OmpQ, a virulence factor envolved in biofilm formation by Bordetella bronchiseptica

CATTELAN, N; ARNAL, L; YANTORNO, OM

Mar del Plata

Congreso; X Congreso de Microbiología General; 2014

Sociedad Argentina de Microbiología General

Bordetella species are small aerobic, Gram-negative bacteria that colonize the respiratory tract of humans and animals. Bordetella pertussis, a strictly obligate human pathogen, is the etiologic agent of whooping cough, while B. bronchiseptica mainly infects animals causing a variety of respiratory diseases (1). It has been demonstrated by us and other groups that these bacteria are capable of living as sessile communities, known as biofilms, on abiotic surfaces and in the respiratory tract of mice (2-4). OmpQ is a general outer membrane porin of Bordetella, whose expression is regulated by the two-component system BvgAS, together with all the virulence factors of these bacteria (6). We had previously found, using proteomic approaches, a higher expression level of the general porins OmpP and OmpQ in B. pertussis biofilm cells than in planktonic cells, either for reference and clinical strains. (5). The purpose of this work was to study the contribution of OmpQ to biofilm formation by B. bronchiseptica. To this aim an in-frame, non-polar mutation was obtained through allelic exchange on B. bronchiseptica RB50 strain. No differences were observed on planktonic growth between the wild-type and ΔompQ strains, nevertheless, quantification of the biomass adhered to the wells of microtiter plates at 48 h of biofilm culture showed significant differences between both strains, observing a reduction of the biofilm biomass on the OmpQ defective strain. Next, we studied the ompQ gene expression profile during the biofilm formation process, observing an increment of its expression at 48 h of biofilm culture, indicating a specific role of OmpQ at later stages of biofilm development. In addition, we decided to study the potential use of OmpQ to act as an antigen that could prevent biofilm formation. To this aim, OmpQ was recombinantly expressed in E. coli, purified and inoculated into mice to obtain afterwards polyclonal serum. The serum, anti-OmpQr, showed recognition against OmpQ and recombinant OmpQ (OmpQr). When the anti-OmpQr serum was added to the growth medium, a reduction of the biofilm biomass level of B. bronchiseptica was observed in a dose-dependent manner. In conclusion, our results contribute to the identification of new key factors for Bordetella biofilm development that could act as protective antigens by inhibiting biofilm formation and, in addition, lead to a better understanding of the mechanisms involved in the process of B. bronchiseptica biofilm formation.