HA2 from the Helicoverpa armigera nucleopolyhedrovirus: a WASP-related protein that activates Arp2/3-induced actin filament formation

Virus Res. 2007 Jul;127(1):81-7. doi: 10.1016/j.virusres.2007.03.021. Epub 2007 Apr 30.


Filamentous actin is required for the productive replication of lepidopteran nucleopolyhedroviruses. We have demonstrated that nucleocapsids of the Helicoverpa armigera nucleopolyhedrovirus (HearNPV) are capable of nucleating actin polymerization in vitro in a dose-dependent manner. Actin polymerization is the main mechanism used in cell locomotion and is also utilized by the Listeria bacteria and by vaccinia virus for intracellular and intercellular movements. The WASP family of proteins has been shown to stimulate the assembly of branched actin filaments by the Arp2/3 complex. The process is conserved in eukaryotic cells. HearNPV ORF 2 (HA2), a WASP homologue, could nucleate branched actin filaments in the presence of Arp2/3 complex in vitro. We also demonstrate that HA2 co-localizes with Arp2/3 complex in the nucleus of infected cells, suggesting that HA2 and Arp2/3 complex are involved in nuclear actin polymerization. In summary, HA2 activates Arp2/3-induced actin filament network formation in vitro and in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin-Related Protein 2 / metabolism*
  • Actin-Related Protein 3 / metabolism*
  • Actins / chemistry
  • Actins / physiology*
  • Animals
  • Cell Line
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / physiology
  • Moths / virology*
  • Nucleopolyhedroviruses / chemistry*
  • Nucleopolyhedroviruses / genetics
  • Open Reading Frames
  • Viral Proteins / metabolism
  • Wiskott-Aldrich Syndrome Protein / metabolism
  • Wiskott-Aldrich Syndrome Protein Family / chemistry
  • Wiskott-Aldrich Syndrome Protein Family / pharmacology*


  • Actin-Related Protein 2
  • Actin-Related Protein 3
  • Actins
  • HA2 protein, Helicoverpa armigera nucleopolyhedrovirus
  • Microfilament Proteins
  • Viral Proteins
  • Wiskott-Aldrich Syndrome Protein
  • Wiskott-Aldrich Syndrome Protein Family