Experts believe that the coronavirus will mutate several more times. However, the president of the Society for Virology, Ralf Bartenschlager, assumes that the number of variants will remain "manageable." "But one cannot seriously say whether we have already reached the end of the line or whether relevant mutants will still follow."
The better viruses adapt to the host, the less damage they usually do to the host, explained the professor of molecular virology at Heidelberg University. "But you can't always say that."
Richard Neher of the University of Basel is also certain: "The virus will continue to evolve, as we know from other human coronaviruses or from influenza." Coronaviruses from the animal kingdom are highly variable, he said, especially in the region of the spike protein, which sits on the outside and is important for infection. Thus, no natural stop is expected, he said. "But how this evolution changes the properties of the viruses and how much latitude the virus has in this regard is not clear at the moment," the biophysicist said.
The spike protein is the part of the coronavirus that plays the most important role in its spread, he says, because it uses this protein to enter host cells and antibodies of the immune system can recognize the surface protein. "Much less is known about the effects of other mutations," Neher explains. Bartenschlager also admits that these are not being studied as much as changes in the spike protein at the moment.
Klaus Überla of the Virological Institute at the University Hospital Erlangen explains that mutations in other viral proteins could also increase transmissibility. "Imagine that a mutation helps the virus evade detection by the innate immune system. The result could be a higher viral load and thus higher transmissibility." This part of the immune system responds rapidly and quite nonspecifically to pathogens and foreign substances.
How dangerous future mutants will be is unpredictable, according to Überla. "The major selection pressure is transmissibility," he explains. "Better transmissibility may be associated with more benign or severe disease courses." Bartenschlager says, after all, "The better viruses adapt to the host, the lower the damage to the host, as a rule." But the rule doesn't always apply either, the expert emphasizes.
Viruses escape the immune system more easily
Neher expects so-called immune evasion to become the more relevant component in the coming years. Mutations make it easier for viruses to escape the immune system.According to Bartenschlager, so-called recombinations of two corona types are also conceivable. "If two variants infect a cell, it may be that there is an exchange of gene pieces," the virologist explains. He refers to chimeras - in biology, an organism made up of genetically different cells; in mythology, mixed creatures such as sphinxes, centaurs or mermaids. However, Bartenschlager also says that this is not yet an issue with Sars-CoV-2.
Image by Samuel F. Johanns