosome, and inhibit protein synthesis. No data is available on
these events with T. gondii, precluding a systematic approach to drug
development. This proposal outlines rational strategy for the selection, testing and
design of protein synthesis inhibitors with activity against Toxoplasma
gondii, both for the actively replicating tachyzoite stage present in acute
infections and for the more dormant bradyzoite stage responsible for
relapse. Drugs suggest to have in vivo activity will be assessed for
uptake into extracellular and intracellular parasites, for inhibition of
protein synthesis in T. gondii in vitro and for interaction with T. gondii
ribosomes. Development of and in vitro method for production of cysts is
necessary to carry out these experiments with bradyzoites, and forms an
important part of the proposal. Initial experiments will be done with
currently available protein synthesis inhibitors, concentrating on selected
agents in the macrolide and lincosamide class. Subsequently, new compounds
will be selected and/or designed, in conjunction with the Macrolide
Discovery Core, based on structure-activity relationships defined in the
initial experiments. The second major aim is the identification and molecular characterization
of selected new therapeutic targets in T. gondii. This parasite must
salvage purine from the host cell. Tachyzoite and later bradyzoite
components involved in purine nucleoside transport will be characterized as
possible targets for therapeutic intervention. Characterization of
bradyzoite-derived cDNA libraries and bradyzoite-specific clones will allow
the molecular characterization and analysis of these and other new pathways
for parasiticidal drug development. Four projects and three core components are included. These component
parts are extensively interwoven with one another to rapidly and
efficiently accomplish the scientific goals set forth above.
StatusFinished
Effective start/end date9/1/918/31/99

Funding

  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health

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Hypoxanthine Phosphoribosyltransferase
Toxoplasma
Hypoxanthine
Proteins
Guanine
Molecular Models
Toxoplasmosis
Enzymes
Parasites
Escherichia coli
Databases
Organized Financing
Insertional Mutagenesis
Drug Design
hypoxanthine-guanine-xanthine phosphoribosyltransferase
Drug Discovery
Substrate Specificity
Site-Directed Mutagenesis
Recombinant Proteins
Biochemistry

ASJC

  • Medicine(all)
  • Immunology and Microbiology(all)