Until recently, the development of vaccines for use in humans relied on the response to attenuated or whole-cell preparations, or empirically selected antigens. The post-genomic era holds the possibility of rational design of novel vaccines for important human pathogens. The discovery and development of these new vaccines is likely to be accomplished through integrated proteomic strategies. Although most proteomic studies are based on two-dimensional gel electrophoresis (2D-PAGE) as a separation technique, new methods have been developed within the past two years that provide complementary information concerning microbial protein expression. The 2D-PAGE technique in combination with Western blotting has been successfully applied in the discovery of antigens from Helicobacter pylori, Chlamydia trachomatis and Borrelia garinii. Two-dimensional semi-preparative electrophoresis has provided complementary information regarding membrane protein expression in a strain of H. pylori. Through two-dimensional liquid chromatography-tandem mass spectrometry, the most comprehensive information to date regarding protein expression in yeast was obtained. This technique may shortly become an important tool in vaccinology. This review of the current state of bacterial proteomics as applied in vaccinology presents analytical techniques for protein separation, proteomics without gels, reverse vaccinology, and functional approaches to the identification of virulence proteins in microbes.
