The intimate association of virulent bacteria with host cells is generally recognized as an early and critical event in establishing infection. Because little is known about virulence mechanisms of spirochetes, our work is focused on understanding the pathogenesis of spirochetal diseases at the level of bacterium host cell surface interactions. Investigations of the pathogenesis of syphilis are limited by lack of an in vitro growth system for Treponema pallidum. In comparison, growth of the Lyme disease agent, Borrelia burgdorferi, in culture makes this organism attractive for study. Studies in this laboratory indicate that B burgdorferi, like T. pallidum, attaches to and penetrates some eucaryotic cell monolayers. Based on these data and the morphologic and pathogenic similarities between these organisms, it is possible that a generalized mechanism of spirochetal virulence exists. A study of both organisms is, therefore, proposed. In attachment assays with B burgdorferi and human umbilical vein endothelial cells (HUVEC), we have identified four putative borrelial adhesin molecules. Monoclonal antibodies, chromatography, and molecular cloning will be used to isolate these molecules for biochemical and functional characterization. Colonial growth of B. burgdorferi, on solid media will be exploited to 1) define the association between distinct colony morphology and ability to attach to and/or invade HUVEC monolayers, and 2) isolate and create mutants altered in attachment and/or invasion capabilities. The purified adhesins and the mutants isolated will be used in the third project section, which involves an analysis of the characteristics and mechanism of B. burgdorferi and T. pallidum penetration of endothelial tissue. The unique invasive potential of these organisms will be explored using cultured cell systems and excised human umbilical vein segments. These studies will enhance knowledge of spirochetal virulence mechanisms and will provide the basis for further studies on long-range objective, which are to learn 1) the importance of attachment of spirochetes to host cells, 2) how spirochetes pass in and out of the circulation and 3) why and how certain tissues are targeted in disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29AI026804-05
Application #
3454805
Study Section
Bacteriology and Mycology Subcommittee 2 (BM)
Project Start
1989-04-01
Project End
1994-03-31
Budget Start
1992-04-01
Budget End
1993-03-31
Support Year
5
Fiscal Year
1992
Total Cost
Indirect Cost
Name
University of Texas Health Science Center San Antonio
Department
Type
Schools of Dentistry
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Cadavid, D; Thomas, D D; Crawley, R et al. (1994) Variability of a bacterial surface protein and disease expression in a possible mouse model of systemic Lyme borreliosis. J Exp Med 179:631-42
Thomas, D D; Cadavid, D; Barbour, A G (1994) Differential association of Borrelia species with cultured neural cells. J Infect Dis 169:445-8
Shoberg, R J; Jonsson, M; Sadziene, A et al. (1994) Identification of a highly cross-reactive outer surface protein B epitope among diverse geographic isolates of Borrelia spp. causing Lyme disease. J Clin Microbiol 32:489-500
Sadziene, A; Barbour, A G; Rosa, P A et al. (1993) An OspB mutant of Borrelia burgdorferi has reduced invasiveness in vitro and reduced infectivity in vivo. Infect Immun 61:3590-6
Comstock, L E; Fikrig, E; Shoberg, R J et al. (1993) A monoclonal antibody to OspA inhibits association of Borrelia burgdorferi with human endothelial cells. Infect Immun 61:423-31
Shoberg, R J; Thomas, D D (1993) Specific adherence of Borrelia burgdorferi extracellular vesicles to human endothelial cells in culture. Infect Immun 61:3892-900
Comstock, L E; Thomas, D D (1991) Characterization of Borrelia burgdorferi invasion of cultured endothelial cells. Microb Pathog 10:137-48
Riviere, G R; Weisz, K S; Adams, D F et al. (1991) Pathogen-related oral spirochetes from dental plaque are invasive. Infect Immun 59:3377-80
Sadziene, A; Thomas, D D; Bundoc, V G et al. (1991) A flagella-less mutant of Borrelia burgdorferi. Structural, molecular, and in vitro functional characterization. J Clin Invest 88:82-92