X-ray structure of Fasciola hepatica Sigma class glutathione transferase 1 reveals a disulfide bond to support stability in gastro-intestinal environment

Sigma-Class Glutathione Transferases (GSTσ): A New Target with Potential for Helminth Control

Glutathione transferases (GSTs EC 2.5.1.18) are critical components of phase II metabolism, instrumental in xenobiotics' metabolism. Their primary function involves conjugating glutathione to both endogenous and exogenous toxic compounds, which increases their solubility and enables their ejection from cells. They also play a role in the transport of non-substrate compounds and immunomodulation, aiding in parasite establishment within its host. The cytosolic GST subfamily is the most abundant and diverse in helminths, and sigma-class GST (GSTσ) belongs to it. This review focuses on three key functions of GSTσ: serving as a detoxifying agent that provides drug resistance, functioning as an immune system modulator through its involvement in prostaglandins synthesis, and acting as a vaccine antigen.

Prevalence of fasciolosis (Liver flukes) infection in cattle in Zamfara, Nigeria: A slaughterhouse surveillance data utilizing postmortem examination

Bovine fasciolosis, caused by Fasciola gigantica (F. gigantica) and rarely F. hepatica, is an economically important disease affecting cattle in tropical Africa. The aims of this study were to determine a year prevalence of bovine fasciolosis and correlate determinants of infection in slaughtered cattle at the municipal abattoir in Zamfara, Nigeria. Fasciola gigantica was detected in 15% (1740/11,562) cattle slaughtered during a daily postmortem examination (PME) between November 2016 and October 2017. This approach demonstrated an increase risk of liver fluke infection in older cattle (p = 0.001, AOR = 1.476, 95% CI: 1.188-1.832) and during rainfall (p = 0.003, AOR = 1.604, 95% CI: 1.176-2.187). Liver condemnation had been significantly found in hot-dry season (p ≤0.001, AOR = 0.518, 95% CI: 0.417-0.643) and adult cattle (p = 0.003, AOR = 1.726, 95% CI: 0.586-0.899). This study is an account of bovine fasciolosis prevalence and infection dynamics in part of the northwest region of Nigeria, which provides preliminary information for further studies to guide the design of appropriate control steps to lower the impact of the disease and safeguard public health.

Characterization of a novel glycosylated glutathione transferase of Onchocerca ochengi, closest relative of the human river blindness parasite

Filarial nematodes possess glutathione transferases (GSTs), ubiquitous enzymes with the potential to detoxify xenobiotic and endogenous substrates, and modulate the host immune system, which may aid worm infection establishment, maintenance and survival in the host. Here we have identified and characterized a σ class glycosylated GST (OoGST1), from the cattle-infective filarial nematode Onchocerca ochengi, which is homologous (99% amino acid identity) with an immunodominant GST and potential vaccine candidate from the human parasite, O. volvulus, (OvGST1b). Onchocerca ochengi native GSTs were purified using a two-step affinity chromatography approach, resolved by 2D and 1D SDS-PAGE and subjected to enzymic deglycosylation revealing the existence of at least four glycoforms. A combination of lectin-blotting and mass spectrometry (MS) analyses of the released N-glycans indicated that OoGST1 contained mainly oligomannose Man₅GlcNAc₂ structure, but also hybrid- and larger oligommanose-type glycans in a lower proportion. Furthermore, purified OoGST1 showed prostaglandin synthase activity as confirmed by Liquid Chromatography (LC)/MS following a coupled-enzyme assay. This is only the second reported and characterized glycosylated GST and our study highlights its potential role in host-parasite interactions and use in the study of human onchocerciasis.