The use of immunogold-silver staining to study antigen variation and bacterial entry into eukaryotic cells by conventional light microscopy.

Immunogold-silver staining is a sensitive staining technique that enables the visualisation of the presence of individual antigens by conventional light microscopy. The application of this method to detect the antigenic heterogeneity of bacterial surface components and also the localisation of intracellular or extracellular bacteria is described. The latter application involved selective immuno-silver staining of the extracellular bacteria and counterstaining of the intracellular bacteria and the eukaryotic cells by crystal violet. The efficacy of the assay was confirmed by transmission electronmicroscopy of the silver-stained specimens. Immunogold-silver staining was shown to be useful for studying bacterial antigen variation and the uptake of bacteria by eukaryotic cells.