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A recent mutation has made the SARS-CoV-2 coronavirus more infectious, but at the same time made it much more vulnerable to vaccines in development, a study published in the prestigious scientific journal Science found.
The mutation in question is called D614G and it first appeared in Europe and then soon spread to the continent. A joint study from the University of North Carolina at Chapel Hill and the University of Wisconsin-Madison found that although the D614G mutant strain spreads faster and replicates more efficiently than the original version discovered in Wuhan, it also became more vulnerable to antibody and anti-vaccine therapies in preparation, writes the press release from the universities that signed the publication.
It was also found that despite faster replication, the pathogen does not cause more dangerous symptoms than its predecessor.
One of the study’s authors, epidemiologist Ralph Baric, said that the D614G virus spreads ten times more efficiently than the original strain and also multiplies faster in the epithelial cells of the nose. Baric has been studying various coronaviruses for more than thirty years, and his work has been instrumental in the development of the well-known anti-COVID-19 drug, Remdesivir.
The role of crown-forming protein peaks
The spikes of coronavirus are the keys that open the locks of our cells. In this case, the block is a receptor protein called ACE-2 (angiotensin converting enzyme 2), to which the pathogen binds with its protein spike. However, another very important protein, the TMPRSS2 protease, is required to activate the peak. With these two molecules, SARS-CoV-2 can now enter the cell, which it then diverts to ensure its own reproduction.
A beneficial and disadvantageous mutation
How did the D614G strain come about?
Viruses make their own copies with infected cells, so they multiply. However, the copying process is not perfect, errors may appear, and mutant strains may appear different from the original. The new mutations often have no effect on the behavior of the virus, but can sometimes change it.
Proteins are composed of amino acids. In the present case, due to a copy error, aspartic acid (abbreviated D) was replaced by glycine (G) at amino acid position 614 of the protein peak. This caused a change in the structure of the protein peaks, facilitating the entry of the modified coronavirus into the host cell.
The new ability favors the pathogen at first glance, however the altered protein spikes may have become a weak point in SARS-CoV-2 because antibodies can more easily neutralize the virus through them.
The resulting vaccines induce the production of these antibodies.
Virus variants were tested in hamsters
To find out how the D614G strain differs from the original virus, the researchers infected hamsters with the two variants. The infected rodents were then caged and placed with about eight healthy hamsters; The two groups could not physically contact each other, but air could flow freely between them. The researchers re-examined the animals shortly after.
- The parent virus did not infect any healthy hamsters on the second day, but on the fourth day all the animals contracted the pathogen.
- In contrast, the D614G variant infected six individuals as early as the second day, and by the fourth day, the virus was detected in all rodent organisms.
As a result, the mutant virus replicates 10 times faster and therefore infects more efficiently.
“We have shown that the mutant virus spreads more efficiently in the air than the original, and this may be the reason why it has become dominant among humans,” Yoshihiro Kawaoka, who was also involved in the research, wrote in a statement. issued.
Experts have also shown that although it spreads faster, fortunately D614G does not aggravate the course of the disease.
(A detailed study of the results can be read by clicking here).
Effective and safe vaccines on the horizon
Therefore, one of the conclusions of the study is that the D614G virus strain appears to be it may be more sensitive to the immune response elicited by vaccines than its predecessor, and that’s definitely good news.
There has been encouraging news about the efficacy of various vaccines in recent weeks. Both Moderna and Pfizer-BioNTech provided nearly 95 percent protection in the third phase of clinical trials. These are RNA vaccines, which are a completely new technology: they do not transmit the virus, but its genetic sequence, the messenger RNA. The role of messenger RNA is to make the coronavirus grow with the cells and thus trigger the response of the immune system, the production of antibodies. For one thing, the method is safe, as it doesn’t cause infection, and it’s cheap too.
The 92 percent effectiveness of the Russian Sputnik V vaccine is also very promising. This vaccine contains an adenovirus from which the genes responsible for replication have been removed. The so-called vector cannot infect and cause disease, but the genetic material of SARS-CoV-2 can be incorporated, which then triggers the necessary immune response in the body. Vector vaccine technology is not entirely new, with several independent studies examining its effectiveness and safety, with researchers from AstraZeneca and the University of Oxford experimenting with similar vaccines.
AstraZeneca’s development has also been well tested. The first data released on November 19 showed that the vaccine triggered proper immune function in those over 70, meaning it also protects the elderly from coronavirus.
Last but not least, preliminary data on Sinovac Biotech in China have recently been published, suggesting that the vaccine elicited a rapid immune response in the first two phases of clinical trials. Vaccination uses inactivated viruses, that is, dead, not live, pathogens to prime the body. The method has been used for a long time, including vaccination against influenza.
In addition to Sinovac Biotech, three other Chinese vaccines are already in the third phase of clinical trials.
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