Topological location and biological significance of phospholipids in the membrane of Newcastle disease virus. Hydrolysis of phospholipids in intact virion with pure phospholipases A2, C, and D.
The composition, topological distribution and biological significance of phospholipids in the membrane of Newcastle disease virus (NDV) grown in embryonated chicken eggs were investigated. Phosphatidylethanolamine and sphingomyelin were the predominant phospholipids in NDV membrane. The location of phospholipids in the lipid bilayer of the membrane was studied by assessing their reactivities with highly purified phospholipase A2 (Agkistrodon halys blomhoffi) and phospholipase D (Streptomyces chromofuscus), and the biological role of membrane phospholipids was also investigated by using pure phospholipases A2, C (Bacillus cereus) and D. Choline-containing phospholipids were found predominantly in the outer layer of the membrane. The inner layer was composed mainly of aminoglycerophospholipids, though a fair amount of them also appeared to be located in the outer half of the bilayer. When intact virion was treated with phospholipase C, marked decreases in hemolytic activity and infectivity mediated by viral fusion (F) glycoprotein were observed, but hemagglutinating and neuraminidase activities did not change significantly. Apparently complete hydrolysis of phospholipids in the outer half of the lipid bilayer with phospholipase D caused about 22% decrease in the original hemolytic activity. On the other hand, when all phosphatidylcholine and aminoglycerophospholipids in the outer half of the viral membrane were hydrolyzed with purified phospholipase A2, no significant change in viral hemolytic activity or morphology was detected. No marked change of hemagglutinating and neuraminidase activities was detected on treatment of NDV with phospholipases A2 and D. The above results suggest that the integrity of fatty acid ester of glycerophospholipids in NDV membrane is not essential for the manifestation of viral activities, though polar groups of the phospholipids in the outer half of the membrane may be involved in the function of fusion (F) glycoprotein, but not in that of hemagglutinating and neuraminidase (HN) glycoprotein of NDV.
D006868:Hydrolysis; D008563:Membrane Lipids / Q000032:analysis*; D009522:Newcastle disease virus / Q000032:analysis* / Q000187:drug effects; D017830:Octoxynol; D010739:Phospholipase D; D010741:Phospholipases A; D054467:Phospholipases A2; D010743:Phospholipids / Q000032:analysis*; D011092:Polyethylene Glycols; D010738:Type C Phospholipases
D008563:Membrane Lipids; D010743:Phospholipids; D011092:Polyethylene Glycols; D017830:Octoxynol; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D010739:Phospholipase D