BUDDING OF ENVELOPED VIRUSES FROM THE PLASMA-MEMBRANE

Many enveloped viruses are released from infected cells by maturing an d budding at the plasma membrane. During this process, viral core comp onents are incorporated into membrane vesicles that contain viral tran smembrane proteins, termed 'spike' proteins. For many years these spik e proteins, which are required for infectivity, were believed to be in corporated into virions via a direct interaction between their cytopla smic domains and viral core components. More recent evidence shows tha t, while such direct interactions drive budding of alphaviruses, this may not be the case for negative strand RNA viruses and retroviruses, These viruses can bud particles in the absence of spike proteins, usin g only viral core components to drive the process. In some cases the s pike proteins, without the viral core, can be released as virus-like p articles. Optimal budding and release may, therefore, depend on a 'pus h-and-pull' concerted action of core and spike, where oligomerization of both components plays a crucial role.