Soluble Proteins Isolated fromBorrelia burgdorferiby Extraction with Triton X-114 Confer Resistance to Experimental Infection

Fractionation ofBorrelia burgdorferiwas made by extraction of infectious spirochetes using the detergent Triton X-114. Gel electrophoresis analysis of hydrophilic and hydrophobic proteins demonstrated that detergent extraction resulted in two populations of proteins with nonoverlapping electrophoretic profiles. Immunoblot analysis with monoclonal antibodies reactive with two abundant membrane proteins demonstrated that hydrophilic proteins were uncontaminated with hydrophobic proteins. In addition, assay of thymidine incorporation into and secretion of tumor necrosis factor-α from splenocytes coculturedin vitrowith either detergent or aqueous phase proteins showed that lymphocyte mitogenic and macrophage activation activities ofB. burgdorferiwere completely absent from the hydrophilic phase proteins. The Triton X-114 aqueous and detergent phase proteins were used to immunize BALB/c and separately μMT/μMT (B cell knockout) mice that were subsequently challenged with infectiousB. burgdorferi.The hydrophilic phase proteins were able to induce protective resistance to infection in either strain of mice demonstrating that potential candidate vaccine antigens are contained in the biochemical class of antigens which is devoid of both lymphocyte mitogen activity and major outer surface proteins. Furthermore, the ability to vaccinate B cell knockout mice suggests that the humoral antispirochete immune response is not the exclusive basis for protective immunity.