Construction of a Protective Vaccine Against Lipopolysaccharide-Heterologous Pseudomonas aeruginosa Strains Based on Expression Profiling of Outer Membrane Proteins During Infection

Abstract

Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen, which causes infectious disease in patients with cystic fibrosis and compromised immunity. P. aeruginosa is difficult to eradicate because of its intrinsic resistance to most traditional antibiotics as well as acquired resistance mechanisms after decades of antibiotic usage. A full understanding of the P. aeruginosa pathogenesis mechanisms is necessary for the development of novel prevention and treatment strategies. To identify novel vaccine candidates, here we comprehensively examined the expression levels of all the known outer membrane proteins in two P. aeruginosa strains in a murine acute pneumonia model. OprH was one of the most highly expressed proteins during infection. In addition, OprH is known to be highly immunogenic and accessible by host proteins. Thus, it was chosen as a vaccine candidate. To further identify vaccine candidates, 34 genes highly expressed during infection were evaluated for their contributions in virulence by testing individual transposon insertion mutants. Among them, fpvA, hasR, and foxA were found essential for bacterial virulence and therefore included in vaccine construction. Immunization with a mixture of FpvA, HasR, and FoxA rendered no protection, however, while immunization by OprH refolded in liposomes elicited specific opsonic antibodies and conferred protection against two lipopolysaccharide-heterologous P. aeruginosa strains (PA14 and PA103). Overall, by studying the expression profile of the P. aeruginosa outer membrane proteins during infection, we identified OprH as a potential vaccine candidate for the prevention of lung infection by P. aeruginosa.

Intranasal Peptide-Based FpvA-KLH Conjugate Vaccine Protects Mice From Pseudomonas aeruginosa Acute Murine Pneumonia

“…P. aeruginosa uses FpvA to bind the high-affinity siderophore pyoverdine to capture iron from the host environment and translocate it to the cell cytoplasm through a TonB-dependent system (15). Studies from Wu et al and Liu et al have previously identified and tested FpvA as a potential antigen against P. aeruginosa (16, 17). FpvA displays numerous characteristics often associated with protective antigens: (1) FpvA is present on the surface of the bacterium (18), (2) is expressed during infection (10, 17, 19), (3) is important for bacterial homeostasis and virulence (12, 17, 20, 21), and (4) is present in the majority of P. aeruginosa strains including isolates from CF patients (22, 23).…”

“…Studies from Wu et al and Liu et al have previously identified and tested FpvA as a potential antigen against P. aeruginosa (16, 17). FpvA displays numerous characteristics often associated with protective antigens: (1) FpvA is present on the surface of the bacterium (18), (2) is expressed during infection (10, 17, 19), (3) is important for bacterial homeostasis and virulence (12, 17, 20, 21), and (4) is present in the majority of P. aeruginosa strains including isolates from CF patients (22, 23). In addition, iron acquisition receptor-based vaccines are protective against E. coli, Klebsiella spp., Salmonella enterica serovar Enteritidis, Neisseria gonorrhoeae, Neisseria meningitidis, Staphylococcus aureus , and Haemophilus parasuis in different animal models (24–31).…”

Pseudomonas aeruginosa ExsA Regulates a Metalloprotease, ImpA, That Inhibits Phagocytosis of Macrophages

“…Phagocytosis and intracellular survival assays. The macrophage phagocytosis assay was conducted as described previously, with minor modifications (67). Briefly, 2 ϫ 10 5 iBMDMs were seeded into each well of a 24-well plate 24 h before infection.…”

“…Next, 10 l of the bacterial suspension was inoculated into each nostril of the mouse, resulting in 1 ϫ 10 7 CFU per mouse. At 3 h postinfection, the BALF was collected as described previously (67). Cells in the BALF from each mouse were collected by centrifugation, resuspended in 500 l 1ϫ red blood cell (RBC) lysis buffer (0.84% NH 4 Cl) for 2 min at room temperature, and then washed once with flow cytometry (FCM) buffer (2% bovine serum albumin [BSA] and 0.5 mM EDTA in PBS [pH 7.4]).…”

<p>Mechanistic research holds promise for bacterial vaccines and phage therapies for <em>Pseudomonas aeruginosa</em></p>

“…OprH was one of the most highly expressed proteins during infection. In addition, OprH is known to be highly immunogenic and accessible by host proteins 79…”