Untangling the origin of viruses and their impact on cellular evolution

Arshan Nasir, Feng Jie Sun, Kyung Mo Kim, Gustavo Caetano-Anollés

Research output: Contribution to journalArticlepeer-review


The origin and evolution of viruses remain mysterious. Here, we focus on the distribution of viral replicons in host organisms, their morphological features, and the evolution of highly conserved protein and nucleic acid structures. The apparent inability of RNA viral replicons to infect contemporary akaryotic species suggests an early origin of RNA viruses and their subsequent loss in akaryotes. A census of virion morphotypes reveals that advanced forms were unique to viruses infecting a specific supergroup, while simpler forms were observed in viruses infecting organisms in all forms of cellular life. Results hint toward an ancient origin of viruses from an ancestral virus harboring either filamentous or spherical virions. Finally, phylogenetic trees built from protein domain and tRNA structures in thousands of genomes suggest that viruses evolved via reductive evolution from ancient cells. The analysis presents a complete account of the evolutionary history of cells and viruses and identifies viruses as crucial agents influencing cellular evolution.

Original languageEnglish (US)
Pages (from-to)61-74
Number of pages14
JournalAnnals of the New York Academy of Sciences
Issue number1
StatePublished - Apr 1 2015


  • Evolution
  • Parasitism
  • Protein domains
  • Structure
  • Transfer RNA
  • Viruses

ASJC Scopus subject areas

  • General Neuroscience
  • General Biochemistry, Genetics and Molecular Biology
  • History and Philosophy of Science


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