ACQUIRED-RESISTANCE TO BORRELIA-BURGDORFERI INFECTION IN THE RABBIT -COMPARISON BETWEEN OUTER SURFACE PROTEIN-A VACCINE-DERIVED AND INFECTION-DERIVED IMMUNITY

Intradermal inoculation of the rabbit with Borrelia burgdorferi, sensu lato, results in the consistent development of erythema migrans (EM), dermal infection, and visceral dissemination of the spirochete. Withi n 5 mo, EM as well as dermal and visceral infection are cleared and th e animals exhibit immunity to reinfection. This study compares infecti on-derived immunity with acquired resistance resulting from the admini stration of a lipidated recombinant outer surface protein A (OspA) vac cine presently undergoing human trial. 4 of 11 OspA vaccinated rabbits , challenged intradermally at each of 10 sites with 10(5) low passage B. burgdorferi, developed EM as well as dermal and disseminated infect ion. After identical challenge, 2 of the 11 infection-immune rabbits d eveloped a dermal infection, but not EM or disseminated infection. Fur ther, ELISA anti-OspA titers did not correlate with the status of immu nity for either OspA vaccinated or infection-immune rabbits. Prechalle nge ELISA anti-OspA titers were relatively low in the infection-immune group. This study demonstrates that a state of partial immunity to ex perimental Lyme disease may result that could potentially mask infecti on. Further, our data strongly suggest that immunogen(s) other than Os pA is/are responsible for stimulating acquired resistance in the infec tion-immune rabbit.