Coinoculation of Borrelia spp. with tick salivary gland lysate enhances spirochete load in mice and is tick species-specific

C3H/HeN mice were inoculated with 10(6) spirochetes, either Borrelia burgdorferi strain N40 or the Portuguese strain of B. lusitaniae, PotiB2. Mice receiving spirochetes comoculated with salivary gland lysate (SGL) demonstrated significantly higher spirochete loads in target organs as measured by quantitative real-time polymerase chain reaction. This effect was tick dependent. in that Ixodes ricinus SGL specifically enhanced B. lusitaniae load, whereas I. scapidaris SGL specifically increased B. burgdorferi N40 load, but did not significantly affect the dissemination of B. lusitaniae. Protein profile analysis indicated at least 5 major protein differences between I. scapiularis and I. ricinus SGL, which can possibly account for this specific tick-spirochete interaction.