The Wiley Influenza Virus, Porcine and Otherwise | Big Think

The Wiley Influenza Virus, Porcine and Otherwise

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Old age offers protection against swine flu, says Peter Palese, chairman of microbiology at the Mt. Sinai Medical Center.

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TRANSCRIPT:

Paul Hoffman: I’d like to introduce our first presenter. He’s going to talk about influenza and swine flu. Peter Palese. He is the chairman and a professor of the department of microbiology at Mt. Sinai Medical Center, here in New York. Please welcome Peter Palese.

Peter Palese: I would like to discuss briefly influenza viruses and the disease which is caused by these viruses.

So the viruses are in RNA [ribonucleic acid] containing virus. So it has this genetic information RNA. And if you look at this particle, it has eight RNA segments so they are one in the center and one, two, three, four, five, six, seven RNA. These are like mini chromosomes which are the genetic information of the virus.

This virus also has a very important characteristic and that is, on the surface, it has spikes. And one can see this in the electron micrograph. They are spikes associated with this various on the surface, and that’s actually what the immune system when we get infected, sees. So these surface proteins are called the hemagglutinin and neuraminidase, so these are two proteins which are on the outside.

We should also understand that the virus is very, very small. A cell which is infected by this virus is much, much larger. Not only larger than this room but it’s probably as large as the Empire State Building. So we are really dealing here with a very small virus which can within 8 hours, infect us all and kill this Empire State Building and make about a hundred thousand new virus particles. So this is a virus which can cause a disease.

In humans, we know that there is influenza every season in the Northern Hemisphere from November to March. And also many people know that a hallmark of the virus is that it changes. And if you look here at the different influenza viruses which have circulated in the last century, we know about the 1918 virus, which was, in terms of number of deaths, a very important historic event because within probably three month period, from November 1918 to about February of 1919, in the US alone, about three quarter of a million people died. So this virus, 1918, belongs to what we call the H1 sub-type. It means that it has a hemagglutinin of this H1 sub-type.

And this virus was also replaced in 1957 by a separate virus, a different virus which has a hemagglutinin II sub-type and that sub-type was prevalent for about 11 years.

And then in 1968, a new sub-type emerged, an H3 virus which, is actually still with us in 2009.

In addition to this there was also, in 1977, another H1 virus reappearing, and it turned out that it was very similar to a 1950 strand.

So in 2009, we have H1 viruses, we have H3 viruses circulating, and then in also an influenza virus. So the complexity of influenza is quite impressive that we have this co-circulating strand. And that explains why, for example, vaccines, which are very helpful, they are not perfect but they are very important way of preventing influenza, why vaccines have to have three different components. So for the last season, that means 2008 to 2009, we had in the vaccine formulation, three different influenza virus components; we had the H1 component, and this was an isolate from Brisbane, isolate number 59 and isolate in 2007; an H3 component; and an influenza B virus component, isolated in 2006.

Now that would be all very good if we could use these vaccines for several years. But unfortunately influenza also changes within, not only this major changes from 1918 to 1957 to 1968, but also within one of these H1 or H2 or H3; there are constantly changes going on. And that means, that the vaccines has to be changed as well.

For the 2009/2010 season, we have a vaccine formulation now which is being produced by manufacturers and there is actually a new strand and new influenza B virus. So for the season which will start in November of 2009, this is the new vaccine formulation.

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