Stable expression of Escherichia coli beta-glucuronidase A (GusA) in Giardia lamblia: application to high-throughput drug susceptibility testing.
OBJECTIVE
In order to create a suitable model for high-throughput drug screening, a Giardia lamblia WB C6 strain expressing Escherichia coli glucuronidase A (GusA) was created and tested with respect to susceptibility to the anti-giardial drugs nitazoxanide and metronidazole.


METHODS
GusA, a well-established reporter gene in other systems, was cloned into the vector pPacVInteg allowing stable expression in G. lamblia under control of the promoter from the glutamate dehydrogenase (gdh) gene. The resulting transgenic strain was compared with the wild-type strain in a vitality assay, characterized with respect to susceptibility to nitazoxanide, metronidazole and -- as assessed in a 96-well plate format -- to a panel of 15 other compounds to be tested for anti-giardial activity.


RESULTS
GusA was stably expressed in G. lamblia. Using a simple glucuronidase assay protocol, drug efficacy tests yielded results similar to those from cell counting.


CONCLUSIONS
G. lamblia WB C6 GusA is a suitable tool for high-throughput anti-giardial drug screening.
Müller
Joachim
J
Institute of Parasitology, University of Berne, Berne, Switzerland. joachim.mueller@ipa.unibe.ch
Nillius
Dorothea
D
Hehl
Adrian
A
Hemphill
Andrew
A
Müller
Norbert
N
D000818:Animals; D000981:Antiprotozoal Agents / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics; D017930:Genes, Reporter; D016829:Giardia lamblia / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005966:Glucuronidase / Q000096:biosynthesis* / Q000235:genetics; D008795:Metronidazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D009574:Nitro Compounds; D004364:Pharmaceutical Preparations; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D013844:Thiazoles / Q000494:pharmacology
D000981:Antiprotozoal Agents; D029968:Escherichia coli Proteins; D009574:Nitro Compounds; D004364:Pharmaceutical Preparations; D011994:Recombinant Proteins; D013844:Thiazoles; D008795:Metronidazole; D005966:Glucuronidase; C041747:nitazoxanide