Structure and assembly of archaeal viruses

Area of Science:

• Virology
• Microbiology
• Molecular Biology
• Astrobiology

Background:

• Archaea viruses, part of the virosphere, are largely enigmatic, with most characterized viruses infecting extremophiles.
• These viruses exhibit unique virion morphotypes not seen in bacterial or eukaryotic viruses.
• Recent studies reveal archaeal viruses are prevalent in moderate environments, impacting microbial community turnover and global biogeochemical cycles.

Purpose of the Study:

• To review recent advancements in understanding the molecular organization and assembly of archaeal viruses.
• To compare archaeal virus assembly with that of bacterial and eukaryotic viruses, exploring evolutionary implications.
• To highlight molecular adaptations enabling archaeal virus stability in extreme environments.

Main Methods:

• Review of existing literature on archaeal virus families, virion structure, and assembly mechanisms.
• Comparative analysis of archaeal virus morphogenesis pathways against those of bacterial and eukaryotic viruses.
• Discussion of evolutionary conservation and divergence in viral assembly strategies.

Main Results:

• Introduction of 20 officially recognized archaeal virus families.
• Icosahedral archaeal viruses generally utilize conserved assembly mechanisms (e.g., HK97 fold, double jelly-roll proteins) shared with bacterial and eukaryotic viruses.
• Archaea-specific viruses exhibit distinct, unique virion assembly mechanisms.
• Identification of molecular adaptations contributing to virus stability in extreme conditions.

Conclusions:

• The assembly of many archaeal viruses reflects deep evolutionary conservation of viral morphogenesis pathways.
• Archaea-specific viruses showcase novel assembly strategies, expanding our understanding of viral diversity.
• The archaeal virosphere remains a frontier in virology, with significant potential for novel discoveries.