All over the world, in Australia, in Mexico, in Great Britain, in South Africa, in Nigeria and now also in Austria, mutations of the coronavirus have appeared that have one thing in common: They make the virus more contagious. Mutations are normal in viruses. But: In this case, the changes seem to happen particularly quickly.
“Coronaviruses mutate relatively slowly compared to influenza viruses, for example,” says Norbert Novotny, virologist at the University of Veterinary Medicine, Vienna. “On average, there is a mutation every fortnight.” Under the conditions of a pandemic, this rule no longer applies: “Sars-CoV-2 now occurs billions of times worldwide. The mutations are increasing accordingly.” Because the mutations make the virus more contagious, the mutation rate will continue to accelerate.
The good news: precisely because all known mutations relate to infectivity, it is unlikely that the virus will cause more severe courses or even become more fatal. “The virus has no advantage if it becomes more deadly. On the contrary: that would also be the end of the virus.”
Mutations – the way to success
From the perspective of the virus, Sars-CoV-2 is already a success story without the increased infection – right from the start. In the winter of 2019 it passed the first hurdle and jumped to a promising new host at a live animal market in Wuhan, China: humans. Man is a particularly good host. Its numbers far exceed that of wild animals and people live very close together. These are ideal conditions for it to spread quickly and mutate quickly.
The virus has also successfully cleared another potential hurdle, namely that of being able to be transmitted efficiently from person to person. Due to the mutations, the infection of the virus, its infectivity, has improved even further, and it can only improve the more hosts there are: With every virus infection, viruses multiply in the body. Each of these “copies” is a chance for a mutation and thus a better adaptation to the new host population. In this way, the mutated SARS-CoV-2 variant in the UK was able to increase its infection by fifty to sixty percent.
The British mutation is a total of fourteen changes compared to the alleged original, as Nowotny explains. Some of these changes relate to the famous spike protein with which SARS-CoV-2 docks to the body cells, more precisely: to the ACE-2 receptors. “The easier the virus can dock, the easier it is for a person to become infected.”
Mutations of the SARS-CoV-2 spike protein, which increase the infectivity of the virus, have arisen worldwide independently of one another. This means that all variations relate to the spike protein and increase the contagion.
No impairment of vaccination
There is good news here too: the mutations only affect about one percent of the spike protein, i.e. a very small part of this particular part of the virus. Therefore, they do not render the vaccines, which also target this protein, ineffective. “The vaccination works just as well,” said Nowotny.
It is unlikely that mutations will go unnoticed. The British virus variant, for example, was exposed because the 14-day case incidence in south-east Great Britain had increased suspiciously. Researchers in the UK suspect that blood plasma therapy may have triggered the mutation in a Covid 19 patient. Via the antibody-rich blood plasma that was given to the patient, the virus population that was already present in the patient’s body cells came under pressure to adapt.
However, this thesis has not yet been proven and is only an assumption, as Norbert Nowotny also emphasizes. The explosive thing about the thesis would be that this British virus variant would then be targeted mutations of the virus in order to escape the environment saturated with antibodies. “Viruses mutate essentially through trial and error, not intentionally,” says Nowotny.
As soon as virus mutations are known, their genetic data is saved. In the UK, for example, five to ten percent of all Covid-19 diseases are sequenced. The data is entered in the publicly accessible GISAID database, where it is available to all scientists for further research.
The causes of the pandemics remain
Will people have to live with pandemics in the future? Nowotny reminds us that pandemics occur every ten to 15 years, most recently the so-called swine flu. While the vaccinations are an unprecedented success story, they did not touch the causes of pandemics: “Many pandemics are zoonoses, that is, they originate in wild animals. Humans are pushing more and more into their habitat and thus increasing the risk for Zoonoses. “
Around 60 percent of all infectious diseases in humans can be traced back to zoonoses. Nowotny gives the example of the palm plantations for palm oil production, for which the primeval forest is being cleared. “I do hope that people learn from this most severe pandemic in 100 years.”