Related Experiment Videos
Efficiency of measles virus entry and dissemination through different receptors
Urs Schneider1, Veronika von Messling, Patricia Devaux
1Molecular Medicine Program, Mayo Foundation, Rochester, Minnesota 55905, USA.
Abstract:
The efficiency with which different measles virus (MV) strains enter cells through the immune cell-specific protein SLAM (CD150) or other receptors, including the ubiquitous protein CD46, may influence their pathogenicity. We compared the cell entry efficiency of recombinant MV differing only in their attachment protein hemagglutinin (H). We constructed these viruses with an additional gene expressing an autofluorescent reporter protein to allow direct detection of every infected cell. A virus with a wild-type H protein entered cells through SLAM two to three times more efficiently than a virus with the H protein of the attenuated strain Edmonston, whereas cell entry efficiency through CD46 was lower. However, these subtle differences were amplified at the cell fusion stage because the wild-type H protein failed to fuse CD46-expressing cells. We also proved formally that a mutation in H protein residue 481 (asparagine to tyrosine) results in improved CD46-specific entry. To define the selective pressure exerted on that codon, we monitored its evolution in different H protein backgrounds and found that several passages in CD46-expressing Vero cells were necessary to shift it in the majority of the MV RNA. To verify the importance of these observations for human infections, we examined MV entry into peripheral blood mononuclear cells and observed that viruses with asparagine 481 H proteins infect these cells more efficiently.
Insights
Measles virus (MV) entry efficiency varies by receptor, influencing pathogenicity. Specific mutations in the H protein enhance CD46-mediated cell entry, impacting infection of immune cells.
Area of Science:
- Virology
- Immunology
- Cell Biology
Background:
- Measles virus (MV) pathogenicity is linked to its cell entry efficiency via receptors like SLAM (CD150) and CD46.
- The hemagglutinin (H) protein mediates MV attachment and entry, with different strains exhibiting varying receptor specificities.
Purpose of the Study:
- To compare the cell entry efficiency of recombinant MVs with distinct H proteins.
- To investigate the role of specific H protein residues in receptor usage and viral pathogenicity.
- To understand the evolutionary pressures on the MV H protein during cell culture adaptation.
Main Methods:
- Construction of recombinant MVs expressing an autofluorescent reporter protein.
- Comparative analysis of MV entry efficiency through SLAM and CD46 using different H proteins.
- Site-directed mutagenesis of the H protein at residue 481.
- Serial passage of MV in CD46-expressing cells.
- Assessment of MV entry into primary human immune cells (peripheral blood mononuclear cells).
Main Results:
- Wild-type H protein showed 2-3 times higher SLAM-mediated entry than Edmonston strain H protein, with lower CD46 entry efficiency.
- Wild-type H protein failed to efficiently mediate cell fusion with CD46-expressing cells.
- A mutation (N481Y) in the H protein significantly improved CD46-specific entry.
- Multiple passages in CD46-expressing cells were required to establish the N481Y mutation.
- MV with asparagine at H protein residue 481 demonstrated more efficient infection of peripheral blood mononuclear cells.
Conclusions:
- Subtle differences in MV H protein receptor binding efficiency are amplified during cell fusion.
- The N481Y mutation in the H protein confers a selective advantage for CD46-mediated entry.
- Adaptation to CD46-expressing cells drives the evolution of specific H protein residues.
- H protein residue 481 influences MV tropism and pathogenicity, particularly in human immune cells.