Figure 5.

Immunization with BBI36, BBI39, or their combination interferes with spirochete transmission from infected ticks to naive rodent hosts. Mice (n = 3 animals/group) were immunized with either BBI36 or BBI39 or their combination (combo) or phosphate-buffered saline (PBS) with adjuvant (control). Ten days after final immunization, mice were bled to check development of specific antibodies and allowed to be parasitized by Borrelia burgdorferi–infected nymphs (n = 5 ticks/mouse). A, Enzyme-linked immunosorbent assay (ELISA) and immunoblot analysis showing high-titer serum antibodies induced in individual immunized mouse, as detailed in Figure 4A. B, Borrelia burgdorferi burden in fully engorged nymphs assessed by measuring copies of the B. burgdorferi flaB RNA and normalized against tick β-actin levels. Bars represent the mean ± SEM of 3 quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses derived from 3 independent infection experiments (*P < .05). C, Murine tissues were assessed for spirochete transmission during early (1 week) or late (3 weeks) infection. Total RNA was isolated from murine samples, and B. burgdorferi flaB was measured using qRT-PCR, normalized against corresponding murine β-actin levels. The animal studies were repeated 3 times, and the bars represent the mean measurements ± SEM of 3 experiments. Mice immunized with BBI36, BBI39, or their combination had significantly less B. burgdorferi burden (*P < .05) than control mice.