Inhibition of Borrelia burgdorferi migration from the midgut to the salivary glands following feeding by ticks on OspC-immunized mice

Borrelia burgdorferi-infected ticks were fed on either OspC-immunized mice or normal, nonimmunized mice. After 72 h, the ticks were detached, followed by dissection and subsequent culturing in Barbour-Stoenner-Kelley II mediu m of the salivary glands from each tick to determine the presence of borrel iae. Forty percent (10 of 25) of salivary glands from ticks that had fed on nonimmunized mice were culture positive, while only 7.4% (2 of 27) of sali vary glands from ticks: that had fed on OspC-immunized mice were culture po sitive, thus indicating a much reduced borrelial migration from the midgut when the bloodmeal contained anti-OspC antibodies. Fluorescent antibody sta ining of the corresponding midguts from ticks that had fed on the OspC-immu nized mice showed that borreliae were present but did not produce OspC. In contrast, borreliae in midguts from ticks that had fed on normal mice demon strated substantial ospC expression. This study provides evidence that, dur ing tick feeding on an OspC-immunized host, transmission of borreliae from the tick is prevented; it also suggests that OspC functions in a tick-to-ho st transmission mechanism.