PHOSPHOLIPID BIOSYNTHESIS AND POLIOVIRUS GENOME REPLICATION, 2 COUPLED PHENOMENA

Poliovirus infection leads to an increase of phospholipid synthesis and the proliferation of new membranes, giving rise to a great number of cytoplasmic vesicles in the infected cells. Viral RNA replication is physically associated with these newly-synthesized membranes. Cerulenin, an inhibitor of lipid biosynthesis, effectively blocks the growth of poliovirus in HeLa cells. The presence of cerulenin after virus entry prevents the synthesis of poliovirus proteins. However, if this antibiotic is added at later stages of the virus replication cycle, it has no effect on viral translation itself, nor on the proteolytic processing and myristoylation of poliovirus proteins. The synthesis of viral, but not cellular RNA is selectively inhibited by cerulenin. Analysis of the viral RNA made in poliovirus-infected cells by specific minus- or plus-stranded RNA probes suggests a selective blockade by cerulenin of plus-strand RNA synthesis. Finally, the synthesis of phospholipids and the proliferation of membranes does not take place if cerulenin is added to the culture medium. These findings indicate that continuous phospholipid synthesis is required for efficient poliovirus genome replication and provide new insights towards the understanding of the molecular events that occur during poliovirus growth.