The ratio of plasma membrane cholesterol to phospholipid and the inhibition of Sindbis virus maturation by low NaCl medium.

Sindbis virus maturation is inhibited by low NaCl medium in chick embryo cells and in one strain of BHK cells, but not in another strain of BHK cells which has a different passage history. The plasma membrane of the cells in which Sindbis virus maturation is resistant to low NaCl medium has a higher ratio of cholesterol to phospholipid than the other cells. Cholesterol-containing liposomes, but not cholesterol-free liposomes, can release Sindbis virus from low NaCl-inhibited cells. These results suggest that low NaCl medium may block Sindbis virus maturation by a mechanism which is influenced by the ratio of plasma membrane cholesterol to phospholipid.