Immunoproteomic Analysis of Proteins Expressed by Two Related Pathogens, Burkholderia multivorans and Burkholderia cenocepacia, during Human Infection

Minu Shinoy,Ruth Dennehy,Máire Callaghan,Lorraine Coleman,Siobhán Mcclean,Sean Doyle,Kirsten Schaffer,Stephen Carberry,Michael Tunney

doi:10.1371/journal.pone.0080796

Abstract

Burkholderia cepacia complex (Bcc) is an opportunistic bacterial pathogen that causes chronic infections in people with cystic fibrosis (CF). It is a highly antibiotic resistant organism and Bcc infections are rarely cleared from patients, once they are colonized. The two most clinically relevant species within Bcc are Burkholderia cenocepacia and Burkholderia multivorans. The virulence of these pathogens has not been fully elucidated and the virulence proteins expressed during human infection have not been identified to date. Furthermore, given its antibiotic resistance, prevention of infection with a prophylactic vaccine may represent a better alternative than eradication of an existing infection. We have compared the immunoproteome of two strains each from these two species of Bcc, with the aim of identifying immunogenic proteins which are common to both species. Fourteen immunoreactive proteins were exclusive to both B. cenocepacia strains, while 15 were exclusive to B. multivorans. A total of 15 proteins were immunogenic across both species. DNA-directed RNA polymerase, GroEL, 38kDa porin and elongation factor-Tu were immunoreactive proteins expressed by all four strains examined. Many proteins which were immunoreactive in both species, warrant further investigations in order to aid in the elucidation of the mechanisms of pathogenesis of this difficult organism. In addition, identification of some of these could also allow the development of protective vaccines which may prevent colonisation.

Highlights

Burkholderia cepacia complex (Bcc) is a heterogenous group of Gram negative bacteria comprising at least 17 species
This study identified a wide range of proteins expressed by the two most common Burkholderia species that colonise cystic fibrosis (CF) patients during infection
There has been no study to examine or identify the membrane proteins expressed by any Bcc species during human infection

Summary

Introduction

Burkholderia cepacia complex (Bcc) is a heterogenous group of Gram negative bacteria comprising at least 17 species It is one of a number of opportunistic pathogens that causes chronic respiratory infections in people with the genetically inherited diseases cystic fibrosis (CF) and chronic granulomatous disease (CGD). There are two species that are of particular interest, Burkholderia cenocepacia which is the most virulent species and Burkholderia multivorans, which is currently the most frequently isolated Bcc species from newly colonised CF patients [2,3]. Together these species account for 85% to 95% of Bcc CF infections. We and others have shown that environmental Bcc strains have the potential to be as virulent as clinical strains [6,7]

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Conclusion