Dansylcadaverine and cytochalasin D enhance rotavirus infection of murine L cells.

Although murine L cells bind and internalize rotavirus as well as permissive cell lines, L cells are essentially nonpermissive for rotaviruses. In nonpermissive cell lines such as L cells, internalized rotavirus fails to uncoat and remains as infectious, double-shelled particles. This block in the infectious cycle can be overcome by direct lipofection of viral particles into the L cell cytoplasm. We hypothesized that the internalized rotavirus particles within L cells are sequestered in the endocytic pathway and are unable to initiate infection. L cells were pretreated with a variety of inhibitors of endocytosis prior to infection with rhesus rotavirus. While agents which inhibit acidification of endosomes had no effect on rotavirus infection, two potential direct inhibitors of vesicular transport, dansylcadaverine and cytochalasin D, enhanced rotavirus infection of L cells 5- to 10-fold. All of the drugs, including both inhibitors of endocytosis and lysosomotrophic agents, significantly reduced infection of L cells by serotype 1 reovirus which is known to infect L cells by the endocytic pathway. Time course studies demonstrated that the drugs were effective in promoting rotavirus infection of L cells in only the early phases of infection. Pretreatment of L cells with dansylcadaverine significantly decreased the number of intact, double-shelled rotavirus particles sequestered within the cells. Inhibition of endocytosis may increase the efficiency of infection of L cells by rotavirus by allowing an increased proportion of attached rotavirus virions to enter cells by a productive route which is probably direct membrane penetration.