doi:10.1038/nindia.2012.186 Published online 19 December 2012
Researchers have discovered a new class of glutathione transferase (GST) enzymes in Fasiola gigantica, a tropical liver fluke that causes fasiolosis in grazing animals and humans in Asian and African countries. GSTs play vital role in detoxifying foreign chemicals and modulating immune response in all animals, including the liver fluke.
This new class of GSTs found in the tropical liver fluke could be exploited to develop a novel vaccine to combat fasiolosis.
The concern is that liver flukes have grown resistant to triclabendazole (TCBZ), the drug of choice against fasiolosis. Although no commercially available vaccine against liver fluke is available, clinical trials targeting GSTs in Schistosome sp., a parasitic worm, have shown encouraging results.
In the hope of finding similar enzyme target in tropical liver fluke, the researchers prepared water-soluble cell extract using a virulent strain of tropical liver fluke. Using this sample, they identified Sigma class GST, a new class of GST enzymes in the tropical liver fluke.
This previously undiscovered Sigma class GST in F. gigantica appeared highly similar to the recently discovered Sigma class GST of F. hepatica, the temperate liver fluke, except four amino acid variations. This minor variation between the two Sigma class GST sequences suggests that both liver flukes will trigger very similar immunological responses during host-parasite interactions.
This shows the potential of Sigma class GST to produce vaccines that could target both temperate and tropical liver flukes. The researchers say that the similarities between Fasiola and Schistosoma Sigma class GST raise the possibility of producing a single cross-protecting vaccine against these parasitic worms.
The authors of this work are from: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Faculty of Veterinary Science and School of Biological Sciences, University of Liverpool, School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland, and Liverpool School of Tropical Medicine, U.K., Tamil Nadu Veterinary and Animal Sciences University, Chennai, and Aligarh Muslim University, India.