At the moment, influenza, or “flu” is a disease which kills many thousands of people despite the availability of a different vaccine every year. A new flu vaccine has to be manufactured each year to accommodate the changes that are seen in the flu virus. The virus mutates, which means different antibodies are needed to recognise it.
The parts of the flu virus which mutate are surface proteins called haemagglutinins. These haemagglutinin proteins are composed of a “head” and a “stem” region. The head region is the part of the protein which changes slightly – a process which can be known as “drift”.
A flu vaccine usually contains dead or weakened versions of the flu virus, so that the body produces antibodies which are complementary to the viral haemagglutinins. These antibodies can then fight the flu virus if the vaccinated person becomes infected, inducing the immune system to get rid of the virus in order to avoid illness.
However, a flu vaccine will only work for the specific virus the person is vaccinated against. If the viral proteins drift (mutate) then the antibodies the body has made will not work, because they are no longer complementary to the proteins. This is why a new flu vaccine is manufactured every year. But new scientific advances hope to change this one day.
Scientists are working towards creating a vaccine which will induce antibodies which attack the stem of the haemagglutinin viral surface protein. Unlike the head region, the stem of the haemagglutinin molecule does not mutate, so antibodies which attack the stem will work against any strain of the flu virus. Because the immune system “remembers” molecular regions it has encountered before, these antibodies will be produced each time a person is infected with a flu virus – which all have the same haemagglutinin stem. It is hoped for this reason that the immunity to the flu virus will be long lasting, and stop the need for different flu vaccines each year.
This technology is still in its early stages, and we are unlikely to be seeing a universal flu vaccine being produced very soon. But scientists hope that it will progress well in the next few years, and could be within our reach in a decade’s time.
Watch http://www.youtube.com/watch?v=NVm2W56yjt0 to see a CNN news piece on this.