The uninfected larvae acquire Borrelia
only after taking a blood meal from
infected white - footed mice previously bitten
by other
infected ticks.
Although this high dose elicited a seroconversion in all mice injected with either B31 - A3 (2/2) or ospC7 mutant bacteria (4/4),
only mice inoculated with B31 - A3 became
infected (2/2), as assessed
by xenodiagnosis with larval
ticks and reisolation from mouse tissues.