The detection of viral particles in intestinal epithelial cells implicates the occurrence of viral replication in intestinal tissue. In one patient with sucrase isomaltase deficiency, astrovirus particles were found in the lower regions of the villus. In another patient with severe enteropathy due to sensitivity to cow's milk formula, the viral particles were localized in the "exposed surface epithelium." The underlying gastrointestinal problems of these two patients, however, made assessment of the actual significance of the astrovirus infections difficult. So far, the histological effects of human astrovirus-related infections has not yet been studied.
PATHOGENESIS IN CELL CULTURE
Viral entry into cells was studied using a transformed cell line of human embryonic kidney (HEK) cells. The use of chemicals that inhibit viral infection, such as lysosomotropic agents and inonophore monensin, elucidates endocytosis as a necessary step in the successful entry of astroviruses into cells. Furthermore, ultrastructural analysis demonstrated that ten minutes after viral attachment to the cell membrane, viral particles were internalized through invagination of the cell membrane.