Abstract
Giardia lamblia is a causative agent of persistent diarrhoea widespread in regions with low hygienic standards. Laboratory research is based on cloned lines issuing from various patient isolates typed in the late 1980s and 90s using restriction analysis and serology. In the present study, we compared the well-characterized strain WBC6 with another clone of the parent WB isolate termed WBA1 and with a clone from another isolate, GS/M-83-H7, using shotgun mass spectrometry proteomics. We identified 398 proteins differentially expressed between the GS and both WB isolates and 97 proteins differentially expressed between the two WB isolates. We investigated the expression levels of the predominant variant-specific surface proteins (VSPs) in each clone and matched the previously described major VSPs of each strain to the corresponding open reading frame sequences identified by whole-genome sequencing efforts. Furthermore, since the original WB isolate comes from a patient treated with metronidazole, we compared the susceptibilities of the strains to nitro compounds, as well the expression levels of enzymes involved in nitro reduction and on the corresponding enzyme activities and found distinct differences between the three strains.
Highlights
Another extensively studied G. lamblia strain, namely clone GS/M-83-H7, representing an assemblage B genotype, originates from the human isolate GS obtained in Alaska and axenized by isolation of trophozoites from infected neonatal mice (Nash et al, 1985)
Since the original WB isolate comes from a patient treated with the nitroimidazole metronidazole, and since antigenic variation has been shown to be influenced by drug exposure (Müller et al, 2019), we compared the susceptibilities of the strains to nitro compounds and had a closer look on enzymes involved in nitro reduction and on the corresponding enzyme activities
Drug susceptibility of G. lamblia trophozoites of the strains C6, A1 and H7 was tested in 96-well plates inoculated with 103 trophozoites per well and MET, NTZ or ALB at various concentrations and incubated in an anaerobic growth chamber (85% N2, 10% H2, 5% CO2)
Summary
WBC6 trophozoites bearing non-TSA417-type VSPs appear during the process of excystation (Meng et al, 1993; Svärd et al, 1998) Another extensively studied G. lamblia strain, namely clone GS/M-83-H7, representing an assemblage B genotype, originates from the human isolate GS obtained in Alaska and axenized by isolation of trophozoites from infected neonatal mice (Nash et al, 1985). This clone expresses a major surface antigen, VSP H7, which is immuno-reactive to a specific, cytotoxic mAb (mAb G10/4). Since the original WB isolate comes from a patient treated with the nitroimidazole metronidazole, and since antigenic variation has been shown to be influenced by drug exposure (Müller et al, 2019), we compared the susceptibilities of the strains to nitro compounds and had a closer look on enzymes involved in nitro reduction and on the corresponding enzyme activities
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