Tuesday, May 8, 2012

Discovery paves the way for a lasting flu vaccine

Every year sees the outbreak of a new flu virus that manages to spread around the globe. Even though we are constantly developing flu vaccines to prevent an outbreak, the virus manages to find a way to mutate and prevent eradication. Because vaccines enable the immune system to recognize a specific variant of the influenza virus that causes the flu, it is possible to escape detection by shape-shifting. This is exactly what influenza is doing, but a new concept for a flu vaccine should be able to prevent this. Despite changing appearances, a new vaccine would enable the immune system to recognize the virus and consequently destroy it.

Viral structure
There are many different variants of the influenza virus, but they have a couple of things in common. They can all be recognized by two specific proteins that are present on the viral surface. They are called hemagglutinin and neuraminidase, or H and N for short. There are many different forms of H and N, which are used to give names to the virus. Well-known is H5N1, the variant that caused bird flu. Luckily, it is not very effective in humans, but mutations could make it deadly.
Influenza virus type H5N1.
Scientists from the University of British Columbia noted that a vaccine developed for the 2009 version of H1N1, which is another form of influenza, has special capabilities. They found that the vaccine also protects against other types of influenza, including the aforementioned H5N1. Because the vaccine is aimed at the part of the H molecule that normally do not mutate, its structure is more or less the same in many different influenza viruses. Therefore, shape-shifting will not help the virus to escape an immune system that has been fortified with this particular H1N1 vaccine.

New vaccine
According to the scientists, the way the immune system works has made it difficult to create a vaccine that only targets the stable part of the H molecule, which has left us with many different vaccines targeting variable parts. The discovery made by the University of British Columbia gives rise to new possibilities of developing a vaccine that can protect against future forms of the influenza virus. It is not very likely that the stable part of H will evolve after we target it with new a vaccine: the stable part is used to enter human cells, therefore enabling infection. Its structure is crucial and cannot simply undergo evolutionary changes, making it an excellent therapeutical target.

Influenza has been bothering humanity for a long time. Most famous is the 1918 outbreak that cost the lives of millions of people. The world has seen many more epidemics and pandemics, including recent outbreaks of bird flu and swine flu. Even though those two outbreaks did not cause large numbers of casualties, mutations can make influenza deadly in the future. The question remains whether that will actually happen, but if we can find a universal vaccine based on the aforementioned discovery, we need not to worry anymore about future outbreaks. Of course, it remains to be seen whether we can actually produce a functioning therapeutic based on the 2009 H1N1 vaccine.

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