Capsid assembly and DNA packaging in herpes simplex virus

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• The Herpes Simplex Virus type 1 (HSV-1) virion comprises a lipid envelope, tegument, icosahedral capsid, and DNA core.
• The HSV-1 capsid, composed of 162 capsomers, includes major protein VP5 and minor proteins VP19C, VP23, and VP26.

Purpose of the Study:

• To review current knowledge on the structure and assembly of the HSV-1 capsid.
• To summarize the roles of viral proteins and genetic factors in capsid formation and DNA packaging.

Main Methods:

• Cryoelectron microscopy has elucidated capsid shell structure.
• Recombinant baculoviruses facilitated analysis of capsid assembly proteins.
• An in vitro system identified assembly intermediates and maturation pathways.

Main Results:

• The HSV-1 capsid is an icosahedral structure with 162 capsomers.
• Assembly involves structural proteins, protease, scaffolding protein preVP22a, and seven DNA packaging proteins.
• An in vitro system revealed a procapsid intermediate that matures into the final capsid.

Conclusions:

• Significant progress has been made in understanding HSV-1 capsid structure and assembly.
• The identified assembly pathway and intermediates provide insights into viral morphogenesis.
• Further research on DNA packaging genes is ongoing.