Does the H1N1 flu vaccine protect against swine flu?

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luis asked the Naked Scientists:
Hello Chris,
I have been listening to you guys for about a year. I'm in Queens New York, about 2 miles away from the epicenter of the Swine Flu (H1N1) outbreak in New York. I have a few questions that I hope you would find the answers to.
What antigen do flu vaccines target? I was under the impression that they target the H or N antigen. If that is the case...why don't previous H1N1 vaccination protect against the new H1N1?

I understand that the new virus has Swine, Human, and Horse genetic material but that shouldn't matter just as long as the H1N1 antigens are maintained.
please explain
Thank you,
Wit of a twit

What do you think?


Offline glovesforfoxes

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Does the H1N1 flu vaccine protect against swine flu?
« Reply #1 on: 03/06/2009 18:21:05 »
"On the surface: the HxNx nomenclature

Like most viruses, the currently spreading swine flu virus has a coat formed of proteins which surround the genetic material that allows the virus to hijack a cell and reproduce. These coat proteins are critical in a variety of ways: they determine which cells the virus can latch onto and infect and, being exposed, they're the things that antibodies recognize when your body generates an immune response to the virus. For the flu virus, the major coat proteins are called hemagglutinin and neuraminidase—the H and N of the commonly used nomenclature for identifying these viruses.

Given the large and diverse flu virus population, there are many variants of each of these two proteins, but they fall roughly into a limited number of classes: according to the CDC, there are 16 known hemagglutinin classes, and nine of the neuraminidase. As such, it's possible to identify categories of viruses based on their specific combination of these two genes, leading to the typical nomenclature that we see in press reports about influenza: H1N1, H3N2, etc.

It would be reassuring if these broad categories lined up nicely with the virus' hosts, so that this nomenclature was informative. Unfortunately, given the influenza virus' tendency to mutate and hop among species, that's not the case. So, for example, pigs carrying the virus are most often infected with an H1N1 subtype but, according to the World Health Organization, at least three other subtypes have also been found. The viruses currently known to circulate in humans are H1N1, H1N3, and H3N2. Two of those also appear in pigs, and the CDC indicates that all known subtypes of influenza virus can circulate in bird populations.

To add to the confusion, there is a lot of variability within these broad groupings. That's why, even if you've received a vaccine against an H1N1 virus, it may not protect you against the H1N1 virus that actually starts circulating in a given year. The differences within a group can also contribute to the host range, virulence, and other properties of the virus. So, even if a given subtype of virus doesn't circulate in humans at the moment, there's no guarantee that it won't at some point in the future."

- taken from edited bold for where the question is answered

So the upshot of it seems that the nomenclature system is not very useful or informative to biologists, just a way of classifying them.

Hope this helps :)
« Last Edit: 03/06/2009 18:33:18 by glovesforfoxes »
The animals of the world exist for their own reasons. They were not made for humans any more than blacks were made for whites, or women for men. - Alice Walker