|
Discovery of Giant Viruses Marked a Turning Point in The Effort to Determine The Origin of Viruses
|
Matia Sadat Borhani *   , Mohammad Javad Rahmati |
| Gonbad Kavous University & Gonbad Kavous University |
|
|
Abstract: (10 Views) |
The discovery of giant viruses, with their complex genomes and structures resembling those of cells, has revolutionized the traditional theoretical framework of virology. The 1.2-megabase genome of Acanthamoeba polyphaga mimivirus, supports the reduction (cell-to-virus transformation) or escape (derivation from cellular components) theories of viral origin. However, not all viral genes originate from cellular homologs, thereby also bolstering the independent ancient origin (virus-first) theory. This apparent contradiction lies at the heart of the debate surrounding the placement of viruses in the tree of life. Since none of the classical theories of viral origin (virus-first, reduction, escape) can alone explain all the evidence, hybrid and modern theories (such as the chimeric and symbiogenic models) have been proposed. Given the extraordinary genetic diversity of viruses and their extensive gene exchange with cellular hosts, the traditional tree of life model has been deemed inadequate for representing viral evolution. Instead, the theoretical framework of the "forest of life" is proposed as a more comprehensive model, in which viruses are not a minor branch but an integral and influential component of life's complex network, playing a pivotal role in horizontal gene transfer and shaping cellular genomes throughout evolutionary history.
|
|
| Keywords: Evolutionary Forest, Transposable genetic elements Luca, Mimivirus |
|
|
Full-Text [PDF 672 kb]
(18 Downloads)
|
Type of Study: Review |
Subject:
Special
Received: 2025/02/25 | Accepted: 2026/01/23
|
|
|
|
|
|
|
| Send email to the article author |
|
|
|
| Add your comments about this article |
|
|
|
