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Updated: May 11, 2025
Reverse Genetics Mediated Recovery of Infectious Murine Norovirus
Published on: June 24, 2012
Membrane asymmetry facilitates murine norovirus entry and persistent enteric infection
Brittany M Stewart1, Linley R Pierce1, Mikayla C Olson1
1Departments of Immunology and Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
Abstract:
Norovirus, the leading cause of gastroenteritis worldwide, is a non-enveloped virus whose tropism is determined in part by the expression patterns of entry receptors. However, the contribution of cellular lipids to viral entry is not well understood. Here, we determined that the asymmetrical distribution of lipids within membrane bilayers is required for murine norovirus (MNV) replication. Specifically, TMEM30a, an essential subunit of lipid flippases, is required for MNV replication in vitro. Disruption of TMEM30a in mouse intestinal epithelial cells prevents persistent, enteric infection by MNV in vivo. Mechanistically, TMEM30a facilitates MNV binding and entry. Surprisingly, exoplasmic phosphatidylserine (PS), a typical marker of dying cells, does not inhibit MNV infection. Rather, TMEM30a maintains a lipid-ordered state that impacts membrane fluidity that is necessary for the low affinity, high avidity binding of MNV to cells. Our data provides a new role for lipid asymmetry in promoting non-enveloped virus infection in vitro and norovirus persistence in vivo.
Insights
Cellular lipid asymmetry is crucial for norovirus replication. The protein TMEM30a maintains this asymmetry, enabling norovirus binding and entry for persistent infection.
Area of Science:
- Virology
- Cell Biology
- Biochemistry
Background:
- Norovirus is a major cause of gastroenteritis globally.
- Viral entry mechanisms, particularly the role of cellular lipids, are not fully understood.
- Lipid asymmetry in cell membranes is essential for various cellular processes.
Purpose of the Study:
- To investigate the role of cellular lipids in norovirus entry and replication.
- To determine the specific contribution of lipid asymmetry to norovirus infection.
- To identify cellular factors involved in norovirus-lipid interactions.
Main Methods:
- Utilized in vitro and in vivo models using murine norovirus (MNV).
- Investigated the function of TMEM30a, a component of lipid flippases.
- Assessed viral binding, entry, and replication in cells with disrupted TMEM30a.
- Analyzed the impact of exoplasmic phosphatidylserine (PS) on infection.
Main Results:
- TMEM30a is essential for MNV replication in vitro.
- Disruption of TMEM30a in intestinal cells prevents persistent MNV infection in vivo.
- TMEM30a facilitates MNV binding and entry by maintaining a lipid-ordered state.
- Exoplasmic PS does not inhibit MNV infection, contrary to expectations.
Conclusions:
- Lipid asymmetry, regulated by TMEM30a, is critical for non-enveloped virus infection.
- TMEM30a plays a key role in norovirus entry by influencing membrane fluidity and binding.
- This study reveals a novel mechanism for norovirus persistence mediated by lipid asymmetry.
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