title: Overexpression, purification and validation of antigenic Salmonella enterica serovar Typhi proteins identified from LC-MS/MS.
abstract: In our earlier study, an immunoblot analysis using sera from febrile patients revealed that a 50-kDa band from an outer membrane protein fraction of Salmonella enterica serovar Typhi was specifically recognized only by typhoid sera and not sera from other febrile illnesses. Here, we investigated the identities of the proteins contained in the immunogenic 50-kDa band to pinpoint antigens responsible for its immunogenicity. We first used LC-MS/MS for protein identification, then used the online tool ANTIGENpro for antigenicity prediction and produced recombinant proteins of the lead antigens for validation in an enzyme-linked immunosorbent assay (ELISA). We found that proteins TolC, GlpK and SucB were specific to typhoid sera but react to antibodies differently under native and denatured conditions. This difference suggests the presence of linear and conformational epitopes on these proteins.
authors.affiliation: Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800, Minden, Penang, Malaysia.
authors.forename: Chai Fung
authors.initials: CF
authors.lastname: Chin
authors.forename: Boon Aun
authors.initials: BA
authors.lastname: Teh
authors.forename: Amy Amilda
authors.initials: AA
authors.lastname: Anthony
authors.forename: Ismail
authors.initials: I
authors.lastname: Aziah
authors.forename: Asma
authors.initials: A
authors.lastname: Ismail
authors.forename: Eugene Boon Beng
authors.initials: EB
authors.lastname: Ong
authors.forename: Theam Soon
authors.initials: TS
authors.lastname: Lim
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000276:immunology* / Q000302:isolation & purification; D002853:Chromatography, Liquid; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry* / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D013058:Mass Spectrometry; D012485:Salmonella typhi / Q000737:chemistry* / Q000276:immunology*; D014435:Typhoid Fever / Q000276:immunology* / Q000382:microbiology; D015854:Up-Regulation
chemical_list: D001425:Bacterial Outer Membrane Proteins; D000939:Epitopes