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Asked by to Heather on 18 Jun 2014. This question was also asked by .
Question: what type of virus mutates so frequently that you need a vaccination for it every year?
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Heather Ritchie answered on 18 Jun 2014:
Viruses are very interesting as different viruses have different mutation rates. So some viruses don’t mutate much at all and vaccinations have been developed very successfully. An example of this was the vaccination created for smallpox and it worked so well the world has been declared free of smallpox.
However, some viruses mutate at incredibly fast rates that it is impossible to develop vaccinations for them. HIV mutates so quickly that as soon as they develop a vaccination for it it stops working because the virus has already mutated!
Other viruses mutate at different rates and develop different strains. The most common example of this is the influenza virus – the flu! The flu virus mutates enough within a year that the immunity you receive from your previous year’s vaccination can’t recognise the mutations the following year. Every year you can get a vaccination for the flu that will protect you against the three or four most common “strains” of flu for that year.
Comments
Ditte commented on :
Following on from Heather’s great answer…..
Those viruses that mutate frequently usually have genes made up of RNA. RNA is similar to DNA, but slightly less stable. The reason why these viruses have more mutations is because they are really really really bad at making copies of themselves, so every time they make a new virus copy, they make some mistakes in the genes. It is the same as when human, animal and plant genes slowly change over millions of years, a process also called evolution, but for some viruses this can happen within a day.
Some of the viruses that changes must frequently are the flu virus, HIV and Hepatitis C virus. I work on the hepatitis C virus genes in the human liver and have found out that one liver may contain 100s of different hepatitis C viruses. We are lucky that there is a vaccination for flu, but unfortunately there is none for HIV and hepatitis C virus, we are working on it though……
Rebecca commented on :
In addtion to virsuses accumulating changes by making mistakes when they copy themselves (called antigenic drfit) the influenza virus can also change via much larger changes called antigenic shift.
The influenza virus has 8 segments, when two different influenza viruses infect the same individual or animal a new virus can be created which has a new combination of the 8 segments some taken from one of the viruses and the rest from the second. This can result in a very different virus in just one infection for which a new vaccine will need to be created.
pokemaster1 commented on :
i believe that the influenza virus mutates so rapidly that you need a vaccination every year. that is the answer to your question. thanks for making me think parasite123.
Ben commented on :
As @pokemaster1 says, RNA viruses like influenza and HIV mutate very rapidly and this is part of the reason why they’re so successful at infecting us, and considered such a threat.