Development of a Broadly Protective, Self-Adjuvanting Subunit Vaccine to Prevent Infections by Pseudomonas aeruginosa

Abstract

Infections caused by the opportunistic pathogen Pseudomonas aeruginosa can be difficult to treat due to innate and acquired antibiotic resistance and this is exacerbated by the emergence of multi-drug resistant strains. Unfortunately, no licensed vaccine yet exists to prevent Pseudomonas infections. Here we describe a novel subunit vaccine that targets the P. aeruginosa type III secretion system (T3SS). This vaccine is based on the novel antigen PaF (Pa Fusion), a fusion of the T3SS needle tip protein, PcrV, and the first of two translocator proteins, PopB. Additionally, PaF is made self-adjuvanting by the N-terminal fusion of the A1 subunit of the mucosal adjuvant double-mutant heat-labile enterotoxin (dmLT). Here we show that this triple fusion, designated L-PaF, can activate dendritic cells in vitro and elicits strong IgG and IgA titers in mice when administered intranasally. This self-adjuvanting vaccine expedites the clearance of P. aeruginosa from the lungs of challenged mice while stimulating host expression of IL-17A, which may be important for generating a protective immune response in humans. L-PaF’s protective capacity was recapitulated in a rat pneumonia model, further supporting the efficacy of this novel fusion vaccine.

Effect of Two Unique Nanoparticle Formulations on the Efficacy of a Broadly Protective Vaccine Against Pseudomonas Aeruginosa

“…Because these are T3SS scaffold proteins required for the early stages of infection for these strains (Goure et al, 2004), vaccine escape is reduced due to the fact that mutations in these proteins would impact assembly of an active T3SS and render them nonpathogenic (Goure et al, 2004). When delivered intranasally (IN), we demonstrated that PcrV + PopB admixed with dmLT (double-mutant labile toxin from Enterotoxigenic E. coli) protected mice against acute Pa pulmonary challenge (Das et al, 2020). To reduce costs associated with their production and formulation, we genetically fused PcrV and PopB to produce PaF (Pa Fusion), which elicited protection against Pa in mouse and rat models (Das et al, 2020).…”

“…When delivered intranasally (IN), we demonstrated that PcrV + PopB admixed with dmLT (double-mutant labile toxin from Enterotoxigenic E. coli) protected mice against acute Pa pulmonary challenge (Das et al, 2020). To reduce costs associated with their production and formulation, we genetically fused PcrV and PopB to produce PaF (Pa Fusion), which elicited protection against Pa in mouse and rat models (Das et al, 2020). To further reduce the potential reactogenicity associated with IN delivery of dmLT (Norton et al, 2012), we fused the A1 subunit (LTA1) to PaF (L-PaF) (Das et al, 2020).…”

“…To reduce costs associated with their production and formulation, we genetically fused PcrV and PopB to produce PaF (Pa Fusion), which elicited protection against Pa in mouse and rat models (Das et al, 2020). To further reduce the potential reactogenicity associated with IN delivery of dmLT (Norton et al, 2012), we fused the A1 subunit (LTA1) to PaF (L-PaF) (Das et al, 2020). LTA1 has been shown to stimulate a balanced Th1/Th2/Th17 and mucosal immune response characterized by production of IgA and IL-17A (Norton et al, 2012).…”

A Pseudomonas aeruginosa-Derived Particulate Vaccine Protects against P. aeruginosa Infection

“…The difficulty in recombinant production of PopB may be due to the absence of its chaperon, PcrH. PcrH has been shown to provide structural support to PopB, leading to its optimal protein formation and production [ 20 , 42 , 43 , 44 ].…”

Secretory System Components as Potential Prophylactic Targets for Bacterial Pathogens

“…The translocator proteins as vaccine antigens were used also by Das et al [244]. The group used a self adjuvating construct composed of a fusion of PcrV-PopB, LT1-PcrV-PopB, or separate proteins with a separate addition of mutated heat-labile enterotoxin (dmLT).…”