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Characterization of a genus-specific chlamydial antigen
Abstract
Chlamydia has been identified as a major human and animal pathogen worldwide. The development of effective treatments and methods of prevention of chlamydial disease relies on the understanding of the immunobiology of the organism. This dissertation describes the characterization of a genus-specific antigen isolated from the supernatants of infected cell cultures, termed the glycolipid exoantigen, or GLXA. Initial characterization studies compared GLXA to a class of known glycolipid antigens, the lipopolysaccharides, or LPSs. Results from SDS-PAGE, antibody binding profiles, Limulus ameobocyte lysate assays, and mitogenicity experiments indicated that GLXA differs from various known LPSs by all four parameters. Further characterization of GLXA biochemically and biologically was hindered by impure samples of antigen. Thus, experiments were carried out to determine the most efficient and effective purification method for purification of GLXA. Size fractionation coupled with nucleic acid digestion was effective in yielding pure GLXA samples when analyzed by PAGE, spectrophotometric scanning, enzyme digestion experiments and electron microscopy. A number of biochemical characteristics were then determined for GLXA. Results from these studies indicated that GLXA is a large molecular weight antigen and appears to exist as 10-50nm blebs that may aggregate with purification. In addition, antibody studies coupled with various biochemical treatments suggested that recognition of the relevant epitopes of GLXA are sensitive to environmental and biochemical conditions. Finally, the role of GLXA in infection and disease was investigated. GLXA samples (isolated in various manners) were not mitogenic or cytotoxic for murine splenocytes; however, GLXA isolated by hydrophobic/affinity chromatography exhibited an antiproliferative effect that was not attributable to cytotoxicity. Leukocytes from previously infected mice were not stimulated by GLXA preparations in vitro; however, further studies are necessary to determine the host response to GLXA during infection. GLXA was detectable in supernatants from primary cultures infected with various strains of Chlamydia, indicating an in vivo relevance for the antigen. Finally, pretreatment studies demonstrated that GLXA may play a role in infectivity of the organism. Results from this study strengthen the argument that GLXA is a relevant chlamydial antigen which may play a significant role in chlamydial infection and/or disease.
Subject Area
Microbiology|Immunology
Recommended Citation
Troidle, Karen M, "Characterization of a genus-specific chlamydial antigen" (1992). Doctoral Dissertations Available from Proquest. AAI9233170.
https://scholarworks.umass.edu/dissertations/AAI9233170