A FLAGELLA-LESS MUTANT OF BORRELIA-BURGDORFERI AS A LIVE ATTENUATED VACCINE IN THE MURINE MODEL OF LYME-DISEASE

The immunogenicity and protective efficacy of an attenuated isolate of Borrelia burgdorferi, the agent of Lyme disease, were evaluated. An i sogenic pair of isolates of strain HB19 differed in the expression of flagella; neither produced systemic infection or persisted in the skin of mice, In a comparison of intradermally administered live flagella- bearing and flagella-less cells, the flagellaless isolate was equal to or superior to the flagella-bearing wild type in eliciting growth-inh ibiting antibodies and preventing infection in mice. In a comparison o f live and killed flagella-less cells, immune responses to live cells were superior to those to killed cells, as assessed by ELISA, growth i nhibition assay, and infectious challenge. The dose protecting 50% of mice was 10(3.8) and 10(5.2) for live and killed cells, respectively ( P <.05).