Fig. 8. Ixodes Dome1 and JAK–STAT signaling pathway is required for optimal blood meal engorgement of B. burgdorferi-infected ticks and spirochete transmission to mice.

(A) Transstadial knockdown of Dome1, JAK, and STAT in infected unfed nymphs. Larvae that had engorged on B. burgdorferi-infected mice were microinjected with target dsRNA and allowed to molt. Transcripts in the infected nymphs were analyzed by RT-qPCR. (B) B. burgdorferi levels in unfed nymphs, as measured by the RT-qPCR assessment of flaB transcripts normalized against tick Actb levels. (C) Damaged tick mouthparts. Unlike the control or JAK-knockdown ticks, the detached Dome1- or STAT-knockdown ticks displayed distorted mouthparts (arrowheads). (D to F) The feeding parameters for the various groups are presented as the tick attachment time (D), number of fed ticks (E), and engorgement weight (F). Asterisks denote significant differences between dsDome1 or dsSTAT to other groups. **P < 0.05, determined using two-tailed Student’s t test. (G and H) Assessment of pathogen transmission to mice. 12 days after tick feeding, infection in individual animals was assessed by sera immunoblotting (G), or RT-qPCR assays (H) using one tissue sample per organ, except for proximal and distant skin samples relative to tick bite sites, by measuring copies of B. burgdorferi flaB transcripts normalized against mouse Actb levels. Arrows indicate murine tissue samples in dsDome1 or dsSTAT groups where flaB transcripts remain undetectable. For immunoblotting, sera from naïve mice and mice that were previously infected with B. burgdorferi were used as negative (−) and positive (+) controls, respectively. Loading controls are presented in fig. S12. Results are representative of three independent experiments where quantitative data are shown as individual data points; error bars show the means ± SDs (n = 9 to 36). White bar: 100μμm. *P < 0.05, determined using two-tailed Mann-Whitney U test; n.s., not significant.