Fig. 1

Experimental design and sample collection. a Mice were experimentally infected with spirochetes of B. afzelii grown in BSK-II medium (n = 10) while the uninfected group received an injection containing only BSK-II medium (n = 10). At day 30 (3 weeks post-infection), mice were infested with I. ricinus larvae (n = 100 per mouse). Sera of mice were rcollected to check infection by western blot and engorged ticks were collected and used for tick microbiota analysis. b Mice were immunized with a live vaccine containing E. coli BL21 (n = 5) or with a mock vaccine (PBS) (n = 5) at day 0. Subsequently, mice were experimentally infected with B. afzelii at day 7 followed by a booster shot of the live or mock vaccine at day 14. Mice from both groups were then infested with I. ricinus larvae (n = 100 ticks per mouse) at day 30. Mice sera were collected at different timepoints as indicated for ELISA experiments and engorged ticks were collected and their DNA extracted for tick microbiota analysis and pathogen level quantification