Ultrastructural Localization of Carbohydrate Determinants of Lipopoly-Saccharide of 'Coxiella burnetii' (Phase 1) by Monoclonal Antibodies

摘要

Coxiella burnetii, the etiological agent of Q fever, is an obligate phagolysosomal bacterium and an unorthodox spore former. Morphologically distinct cell types, produced by a developmental cycle, are defined as a large cell (LCV) and small cell variants (SCV). Recent study has shown that phase I lipopoly-saccharide (LPS-I) is differentially expressed among the cell variants. This antigenic variation was investigated further by use of a series of monoclonal antibodies (MAbs), directed against LPS-I, and post-embedding immuno-labelling techniques. Since these MAbs recognize carbohydrate determinants of LPS-I, the specificity of the labelling was tested by carbohydrate reducing and oxidizing reagents prior to labelling. We conclude that the LPS-I epitope recognized by MAb 1135 is differentially expressed among the cell variants. The pattern of immuno-labelling suggests that the morphologic variants undergo differentiation as a genetic mechanism for antigenic masking. The specificity of the MAbs for the carbohydrate epitopes of the LPS was verified by the use of either Na-m-periodate or phenol-water. The absence of the label after chemical treatment stresses caution in the use of etching solutions, which have been described for enhancing antigen recognition. Reprints. (aw)