Potassium tartrate-glycerol as a density gradient substrate for separation of small, round viruses from human feces.

Cesium chloride density gradients are frequently used for virus concentration or purification in the preparation of human feces for examination by electron microscopy, Disruption of some of the fecal viruses occurs if they are pelleted from the density gradient in an additional concentration step. This report highlights an important limitation imposed by the use of cesium chloride as a density gradient substrate in attempting to recover small, round, virus-like particles from feces and suggests an alternative substrate which preserves virus morphology without the use of additional protective agents.