αVβ3-integrin routes herpes simplex virus to an entry pathway dependent on cholesterol-rich lipid rafts and dynamin2

HSVs enter cells in a receptor-dependent [nectin1 or herpesviruses entry mediator (HVEM)] fashion by fusion of the viral envelope with plasma membrane (neutral pH compartment), by endocytosis into neutral or acidic compartments, or by macropinocytosis/phagocytosis. The cellular determinants of the route of entry are unknown. Here, we asked what cellular factors determine the pathway of HSV entry. CHO cells lack beta(3)-integrin and the respective alpha-subunits' heterodimers. We report that, in the absence of alpha(v)beta(3)-integrin, HSV enters CHO-nectin1 cells through a pathway independent of cholesterol-rich rafts and dynamin2. In the presence of alpha(v)beta(3)-integrin, HSV enters CHO-nectin1 cells through a pathway dependent on cholesterol-rich rafts and dynamin2. HSV enters J-nectin1 and 293T cells through a neutral compartment independent of cholesterol-rich rafts and dynamin2. alpha(v)beta(3)-integrin overexpression in these cells modifies the route of entry to an acidic compartment dependent on cholesterol-rich rafts and dynamin2, hence similar to that in alpha(v)beta(3)-integrin-positive CHO-nectin1 cells. In some cells, the diversion of entry from an integrin-and raft-independent pathway to an acidic compartment requiring cholesterol-rich lipids rafts and dynamin2 is irreversible. Indeed, HSV cannot infect CHO-nectin1-alpha(v)beta(3) cells through any compartment when the alpha v beta 3-integrin-dependent pathway is blocked by anti-integrin antibody, anti-dynamin2, or anti-acidification drugs. We conclude that the alpha v beta 3-integrin is a determinant in the choice of HSV entry pathway into cells. Because the pathway dictated by alpha v beta 3-integrin is through lipid rafts, the platforms for a number of Toll-like receptors, current findings raise the possibility that alpha v beta 3-integrin acts as a sentinel of innate immunity.