Lyme disease is a tick-borne zoonosis. The major tick vectors of B. burgdorferi are Ixodes species which lack host specificity. Control of this disease through reducing the population of the rodent reservoirs and larger mammalian hosts is impractical and may actually be counterproductive. The widespread use of acaricides is of questionable effectiveness and may have adverse environmental effects due to their lack of specificity. A major step toward the control of Lyme disease in domestic animals and humans is the development of a safe, effective and relatively inexpensive vaccine. The number of cases of Lyme disease in domestic animals and humans are increasing. Lyme disease is a complex zoonosis maintained in natural foci between its tick vectors and animal hosts. Recreational activities and living close to "nature" has resulted in greater exposure to the tick vectors. We have shown that hamsters can be protected from experimental infection by B. burgdorferi by either passive or active immunization. This suggests the feasibility of a Lyme disease vaccine for protecting both domestic animals and humans from this disease. The identification and characterization of the antigen(s) of B. burgdorferi responsible for immunity to infection will facilitate the development of a safe and effective vaccine for Lyme disease. In addition, these studies should increase our understanding of the nature of the immune response to B burgdorferi. The specific aims of this proposal are: 1) To identify immunotypes of B. burgdorferi in various geographical areas, 2) to identify the antigenic components(s) of B. burgdorferi associated with immunotype specificity, 3) to characterize antigenic components(s) of B. burgdorferi associated with immunotype specificity, 4) to investigate interaction of immunotype specific antibody with B. burgdorferi and 5) to develop oligonucleotide probes to identify the physical location of the gene(s) that express the immunogenic components(s) of B. burgdorferi.