HIGH c-di-GMP INTRACELLULAR LEVELS ATTENUATE VIRULENCE OF BORDETELLA BRONCHISEPTICA

BOEHM, DYLAN; DAMRON, FH; GUTIÉRREZ, MARÍA DE LA PAZ; WONG, TING; SISTI, FEDERICO; HALL, JESSE; FERNANDEZ, JULIETA

Bruselas

Simposio; 12th International Symposium on Bordetella; 2019

Bordetella Society

C-di-GMP is a universal bacterial second messenger that regulates a wide variety of phenotypes. In our recent studies we recognized that during in vitro culture conditions c-di-GMP regulates motility and biofilm formation of Bordetella bronchiseptica. However, the role of c-di-GMP signaling during Bordetellainfecton has not been investigated.In order to evaluate the importance of c-di-GMP during Bordetella infec?on, we constructed a plasmid to overexpress the diguanylate cyclase encoded by the B. bronchiseptica bdcA gene. The resulting strain produces high amounts of c-di-GMP (Bb-pBdcA). Outbred CD1 mice were challenged with 1x106 CFU of either the Bb-pBdcA strain or a control strain with empty plasmid (Bb-pEmpty). At 1, 4, and 7 days post challenge mice were: euthanized, bacterial burden was determined, immune cells populations were profiled by flow cytometry, and cytokine quantification was performed,There were significantly less viable Bb-pBcdA bacteria recovered from the respiratory tract compared to the control strain. Bb-pEmpty infected lungs were notably more inflamed than Bb-pBdcA lungs.Furthermore, Bb-pEmpty infected mice had higher levels of pro-inflammatory cytokines (IL-6, IL-1B and TNF-a) and infiltrating phagocytes. In other studies, we have observed that Bb-pBdcA has lower gene and protein expression of the Type Three Secretion System (TTSS) than the control strain. Taken together,these data suggest that ectopic production of high c-di-GMP levels affects B. bronchiseptica capability of infecting and persisting within the host.