The new corona virus is mutating – is it becoming more infectious?
Viruses mutate. When reproducing in the host cells, copying errors occur which affect the “success” of the copied pathogens. RNA viruses – which include the novel corona virus – generally mutate faster than DNA viruses because, in contrast to them, they cannot use the DNA correction mechanisms of the host cells.
It is therefore no wonder that SARS-CoV-2 has also mutated several times. It is already one of the most genetically analyzed pathogens; the central database GISAID now lists more than 16,000 genome sequences of the 29,903 bases of the virus. By comparing these viral RNA sequences, the researchers can track where and how strongly SARS-CoV-2 has mutated.
>> Corona virus: All news in the live ticker
In March, scientists warned that there were already two or three strains of the virus, one of which was more aggressive than the other and caused more serious diseases. This was not good news, because if several strains of the pathogen were circulating, this could make it more difficult to find an efficient vaccine – which has not yet existed, however. For influenza viruses, the causative agents of seasonal flu, for example, the vaccination has to be adjusted every year because they mutate quickly – faster than SARS-CoV-2.
SARS-CoV-2 mutates rather slowly
A new study by the University of Glasgow now contradicts the earlier finding from March: SARS-CoV-2 has indeed mutated, but according to the study it has not changed so much that different strains could be mentioned. Furthermore, most of the mutations known to date do not appear to affect the severity of the Covid-19 disease caused by the virus.
The scientists, who published their results in the journal «Virus Evolution», examined the genome of virus samples collected during the pandemic. So far, they have found 7237 mutations in these samples – which sounds like a lot, but, as the researchers emphasize, is rather little for an RNA virus. Compared to other RNA viruses, SARS-CoV-2 mutates rather slowly. However, since the virus has now spread worldwide and the number of infected people – and therefore the number of copying processes – is high, many genetic changes have nevertheless occurred.
The number of mutations is likely to increase as the pandemic continues to spread. Of course, this is not necessarily a reason to worry, as study co-author Oscar MacLean says: “It is important that people do not worry about virus mutations. Mutations are normal and have to be taken into account when a virus moves through a population. »
The overview of the situation in Switzerland:
Mutations could bring about better adaptation to people
Another study that deals with the genome of SARS-CoV-2 has been published in the specialist journal “Infection, Genetics and Evolution”. University College London scientists analyzed the SARS-CoV-2 genomes derived from more than 7,500 infected individuals and were able to identify 198 mutations that occurred multiple times and independently. They could therefore affect the evolution of the virus.
However, the mutations were not evenly distributed across the genome of the virus, but particularly often concerned three proteins that are involved in the construction of new viruses. The building instructions for the important spike protein that binds to the host cells were also frequently changed. This suggests that the virus adapts better to the new host by optimizing the binding site. This makes it easier for the pathogen to enter the cell.
Here, too, the scientists emphasize that the changes in themselves are not cause for concern. Co-author Francois Balloux states: «Mutations as such are not bad and so far nothing indicates that SARS-CoV-2 mutates faster or slower than expected. So far we have not been able to say whether SARS-CoV-2 will be more or less contagious or fatal. »
The results also showed that the diversity of virus samples in many cases within a country was just as great as it is worldwide. This is probably due to the fact that several infected people who traveled independently of one another carried the virus into the country. In these cases, there was therefore no “patient zero” from whom all infections originated.
Corona virus – the situation worldwide:
Mutations could increase infectivity
An as yet untested study by the Los Alamos National Laboratory in New Mexico, published by BioRxiv, suggests that the virus adapts quickly to humans. It also shows that certain mutations could increase the infectiousness of the pathogen. So far, the scientists have identified 14 mutations that also affect the spike protein. They focused on a mutation called «D614G», which is located at a point on the protein that is recognized by antibodies from the immune system.
This mutation may therefore influence the body’s immune response: it could cause the infection to last longer by arming itself against the antibodies by the changes. It is also possible that «D614G» – which is close to the binding site of the spike protein with the human ACE protein – makes it easier for the virus to penetrate the cell and thus increases infectivity.
The consequence of a longer duration of the infection would be a longer and stronger excretion and spread of viruses, which would be a selection advantage for them. In turn, the easier entry into the cell would increase the epidemic by increasing the capacity for infection. However, it has not yet been clarified whether «D614G» actually affects the properties of SARS-CoV-2 in this way.
An analysis of viruses collected in the English city of Sheffield suggests that this could be the case. It showed that these mutant viruses quickly prevailed against other variants – those infected with this virus had a higher viral load than other patients. However, there was no evidence of a more severe course in these infected people. The assumption is also supported by the fact that the “D614G” mutation was first detected in Germany at the end of January, but was already the most common variant in Europe at the end of April.
What you need to know about the corona virus:
Since you have scrolled this far, we assume that you like our journalistic offer. As you may know, we recently decided not to introduce a login requirement at watson. There will also be no payment barriers with us. We do not want to create any barriers to access to watson because we believe that in a democracy everyone should be able to get information easily and at any time. If you still want to support us with a small amount, please do so here.