Influenza virus assembly and budding

Virology. 2011 Mar 15;411(2):229-36. doi: 10.1016/j.virol.2010.12.003. Epub 2011 Jan 14.


Influenza A virus causes seasonal epidemics, sporadic pandemics and is a significant global health burden. Influenza virus is an enveloped virus that contains a segmented negative strand RNA genome. Assembly and budding of progeny influenza virions is a complex, multi-step process that occurs in lipid raft domains on the apical membrane of infected cells. The viral proteins hemagglutinin (HA) and neuraminidase (NA) are targeted to lipid rafts, causing the coalescence and enlargement of the raft domains. This clustering of HA and NA may cause a deformation of the membrane and the initiation of the virus budding event. M1 is then thought to bind to the cytoplasmic tails of HA and NA where it can then polymerize and form the interior structure of the emerging virion. M1, bound to the cytoplasmic tails of HA and NA, additionally serves as a docking site for the recruitment of the viral RNPs and may mediate the recruitment of M2 to the site of virus budding. M2 initially stabilizes the site of budding, possibly enabling the polymerization of the matrix protein and the formation of filamentous virions. Subsequently, M2 is able to alter membrane curvature at the neck of the budding virus, causing membrane scission and the release of the progeny virion. This review investigates the latest research on influenza virus budding in an attempt to provide a step-by-step analysis of the assembly and budding processes for influenza viruses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Hemagglutinins, Viral / metabolism
  • Humans
  • Influenza A virus / physiology*
  • Neuraminidase / metabolism
  • Nucleocapsid Proteins
  • Protein Multimerization
  • RNA-Binding Proteins / metabolism
  • Viral Core Proteins / metabolism
  • Viral Matrix Proteins / metabolism
  • Viral Proteins / metabolism
  • Virus Assembly*
  • Virus Release*


  • Hemagglutinins, Viral
  • M1 protein, Influenza A virus
  • M2 protein, Influenza A virus
  • NP protein, Influenza A virus
  • Nucleocapsid Proteins
  • RNA-Binding Proteins
  • Viral Core Proteins
  • Viral Matrix Proteins
  • Viral Proteins
  • hemagglutinin fusogenic peptide, influenza virus
  • NA protein, influenza A virus
  • Neuraminidase