Use of Toxoplasma gondii expressing beta-galactosidase for colorimetric assessment of drug activity in vitro

Antimicrob Agents Chemother. 1997 Sep;41(9):1849-53. doi: 10.1128/AAC.41.9.1849.

Abstract

A microtiter assay for drug evaluation has been developed with a strain of Toxoplasma gondii that expresses bacterial beta-galactosidase. By using chlorophenol red-beta-D-galactopyranoside (CPRG) as the substrate for beta-galactosidase, the efficacy of a drug against the parasite can be determined with a colorimetric readout. Drugs known to have activity against T. gondii (specifically, pyrimethamine, sulfadiazine, atovaquone, and clindamycin) were tested, and efficacies were determined by CPRG cleavage. The 50% inhibitory concentrations determined by the CPRG-based colorimetric assay were similar to those determined by the traditional radiolabelled uracil incorporation assay. Since CPRG is nontoxic to the parasite, viable drug-treated parasites can be obtained at the conclusion of the assay for further evaluation if desired. This assay provides a high-throughput and nonradioactive alternative for the identification of anti-T. gondii compounds.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Colorimetry
  • Enzyme Stability
  • Humans
  • Toxoplasma / drug effects*
  • Toxoplasma / enzymology*
  • Toxoplasma / genetics
  • Tritium
  • Uracil / metabolism
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism*

Substances

  • Bacterial Proteins
  • Tritium
  • Uracil
  • beta-Galactosidase