Nothing is known exactly – this also applies to the further course of the corona pandemic. However, experts give a few assessments when asked what may come next.
Epsilon, lambda, pi or omega: the Greek alphabet still has 20 letters that follow after delta.
Although the variants epsilon and even lambda already exist, the alphabet will still be sufficient for a while if the coronavirus continues to mutate and produce new relevant mutants. But how can it continue from a virological point of view?
The answer to this question is like looking into the crystal ball. Nevertheless, some researchers venture into predictions and are particularly certain of one point: The coronavirus will continue to change. However, the President of the Society for Virology, Ralf Bartenschlager, assumes that the number of variants will remain “manageable”. However, it is not yet possible to say for sure whether relevant mutants will follow.
Compared to other viruses, Sars-CoV-2 mutates slowly, says the Professor of Molecular Virology at the University of Heidelberg. This is due to the relatively large genome. ‘When the genome becomes long and longer, you can no longer afford to make a lot of mistakes,’ says Bartenschlager. The virus’s enzymes would have to work very precisely, and many errors would be repaired.
Richard Neher from the University of Basel is also certain: ‘The virus will continue to develop, as we know from other human coronaviruses or the flu.’ Coronaviruses from the animal kingdom are very variable, especially in the region of the spike protein, which is on the outside and is important for the infection. So no natural stop is to be expected. ‘But how this evolution changes the properties of viruses and how much leeway the virus has in this regard is not clear at the moment,’ says the biophysicist.
The spike protein is the part of the coronavirus that plays the most important role in spreading it, as it uses this protein to penetrate host cells and antibodies of the immune system can recognize the surface protein. “Much less is known about the effects of other mutations,” explains Neher. Bartenschlager also admits that these are currently not being investigated as much as changes to the spike protein.
Klaus Überla from the Virological Institute at the University Hospital Erlangen explains that mutations of other viral proteins could also increase the transferability. «Imagine that a mutation helps the virus to escape recognition by the innate immune system. The consequence could be a higher virus load and thus a higher transferability. ‘ This part of the immune system reacts quickly and quite unspecifically to pathogens and foreign substances.
According to Überla, it is impossible to predict how dangerous future mutants will be. “The main selection pressure is transferability,” he explains. ‘Better transferability can go hand in hand with more harmless or severe disease courses.’ After all, Bartenschlager says: ‘The better viruses adapt to the host, the less damage is usually to the host.’ The expert emphasizes, however, that the rule does not always apply.
Neher assumes that so-called immune evasion will become the more relevant component in the coming years. Mutations mean that the viruses escape the immune system more easily.
According to Bartenschlager, so-called recombinations of two corona types are also conceivable. ‘If two variants infect a cell, it is possible that pieces of the gene will be exchanged,’ explains the virologist. He speaks of chimeras – in biology an organism made up of genetically different cells, in mythology hybrid beings such as sphinx, centaurs or mermaids. However, Bartenschlager also says that this has not yet been an issue with Sars-CoV-2.
