Having the flu is a real hit.
And for some vulnerable groups it can be fatal. The previous flu season, 2017/2018, was the record number that ended up in hospitals and 1,400 who died from influenza, according to the Public Health Institute.
It is our own body's fight against the virus that gives the feeling of illness, says Tone Gregers. She is the first teacher of biology at the University of Oslo.
– The body grows the temperature, because then it becomes unfavorable for the virus to multiply in our cells. Some inflammatory agents that kill the infected cells are secreted and eventually a more lasting immune response is formed, says Gregers, who has also written a book on vaccines.
We can also get such a lasting immune response by taking
However, it cannot last long. Your immune system may not necessarily know the flu virus when it hits again next season.
It's about how a virus turns into many. senior researcher at the National Institute of Public Health and head of the National Influenza Center.
Because when the flu virus spreads in our body, there are many errors along the way: The pathogen of the virus mutates very easily.
Many mutations can cause the virus to stop functioning. But as long as they can still attack our cells ̵
– The influenza virus can change the suit and sneak away from the immune system. That's why measles is a childhood disease, while flu has episodes in life, Hungnes explains.
In addition, there are several different types of influenza viruses. And within each of these types, the viruses change from year to year.
But what is it about the flu virus that causes it to mutate so often?
Part of the explanation is about what the genetic material is made of. Thus, the recipe is inside the virus, which tells how the virus is to multiply.
For while the viruses that, for example, give chickenpox and herpes have the same type of hereditary substance as us – the DNA influenza virus has a recipe made from another substance.  – Influenza virus is an RNA virus and they mutate much faster, explains Bjarne Bogen, professor of immunology at the KG Jebsen Center for Research on Influenza Vaccines at the University of Oslo.
And it is not just the flu virus that has this easily mutated inheritance.
– The HIV virus is also an RNA virus, and it mutates extremely quickly, while there are other viruses that do not change much, and then a vaccine will be a lifetime, says Bogen.
Mutates inside the body
But as long as the virus is outside the body, this internal recipe lies untouched in a small capsule.  So they cannot live or reproduce without cutting someone else's cells. Therefore, viruses have not been considered as living beings.
But when a small virus capsule hits one of your cells, it attaches and injects its inheritance. Then your cells think the virus's inheritance is your own.
The consequence is that your own cells do the job for the virus and create a bunch of new viruses.
And this is when the mutations occur.
– We have flu viruses that circulate throughout the year – either in the air or in humans. As long as the viruses can visit a host, they change, says Gregers.
And there are many changes in RNA viruses, which have a more fragile genetic material than DNA viruses.
Spikes on the surface
But to make it even more confusing, measles also has a legacy made of unstable RNA.
And this disease we have good vaccines against.
So to really understand what's so special about the flu virus, we have to look at the outside of the viral capsule that is around the hereditary.
There are some proteins that act as nails that can be attached to our cells. And the flu virus spikes are very flexible compared to other viruses.
– The influenza virus can withstand many more changes in the proteins that sit on the surface, explains Hungnes.
So the proteins on the surface can change as the inheritance mutates without stopping real. And so they escape from our immune system, which has only learned to recognize an old variant of the nails.
The corresponding nails on the outside of the measles virus, on the other hand, cannot withstand any particular change.
Mixtures of viruses
But Bogen and his colleagues are trying to make a vaccine that can protect against all types of influenza. Ideally for the rest of life.
The hope is that the new vaccine will also be able to provide protection against pandemics.
Regularly, an influenza virus is transmitted from animals to humans and creates a new global flu wave. The last was swine flu in 2009.
Bird flu and swine flu may be fatal to people who get it, but it rarely infects the species.
But some of the worst pandemics we have had are due to a cross between human and animal viruses.
Spanish disease may have been a cross
Both Asian disease in the 50s and Hong Kong disease in the 90s were the result of such crossings. can occur inside an animal that is infected, for example with both swine flu and human influenza simultaneously.
When the virus multiplies inside one of the cells of this animal, little bird flu and a human influenza virus may end up in a new virus.  – It is when you get a combination of genetic material from these different viruses that you get quite radically different viruses, says Bogen. [1 9659002] If such a mixed virus easily infects people – and causes serious illness – it can quickly lead to another deadly pandemic.
This article was first published on Forskning.no