Bordetella bronchiseptica adherence to cilia is mediated by multiple adhesin factors and blocked by surfactant protein A.
In the virulent state (Bvg+), Bordetella bronchiseptica expresses adhesins and toxins that mediate adherence to the upper airway epithelium, an essential early step in pathogenesis. In this study, we used a rabbit tracheal epithelial cell binding assay to test how specific host or pathogen factors contribute to ciliary binding. The host antimicrobial agent surfactant protein A (SP-A) effectively reduced ciliary binding by Bvg+ B. bronchiseptica. To evaluate the relative contributions of bacterial adhesins and toxins to ciliary binding, we used mutant strains of B. bronchiseptica in the binding assay. When compared to Bvg+ or Bvg- phase-locked B. bronchiseptica strains, single-knockout strains lacking one of the known adhesins (filamentous hemagglutinin, pertactin, or fimbriae) displayed an intermediate ciliary binding capacity throughout the coincubation. A B. bronchiseptica strain deficient in adenylate cyclase-hemolysin toxin also displayed an intermediate level of adherence between Bvg+ and Bvg- strains and had the lowest ciliary affinity of any of the Bvg+ phase strains tested. A B. bronchiseptica strain that was missing dermonecrotic toxin also displayed intermediate binding; however, this strain displayed ciliary binding significantly higher than most of the adhesin knockouts tested. Taken together, these findings suggest that virulent-state B. bronchiseptica expresses multiple adhesins with overlapping contributions to ciliary adhesion and that host production of SP-A can provide innate immunity by blocking bacterial adherence to the ciliated epithelium.
Edwards
Jessica A
JA
Arizona Respiratory Center, Room 2338, AHSC Arizona Health Sciences Center, 1501 N. Campbell Avenue, Tucson, AZ 85724-5030, USA.
Groathouse
Nathan A
NA
Boitano
Scott
S
D018829:Adhesins, Bacterial / Q000502:physiology*; D000818:Animals; D001422:Bacterial Adhesion; D016950:Bordetella bronchiseptica / Q000502:physiology*; D002923:Cilia / Q000382:microbiology*; D006388:Hemagglutinins / Q000502:physiology; D037662:Pulmonary Surfactant-Associated Protein A / Q000494:pharmacology*; D011817:Rabbits
D018829:Adhesins, Bacterial; D006388:Hemagglutinins; D037662:Pulmonary Surfactant-Associated Protein A