JUNV infects Vero cells by clathrin mediated endocytosis”

MARTINEZ, M.GUADALUPE, CORDO, SANDRA M. AND CANDURRA, NÉLIDA A.

Rosario, Santa Fé, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB); 2006

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB)

Junin virus (JUNV) entry is conducted by receptor mediated endocytosis. Previous results, using compounds that specifically blocked different entry pathways, have suggested that JUNV would use clathrin mediated endocytosis to infect Vero cells. To further explore the cellular entry mechanism of JUNV, assays with 35S-methionine-labeled virions were performed and the kinetics of binding and internalization was determined. We found that with chlorpromazine (CPZ), which inhibits clathrin mediated endocytosis or nystatin (NT), that alters lipid raft microdomains impairing caveolae mediated endocytosis, virion binding does not seem to be affected. In contrast, radioactivity levels that represents internalization of JUNV, showed a significant reduction when cultures were treated with CPZ. To have a direct evidence JUNV entry, transmission electron microscopy (EM) was performed. EM showed JUNV particles of about 60 to 100 nm in membrane depressions that had an electron-dense coating. In addition JUNV particles were found within invaginations of the plasma membrane and vesicles that resembled those of pits and clathrin-coated vesicles. Taken together our results demonstrate clathrin mediated endocytosis as the main JUNV entry pathway into Vero cells and represents an important contribution to the characterization of arenavirus multiplication cycle.