This project serves to consolidate and to expand our efforts at identifying, localizing, and characterizing genes and gene products which are important in host pathogen relationships. While we have used colloidal gold and ferritin labeling to identify important cellular components which are located on the surface of various pathogens, new techniques of cryofixation, cryoultramicrotomy and immune-labeling will allow precise localization of important antigens which may be located inside the cell. A broad range of molecular techniques will allow tracking of antigens through synthesis, processing and genetic control modulation. Recently, intimate associations between nucleic acids and elaborated membrane vesicles have been demonstrated in a number of pathogenic microorganisms, including Borrelia burgdorferi. Efforts are underway to determine the structure, composition and possible role of these membrane vesicles in the pathobiology of B. burgdorferi. Initial experiments have suggested that membrane vesicles are composed of a unique subset of glycosylated proteins, which are detectable in urine, blood and tissues of infected animals. An electron microscope antigen capture/detection method has been developed and patented.