ABSTRACT
Specific pathogen-free dogs were experimentally infected with Borrelia burgdorferi sensu stricto using nymphal or adult female Ixodes scapularis ticks artificially infected with spirochetes by capillary feeding. The ticks were capillary fed B. burgdorferi isolate 610, previously isolated from a dog with Lyme disease and grown in BSK medium. This isolate induced clinical signs in the dogs similar to those for dogs infested with ticks naturally infected with B. burgdorferi. Adult ticks were more efficient than nymphs in transmitting spirochetes to the dogs. One of five dogs infested with nymphal ticks capillary fed B. burgdorferi was skin biopsy culture and serologically positive, and demonstrated lameness. In contrast, all five dogs infested with adult female ticks that had been capillary fed with B. burgdorferi were culture and serologically positive, with one dog developing lameness. The immunoblot profiles of dogs challenged with female ticks infected by capillary feeding (8 weeks post challenge) were similar to immunoblots (4 weeks post challenge) from dogs challenged with naturally infected females collected in the field. These studies demonstrated that B. burgdorferi cultured in BSK medium can be capillary fed to either nymphal or adult female ticks under laboratory controlled conditions for the purpose of transmitting the spirochete to dogs during the tick's blood meal. This tick infection system would be useful for a controlled and defined challenge of vaccinated and non-vaccinated dogs for proper evaluation of vaccine efficacy, which is difficult to achieve using field-collected ticks. Furthermore, this system may also be useful for investigation of the pathogenesis of Lyme disease, evaluation of the pathogenicity of new isolates of B. burgdorferi, or evaluation of antibiotic therapy.
