The ferrous iron transporter IRP1-3 is required for Bordetella pertussis pathogenesis

CAFIERO, JUAN HILARIO; LAMBERTI, YANINA; ALVAREZ HAYES, JIMENA; RODRIGUEZ, MARIA EUGENIA

Buenos Aires

Simposio; 11th International Bordetella Symposium; 2015

International Bordetella Society

Bordetella pertussis (Bp) survives inside macrophages in compartments with early endosome characteristics. IRP1-3 is one of Bp high affinity iron transporters and the only active at the pH inside early endosomes. To control a bacterial infection, IFN gamma is produced by the host, which depletes iron from phagocytic cells, in order to restrict the growth of intracellular pathogens. This might determine that during Bp intracellular survival there is low iron availability.Objective: Determine the role of IRP1-3 in Bp pathogenesis.Materials and methods: A Bp IRP1-3 null mutant strain and a complemented strain were constructed. The growth in SS liquid medium of these and the parental (wt) strain were measured in parallel and showed no differences. Iron depleted cultures of the strains were compared in an infection assay of PMA differentiated IFN-γ treated THP-1 cells. Immunofluorescence microscopy was used to analyze the uptake of bacteria. The intracellular survival of the strains inside THP-1 cells was analyzed in a polymyxin B protection assay, and the CFU/THP-1 was enumerated at 2, 24 and 48 hours post infection (pi) and normalized to the attachment level of each strain. To analyze the role of IRP1-3 in vivo, BALB/c mice were infected intranasally with either Bp wt or Bp∆IRP1-3 and the lung colonization was evaluated at 0 and 6 days pi. Results: Bp∆IRP1-3 adhered significantly less (p