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amoebae

TWiV 543: Stoned and senile

14 April 2019 by Vincent Racaniello

The TWiV team discusses Medusavirus, isolated from a hot spring in Japan, and induction of neurodegeneration by recurrent herpes simplex virus 1 infection of mice.

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Filed Under: This Week in Virology Tagged With: alzheimer's disease, amoebae, dementia, giant virus, herpes simplex virus 1, histone, horizontal gene transfer, Medusavirus, memory loss, mouse model, NCLDV, neurodegereration, reactivation, viral, virology, virus, viruses

Can a virus be revived?

14 March 2014 by Vincent Racaniello

PithovirusIn Carl Zimmer’s New York Times article describing the recovery of the giant virus Pithovirus sibericum from the Siberian permafrost, he used the words revive and resurrect. Can a virus be restored to life?

The headline of the article read ‘Out of Siberian ice, a virus revived‘. Within the body of the article, Zimmer wrote ‘From Siberian permafrost more than 30,000 years old, they have revived a virus that’s new to science’, and later considered the ‘risk of an outbreak of resurrected viruses’. Both words mean ‘restore to life’.

When most people say ‘virus’ they usually mean the very small virus particle that infects cells. Virus particles are not living: they are assemblies of protein, nucleic acid, and sometimes lipids that do nothing until they infect a cell. That is why they are called obligate intracellular parasites. In the case of Pithovirus, infectious virus particles were present in the frozen sample that were able to infect amoeba in the laboratory.

To say that a virus was revived or resurrected is wrong, although I understand that the idea of bringing anything back to life has a great deal of general appeal. The key fact in this story is that the infectivity of the virus particle was maintained for over 30,000 years in the Siberian permafrost. I realize that this does not make for compelling headlines, but mine would have been: ‘Infectious virus recovered from Siberian ice after 30,000 years’. I suspect that Zimmer might understand this, but as he’s told me before, sometimes it’s much easier (and requires fewer words) to write something for the non-scientist that is not quite right.

Even virologists confuse the living with the non-living. When Paul Bieniasz and his laboratory reported that they had reconstituted an infectious retrovirus from viral sequences in the human genome, they used the phrase ‘the resurrection of this extinct infectious agent’.

A virus particle is not alive, but a virus infected cell certainly is living. A virus can be viewed as an organism with two phases, a non-living virus particle, or virion; and an infected cell, which is alive.  This definition solves the problem of whether a virus is alive or not, a subject of much debate here and elsewhere. Even if we use this terminology, the use of resurrect and revive to describe viral infectivity is still wrong, because virus particles cannot be brought back to life – they are not alive to begin with.

Filed Under: Basic virology, Information Tagged With: amoebae, life, living, permafrost, Pithovirus sibericum, resurrect, revive, Siberia, viral, virology, virus

TWiP 17: Entamoeba histolytica

6 October 2010 by Vincent Racaniello

Hosts: Vincent Racaniello and Dickson Despommier

On episode 17 of the podcast This Week in Parasitism, Vincent and Dickson continue their discussion of protozoan parasites that cause diarrhea with a review of amebic dysentery caused by Entamoeba histolytica.

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TWiP is brought to you by the American Society for Microbiology at Microbeworld.org.

Links for this episode:

  • Entamoeba histolytica cyst
  • Entamoeba histolytica trophozoite
  • Entamoeba histolytica life cycle
  • Galactose prevents attachment of amoebae to cells
  • Entamoeba histolytica life cycle
  • Charcot-Leyden crystal
  • Letters read on TWiP 17

Download TWiP #17 (55 MB .mp3, 76 minutes)

Subscribe to TWiP (free) in iTunes, at the Zune Marketplace, by the RSS feed or by email

Send your questions and comments to twip@microbe.tv

Filed Under: This Week in Parasitism Tagged With: amoeba, amoebae, Despommier, dysentery, entamoeba histolytica, parasite, parasitism, racaniello, twip

TWiV 63: Melting pot virus

20 December 2009 by Vincent Racaniello

marseillevirus_genomeHosts: Vincent Racaniello, Alan Dove, and Rich Condit

On episode 63 of the podcast This Week in Virology, Vincent, Alan, and Rich talk about US government contract for freeze-dried smallpox vaccine, red squirrels in the UK threatened by poxvirus, and Marseillevirus, another DNA virus from amoebae built for comfort and speed.

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Click the arrow above to play, or right-click to download TWiV #63 (64 MB .mp3, 89 minutes)

Subscribe to TWiV (free) in iTunes , at the Zune Marketplace, by the RSS feed, or by email.

Links for this episode:

  • US Government awards contract to Bavarian Nordic for freeze-dried smallpox vaccine (pdf and clinical trial)
  • UK red squirrels threatened by poxvirus: news article one and two, epidemiology and experimental infection
  • Another huge virus from amoebae (Wired article, PNAS article, review article)
  • Discussion on rabies bait vaccine at virology blog, and status of the program
  • Viral diseases of humans (pdf)

Weekly Science Picks
Rich Infectious Awearables
Alan Darwine
Vincent Microbial Art

Send your virology questions and comments (email or mp3 file) to twiv@microbe.tv or leave voicemail at Skype: twivpodcast. You can also post articles that you would like us to discuss at microbeworld.org and tag them with twiv.

Filed Under: This Week in Virology Tagged With: amoebae, dryvax, lyophilize, marseillevirus, mimivirus, poxvirus, rabies, smallpox, squirrel, TWiV, vaccine, viral, virology, virus

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by Vincent Racaniello

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