Identification of lipid components of human serum lipoproteins involved in the inhibition of Sindbis virus infectivity, hemagglutination, and hemolysis.

Human serum high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL) were isolated and tested for their ability to inhibit Sindbis virus infectivity, hemagglutination and hemolysis. VLDL and LDL produced a strong reduction on both viral infectivity on Vero cell monolayers and attachment and fusion with erythrocytes, whereas HDL appeared to be only a weak inhibitor. Lipid and protein components were extracted from each class of lipoproteins to identify the molecules responsible for the inhibiting activity. Only the lipid moiety was found to inhibit Sindbis virus biological activities. Among the individual lipid components of lipoproteins, neutral lipids (cholesterol, oleic acid and palmitic acid) and negatively charged phospholipids (phosphatidylserine and phosphatidylinositol) and glycolipids (GM 3 ganglioside and cerebroside sulphate) were able to neutralize the virus suggesting that either hydrophobic or electrostatic interactions are involved in the inhibition.