• Question: Is it possible for a cell that is a product of a virus infected cell to be infected by a new virus?

    Asked by to Bethany, Hannah, Keith, Peter, Ramya on 24 Jun 2014. This question was also asked by .
    • Photo: Keith Grehan

      Keith Grehan answered on 24 Jun 2014:


      If I am reading this right you’re asking if when a virus infected cell divides is the new cell (normally called daughter cells) susceptible to a new viral infection. If I’m right here then the answer is yes it is, sometimes infection with one virus can give immunity to further infection but this is for the organism as a whole since it is the cells of the organism’s immune system that will be responding to the virus. A good example of this would be mumps virus where having an infection of mumps renders you immune, this is the system we take advantage of when we get a mumps vaccination. We get the immunity without needing to have a disease 🙂
      It is also possible that infection with one virus may lead to lasting immunity against other viruses if those other viruses are very similar, this is basically where your immune system treats the new virus just like the old and same strategy works against it there is some evidence of this with flu and this is why there is a lot of hope that we might someday soon have a flu vaccine that works against all flu types.
      If instead you mean can a single cell be infected with more than one virus then again the answer is yes. A major concern with many of the recent flu outbreaks in livestock has been the risk of reassortment of two (or possibly even more!) viruses within a single cell. Reassortment is where 2 viruses get there genetic material mixed up. Imagine the cell as a card dealer shuffling cards if you give that person 2 decks of cards (2 viruses) then when the shuffle those the decks will get mixed up. When these viruses get replicated with the mixed up genes sometimes the result is a new virus that is sometimes much more dangerous than either virus on its own. We think this is what happened during really big flu out breaks in 1957 and 1968. Even the 1918 flu may have resulted from one of these mixing events most likely within a pig. Pigs are often a problem with flu as they can get almost every sort of flu so reassortment is always something health professionals have to worry about, this is also why outbreaks of things like swine-flu are treated so seriously even when there are very few or even no human cases

    • Photo: Bethany Dearlove

      Bethany Dearlove answered on 25 Jun 2014:


      I think Keith probably has you covered here for the main viral options. Your question reminded me of a talk I went to in Chicago last year, which was looking at a bacteria (Moranella endobia) of a bacteria (Tremblaya princeps), of a mealy bug (Planococcus citri. It seems that this three way relationship is a symbiotic one though – and helps the mealy bug survive.

      There’s a great article about it with pictures at http://phenomena.nationalgeographic.com/2013/06/20/snug-as-a-bug-in-a-bug-in-a-bug/.

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