IMMUNIZATION OF MICE BY RECOMBINANT OSPA PREPARATIONS AND PROTECTION AGAINST BORRELIA-BURGDORFERI INFECTION-INDUCED BY IXODES-RICINUS TICK BITES

The wide distribution of Borrelia burgdorferi, the spirochete causing Lyme borreliosis, represents a human health hazard in many areas of th e world. Vaccination has been proposed as an effective prevention stra tegy. Vaccination experiments were conducted with preparations of reco mbinant outer surface protein A (OspA) derived from Borrelia burgdorfe ri strain ZS7. Mice received three doses (1 mu g each) of the antigens adsorbed to aluminum hydroxide. A strong immune response to the vacci ne antigen was observed. Mice were challenged after immunization, usin g Ixodes ricinus nymphal ticks infected with Borrelia burgdorferi stra in ZS7. Infection was investigated by ear biopsy culture, xenodiagnosi s with uninfected larvae and serological response to Borrelia burgdorf eri antigens. All unimmunized control animals were found to be infecte d, while all immunized animals were found to be protected against infe ction by Borrelia burgdorferi. In addition, most adult ticks derived f rom nymphs that fed on immunized mice were found to be free of spiroch etes.