| Abstrakt: |
In Europe, the Lyme borreliosis (LB) agents like Borrelia burgdorferisensu stricto (ss), B. afzelii, and B. gariniiare maintained in nature by enzoonotic transmission cycles between vertebrate hosts and Ixodes ricinusticks. The outer surface protein C is a highly antigenic protein expressed by spirochaetes during transmission from ticks to mammals as well as during dissemination in the vertebrate hosts. Previous studies based on analysis of ospCgene sequences have led to the classification of ospCgenotypes into ospCgroups. The aim of this study was to analyse and compare ospCgroup distribution among isolates of the rodent-associated genospecies, B. afzelii, at 3 levels (questing ticks, ticks feeding on rodents, and xenodiagnostic ticks). Isolates were obtained during a study carried out in 2 LB endemic areas located on the Swiss Plateau [Portes-Rouges (PR) and Staatswald (SW)], where rodents were differently infested by co-feeding ticks (Pérez et al., unpublished data). Overall, we identified 10 different ospCgroups with different distributions among isolates from questing ticks, ticks that detached from rodents, and xenodiagnostic ticks at the 2 sites. We observed a higher ospCdiversity among isolates from ticks that fed on rodents at SW, and mixed infections with 2 ospCgroups were also more frequent among isolates from ticks that fed on rodents at SW (n=18) than at PR (n=1). At both sites, B. afzeliiisolates obtained from larvae that were feeding on the rodents simultaneously with nymphs displayed a higher diversity of ospCgroups (mean number of ospCgroups: 2.25 for PR and 1.75 for SW) than isolates from larvae feeding without nymphs (mean number of ospCgroups: 1.17 for PR and 1 for SW). We suggest that co-feeding transmission of Borrelia, previously described in laboratory models, contributes in nature in promoting and maintaining ospCdiversity within local tick populations. |
Full Text from ScienceDirect