Measles virus structural components are enriched into lipid raft microdomains: a potential cellular location for virus assembly

The process of measles virus (MV) assembly and subsequent budding is though t to occur in localized regions of the plasma membrane, to favor specific i ncorporation of viral components, and to facilitate the exclusion of host p roteins. We demonstrate that during the course of virus replication, a sign ificant proportion of MV structural proteins were selectively enriched in t he detergent-resistant glycosphingolipids and cholesterol-rich membranes (r afts). Isolated rafts could infect the cell through a membrane fusion step and thus contained all of the components required to create a functional vi rion. However, they could be distinguished from the mature virions with reg ards to density and Triton X-100 resistance behavior. We further show that raft localization of the viral internal nucleoprotein and matrix protein wa s independent of the envelope glycoproteins, indicating that raft membranes could provide a platform for MV assembly. Finally, at least part of the ra ft MV components were included in the viral particle during the budding pro cess. Taken together, these results strongly suggest a role for raft membra nes in the processes of MV assembly and budding.