Animation of influenza virus replication

I found the following animation on YouTube depicting replication of an H1N1 influenza virus. It’s entitled “Antigenic shift – the spread of a new, mutated virus”. It is visually appealing but contains at least one error. If you think you know what it is, post it in the comments below.

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  • Chris Upton 5 May 2009, 6:12 pm

    Nothing useful there….
    More mis-information…

    Error? Doesn't show virus budding.
    Was there anything remotely accurate?

  • gbarendt 5 May 2009, 6:44 pm

    A lot of things seemed wrong. For one thing, I don't think there's any reason why influenza A should be the only one capable of antigenic shift, right?

  • Trine 5 May 2009, 6:46 pm

    Okay, my guess: It's not true that only influenza A is capable of antigenic shift, correct?

    One question – the video seems to show many influenza viruses on the outside of each cell – is this what typically happens? I always thought of it as one virus inside one cell, but of course that wouldn't allow for the mixing.

    Oh, and one more guess….when the mutated viruses pop out of the cell, I bet they don't make that sound.

  • Corey Philipp 5 May 2009, 6:57 pm

    If that was intended to be the ping respiratory tract then the bubbly sounds give me the impression that the pig is drowning and probably not a very infectious animal. 🙂 I would expect the cell lysis process to contain a considerable amount of mucus cementing the virons in place more than depicted. I would also expect the typical respiratory convulsions that would cause the expulsion of the virus out of the airways into an aerosol. I'm probably missing the obvious errors though…

    Given the apoptosis that occurring could we presume that the animators decided that this new virus had a virulent version of the PB2-F2 gene, with asparagine at amino acid 66?

  • o.jeff 5 May 2009, 7:28 pm

    I'll take a stab: The video states that the current flu is formed from elements of human, pig, and avian virus strains. This statement was made by a CDC employee during an official briefing, which would normally be a good source. However, others, including our hose, have looked at the published viral genome sequences and not found this to be true.

  • Megan 6 May 2009, 2:22 am

    Influenza doesn’t lyse cells; it buds from the membrane.

    Also, not sure about type A being the only one to undergo antigenic shift. Are B and C single species strains?

  • ppga 5 May 2009, 9:57 pm

    I'm thinking this new H1N1 is a triple reassortment, not a mutation. I believe the statement that influenza A is the only type that can experience antigenic shift is correct. Types B and C can drift, but not shift? The new H1N1 is a reassortment of pig, avian and human flus that now can infect humans. I think the term “drift” refers to mutations, not “shift”, which indicates reassortment?.

  • ppga 5 May 2009, 10:10 pm

    From wikipedia, a decent visual aid:

  • Marie 5 May 2009, 11:23 pm

    It looked like cilia bearing cells were being blown up by viruses in the animation. This is a study on mice, but sounds like that would not happen in that species, maybe not even epithelial cell destruction.

  • ElDean 6 May 2009, 1:28 am

    2. I think that the mechanism they employed for emerging of the new strains was wrong, as they considered the new emerging strain of the virus to be of one “new” type (the green coloured particles), though I think this is not the case, many combinations of genetic material exchange could take place between the different viruses, resulting in the production of many new strain – not only one 'green' – and then this 'green' one would be present in a mosaic of different new reassortants, but this would be the only one that have the capabilities to transmit freely between humans … simply I needed to see not only green colours getting out from the cells, but green and other colours (I think this is now more easy :-))

  • ET 6 May 2009, 4:45 am

    Was the Histological section itself wrong? Ciliated cells (upper respiratory) surrounded by squamos epithelium (alveoli) WOuldn't influenza attach up high, and then get spread into the lower respiratory tract? Although, Im not as sure about this in procine respiratory tissues.

  • thor183 6 May 2009, 9:35 am

    I say its the budding. It's an enveloped virus.

  • joel 6 May 2009, 11:28 am

    1. Reassortment occurs in viruses containing 2 or more DNA or RNA segments. Mutations are generally point changes. 2. Since most reassortments are less fit than the original, I would expect than a single “lucky” reassortment virion would have to go on to infect other cells over several life cycles. By the time the infection got as serious as the animation the “lucky” variety would be the overwhelming rule and others would be an exception.

  • Trine 6 May 2009, 4:46 pm

    Okay I have one more idea – the video almost looks like the viruses burst out of the cell as it dies. but the process is different than that, right? it involves budding, though to be honest I have no idea what that would look like.

  • Michael 7 May 2009, 10:42 am

    One obvious error is that this is NOT swine flu, as this virus is not currently resident in the pig population for transmission to humans, as depicted in the animation.

  • profvrr 7 May 2009, 10:47 am

    GIven the general inaccuracy of the animation, I don't think the authors would know about PB1-F2 and its effects.

  • profvrr 7 May 2009, 10:48 am

    Not as far as we know. We might not have detected it yet. Or the virus might have arisen in a human.

  • profvrr 7 May 2009, 10:49 am

    Cells can be infected with one virion, or many, or any number in between. It depends on how much virus is received from, say, an aerosol. But you can imagine if a cell is producing a lot of virus, the neighboring cells would in turn be infected with more than one particle. You are correct, you need more than one virion per cell to get reassortment.

  • Me 7 June 2009, 5:59 pm

    Influenza does not lyse the cell it buds out to infect other cells. And yes only influenza A undergoes antigenic shift because its the only one that effects multiple species.

  • Dana Wolf 12 October 2009, 8:54 am

    Could you kindly send me the animation?

  • Martin 3 November 2009, 2:43 pm

    Maybe I'm too late to answer to this question but nevertheless: First : I think that Influenza type A is not only virus capable of antigenic shift. Second: current flu is similar is not so new strain, I think that we have already seen it in the past (or something very similar). Third: As someone already said: their is no lysis, but only burst. And my question: is H1N1 really combination of Swine/Avian and Human strains. Thank you for answer.

  • profvrr 9 November 2009, 9:55 am

    Yes, the 2009 influenza H1N1 strain has RNA segments from human,
    avian, and swine strains.

  • profvrr 9 November 2009, 5:55 pm

    Yes, the 2009 influenza H1N1 strain has RNA segments from human,
    avian, and swine strains.