Proteomics and in Silico Approaches To Extend Understanding of the Glutathione Transferase Superfamily of the Tropical Liver Fluke Fasciola gigantica

Abstract

Fasciolosis is an important foodborne, zoonotic disease of livestock and humans, with global annual health and economic losses estimated at several billion US$. Fasciola hepatica is the major species in temperate regions, while F. gigantica dominates in the tropics. In the absence of commercially available vaccines to control fasciolosis, increasing reports of resistance to current chemotherapeutic strategies and the spread of fasciolosis into new areas, new functional genomics approaches are being used to identify potential new drug targets and vaccine candidates. The glutathione transferase (GST) superfamily is both a candidate drug and vaccine target. This study reports the identification of a putatively novel Sigma class GST, present in a water-soluble cytosol extract from the tropical liver fluke F. gigantica. The GST was cloned and expressed as an enzymically active recombinant protein. This GST shares a greater identity with the human schistosomiasis GST vaccine currently at Phase II clinical trials than previously discovered F. gigantica GSTs, stimulating interest in its immuno-protective properties. In addition, in silico analysis of the GST superfamily of both F. gigantica and F. hepatica has revealed an additional Mu class GST, Omega class GSTs, and for the first time, a Zeta class member.

A prospective view of animal and human Fasciolosis

“…These recent technological developments have allowed more in depth analysis of these two Fasciola species to further our understanding of fluke biology and how they infect and persist within their hosts. Several secretome data sets are available for both species (154)(155)(156)(157)(158), which for F. hepatica are being complimented by analysis of the exosome component of the secreted proteins (159,160) as well as glycan analysis of these proteins (161; Ravida et al, unpublished), allowing in depth analysis of those proteins directly interacting with the host. A complete set of transcriptomes from the life cycle stages present within the definitive host, ranging from metacercariae to mature adult flukes are now available, allowing analysis of the extensive differential expression that occurs within this host, particularly as the parasite migrates through the liver (36).…”

Purification of native Sigma class glutathione transferase from Fasciola hepatica

“…Using a local 'in house' MASCOT database (www.matrixscience.com) of the F. hepatica genome, the acquired MGF files submitted for a MS/MS ion search, using parameters previously described [24]. Homology was determined to be significant (p<0.05) for proteins with MASCOT ion scores greater than 32.…”

Saprotrophic proteomes of biotypes of the witches' broom pathogen Moniliophthora perniciosa

“…Merged files were submitted to a MASCOT MS/MS ions search within a locally installed MASCOT server to search the NCBInr protein database (16/12/2015). Search parameters were as described in Morphew et al (2012). BLAST searches were used to obtain functional hypotheses for M. perniciosa accessions without functional annotation.…”