Are Viruses Really Alive?

Are viruses alive or have we been defining life wrong for a century? This science documentary dives into virology, microbiology, and evolution to ask what is life, and where the line actually falls. A jar of crystals sits on a shelf in 1935. Dissolve a pinch in water, wipe it on a leaf, and the plant dies. A virus catches a virus and gets sick. Another one keeps a stolen fragment of its enemy's DNA as an immune system. Viruses that infect bacteria talk to each other using a word six amino acids long, and some of them lie in it. And a virus frozen in Siberian permafrost for 30,000 years thaws out and starts infecting again, as though nothing had happened. In this video we trace 90 years of the argument, from Wendell Stanley crystallising a virus in 1935 and winning a Nobel Prize for it, to the giant viruses that were mistaken for bacteria for 11 years, to pandoraviruses whose genes match nothing else on Earth, to the 2024 discovery of "obelisks" in the human mouth that fit nowhere on the tree of life. We cover the hard counterargument that giant viruses are gene thieves rather than a fourth domain of life, and the idea from the Pasteur Institute that the whole question has been aimed at the wrong object. How can a bacterium with 182 genes be alive while a virus with 2,500 is not? If a mule can't evolve, is a mule alive? Was a virus frozen for 30,000 years dead, or just switched off, and if you can't tell the difference, what were you measuring? And what does it mean that 8% of your DNA is virus, that your placenta was built by a viral gene, and that your memories may travel between neurons inside viral shells? Drop a comment: After all this, do you think a virus is alive? ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SOURCES ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ DEFINING LIFE — AND FAILING TO ▸ Stanley, W. M. (1935). "Isolation of a crystalline protein possessing the properties of tobacco-mosaic virus." Science, 81(2113): 644–645. ▸ Moreira, D., & López-García, P. (2009). "Ten reasons to exclude viruses from the tree of life." Nature Reviews Microbiology, 7(4): 306–311. ▸ Forterre, P. (2013). "The virocell concept and environmental microbiology." The ISME Journal, 7(2): 233–236. ▸ Nakabachi, A., et al. (2006). "The 160-kilobase genome of the bacterial endosymbiont Carsonella." Science, 314(5797): 267. ▸ Tamames, J., Gil, R., Latorre, A., Peretó, J., Silva, F. J., & Moya, A. (2007). "The frontier between cell and organelle: genome analysis of Candidatus Carsonella ruddii." BMC Evolutionary Biology, 7: 181. THE GIANTS ▸ La Scola, B., et al. (2003). "A giant virus in amoebae." Science, 299(5615): 2033. ▸ Philippe, N., et al. (2013). "Pandoraviruses: amoeba viruses with genomes up to 2.5 Mb reaching that of parasitic eukaryotes." Science, 341(6143): 281–286. ▸ Legendre, M., et al. (2018). "Diversity and evolution of the emerging Pandoraviridae family." Nature Communications, 9: 2285. ▸ Abrahão, J., et al. (2018). "Tailed giant Tupanvirus possesses the most complete translational apparatus of the known virosphere." Nature Communications, 9: 749. ▸ Schulz, F., et al. (2017). "Giant viruses with an expanded complement of translation system components." Science, 356(6333): 82–85. VIRUSES THAT GET SICK, FIGHT BACK AND LIE ▸ La Scola, B., Desnues, C., Pagnier, I., et al. (2008). "The virophage as a unique parasite of the giant mimivirus." Nature, 455(7209): 100–104. ▸ Levasseur, A., et al. (2016). "MIMIVIRE is a defence system in mimivirus that confers resistance to virophage." Nature, 531(7593): 249–252. ▸ Erez, Z., et al. (2017). "Communication between viruses guides lysis–lysogeny decisions." Nature, 541(7638): 488–493. FROZEN — AND UNCLASSIFIABLE ▸ Legendre, M., et al. (2014). "Thirty-thousand-year-old distant relative of giant icosahedral DNA viruses with a pandoravirus morphology." PNAS, 111(11): 4274–4279. ▸ Zheludev, I. N., et al. (2024). "Viroid-like colonists of human microbiomes." Cell, 187(23): 6521–6536. HOW MUCH OF YOU IS VIRUS ▸ Mi, S., et al. (2000). "Syncytin is a captive retroviral envelope protein involved in human placental morphogenesis." Nature, 403(6771): 785–789. ▸ Pastuzyn, E. D., et al. (2018). "The neuronal gene Arc encodes a repurposed retrotransposon Gag protein that mediates intercellular RNA transfer." Cell, 172(1–2): 275–288. ▸ Enard, D., Cai, L., Gwennap, C., & Petrov, D. A. (2016). "Viruses are a dominant driver of protein adaptation in mammals." eLife, 5: e12469. ▸ Nguyen, S., et al. (2017). "Bacteriophage transcytosis provides a mechanism to cross epithelial cell layers." mBio, 8(6): e01874-17. ▸ Suttle, C. A. (2007). "Marine viruses — major players in the global ecosystem." Nature Reviews Microbiology, 5(10): 801–812. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ For business inquiries: [email protected] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━ #Viruses #AreVirusesAlive #WhatIsLife #Virology #Microbiology #GiantViruses #ScienceDocumentary #Biology #Evolution #Science