Electron microscopic studies of lipopolysaccharides from phase I and phase II Coxiella burnetii.

Lipopolysaccharides from phase I (LPSI) Coxiella burnetii Ohio and Nine Mile strains and from phase II (LPSII) Nine Mile stain were negatively and positively and examined with the electron microscope. The ultrastructure of LPSI and LPSII positively stained with uranyl formate or uranyl acetate was ribbon-like. When negatively stained with uranyl acetate, LPSI was ribbon-like but LPSII exhibited hexagonal lattice structures. However, LPSII stained negatively with sodium phosphotungstate and ammonium molybdate exhibited hexagonal lattice ultrastructures which were not identical to those observed when negatively stained with uranyl acetate. The hexagonal lattice structures formed in vitro were due to the interactions of LPSII and the staining reagents rather than to protein-LPS interactions. The differences in the ultrastructures of LPSI and LPSII are undoubtedly based on variations in their chemical composition.