DNA viruses: the really big ones (giruses)

Area of Science:

• Virology
• Microbiology
• Genomics

Background:

• Increasing discovery of large viruses (giruses) with genomes >300 kb.
• These giruses possess more protein-encoding genes than many bacteria.
• Genome gigantism is observed across various hosts and environments, not limited to specific clades.

Purpose of the Study:

• To review the significant differences among large viruses (giruses).
• To highlight variations in morphology, lifestyle, and genome structure within this viral group.
• To address the underappreciated diversity of giruses within the microbiology community.

Main Methods:

• Literature review focusing on large viruses (giruses).
• Comparative analysis of viral morphology, lifestyle, and genome structure.
• Discussion of evolutionary relationships with other viral families.

Main Results:

• Girus genomes can reach up to 1200 kb, encoding up to 900 proteins.
• Infections span bacteria, animals, and predominantly protists.
• Significant morphological, lifestyle, and genomic diversity exists even within the same viral families.

Conclusions:

• The traditional concept of viruses having small genomes is outdated.
• Large viruses exhibit remarkable diversity, challenging existing classifications.
• Further research is needed to understand the evolutionary and ecological implications of giruses.