© GEORG HOCHMUTH
Vienna – From Finland to the Czech Republic to Brazil, a whole jungle of SARS-CoV-2 variants currently seems to be growing. It is clear that the virus family tree has been increasingly branching into variants since late autumn that also extend further away from the trunk. What these accumulated changes are causing is, however, hardly clear and difficult to assess. You have to remain vigilant, but not fall into “alarmism” every week, said the virologist Andreas Bergthaler.
The boom of the term “variant” arose around the end of the year with the realization that the “British variant” (B.1.1.7) spread more quickly than the so-called wild type of the new coronavirus, and not just at the place of its discovery.
The re was also the South Africa variant with its designation B.1.351, which was particularly popular in Austria in Tyrol. What both of them have in common is that they actually have numerous changes (mutations) in their genetic makeup compared to the original pathogen.
Family tree with more and more branches
The SARS-CoV-2 virus can be viewed as a family tree that has repeatedly branched out – and now many, because more than 500,000 genomes have been sequenced worldwide. B.1.1.7 and B.1.351 can, however, be seen as branches that protrude at least unusually far.
The British variant was able to combine more than 17 additional mutations by leaps and bounds for the first time. In addition, there was at least one mutation in the spike protein that was also found in the independently generated B.1.351 branch.
Here you can easily say that it is a new variant, says Bergthaler. But that is not always so clear and also depends somewhat on who is trying to classify it here. Danish, Finnish, Brazilian or Czech “variants” or not – the decisive question is ultimately whether they change the infection process through the accumulation of mutations. Mutations can make the virus more easily transmissible or lead to the fact that it can better escape the body’s own defenses built up by a vaccination (ability to “Immunescape”). In addition, the course of the disease in Covid 19 patients could also be influenced. Ultimately, this leads to the political question of whether the emergence should lead to separate containment measures, such as in Tyrol in the case of the South Africa variant.
New changes weekly
The distribution pattern and the composition of the mutations itself actually change weekly if, for example, a variant suddenly picks up an additional mutation somewhere.
While sequencing is complex, but relatively “relatively simple” with the appropriate team and infrastructure, it is much more difficult to make statements on infectivity and the “immune landscape” based on laboratory tests.
The re are interesting approaches here where new mutations and combinations and their possible effects are played through in simulations before they occur. In reality, however, there are various other influencing factors, explained Bergthaler: “In addition to experiments in the laboratory, you also need solid epidemiological data, and that takes time.”
Ask why the timing of many mutations
The more interesting and still unanswered question is why such mutation clusters have been appearing especially since autumn 2020.
A recent example is the “Czech” version (B.1.258) having known mutations, but also about a new change in position “N439K” of the spike protein has. This mutation has also been seen in Austria since January “in an astonishingly high number”, says Bergthaler: “This is a mutation constellation that is obviously very successful.” You can also find these in wastewater samples. “We don’t have to be alarmist about that. But I believe that it will still be very helpful if we understand what is circulating around us in real time, if possible.” Fortunately, in Austria a lot has developed in terms of monitoring over the past few weeks, said the researcher.
It is currently also evident that the British variant is on the rise, especially in the east of the country. In the west, wastewater samples would meanwhile also show higher B.1.1.7 proportions. In Tyrol it is not yet completely clear how well the spread of B.1.351 has been at least regionally contained. In any case, all question marks about the mutations would clearly show how important it is to push the total numbers down, emphasized Bergthaler: “No matter which variant is behind it at the end of the day.” (WHAT)