CMV induced vascular injury: an electron-microscopic study in the rat.

There is evidence in support of a viral etiology for atherosclerosis. In our study, we demonstrated that cytomegalovirus (CMV) infection in rats caused morphological alterations of the endothelium and subendothelial space of the large vessels and that these alterations are similar to those which are induced by hypercholesterolemia. These alterations consisted of swollen endothelial cells with a surface showing bleb and microvilli formation. In addition, adhesion of leukocytes to the endothelium and the presence of leukocytes (lymphocytes and macrophages) in the subendothelium were found. Lipid accumulation occurred in the endothelium and in the subendothelial space, especially in hypercholesterolemic animals. This lipid accumulation in the subendothelial space consisted of extracellular lipid deposition and of subendothelial located "foam cells". A characteristic phenomenon of the effect of CMV infection of rats was a loosening of the endothelial cells from the basement membrane. The space between the basement membrane and endothelium was expanded and was filed with an increased amount of reticular basal lamina-like material. These observations show that CMV infection is associated with a non-deniding aortic endothelial injury which is consistent with the early events in the process of atherosclerosis.