APODEMUS SP RODENTS, RESERVOIR HOSTS FOR BORRELIA-AFZELII IN AN ENDEMIC AREA IN SWITZERLAND

Borrelia burgdorferi is maintained in nature in transmission cycles al ternatively involving ticks and reservoir hosts. Small rodents like Ap odemus mice and Clethrionomys voles are the primary reservoir of Lyme disease in Europe. In this study, we analyzed by SDS-PAGE and Western blot 20 borrelial isolates from xenodiagnostic ticks fed on four Apode mus sp. mice captured in the Staatswald forest (Switzerland). All isol ates but one showed a homogeneous protein pattern expressing an outer surface protein, (Osp) A of 32 kDa and an OspB of 35 kDa and reacted w ith monoclonal antibody (mAb) I 17.3 specific for B. afzelii. One isol ate expressed an OspA of 32.5 kDa and an OspB of 35 kDa and did not re act with species-specific mAbs I 17.3, D6 and H3TS, but was shown to b elong to B., afzelii by Southern blot analysis. The possibility exists that non-cultivatable borreliae are present in xenodiagnostic ticks. However, our results clearly show that Apodemus sp. are reservoir host s for B. afzelii, since this genospecies is transmitted from Apodemus sp. to feeding larval ticks.