Uropathogenic Escherichia coli Outer Membrane Antigens Expressed during Urinary Tract Infection

Abstract

Uncomplicated urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) represents a prevalent and potentially severe infectious disease. In this study, we describe the application of an immunoproteomics approach to vaccine development that has been used successfully to identify vaccine targets in other pathogenic bacteria. Outer membranes were isolated from pyelonephritis strain E. coli CFT073 cultured under conditions that mimic the urinary tract environment, including iron limitation, osmotic stress, human urine, and exposure to uroepithelial cells. To identify antigens that elicit a humoral response during experimental UTI, outer membrane proteins were separated by two-dimensional gel electrophoresis and probed using pooled antisera from 20 CBA/J mice chronically infected with E. coli CFT073. In total, 23 outer membrane antigens, including a novel iron compound receptor, reacted with the antisera and were identified by mass spectrometry. These antigens also included proteins with known roles in UPEC pathogenesis, such as ChuA, IroN, IreA, Iha, IutA, and FliC. These data demonstrate that an antibody response is directed against these virulenceassociated factors during UTI. We also show that the genes encoding ChuA, IroN, hypothetical protein c2482, and IutA are significantly more prevalent (P < 0.01) among UPEC strains than among fecal-commensal E. coli isolates. Thus, we suggest that the conserved outer membrane antigens identified in this study could be rational candidates for a UTI vaccine designed to elicit protective immunity against UPEC infection.

Colibacillosis in poultry: unravelling the molecular basis of virulence of avian pathogenicEscherichia coliin their natural hosts

“…An alternative approach is to resolve bacterial proteins by two-dimensional gel electrophoresis and transfer them to a membrane that is then probed with host antisera to identify immunogenic constituents by mass spectrometry. This immuno-proteomic approach has successfully led to the identification of important antigens in other bacterial pathogens; K. pneumoniae (Kurupati et al, 2006) and uropathogenic E. coli (Hagan & Mobley, 2007). Surface-localized antigens are likely to play an important role in pathogenesis and also stimulate protective immunity, hence the process can be focused on sheared or outer membrane components from the cell surface.…”

Comparison of virulence factors and expression of specific genes between uropathogenic Escherichia coli and avian pathogenic E. coli in a murine urinary tract infection model and a chicken challenge model

“…The common presence of a set of virulence-associated genes among APEC and UPEC strains as well as similar disease patterns and phylogenetic background indicate a genetic relationship between APEC and UPEC isolates (Kaper et al, 2004;Moulin-Schouleur et al, 2006;Ron, 2006). A few studies have investigated the expression in vivo of specific genes and the whole transcriptome of UPEC strain CFT073 in a murine urinary infection model, and the upregulation of some genes such as iron-related genes and outermembrane protein encoding genes was observed (Snyder et al, 2004(Snyder et al, , 2005Hagan & Mobley, 2007;Haugen et al, 2007). However, there is little information regarding the comparison of the expression of specific genes between UPEC and APEC isolates during an infection in vivo, which is an essential step to define whether APEC can serve as a source of human extraintestinal pathogenic E. coli (ExPEC) or as a reservoir of virulence genes for human ExPEC.…”

A novel gene R049 identified in uropathogenic Escherichia coli provides partial protection in mice from colonization

“…Several UPEC virulence-associated factors, such as FimH, the type 1 fimbrial adhesin [26], PapG, the P fimbrial adhesin [27], and hemolysin [28], have been tested as vaccine targets. In recent years, Hagan et al used an immunoproteomic approach to identify potential vaccine targets in a pyelonephritis strain of E. coli CFT073, and identified 23 antigenic proteins that elicited an immune response during infection [29]. We therefore suggest that the antigenic gene product R049, which has been shown to reduce the bacterial load following immunization, is a new vaccine candidate.…”