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Flavivirus West Nile (Sarafend) egress at the plasma membrane
M L Ng1, J Howe, V Sreenivasan
1Department of Microbiology, National University of Singapore.
Abstract:
West Nile (Sarafend) virus was distinctly observed to bud from the plasma membrane rather than mature intracellularly. This has been observed with transmission electron microscopy. Using conventional scanning electron microscopy, budding at the plasma membrane especially at the filopodia was clearly illustrated. Immunogold labelling against the virus envelope protein was also performed to confirm this mode of exit. The gold particles were observed to be located at the sites where virus budding was seen under the field emission scanning electron microscope.
Insights
West Nile virus exits cells by budding from the plasma membrane, particularly at filopodia. This unique exit mechanism was visualized using advanced electron microscopy and immunogold labeling techniques.
Area of Science:
- Virology
- Cell Biology
- Microscopy
Background:
- West Nile virus (WNV) is a significant public health concern.
- Understanding viral replication and egress is crucial for developing antiviral strategies.
Purpose of the Study:
- To elucidate the precise mechanism of West Nile virus egress from infected host cells.
- To visualize the site and process of WNV particle release.
Main Methods:
- Transmission electron microscopy (TEM) for intracellular maturation assessment.
- Scanning electron microscopy (SEM) for visualizing surface budding.
- Field emission scanning electron microscopy (FESEM) for high-resolution imaging.
- Immunogold labeling targeting the WNV envelope protein.
Main Results:
- West Nile virus particles were observed to bud directly from the plasma membrane.
- Budding was particularly prominent at filopodia extensions of the host cell.
- Immunogold labeling confirmed the presence of viral envelope proteins at budding sites.
- No evidence of intracellular maturation and subsequent release was observed.
Conclusions:
- West Nile virus utilizes a non-lytic, plasma membrane budding mechanism for egress.
- Filopodia serve as key sites for WNV release.
- This finding offers insights into WNV pathogenesis and potential therapeutic targets.