Infection of polarized cultures of human intestinal epithelial cells with hepatitis A virus: Vectorial release of progeny virions through apical cellular membranes

Although hepatitis A virus (HAV) is typically transmitted by the fecal-oral route, little is known of its interactions with cells of the gastrointesti nal tract. We studied the replication of HAV in polarized cultures of Caco- 2 cells, a human cell line which retains many differentiated functions of s mall intestinal epithelial cells. Virus uptake was 30- to 40-fold more effi cient when the inoculum was placed on the apical rather than the basolatera l surface of these cells, suggesting a greater abundance of the cellular re ceptor for HAV on the epical surface. Infection proceeded without cytopathi c effect and did not influence transepithelial resistance or the diffusion of inulin across cell monolayers. Nonetheless, there was extensive release of progeny virus, which occurred almost exclusively into apical supernatant fluids (36.4% +/- 12.5% of the total virus yield compared,vith 0.23% +/- 0 .13% release into basolateral fluids). Brefeldin A caused a profound inhibi tion of HAV replication, but also selectively reduced epical release of vir us. These results indicate that polarized human epithelial cell cultures un dergo vectorial infection with HAV and that virus release is largely restri cted to the apical membrane. Virus release occurs in the absence of cytopat hic effect and may involve cellular vesicular transport mechanisms.