Figure 2.

APH_0455 is secreted by the Dot/Icm T4SS of C. burnetii. Candidate genes were fused to B. pertussis adenylate cyclase (cyaA), transfected into C. burnetii and selected by chloramphenicol resistance. Transformed C. burnetii clones were then used to infect THP-1 cells. Three days post-transfection, THP-1 cells were assayed for cAMP production. Only those constructs that contain a T4SS signal sequence have measurable changes in cAMP production. The results represent the average of two separate experiments each with replicate tests. The p-values were calculated based on comparisons with fold change of C. burnetii transformed by empty plasmid (CyaA only) using two-sided Student's t-tests, α = 0.05. CBU_0655 is CvpA, a known T4SS substrate of C. burnetii.