Chimeric animal and plant viruses expressing epitopes of outer membrane protein F as a combined vaccine against Pseudomonas aeruginosa lung infection

Abstract

Outer membrane protein F of Pseudomonas aeruginosa has vaccine efficacy against infection by P. aeruginosa as demonstrated in a variety of animal models. Through the use of synthetic peptides, three surface-exposed epitopes have been identified. These are called peptides 9 (aa 261-274 in the mature F protein, TDAYNQKLSERRAN), 10 (aa 305-318, NATAEGRAINRRVE), and 18 (aa 282-295, NEYGVEGGRVNAVG). Both the peptide 9 and 10 epitopes are protective when administered as a vaccine. In order to develop a vaccine that is suitable for use in humans, including infants with cystic fibrosis, the use of viral vector systems to present the protective epitopes has been investigated. An 11-amino acid portion of epitope 10 (AEGRAINRRVE) was successfully inserted into the antigenic B site of the hemagglutinin on the surface of influenza virus. This chimeric influenza virus protects against challenge with P. aeruginosa in the mouse model of chronic pulmonary infection. Attempts to derive a chimeric influenza virus carrying epitope 9 have been unsuccessful. A chimeric plant virus, cowpea mosaic virus (CPMV), with epitopes 18 and 10 expressed in tandem on the large coat protein subunit (CPMV-PAE5) was found to elicit antibodies that reacted exclusively with the 10 epitope and not with epitope 18. Use of this chimeric virus as a vaccine afforded protection against challenge with P. aeruginosa in the mouse model of chronic pulmonary infection. Chimeric CPMVs with a single peptide containing epitopes 9 and 18 expressed on either of the coat proteins are in the process of being evaluated. Epitope 9 was successfully expressed on the coat protein of tobacco mosaic virus (TMV), and this chimeric virus is protective when used as a vaccine in the mouse model of chronic pulmonary infection. However, initial attempts to express epitope 10 on the coat protein of TMV have been unsuccessful. Efforts are continuing to construct chimeric viruses that express both the 9 and 10 epitopes in the same virus vector system. Ideally, the use of a vaccine containing two epitopes of protein F is desirable in order to greatly reduce the likelihood of selecting a variant of P. aeruginosa that escapes protective antibodies in immunized humans via a mutation in a single epitope within protein F. When the chimeric influenza virus containing epitope 10 and the chimeric TMV containing epitope 9 were given together as a combined vaccine, the immunized mice produced antibodies directed toward both epitopes 9 and 10. The combined vaccine afforded protection against challenge with P. aeruginosa in the chronic pulmonary infection model at approximately the same level of efficacy as provided by the individual chimeric virus vaccines. These results prove in principle that a combined chimeric viral vaccine presenting both epitopes 9 and 10 of protein F has vaccine potential warranting continued development into a vaccine for use in humans.

Protection against P. aeruginosa with an adenovirus vector containing an OprF epitope in the capsid

“…Various immunogenic peptides have been identified in the outer loops of OprF, among them the B cell epitopes TDAYNQKLSERRAN (peptide 9, identical to Epi6) and NATAE-GRAINRRVE (peptide 10, identical to Epi8) (21). Immunization with a modified cowpea mosaic virus expressing peptide 9 or 10 induced IgG-binding antibodies against OprF and opsonizing antibodies against P. aeruginosa in mice (22). Similar results were reported with the use of OprF peptides expressed by recombinant influenza virus (53).…”

“…Antibodies against OprF are associated with protection in animal models and human infection and are present in the serum of individuals with CF chronically colonized with P. aeruginosa in the lung (22-28, 51, 52). Immunization with recombinant OprF has been shown to generate protective immune responses, and recombinant OprF is being tested as a vaccine candidate against infections with P. aeruginosa in animals and humans (22)(23)(24)(25)(26)(27)(28). Genetic immunization with DNA encoding an OprF/OprI hybrid via a gene gun in mice resulted in humoral immunity against P. aeruginosa (29).…”

“…OprF has been shown to be immunogenic in laboratory animals and humans, and the sequence of OprF suggests that there are several extracellular loops that serve as good B cell epitopes ( Figure 1) (21)(22)(23)(24)(25)(26)(27)(28)(29). The Ad hexon is the most abundant immunogenic of the Ad capsid proteins (30)(31)(32)(33).…”

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

“…Vaccination with outer membrane protein antigens has been shown to be efficacious against P. aeruginosa infection in a number of studies using killed whole cells (9), purified outer membrane preparations (32,33), isolated outer membrane proteins (18,20,39,53), protein fusions (38), or synthetic peptides representing protective epitopes (22,23). The P. aeruginosa major constitutive porin protein, OprF, which has previously been shown to be antigenic (3,20,25) and has high homology among Pseudomonas strains (18,34,40), was chosen as a vaccine target.…”

Characterization of the pscC (Type III secretion) gene of Pseudomonas aeruginosa (PA01) and assessment of immunogenicity of pscC protein in rats

“…Immunization with microbial antigen has delivered the protective immunity in animal models and considered a potential useful vaccine strategy [21]. Based on previous findings, there are various kinds of immunization have been observed against Pseudomonas infection such as killed vaccine [22], purified outer membrane subunit vaccine [23], plasmid immunization [24] and synthetic peptide immunization [25]. The immune response in a mouse animal model to consecutive recombinant protein base vaccine could able to neutralizing the bacterial virulent toxin [26].…”