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Studies on the adaptation of influenza viruses to MDCK cells
Abstract:
The amino acid sequences and biological properties of the haemagglutinin of three variants of the influenza virus X-31 (H3N2) selected for their capacity to grow in MDCK cells are reported. In two variants, amino acid substitutions at HA1 residues 8 and 144 correlated with the loss of a site for glycosylation and specific changes in antigenicity, respectively. In all three variants substitution of an arginine residue for histidine at HA1 position 17 was correlated with increased pH optima of haemolysis. The importance of this substitution for cleavage of the haemagglutinin precursor required to produce infectious virus is discussed in relation to the three-dimensional structure of X-31 haemagglutinin.
Insights
This study analyzes influenza virus X-31 (H3N2) variants, revealing key amino acid changes in haemagglutinin that affect viral growth, antigenicity, and haemolysis. These findings are crucial for understanding influenza virus evolution and developing effective vaccines.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Influenza virus haemagglutinin (HA) is critical for viral entry and is a primary target for neutralizing antibodies.
- Understanding HA mutations is essential for tracking viral evolution and predicting pandemic potential.
- The X-31 (H3N2) influenza virus provides a model system for studying HA function and adaptation.
Purpose of the Study:
- To characterize the amino acid sequences and biological properties of haemagglutinin in three influenza virus X-31 (H3N2) variants selected for enhanced growth in MDCK cells.
- To investigate the correlation between specific amino acid substitutions in HA1 and changes in glycosylation, antigenicity, and haemolysis.
- To discuss the implications of these HA modifications for viral infectivity and the three-dimensional structure of haemagglutinin.
Main Methods:
- Selection of influenza virus X-31 (H3N2) variants with increased growth in Madin-Darby canine kidney (MDCK) cells.
- Amino acid sequencing of the haemagglutinin (HA) protein from selected variants.
- Analysis of biological properties including haemolysis and antigenicity.
- Correlation of observed amino acid substitutions with structural and functional changes.
Main Results:
- Two variants showed amino acid substitutions at HA1 residues 8 and 144, linked to altered glycosylation sites and antigenicity.
- All three variants exhibited a substitution of arginine for histidine at HA1 position 17, associated with increased pH optima for haemolysis.
- This substitution at HA1 position 17 was found to be important for the cleavage of the haemagglutinin precursor.
Conclusions:
- Specific amino acid substitutions in influenza haemagglutinin significantly impact viral properties like growth, antigenicity, and haemolysis.
- The HA1 residue 17 substitution is critical for haemagglutinin precursor cleavage, essential for producing infectious influenza virus.
- These findings contribute to a deeper understanding of influenza virus adaptation and the structural basis of haemagglutinin function.