Transcytosis of infectious human immunodeficiency virus across a tight human epithelial cell line barrier

Contact between various epithelial cell lines and HIV chronically infected mononuclear cell lines results in a massive and rapid budding of HIV virions toward the epithelium followed by their internalization into epithelial endosome-like structures. Here it is shown that as early as 30 minutes after apical contact, primary virus isolates generated from primary peripheral blood leukocytes from HIV-infected patients can cross an epithelial cell line barrier using transcytosis, the characteristic epithelial transcellular vesicular pathway. As the next step in the spread of infection, transcytosed HIV particles can productively infect mononuclear cells located at the basolateral side of the epithelial barrier. These observations suggest an alternative, rapid and efficient mechanism for transmission of HIV across an intact epithelial barrier.