Direct Immunogold Labeling of Herpesvirus Suspensions

Gold particles in colloidal suspension are particularly well suited as markers for immune electron microscopy. Their extreme electron opacity ensures that they are detected with accuracy even at particle sizes of less than 3 nm. Gold spheres can be made easily and inexpensively by reduction of gold chloride with mild acid and heat (1 ), and particles can be prepared in a variety of sizes by varying the nature of the reducing agents (2 ).