Characterization and identification of vaccine candidate proteins through analysis of the group A Streptococcus surface proteome

Abstract

We describe a proteomic approach for identifying bacterial surface-exposed proteins quickly and reliably for their use as vaccine candidates. Whole cells are treated with proteases to selectively digest protruding proteins that are subsequently identified by mass spectrometry analysis of the released peptides. When applied to the sequenced M1_SF370 group A Streptococcus strain, 68 PSORT-predicted surface-associated proteins were identified, including most of the protective antigens described in the literature. The number of surface-exposed proteins varied from strain to strain, most likely as a consequence of different capsule content. The surface-exposed proteins of the highly virulent M23_DSM2071 strain included 17 proteins, 15 in common with M1_SF370. When 14 of the 17 proteins were expressed in E. coli and tested in the mouse for their capacity to confer protection against a lethal dose of M23_DSM2071, one new protective antigen (Spy0416) was identified. This strategy overcomes the difficulties so far encountered in surface protein characterization and has great potential in vaccine discovery.

Conserved anchorless surface proteins as group A streptococcal vaccine candidates

“…Conjecture exists in the scientific literature regarding the biological relevance and certitude of surface expression of anchorless proteins in GAS [5,30]. To validate our findings and to test protective vaccine efficacy of the selected anchorless surface proteins, full-length M1 protein, ADI, TF and FBA were adjuvanted with Complete Freund's Adjuvant (CFA) and used to subcutaneously immunize BALB/c mice and the survival recorded following lethal intraperitoneal M1 GAS challenge.…”

The cell-envelope proteome of Bifidobacterium longum in an in vitro bile environment

“…In relation to this, with the aim of determining the protein profile of the B. longum envelope, and as a first approach to undertaking deeper functional studies, we analysed different subcellular fractions. The application of gel-based and gel-free technologies, combined with high-throughput techniques, allowed us to identify 218 proteins; about 70 % of them were predicted to be, or were previously described as being, in the cell envelope of Gram-positive bacteria (Antikainen et al, 2007;Candela et al, 2007;Eymann et al, 2004;Granato et al, 2004;Jang & Hanash 2003;Kelly et al, 2005b;Nandakumar et al, 2005;Rivera-Amill et al, 2001;Rodríguez-Ortega et al, 2006;Schaumburg et al, 2004;Severin et al, 2007;Silveira et al, 2004;Tjalsma et al, 2008;Wolff et al, 2007). Furthermore, 48 of them are predicted to be integral membrane proteins (contain hypothetical transmembrane segments) and 30 of them have different extracytoplasmic sorting signals.…”

Approach to discover T- and B-cell antigens of intracellular pathogens applied to the design of Chlamydia trachomatis vaccines

“…Therefore, the development of efficacious vaccines against obligate and facultative intracellular pathogens depends largely upon the ability to identify antigen formulations that induce effective B-and T-cell responses (1)(2)(3). Although both genomic and proteomic strategies have been applied successfully to discover B-cell-stimulating vaccines (4)(5)(6)(7), the identification of antigens eliciting effector T cells generally is considered less amenable to high-throughput approaches.…”