The Burkholderia cenocepacia OmpA-like protein BCAL2958: identification, characterization, and detection of anti-BCAL2958 antibodies in serum from B. cepacia complex-infected Cystic Fibrosis patients

Abstract

Respiratory infections by bacteria of the Burkholderia cepacia complex (Bcc) remain an important cause of morbidity and mortality among cystic fibrosis patients, highlighting the need for novel therapeutic strategies. In the present work we have studied the B. cenocepacia protein BCAL2958, a member of the OmpA-like family of proteins, demonstrated as highly immunogenic in other pathogens and capable of eliciting strong host immune responses. The encoding gene was cloned and the protein, produced as a 6× His-tagged derivative, was used to produce polyclonal antibodies. Bioinformatics analyses led to the identification of sequences encoding proteins with a similarity higher than 96 % to BCAL2958 in all the publicly available Bcc genomes. Furthermore, using the antibody it was experimentally demonstrated that this protein is produced by all the 12 analyzed strains from 7 Bcc species. In addition, results are also presented showing the presence of anti-BCAL2958 antibodies in sera from cystic fibrosis patients with a clinical record of respiratory infection by Bcc, and the ability of the purified protein to in vitro stimulate neutrophils. The widespread production of the protein by Bcc members, together with its ability to stimulate the immune system and the detection of circulating antibodies in patients with a documented record of Bcc infection strongly suggest that the protein is a potential candidate for usage in preventive therapies of infections by Bcc.

Postgenomic Approaches and Bioinformatics Tools to Advance the Development of Vaccines against Bacteria of the Burkholderia cepacia Complex

“…No other examples can be found in the literature on the use of live attenuated or killed whole-cell vaccines to combat infections by Bcc. Contrastingly, several virulence factors and proteins have been identified for future use as subunit vaccines [ 22 , 23 , 24 , 25 , 26 , 27 ]. Surface and extracytoplasmatic molecules/structures of pathogens are the first exposed to the host immune system, and therefore expected to trigger the host immune response.…”

“…Therefore, the identified linear epitopes can be part of the conformational B-cell epitope. Recently, using the Bepipred tool for identification of continuous B-cell epitopes, we identified in silico three putative outer membrane proteins with higher probability to be immunogenic and conserved in Bcc [ 24 ]. In particular, the BCAL2958 protein was experimentally demonstrated to be expressed by all the 12 analyzed strains from seven different Bcc species [ 24 ].…”

“…Recently, using the Bepipred tool for identification of continuous B-cell epitopes, we identified in silico three putative outer membrane proteins with higher probability to be immunogenic and conserved in Bcc [ 24 ]. In particular, the BCAL2958 protein was experimentally demonstrated to be expressed by all the 12 analyzed strains from seven different Bcc species [ 24 ]. The presence of anti-BCAL2958 antibodies in sera from cystic fibrosis patients with a clinical record of respiratory infection by Bcc and the ability of the purified protein to stimulate neutrophils in vitro was also observed [ 24 ].…”

“…In particular, the BCAL2958 protein was experimentally demonstrated to be expressed by all the 12 analyzed strains from seven different Bcc species [ 24 ]. The presence of anti-BCAL2958 antibodies in sera from cystic fibrosis patients with a clinical record of respiratory infection by Bcc and the ability of the purified protein to stimulate neutrophils in vitro was also observed [ 24 ]. Structure-based epitope prediction was also recently performed to identify epitopes for the design of new diagnostic molecules for the early detection of Burkholderia infections [ 65 ].…”

Burkholderia cepacia Complex Infections Among Cystic Fibrosis Patients: Perspectives and Challenges

“…Other proteins of putative immunogenic activity have been reported as potential vaccine candidates.However,studiesinaBccinfectionanimalmodelarestilllacking( Table 3).One ofthesepromisingantigensistheOmpA-likeBCAL2958proteinthatwasshowntobehighly conserved in Bcc, to elicit IgG antibodies in CF patients and to elicit an increase of TNFα, elastase,NO,andMPOinneutrophils [166].…”