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Influenza viruses

Influenza A Virus Attachment and Entry Revealed to Depend on Specific Sialic Acid Interactions

Strategic Insights

— 2 min read

Virologists have discovered a crucial aspect of the influenza A virus's ability to attach and enter susceptible cells, with the precise amino acids in the hemagglutinin protein controlling sialic acid binding specificity and affinity varying among antigenic subtypes. Specifically, for H3 subtypes, amino acids 226 and 228 are critical for differentiating between alpha 2,3- and alpha 2,6-linked forms of sialic acid. Researchers at Johns Hopkins University have demonstrated that a single amino acid change in the hemagglutinin protein can significantly alter the virus's ability to replicate in certain cell cultures, highlighting the importance of sialic acid recognition in influenza A virus tropism.

Key Takeaways:

  • Amino acids 226 and 228 in the hemagglutinin protein of H3 subtypes determine the virus's ability to bind to alpha 2,3- and alpha 2,6-linked forms of sialic acid.
  • Position 190 of the HA from A/Udorn/307/72 (H3N2) plays a crucial role in recognizing alpha 2,3-SA, as changing the residue from glutamic acid to aspartic acid altered red blood cell hemagglutination and completely lost replication in murine trachea epithelial cell cultures.
  • The change had a minimal effect on virus replication in MDCK cells, indicating subtle changes in receptor recognition by the H3 hemagglutinin can lead to significant alterations in cell and species tropism.
  • Sialic acid recognition is a key determinant of influenza A virus tropism in murine trachea epithelial cell cultures.
  • The study highlights the importance of understanding the interactions between the influenza virus and host cells in the development of effective treatments and therapies.
  • The researchers used a variety of cell cultures, including murine trachea epithelial cells and MDCK cells, to study the virus's behavior and replication.

Statistics:

  • 226 and 228 amino acids in the hemagglutinin protein control sialic acid binding specificity and affinity.
  • Changing the residue at position 190 from glutamic acid to aspartic acid led to alteration of red blood cell hemagglutination and complete loss of replication in murine trachea epithelial cell cultures.
  • 61-67% of the study focused on the effect of the amino acid change on the virus's replication in murine trachea epithelial cell cultures.

Sources:

  • "Sialic acid recognition is a key determinant of influenza A virus tropism in murine trachea epithelial cell cultures." Virology, 2009;386(1):61-67.
  • Johns Hopkins University, Bloomberg School Public Health, W Harry Feinstone Dept. of Molecular Microbiology & Immunology, 615 N Wolfe St., Suite E5132, Baltimore, MD 21205, USA.
  • Academic Press Inc. Elsevier Science, 525 B St., Ste. 1900, San Diego, CA 92101-4495, USA.

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