Fig 1: Exogenous c-di-AMP enhances B. burgdorferi-induced IFN-I response in vitro and ex vivo.RAW264.7, BMDMs and human THP-1 cells were infected with wild-type (WT) B. burgdorferi 5A4NP1 in the absence and presence of exogenous c-di-AMP (1μg/ml) at an MOI of 10. After 24 hours, supernatants and macrophage cells were collected. The IFN-β protein levels in the supernatant of infected RAW264.7 (A), BMDMs (C), and THP-1 cells (D) were measured by ELISA. The transcript levels of Ifnb1, Cxcl10, or Ifit1 (B) in infected RAW264.7 cells were determined by qRT-PCR analysis (n=3) and normalized with the housekeeping gene actin. The levels of gene expression relative to mock-infected control were reported. The data represent the mean ± SD of at least three experiments (n=3). Statistical significance was assessed using the one-way ANOVA, with *p < 0.05, **p < 0.01 and ***p < 0.001.