B. PERTUSSIS COMPROMISES THE EPITHELIAL BARRIER AND SURVIVES IN NON-DEGRADATIVE INTRACELLULAR COMPARTMENTS

BAROLI, CARLOS; GORGOJO, JUAN PABLO; BLANCA, BRUNO; DEBANDI, MARTINA; RODRIGUEZ, MARÍA EUGENIA

Evento virtual

Congreso; LXIX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2021

Sociedad Argentina de Inmunología

Bordetella pertussis (Bp) is the etiological agent of whooping cough, a reemerging respiratory tract disease. Current vaccines do not prevent transmission and epidemiological data indicates that vaccinated asymptomatic carriers are important reservoirs and constitute a source of transmission to vulnerable unvaccinated subjects. Recent studies suggest the existence of an intracellular niche of persistence inside host macrophages. We here investigated the potential role of the respiratory epithelial barrier in the infectious process and the eventual development of persistent infections. In binding assays Bp showed a clear tropism for tight junctions (TJ) of polarized 16HBE14o- cells as determined by fluorescence microscopy. This tropism seemed to be directed by the bacterial preference for basolateral membrane (BLM) mediated by FHA as addressed using a FHA defective strain. Our results further showed that wild type Bp but not an adenylate cyclase toxin (CyaA) deficient Bp strain disrupted TJ integrity as determined by confocal microscopy. This suggests that access of Bp to BLM in intact monolayers might be granted by the action of local high concentrations of CyaA releasedby the bacteria attached near TJ. The study of bacterial intracellulartrafficking revealed that most internalized bacteria did not colocalizewith lysosomal marker cathepsin D two days after infectionsuggesting that Bp avoids phagolysosomal fusion. Furthermore, weobserved intracellular bacteria colocalizing with recycling pathwaymarker transferrin at this time point, indicating that Bp might survivein non-degradative vesicles with access to nutrients. Accordingly,antibiotic protection assays showed high intracellular survival levelsover the time post infection. Taken together, these results showthat Bp can compromise epithelial barrier, invade cells and persistin intracellular location in the respiratory epithelium, pointing out itspotential relevance as another persistence niche.