OmpQ, a virulence factor involved in Bordetella bronchiseptica biofilm formation

CATTELÁN NATALIA; ARNAL LAURA; YANTORNO OSVALDO

Mar del Plata

Congreso; X Congreso Argentino de Microbiología General SAMIGE; 2014

Sociedad Argentina de Microbiología General SAMIGE

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 (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. In addition, relative expression analysis of the ompQ gene during the biofilm development showed an increment of its expression at 48 h of biofilm culture, indicating a specific role of OmpQ at later stages of biofilm development. Finally, we studied 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, α-rOmpQr showed recognition against OmpQ and recombinant OmpQ (rOmpQ). When the anti-rOmpQ serum was added to the growth medium, a reduction of the biofilm biomass level of B. bronchiseptica was observed in a dose-dependent manner.