Affiliation:
1. Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana 59840.
Abstract
The exposure of surface protein antigens on virulent phase I Coxiella burnetti was compared with that on avirulent phase II cells. Although anti-phase II antibodies did not bind to the surfaces of native intact phase I cells, they bound to phase I proteins if the proteins were solubilized for sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analyzed by immunoblotting. In addition, removal of the phase I lipopolysaccharide (LPS) by trichloroacetic acid exposed surface proteins for reactivity with anti-phase II antibodies, as shown by immunofluorescence assays, direct antibody binding, and immunoelectron microscopy using protein A-colloidal gold conjugates. Based on these observations, a simple model of phase variation is proposed to explain the apparently conflicting notions of the identity of the phase II antigen(s). The model suggests that the phase I LPS sterically hinders access of anti-phase II antibodies to a multitude of shared protein antigens, any one of which may confer phase II specificity. Exposure of these shared protein antigens through the appearance of a more truncated LPS (phase II) or extraction of the smooth-type phase I LPS allows antibody accessibility and therefore confers apparent phase II serospecificity.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
64 articles.
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