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Published on: March 24, 2017
Structural and functional studies of the measles virus hemagglutinin: identification of a novel site required for
J B Patterson1, F Scheiflinger, M Manchester
1Department of Neuropharmacology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA.
Abstract:
The entry of measles virus (MV) into human cells is mediated by the initial attachment of the viral hemagglutinin (HA) to the complement regulatory protein CD46. Two subdomains, one each within CD46 short consensus repeats (SCRs) 1 and 2, are responsible for this interaction. However, little is known about the regions within MV HA needed for a high-affinity CD46 interaction. To better define the HA-CD46 interaction, we took three approaches: chimeric domain swapping, peptide scanning, and alanine scanning mutagenesis. Chimeras of MV HA and the closely related rinderpest virus (RPV) HA were generated and tested for cell surface expression and the ability to hemadsorb CD46+ red blood cells (RBC). Exchanges with the N terminus of RPV were tolerated as MV HA could be replaced with RPV HA up to amino-acid position 154. However, both larger swaps with RPV and a small RPV HA replacement at the C terminus aborted cell-surface expression. Peptide scanning with 51 overlapping peptides derived from three MV HA regions showed one peptide, corresponding to MV HA amino acids 468-487, blocked hemagglutination of African green monkey (AGM) RBCs and inhibited MV infection of Chinese hamster ovary cells (CHO) expressing human CD46. Alanine scanning mutants mapped sites on the MV HA that were not required for trafficking to the cell surface or function in hemagglutination as well as a novel site required for CD46 interaction, amino acids 473-477.
Insights
Researchers identified key regions on the measles virus (MV) hemagglutinin (HA) crucial for binding to human CD46. This finding advances understanding of MV entry and potential therapeutic targets.
Area of Science:
- Virology
- Immunology
- Molecular Biology
Background:
- Measles virus (MV) enters human cells via its hemagglutinin (HA) protein binding to CD46.
- Specific subdomains in CD46 short consensus repeats (SCRs) 1 and 2 mediate this interaction.
- Regions within MV HA essential for high-affinity CD46 binding remain largely uncharacterized.
Purpose of the Study:
- To delineate the specific regions within the MV hemagglutinin (HA) protein responsible for high-affinity interaction with human CD46.
- To provide a detailed molecular understanding of the measles virus-host cell entry mechanism.
Main Methods:
- Chimeric domain swapping between measles virus (MV) HA and rinderpest virus (RPV) HA.
- Peptide scanning using overlapping peptides derived from MV HA regions.
- Alanine scanning mutagenesis to identify critical amino acid residues in MV HA.
Main Results:
- Chimeric HA analysis indicated tolerance for N-terminal RPV exchanges up to amino acid 154, while larger or C-terminal swaps disrupted cell-surface expression.
- Peptide scanning identified a specific peptide (MV HA amino acids 468-487) that inhibited hemagglutination and MV infection.
- Alanine scanning revealed a novel site (amino acids 473-477) critical for CD46 interaction, distinct from regions involved in cell-surface trafficking or hemagglutination.
Conclusions:
- A novel region within the measles virus hemagglutinin (MV HA), specifically amino acids 473-477, is essential for high-affinity interaction with human CD46.
- These findings enhance the understanding of MV entry mechanisms and provide potential targets for antiviral interventions.
