Viral entry is the earliest stage of infection in the "viral life cycle", as the virus comes into contact with the host cell and introduces viral material into the cell. The major steps involved in viral entry are:
- 1. Attachment, when receptors on the viral envelope become connected to complementary receptors on the cell membrane. This attachment causes the two membranes to remain in mutual proximity, favoring further interactions between surface proteins.
- 2. Membrane Fusion or Hemifusion State or Viral Adsorption, as the cell membrane is punctured and made to further connect with the unfolding viral envelope.
- 3. Entry Pore formation, which results from viral proteins establishing a stable opening in the cell membrane.
- 4. Viral Pentration as the viral capsid is injected into the host cell's cytoplasm.
- Subramanian RP, Geraghty RJ (20 Feb 2007). "Herpes simplex virus type 1 mediates fusion through a hemifusion intermediate by sequential activity of glycoproteins D, H, L, and B". Proceedings of the National Academy of Sciences, USA. 104 (8): 2903-8. PMID 17299053.