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Fear of super virus: do mutations make the coronavirus more dangerous?
The SARS-CoV-2 coronavirus is one of the RNA viruses that are considered to be particularly mutation-friendly. In fact, the novel pathogen has changed since the first infections. It has recently been reported that mutations could make the virus less deadly. But now there are also indications that it could become more dangerous.
An analysis from the United States catches the eye: SARS-CoV-2 could have mutated into an even more dangerous variant, it says. Experts have great doubts about this. The corona virus didn't really need any changes - it was pretty well adapted.
Mutation called D614G
The corona virus that appeared about half a year ago has infected tens of millions of people - is it mutating and becoming more dangerous? In a preprint study that has not yet been reviewed, researchers at the American Scripps Research Institute conclude from genome analyzes that a mutation called D614G makes the virus more infectious. The team recently reported that the pathogen can infect more cells under laboratory conditions.
Chance plays a big role
Richard Neher from the University of Basel explains that the D614G mutation is actually very present in the virus strains circulating in Europe and on the east coast of the USA. "However, it cannot be concluded from this dominance that the virus spreads faster with the mutation."
The dominance is not necessarily due to a higher transmission rate or virulence, but coincidence, explains the head of the research group Evolution of Viruses and Bacteria: The D614G virus variant was at the beginning of individual larger outbreaks and subsequently spread more than other variants. "Coincidences play an incredibly important role right at the beginning."
In general, mutations in the coronavirus are absolutely not unusual, emphasizes Neher. In its 30,000 bases, there is an average mutation every two weeks. This means that the mutation rate per base is somewhat lower than in the case of influenza or HIV, but because of the larger genome of SARS-CoV-2, the value is ultimately approximately the same.
Based on the mutations, one could conclude whether two outbreaks are connected - infection chains from person to person cannot be understood. At the recent outbreak in Beijing, for example, genome comparisons suggest that the pathogen was brought into the country from outside - it cannot be said from where exactly.
Medications mostly insensitive to single mutations
SARS-CoV-2 is already very well adapted to humans, says Friedemann Weber, director of the Institute of Virology at the Justus Liebig University in Gießen. "So I ask myself first: What more is needed?" According to a recent study, the D614G mutation gives a little more stability, which could be an advantage for the particles.
It is conceivable that a single mutation makes a big difference, especially with a drug that only acts on a specific enzyme. However, many drugs and vaccine candidates are broadly based and therefore mostly insensitive to individual mutations.
Neher emphasizes that not a single virus isolate with altered pathogenicity is currently known worldwide. "We cannot rule out the possibility that they exist, but it is rather unlikely." Together with his US colleagues, his team developed the "Nextstrain" web application (nextstrain.org), which can be used to track genome sequences that have been fed in, and by which means viruses spread. The software analyzes how a pathogen changes, i.e. which mutations it accumulates during the spread - a kind of family tree is created.
SARS-CoV-2 is introduced several times
Andreas Bergthaler from the Research Institute for Molecular Medicine at the Austrian Academy of Sciences (CeMM.) Explains that SARS-CoV-2 not only landed once in countries like Germany, Austria or the USA, but was imported several times ) in Vienna.
Conclusions about the consequences of detected mutations are not yet possible after six months of the pandemic. But genome comparisons could very well help determine where the virus came from behind a particular outbreak. This in turn is useful when interrupting chains of infection.
The data from "Nextstrain" also allow conclusions to be drawn about the origin of SARS-CoV-2. "We assume with great certainty that the virus has spread from animals to humans in China," said Neher. That had happened once and in the Wuhan region. However, the data cannot be used to infer future adjustments and changes. Bergthaler: "Time will tell in which direction the virus develops." (Ad; source: dpa)