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Measles virus assembly within membrane rafts
S Vincent1, D Gerlier, S N Manié
1Immunité & Infections Virales, VPV, CNRS-UCBL UMR 5537, Faculté de Médecine Lyon RTH Laennec, 69372 Lyon Cedex 08, France.
Abstract:
During measles virus (MV) replication, approximately half of the internal M and N proteins, together with envelope H and F glycoproteins, are selectively enriched in microdomains rich in cholesterol and sphingolipids called membrane rafts. Rafts isolated from MV-infected cells after cold Triton X-100 solubilization and flotation in a sucrose gradient contain all MV components and are infectious. Furthermore, the H and F glycoproteins from released virus are also partly in membrane rafts (S. N. Manié et al., J. Virol. 74:305-311, 2000). When expressed alone, the M but not N protein shows a low partitioning (around 10%) into rafts; this distribution is unchanged when all of the internal proteins, M, N, P, and L, are coexpressed. After infection with MGV, a chimeric MV where both H and F proteins have been replaced by vesicular stomatitis virus G protein, both the M and N proteins were found enriched in membrane rafts, whereas the G protein was not. These data suggest that assembly of internal MV proteins into rafts requires the presence of the MV genome. The F but not H glycoprotein has the intrinsic ability to be localized in rafts. When coexpressed with F, the H glycoprotein is dragged into the rafts. This is not observed following coexpression of either the M or N protein. We propose a model for MV assembly into membrane rafts where the virus envelope and the ribonucleoparticle colocalize and associate.
Insights
Measles virus (MV) proteins M and N, along with envelope glycoproteins, concentrate in membrane rafts. Viral genome presence is crucial for internal MV protein assembly into rafts.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Measles virus (MV) replication involves specific protein localization within host cell membranes.
- Membrane rafts, cholesterol- and sphingolipid-rich microdomains, play roles in viral assembly and budding.
- Previous studies indicated partial localization of MV proteins and glycoproteins in membrane rafts.
Purpose of the Study:
- To investigate the precise localization and requirements for measles virus protein and glycoprotein enrichment in membrane rafts.
- To elucidate the role of the viral genome and protein interactions in raft association during MV assembly.
Main Methods:
- Analysis of MV-infected cells and virus particles using cold Triton X-100 solubilization and sucrose gradient flotation.
- Expression and co-expression of individual and combinations of MV proteins (M, N, P, L) and glycoproteins (H, F) in cells.
- Infection of cells with a chimeric MV (MGV) expressing vesicular stomatitis virus G protein instead of H and F.
Main Results:
- Approximately half of internal MV proteins (M, N) and envelope glycoproteins (H, F) are enriched in membrane rafts.
- Isolated rafts from infected cells contain all MV components and are infectious.
- M and N proteins showed enrichment in rafts during MGV infection, while G protein did not, suggesting genome dependence.
- F glycoprotein intrinsically partitions into rafts; H glycoprotein is recruited to rafts when co-expressed with F, but not with M or N.
Conclusions:
- Measles virus assembly into membrane rafts involves colocalization and association of viral envelope components and the ribonucleoprotein complex.
- The presence of the measles virus genome is essential for the raft assembly of internal viral proteins.
- Specific glycoproteins (F) have intrinsic raft-targeting ability, while others (H) are recruited through interactions.