SUMMARY: The surface ultrastructure of 21 strains of was investigated by electron microscopy. Rat monoclonal antibodies (mAbs) were used to define serogroups and to detect the location of surface antigens. All 21 isolates had capsules as demonstrated by the use of wet and dry Indian ink stains. Negative staining of whole cells with 1% (w/v) methylamine tungstate showed that all 21 isolates carried clumped peritrichous fibrils with strain dependent morphology, density and length (≦0.75μm). Fibrils on 11 of 13 fresh clinical isolates were more conspicuously clumped and easily visible, whereas those on 6 of 8 laboratory strains were indistinct and were at the limits of the resolution of the negative staining technique. Staining with ruthenium red (), followed by thin sectioning, revealed a dense, amorphous staining layer (), up to 24.8φ3.0 nm thick, adjacent to the outer membrane on all of 15 strains examined. All isolates had a less dense staining matrix () extending away from the The structure of the varied between strains. Four rat mAbs (376.1, 381, 391.1 and 403.2) were used to serogroup the 21 strains of Immunonegative staining revealed that the mAbs were not directed against fibrils. Antigens recognized by mAb 376.1 and mAb 391.1 were located on the surfaces of cells, beneath fibrils, and on extracellular vesicles. mAb 381 recognized an antigen which was most accessible on lysed cells, and non-specific binding of mAb 403.2 to grids prevented its localization on the cell surface.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error