title: Proteomic analysis in Giardia duodenalis yields insights into strain virulence and antigenic variation.
abstract: Giardia duodenalis is a protozoan parasite of the small intestine in vertebrates, including humans. Assemblage A of G. duodenalis is one of the two discrete subtypes that infects humans, and is considered a zoonotic assemblage. Two G. duodenalis Assemblage A strains BRIS/95/HEPU/2041 and BRIS/83/HEPU/106, constituting virulent and control strains respectively, were analyzed in one of the first comparative shotgun proteomic studies performed in this parasite. Protein extracts were prepared using a multiplatform approach with both an in-gel and in-solution sample preparation to enable us to assess the complementarity for future Giardia proteomic studies. Protein analysis revealed that BRIS/95/HEPU/2041 possessed a wider and more varied repertoire of variant surface proteins (VSPs), which are hypothesized to be involved in host adaptation, immune evasion, and virulence. A total of 35 VSPs were identified, with three common to both strains, six unique to BRIS/82/HEPU/106, and twenty-six unique to BRIS/95/HEPU/2041. Additionally, up to 25.6% of all differentially expressed proteins in BRIS/95/HEPU/2041 belonged to the VSP family, a trend not seen in the control BRIS/83/HEPU/106. Greater antigen variation in BRIS/95/HEPU/2041 may explain aspects of virulence phenotypes in G. duodenalis, with a highly diverse population capable of evading host immune responses.
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, New South Wales, Australia.
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Emery
authors.forename: Steve
authors.initials: S
authors.lastname: van Sluyter
authors.forename: Paul A
authors.initials: PA
authors.lastname: Haynes
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D016829:Giardia lamblia / Q000276:immunology / Q000472:pathogenicity*; D005873:Giardiasis / Q000469:parasitology*; D006801:Humans; D040901:Proteomics; D015800:Protozoan Proteins / Q000032:analysis* / Q000276:immunology; D053719:Tandem Mass Spectrometry
chemical_list: D015800:Protozoan Proteins
keywords: Giardia duodenalis; Label-free quantitative shotgun proteomics; Variant surface proteins; Virulence