The catecholamine siderophore receptors bfrD and bfrE are required for Bordetella pertussis intramacrophage survival

CAFIERO, HILARIO; LAMBERTI Y; ALVAREZ HAYES, J; RODRIGUEZ, M

Buenos Aires

Congreso; LXIII Reunión Anual de SAI-I Meeting LASID-SAI-FAIC; 2015

Bordetella pertussis (Bp), the causative agent of whooping cough, survives inside macrophages in compartments which have access to transferrin. A recent proteomic study from our group identified the receptors bfrD and bfrE upregulated during Bp growth inside THP-1 cells. These receptors are involved in the uptake of iron sequestered by catecholamines from transferrin, as demonstrated in B.bronchiseptica. However, the functionality of these receptors was never demonstrated in Bp. In this study, we confirmed the upregulation of bfrD in intracellular Bp using a multiple reaction monitoring method. We then constructed a ΔbfrDE mutant and a complemented strain that were used in an infection assay of PMA-differentiated THP-1 cells. Immunofluorescence microscopy showed that there were no differences in the adhesion or the phagocytosis of each strain. The intracellular survival of these strains inside THP-1 cells was analyzed by polymyxin B protection assays by CFU counts and FISH staining of intracellular viable bacteria at 3, 24 and 48 hours post-infection (pi). The ΔbfrDE mutant showed a significant decrease in intracellular survival already after 24 hours pi (p