Polymorphisms in the Pseudomonas aeruginosa type III secretion protein, PcrV – Implications for anti-PcrV immunotherapy

Abstract

The type III secretion system of P. aeruginosa, responsible for acute infection, is composed of over twenty proteins that facilitate cytotoxin injection directly into host cells. Integral to this process is production and secretion of PcrV. Administration of a recently developed, anti-PcrV immunoglobulin, either as a therapeutic or prophylactic has previously demonstrated efficacy against laboratory strains of P. aeruginosa in a murine model. To determine if this therapy is universally applicable to a variety of P. aeruginosa clinical isolates, genetic heterogeneity of pcrV was analyzed among strains collected from three geographically distinct regions; United States, France and Japan. Sequence analysis of PcrV demonstrated limited variation among the clinical isolates examined. Strains were grouped according to the presence of non-synonymous single nucleotide polymorphisms. Representative isolates from each mutant group were examined for the ability of anti-PcrV to bind the protein secreted by these strains. The protective effect of anti-PcrV IgG against each strain was determined using an epithelial cell line cytotoxicity assay. The majority of strains tested demonstrated reduced cytotoxicity in the presence of anti-PcrV IgG. This study provides insights into the natural sequence variability of PcrV and an initial indication of the amino acid residues that appear to be conserved across strains. It also demonstrates the protective effect of anti-PcrV immunotherapy against a multitude of P. aeruginosa strains from diverse global regions with a variety of mutations in PcrV.

Efficacy comparison of adjuvants in PcrV vaccine against Pseudomonas aeruginosa pneumonia

“…With the aim of impeding toxin translocation through the TTSS, we previously identified the molecular target PcrV, which is the cap structure of an injection needle in the type III secretion apparatus . PcrV is present in most P. aeruginosa strains that cause acute infections, especially in the ones associated with poor clinical outcomes . Furthermore, the PcrV's structure is conserved among strains and is not associated with antibiotic resistance .…”

Pangenome-wide and molecular evolution analyses of the Pseudomonas aeruginosa species

“…Results supporting this assumption have been reported, yielding genetic information from the P. aeruginosa genome. For 85 example, genetic variability explored in multiple P. aeruginosa isolates from different regions of the world indicated that pcrV, a member of the type III secretion system, exhibits limited genetic variation in terms of non-synonymous substitutions [10].…”

Salicylidene Acylhydrazides and Hydroxyquinolines Act as Inhibitors of Type Three Secretion Systems in Pseudomonas aeruginosa by Distinct Mechanisms

“…Applied to hydroxyquinolines and salicylidene acylhydrazides, these techniques allowed us to position them as a potentially useful addition to our future therapeutic armamentarium, since both show activity against clinical isolates, disregarding their resistance profile to currently used antipseudomonal antibiotics. Compared to previously described inhibitors of iT3SS in P. aeruginosa (see reference 22 for a review), they may offer a broader spectrum of activity than (i) compounds blocking toxins only (51)(52)(53), the activity of which will probably be restricted to toxin-producing strains, and (ii) antibodies for which activity can be variable due to the polymorphism of the targeted antigens (54). The present data, together with the results obtained previously with INP1855 (35), strongly suggest an advantage for hydroxyquinolines over salicylidene acylhydrazides.…”