Viral infection of cells in culture--approaches for electron microscopy.

In this article we present and discuss three electron microscopical approaches to investigate the pathway of human cytomegalovirus (Herpesviridae) infection in cultivated human macrophages and fibroblasts. These methods include surface scanning electron microscopy and high-pressure freezing combined with freeze-substitution and electron tomography. With this set of methods, basically all steps of the viral cycle can be investigated and documented. These methods are especially helpful to investigate membrane structures, since viral particles of a diameter of 150 nm fit well into a semi-thin section of about 500 nm that can be imaged in three dimensions with STEM tomography.