The mutation of influenza virus

Flu is a common disease with high infectious rate and death rate. So it is necessary to know the common sense of the dissemination of flu. Flu is caused by various viruses. Some certain kinds of viruses will die, however, some will be mixed with other kinds of virus as time goes by. Thus these mixed viruses will cause a serious flu. 

Generally, the influenza virus with mutation causes around 500 thousand people’s death all over the world in flu seasons. Some new viruses presents peaceably in human, so it is regarded as normal clod. Some new created viruses are serious and it can lead to a serious flu. The serious flu may break out every ten to twenty years and it will kill millions of people.

What leads the change of influenza virus? The proteins which covers the virus. It always changes in Hemagglutinin and Neuraminidase and cause mutation in the surface of virus. This is called antigenic shift and it creates some new kinds of virus slowly. Human’s immunity can update their database to prevent these new virus from body, But sometimes, some people’s immunity recognize these mixed viruses as new viruses in mistake, so it fail to recognize that these viruses have attacked their body. Finally, they are attacked by these viruses with mutation and cause a serious flu.

In addition, there is another method to the mutation of influenza virus. That is the mixture of two different kinds of viruses. The two different kinds of viruses can exchange genes and create a new kind of virus, which is called antigenic shift. The shift happens rapidly, so many people’s immunity do not have its information. This kind of virus can cause a large number of people’s contagion. 

There have been some serious flu for the virus virus with mutation. H3N2 flu in Hongkong is caused by antigenic shift. It comes every two or three years and cause a serious flu in some area or countries. Every outbreak make people produce some antibodies and then an increasing number of people with antibodies will block its contagion. Antigenic shift happens every ten to thirty years, for example, H3N2 becomes H1N2. Almost people do not have its antibody, so it may cause the global serious flu.