A Polyclonal Antibody Raised against the Burkholderia cenocepacia OmpA-like Protein BCAL2645 Impairs the Bacterium Adhesion and Invasion of Human Epithelial Cells In Vitro

Abstract

Respiratory infections by bacteria of the Burkholderia cepacia complex (Bcc) remain a life threat to cystic fibrosis (CF) patients, due to the faster lung function decline and the absence of effective eradication strategies. Immunotherapies are regarded as an attractive alternative to control and reduce the damages caused by these infections. In this work, we report the cloning and functional characterization of the OmpA-like BCAL2645 protein, previously identified and found to be immunoreactive against sera from CF patients with a record of Bcc infections. The BCAL2645 protein is shown to play a role in biofilm formation, adherence to mucins and invasion of human lung epithelial cells. The expression of the BCAL2645 protein was found to be increased in culture medium, mimicking the lungs of CF patients and microaerophilic conditions characteristic of the CF lung. Moreover, a polyclonal antibody raised against BCAL2645 was found to inhibit, by about 75 and 85%, the ability of B. cenocepacia K56-2 to bind and invade in vitro CFBE41o- human bronchial epithelial cells. These results highlight the potential of anti-BCAL2645 antibodies for the development of passive immunization therapies to protect CF patients against Bcc infections.

A Polyclonal Antibody against a Burkholderia cenocepacia OmpA-like Protein Strongly Impairs Pseudomonas aeruginosa and B. multivorans Virulence

“…P. aeruginosa F69A isolate IST27 [ 22 ], B. cenocepacia K56-2 [ 23 ] and B. multivorans BM1 [ 24 ] were used in this work and maintained in PIA (Pseudomonas Isolation Agar plates; Becton Dickinson, Heidelberg, Germany). When in use, Escherichia coli was maintained in LB plates [ 21 ]. When necessary, media were supplemented with 150 μg/mL ampicillin.…”

“…The CFBE41o-human bronchial epithelial cell line [ 25 ], was used in this study. Cells were cultured under humidified atmosphere at 37 °C with 5% CO 2 , as previously described [ 21 ].…”

“…We also show that the antibody negatively impacts the ability of the exopolysaccharide-producer B. multivorans to adhere and invade the epithelial cell line, and to form biofilms. The antibody was previously demonstrated to interfere with the adhesion and invasion process of B. cenocepacia to bronchial epithelial cells [ 21 ]. The anti-BCAL2645 is here shown to recognize two homolog proteins from the clinical isolate P. aeruginosa F69A (isolate IST27) with its genome sequenced.…”

Burkholderia pseudomallei Complex Subunit and Glycoconjugate Vaccines and Their Potential to Elicit Cross-Protection to Burkholderia cepacia Complex

“…The B. cenocepacia homolog, BCAL2645, is another one of the lipoproteins identified via Sousa et al’s surface trypsin shaving study, providing evidence that it is a potential surface-exposed target for antibody binding [ 190 ]. Further, Seixas et al recently demonstrated that polyclonal antibodies towards BCAL2645 impair adhesion and invasion of CFBE41o- cells by B. cenocepacia [ 203 ]. The ability of these antibodies to impede adherence suggests a possible mechanism of protection if this antigen were to be used in vaccination.…”

Antibody-Based Immunotherapies as a Tool for Tackling Multidrug-Resistant Bacterial Infections

“…The use for treatment of other bacterial infections has been less common. Our group recently showed that a pAbs against an OmpA-like protein from Burkholderia cenocepacia greatly impairs the ability of these bacteria to adhere and invade human epithelial cells in vitro [41]. Both the adhesion and invasion are highly important steps in the infection process.…”