The corona virus is now widespread in large parts of the world. In Germany, as in many other countries, extensive measures have been introduced to slow down the spread. This approach has also been successful, which is why the restrictions are being relaxed more and more. You can find all current developments in our ticker.
The corona virus that emerged about half a year ago has infected tens of millions of people – is it mutating and becoming more dangerous? In a preprint report 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 could infect more cells under laboratory conditions.
D614G mutation: strong spread just coincidence?
The “D614G” mutation is actually very present in the virus strains circulating in Europe and on the east coast of the USA, explains Richard Neher from the “Universitt Basel”. “From this dominance, however, it cannot be concluded 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 stood at the beginning of single larger outbreaks and subsequently spread more than other variants. “Coincidences play an incredibly big role right at the beginning.”
In general, mutations in the coronavirus are absolutely not unusual, emphasizes Neher. In his 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 can conclude whether two outbreaks are related – infection chains from person to person cannot be traced. 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.
Sars-CoV-2 well adapted to humans – D614G stabilizes spike protein
“Sars-CoV-2” is already very well adapted to people, says Friedemann Weber, director of the Institute for Virology at the “Justus Liebig University Gieen”. “First of all I ask myself: what more is needed?” However, according to a recent study, the D614G mutation gives a little more stability, which could be an advantage for the particles.
As the researchers at the “Scripps Research Institute” found in their studies in cell cultures, particles infected with the “D614G” mutation cells nine times more efficiently than particles without this change. The so-called spike protein plays a crucial role in a successful infection. Research into “D614G” particles has shown that they lose the S1 portion of the cut spike protein less frequently. The scientists conclude that the mutation stabilizes the spike protein. This could at least make the initial infection more efficient.
It is conceivable that a single mutation makes a big difference, especially with a drug that only acts on a certain enzyme. However, many drugs and vaccine candidates are broadly based and therefore mostly insensitive to individual mutations.
Virus spread can be traced
Neher emphasizes that not a single virus isolate with changed pathogenicity is currently known worldwide. “We cannot rule out that they exist, but it is rather unlikely.” Together with his US colleagues, his team developed the “Nextstrain” web application, which can be used to track genome sequences that have been fed in, via which routes 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.
Andreas Bergthaler from the Research Institute for Molecular Medicine of the Austrian Academy of Sciences (CeMM.) Explains from the collected data 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 half a year 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 jumped 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 will develop.”
ml / dpa