Protection againstPseudomonas aeruginosaChronic Lung Infection in Mice by Genetic Immunization against Outer Membrane Protein F (OprF) ofP. aeruginosa

Abstract

The Pseudomonas aeruginosa major constitutive outer membrane porin protein OprF, which has previously been shown to be a protective antigen, was targeted as a DNA vaccine candidate. The oprF gene was cloned into plasmid vector pVR1020, and the plasmid vaccines were delivered to mice by biolistic (gene gun) intradermal inoculation. Antibody titers in antisera from immunized mice were determined by enzyme-linked immunosorbent assay, and the elicited antibodies were shown to be specifically reactive to OprF by immunoblotting. The immunoglobulin G (IgG) immune response was predominantly of the IgG1 isotype. Sera from DNA vaccineimmunized mice had significantly greater opsonic activity in opsonophagocytic assays than did sera from control mice. Following the initial immunization and two consecutive boosts, each at 2-week intervals, protection was demonstrated in a mouse model of chronic pulmonary infection by P. aeruginosa. Eight days postchallenge, both lungs were removed and examined. A significant reduction in the presence of severe macroscopic lesions, as well as in the number of bacteria present in the lungs, was seen. Based on these findings, genetic immunization with oprF has potential for development as a vaccine to protect humans against infection by P. aeruginosa.Pseudomonas aeruginosa, an opportunistic pathogen, is a leading cause of life-threatening infections in immunocompromised individuals. It is an etiological agent of bacteremia, urinary tract infections, and pneumonia in such patients. The mortality from bacteremia and pneumonia caused by P. aeruginosa infections can exceed 50%. Each year, over two million patients develop hospital-associated infections, and an estimated 88,000 patients die as a result.

A Live-Attenuated Pseudomonas aeruginosa Vaccine Elicits Outer Membrane Protein-Specific Active and Passive Protection against Corneal Infection

“…Only a single challenge strain was used in those studies, so the broadness of protection was not evaluated. Immunization with recombinant OprF or OprF peptides has been shown to elicit protective immune responses in a number of infection models other than keratitis (11,30,40) and has been studied in humans as well (21). Crystal and coworkers recently reported the use of an adenovirus vector expressing an OprF peptide in the viral capsid as a subcutaneously delivered vaccine against P. aeruginosa pneumonia by using the agar-bead model of murine pneumonia to challenge the immunized mice (45).…”

Opr86 Is Essential for Viability and Is a Potential Candidate for a Protective Antigen against Biofilm Formation byPseudomonas aeruginosa

“…aeruginosa OMPs have been studied as candidates for vaccine antigens in the form of purified OM preparations (22,24), isolated OMPs (38,48), or protein fusions (1,21). OMPs are more suitable as antigens than lipopolysaccharides, exopolysaccharides, or isolated flagella are for routine clinical use because of the safety and efficacy of OMPs.…”

Chronic Infection by Mucoid Pseudomonas aeruginosa Associated with Dysregulation in T-Cell Immunity to Outer Membrane Porin F

“…Although several PA vaccines have been trialed including those using OprF, OprI, and flagellin (10)(11)(12)(13)(14)(15)(16)(20)(21)(22)(23)(24)(25), studies such as this one raise an additional possibility of exploiting the potency and flexibility of incorporating a large number of stimulatory T-and B-cell epitopes into epitope string vaccines. In other contexts, such as Plasmodium falciparum vaccination, these can be successfully administered in a "prime-boost" regime through incorporation into an adenoviral vector followed by DNA boost (62).…”

“…Because OprF is immunogenic and protective in experimental Pseudomonas (20)(21)(22)(23)(24)(25) and seroreactive in patients with non-CF bronchiectasis with chronic PA infection (37), we further investigated the candidacy of OprF as a CD4 T-cell antigen. A synthetic peptide panel of 20 mers overlapping by 10 amino acids was generated, covering the full coding sequence (Table 2) and binding affinities determined for the HLA-DR alleles, HLA-DR1, -DR3, -DR4, -DR7, -DR9, -DR11, -DR13, and -DR1501 (Table 4).…”

“…In a comparison of aerobic and anaerobic PA biofilms, OprF is up-regulated 39-fold during anaerobic (relative to aerobic) biofilm growth (6). Studies have considered the immunogenicity and protective efficacy of OprF (20)(21)(22)(23)(24)(25), commonly focusing on OprF antibodies.…”