NATURE AND FUNCTION OF STRUCTURAL PHOSPHOLIPIDS OF AN ARBOVIRUS

Semliki Forest virus, a group A arbovirus, contains a number of structural phospholipids, most of which are hydrolyzed by treatment with purified phospholipase C from Clostridium perfringens. The enzyme treatment does not alter the density at which the virus sediments to equilibrium in sucrose gradients. The infectivity of the virus is preserved despite hydrolysis of more then 60% of its phospholipids by limited enzyme treatment at 37 °C. Longer enzyme treatment at 37 °C results in a marked decrease in infectivity but little additional phospholipid hydrolysis. When phospholipase C treatment was arrested by EDTA after 45% of the phospholipid had been hydrolysed, and the virus was then incubated for an additional 30 minutes at 37 °C, inactivation of the virus also occurred. Inactivation of the virus by the enzyme at 37 °C appeared to be associated with release from the virion of its structural proteins. Thus, the results suggest that phospholipids, while not necessary for viral infectivity, do stabilize the structure of the virus. © 1969.