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Genetic changes mean that antibodies directed against Sars-CoV-2 neutralize the virus variants less. This has implications for antibody therapies. However, it is not clear whether the mutations also render the vaccines ineffective.
A young mink at a fur auction, taken in April 2009 in Jyllinge, Denmark.
The news from Denmark raises some alarms. The Danish Serum Institute reports that a new variant of Sars-CoV-2 has formed in mink, which has already infected more than 200 people and can apparently escape parts of the human immune response. The Danish government now fears that a possibly more dangerous variant of Sars-CoV-2 is spreading from Denmark, against which the vaccines currently being tested could also be less effective. A partial blockade was imposed on the seven affected regions in North Jutland on Friday.
There was still too little information available on the new mink variant to be able to really assess the danger, Marion Koopmans of Rotterdam’s Erasmus University explained on request. Neither the transmission from mink to humans nor the fact that the new coronaviruses change genetically in mink is surprising. This was already demonstrated by Koopmans’ team after mink on Dutch farms contracted Sars-CoV-2 for the first time in late April. According to Koopmans, there has been no evidence so far that any of these new virus variants are more dangerous to humans.
According to a communication from the Serum Institute, the new variant in Denmark already shows four genetic changes (mutations) and an important protein as well. It is the so-called Sars-CoV-2 spike protein, that is, the bite with which the virus attaches itself to the receptors of various human cells and then infects them.
It is not yet known whether the new mink variant binds better to cells, reproduces faster, or does more damage to human cells. What is known and alarming, however, is the information from the Serum Institute that antibodies from Covid-19 patients that block the binding of the spike protein to the ACE receptor on the surface of human cells only do so in a Limited to the new mink variant. Apparently, the antibodies no longer correctly recognize the mutated form. This could mean that a person who was already infected with another Sars-CoV-2 variant would have poorer antibody protection against a second infection with the mink variant.
Antibody therapies currently in development, which Donald Trump has also received, for example, also need to be reconsidered. This is also shown by an international study published Thursday that has yet to be reviewed. According to the study, the Danish mink variant is by no means the only Sars-CoV-2 variant that is insensitive to some human antibodies. A variant called N439K has already appeared in twelve countries and in some cases is widespread. In cell culture studies, neutralization due to different antibodies was reduced by more than a factor of two compared to the original variant. Also of concern is that N439K viruses bind better to human cells in cell culture and multiply a bit faster.
As a precaution, all the animals die on a mink farm in North Jutland.
The N439K variant is not yet an acute threat, but based on information available so far, it is somewhat more threatening than the Denmark mink variant. In any case, several antibodies directed against different areas of the peak protein should always be included in a therapeutic cocktail, demand the researchers led by David Robertson from Glasgow. So you have weapons against various variants of viruses.
What this means for vaccine development is not yet clear. The Danish government fears that the vaccines currently being tested may be less effective if the mink variant spreads and then dominates a country or even a continent. Experts consider that this is not proven in any way. Because during a vaccine, the body’s own immune system usually forms a lot of antibodies in a kind of predictive prophylaxis, which are directed against different points of attack of the vaccine virus. This generally means that at least some of the mutated viruses are recognized and neutralized. In addition, after a vaccine, our immune system forms a second weapon, namely T cells, which specifically target a virus.
The killing of all minks, which Denmark has now ordered, is nevertheless a sensible preventive measure. Due to the poor farming conditions, coronaviruses can spread rapidly in mink farms. So it cannot be ruled out that mutations that are also dangerous for humans will arise at some point. Therefore, the Netherlands decided weeks ago to close all mink farms by spring 2021. It remains to be seen whether other countries with such companies, such as Poland, Finland, Spain, the United States or China, will follow suit and when.
A buyer examines mink fur at an auction in Copenhagen in April 2009. The animals spend the few months of their lives in a cage the size of two shoe boxes.
