Health and medicine
- What is the flu?
- Catching and spreading the flu
- When flu viruses attack!
- Three types of flu
- Naming the flu: H-something, N-something
- Testing for the flu
- Antiviral drugs for the flu
- Genetic shift in flu
- Flu vaccine efficacy
- Flu shift and drift
- Two flu vaccines (TIV and LAIV)
- Flu vaccine risks and benefits
- Making flu vaccine each year
- 5 common flu vaccine excuses
- Vaccines and the autism myth - part 1
- Vaccines and the autism myth - part 2
- Flu surveillance
Genetic shift in flu
Find out how the genetic material in the Type A flu virus can get shuffled around to create brand new types of viruses! Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Rishi Desai.
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- How would the parent virus survive if it's mixed offspring beats it at infecting organisms?(4 votes)
- Would it be possible to make a synthetic virus and use the Genetic Shift idea to perhaps result in a cure? To get the synthetic virus to infect the infected cells and have their bits of RNA to kill off or cancel out the other virus when mixed together?
(I realize this is probably some kind of fantasy scenario, but just figured I'd ask.)(3 votes)
- There are viruses that infect bacteria so maybe a virus can be used to attack bacterial diseases at a cellular level. Your idea may have some merit. And btw there's nothing wrong with asking 'fantasy scenario' questions. Most scientific ideas were once science fiction.
Edit 5/10/16. The Soviets used to use viruses that attack bacteria. This may be a stop gap solution to the problem of increasing antibiotic resistant bacteria.
Emphasis on the 'may be' part. There are bacteria that fight back against the viruses attacking them.(3 votes)
- What difference does it make which type of H and N combo there is? Are we immune to some types or what? And what difference does the RNA make as well? Are we immune to certain types of it too? What makes the flu strong or weak?(2 votes)
- Change in "H and N" will allow a new strain of flu virus to which our body does not have immunity... Hence the concerns(2 votes)
- Could you get two kinds of H and/or two kinds of N on one offspring? Like in the video, could you have a yellow H AND a purple H on the same viral body (and either all green N's or a mix)? Or do they always have to match each other?(2 votes)
- This is a good question and I was wondering the same thing. I think the reason it's not possible is because the flu can only have one copy of the hemagglutinin and one copy of the neuraminidase gene. Each virus can only contain 8 segments of DNA - there is not enough physical room for two copies of the same segment and it wouldn't produce a functional virus. As a result, there can only be one H, and one N. Genetic shift allows for variation in which combination an individual virus gets.
Who knows, maybe one day flu will evolve a mechanism for having multiple H's and N's - then we really will be in trouble!!(2 votes)
- Isn't H1N1 also known as swine flu? Also, what kind of flu is H3N2 and H3N1?(3 votes)
- There are different kinds of H1N1. "Swine Flu" was one kind, but there was a much worse "Spanish Flu" kind of H1N1 that killed millions in Europe around WW1. There are probably milder versions too.(3 votes)
- Do other viruses and other microorganisms experience genetic shift also or is it unique to Influenza A viruses?(2 votes)
- Some other viruses can undergo genetic shift, such as the visna virus in sheep. It might also be a factor in the appearance of HIV in humans. However, this isn't something you get with other micro-organisms like bacteria.
Source: https://en.wikipedia.org/wiki/Antigenic_shift(2 votes)
- At6:48, why does this affect Type A viruses only?(2 votes)
- Only A type influenza is categorized using the different hemagglutinin and neuraminidase combinations. There are only 2 known influenza B viruses: B/Yamagata/16/88-like and B/Victoria/2/87-like. So there is no crossing over like with A type.
Source: https://en.wikipedia.org/wiki/Influenzavirus_B(1 vote)
- What is the possibility of two flu virus genetically shifting?(2 votes)
- "Influenza A has eight genomic fragments, thus the probability all eight fragments will be from the same strain is (1/2)8 or 1/256 since there are two options for each fragment. Since there are two strains involved, the probability for packaging a non-recombinant virus is 2/256 or 0.007, whereas the probability for packaging a recombinant virus is 0.993 (1 – 0.007)."
source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4858373/(1 vote)
- I understand how the RNA gets exported from the nucleus and proteins are synthesized (in the rough ER, right?), but how is it packaged? Thanks(1 vote)
- The different parts self-assemble into the complete working virus(2 votes)
- Genetic shift is just another word for Genetic mutation?(1 vote)
- Genetic drift is the accumulation of genetic mutations. Genetic shift is the outright importation of external (another virus' or organism's) genetic code. Since genetic shift isn't due to a replication error, it isn't considered a mutation. The next video goes into great detail about this, if you have time to watch it as well.(1 vote)
So we've talked about how influenza viruses attack cells. But every once in awhile, it's really, really unfortunate, but you'll actually get two viruses that affect the same cell. So imagine how bad you'd feel in that situation. Not only did you get sick from one virus, you actually picked up two. So this can happen in humans. It can happen in other animals, like pigs, as well. And it's really just dumb luck when this happens. It's not like it's a coordinated attack. This is just, by random chance, two viruses are going to want to attack simultaneously. So in the top one, let's say we've got some RNA. I'm going to put eight strands of RNA in red. And it's going to code for little H proteins. This is-- I'm going to name it H-- I don't know-- H3. And I'll do one more hemagglutinin protein here. And remember, it looks like a hand because it holds onto sialic acid. And you've got some neuraminidase over here. Neuraminidase is going to nick that sialic acid. It's going to help that virus exit. And let's say this is N2. So we've got H3N2 as the top virus. And in the bottom virus, I'm going to do, let's say, 5, 6, 7, 8. I'm going to do a slightly different color. This is also an H protein, but this is going to be H1, OK? So this is H1, and I'm using the color to try to help you identify them as being different. And we, of course, have some neuraminidase on this virus as well. And this neuraminidase is green. And let's assume that that is N1. So we've got H1N1 on the bottom. And we've got H3N2 on the top. And these two viruses are ready to go. They're ready to attack this cell. And this cell, of course, before these viruses are coming along, it's doing its normal, routine things. It has DNA. But once these viruses get in there, they basically take over. So the virus RNA gets inside. We've got some of the red RNA there. We've got some of the blue RNA here. And so that RNA starts taking over and commands the cell to make more copies of itself. So all of a sudden, the cell becomes a factory for the blue virus, the blue RNA virus. That's the H1N1. It also becomes a factory for the top virus, the H3N2. They just basically both take over together. And so this cell is torn two ways, doing a job for the two different viruses. And this red RNA is actually coding for things like H3. This is a protein down here it's making. And it's also coding for N2. So you've got N2 here, more N2 protein over here. And on the other side, on the top side, you've got some H1 being made. So two different types of hemagglutinin and proteins are being made at the same time in this cell. And of course, you've got two different types of neuraminidase. You've got some N1 being made over here as well. So this is basically what we see. We see the cell making a lot of protein and RNA. And eventually, this cell is going to start sending out little viruses. And that's what I have on the right side. We have the viruses that are exiting the cell. And what do they look like? I guess that's the question. Well, some of them might actually look exactly like the parents. Like If it actually gets all the same red RNA or the same blue RNA, then it might actually look identical to the parents. It might even pick up the exact same proteins. It might have these purple H3's. It might have some purple H3's. It might have some N2 over here. So, actually, this one looks basically the same as its parent. H3N2 is what we would call this one if we were to name it. And this bottom one, the blue one, actually would look potentially the same as well. This might have some H1 over there, maybe some H1 on this side. And it might also have some N1, right? It might have some neuraminidase over there and there. So if I was to name this bottom one, I would actually name it the same thing. I would name it H1N1. But the interesting thing is that, actually, once in a while, you get some mixing. You might get some mixing happening. Maybe you get a couple of blue strands over here, maybe three blue strands. Maybe you get two blue strands over there. And when you get mixing of the RNA, you might also get some mixing of the protein. You might get some protein over here. That's actually H3 and maybe an H3 over here. And maybe on the bottom one, you'll actually get something different. Maybe on this one, you get an H1, maybe an H over here. So you get some mixing of the H's. And maybe on this side you get an N2, maybe an N2. And of course, that wasn't what the parents looked like, right? And up here maybe you get an N1. So, all of a sudden, things are looking a little different. And If I was to name these viruses that are coming out, these progeny viruses, this top one, this would be an H3 because it's got a purple-looking looking hemagglutinin. And it's a green-looking pair of scissors, and that was the N1 protein, right. So that would be an H3N1. And this bottom one over here, this would be an H1, because that's the yellow-colored hand. And the orange pair of scissors, we said that was N2. So, these are actually quite different. So these are different than the parents, right? And the other ones are the same. So when you have different viruses coming out, what does that mean? Well, if the virus is successful-- let's say this one is really successful at getting people sick, and it transmits from one person to another person really effectively. In fact, maybe the first person gets a few people sick because it's so, so contagious. Maybe a lot of people can get sick from just one person being sick. And of course, that's going to spread in all directions, right? Well, that's going to cause many, many, many people to get sick. And we would say, wow, in this population of people, in this community, H3N1 seems to be the dominant new virus. And that process is called genetic shift. So this process of a new virus emerging after shuffling up its genes is called genetic shift. So that's what people talk about. And this, of course, happens with type A viruses. So, remember, we have type A, B, and C viruses. And this is a process that really affects type A viruses only. Now, sometimes you might get the other possibility. Maybe this will come out, and it becomes kind of a dud. It doesn't really affect too many people. It's not very good at causing disease. And if that's the case, it would soon be forgotten. So this mixing, this genetic shifting, can happen in people. You might have a person that's affected by two viruses. And that person would then turn around and perhaps affect other people. Or it can actually happen in animals. You might actually see this happening in pigs. So there might be a little pig here that gets sick. And this pig then would transmit the disease to maybe the farmer. And sometimes you might hear the term "mixing vessel." And there, the mixing vessel refers to whether it was a human, which was case number one, or a pig, which was case number two, in which the actual mixing of the two type A viruses happened.