Denmark COVID-19 mink variant becomes the focus
Denmark COVID-19 mink variant becomes the focus. Recently, the Danish government stated that it will kill nearly 17 million minks in the country, which has aroused widespread concern from all walks of life. This is because the Danish government announced on November 4 that a mutated strain of coronavirus has infected humans from mink. According to a report from Denmark’s State Serum Institute (SSI), 12 people have been infected with this new mutant, and the neutralizing antibody response of the mutant is weak. Although SSI staff said that this mutant strain is no more dangerous than other new coronavirus strains, they suggested that the currently developed vaccine may be insensitive to this mutant strain.
On November 6, local time, the WHO stated in a routine press conference for COVID-19 pneumonia that since June this year, the number of infections related to mink breeding in Denmark has accumulated to 214, of which 12 cases are related to the mutations reported above. These 12 cases were confirmed in North Jutland, Denmark in September this year. The age of the patients ranges from 7 to 79 years old, of which 8 cases are related to mink raising and 4 cases are community cases.
The World Organization for Animal Health, OIE, also announced that, in addition to Denmark, the United States, Italy, the Netherlands, Spain, and Sweden, a total of 6 countries around the world have reported the COVID-19 virus in mink farms. This means that the mink may become an intermediate host, and the COVID-19 virus may mutate in the cultured mink and pass it back to humans, or it may be passed back to the mink from humans.
Currently, WHO, European Centers for Disease Control and Prevention, and many other organizations suggest that EU/EEA countries and the United Kingdom should take targeted measures. Even the internationally renowned journal Nature has published the following news.
What is the mystery of the mink mutant?
A working paper of SSI studied the characteristics of mutant strains of the new coronavirus. The researchers isolated five mutant strains in Danish mink, namely cluster1 to cluster5, which caused a variety of amino acid mutations on the Spike protein. The Y453F mutation has important research significance.
The amino acid at position 453 of the Spike protein of the Y453F mutant new coronavirus is mutated from tyrosine (Y) to phenylalanine (F), which is a conservative amino acid substitution in the receptor binding region, and is directly substituted with 34 of the host ACE2 receptor. Amino acid contact. ACE2 is histidine (H) at position 34 in the human body, and tyrosine (Y) in mink, so it is speculated that this mutation is to better adapt to the mink host. But at the same time, researchers found that 453F increased its affinity for human ACE2, which may be the reason why the virus invaded the human body, which also explains why the new coronavirus can be transmitted from mink to human.
In addition to the Y453F mutation, it also includes:
1) 69-70deltaHV, the deletion of histidine and valine at amino acids 69 and 70 in the N-terminal region of the S1 subunit;
2) I692V, this position is a conservative substitution at position 692, which is located at 7 amino acids downstream of the furin cleavage site;
3) S1147L, a non-conservative substitution on the S2 subunit;
4) M1229I, a conservative substitution located in the transmembrane region.
SSI researchers obtained two mink mutant isolates, one containing the Y453F mutant strain (F-spike), and the other containing the 69-70deltaHV, 453F, 692V and 1229I mutant strains (ΔFVI-spike). However, the variant strains reported for 12 people were mainly ΔFVI-spike, or cluster 5. Through culture, it was found that after 24 hours, the virus titer of ΔFVI-spike was only one-tenth that of the F-spike mutant and wild-type strains, but after 96 hours, the virus titer of ΔFVI-spike was close to that of the wild-type. The titer of the ΔFVI-spike strain increased 54.7 times during this period, while the average increase of other strains was only 4 times (range 2.6-5.7 times).
Mutations in the SARS-COV-2 Spike protein have caused concern because the impact of these mutations on viral infection or vaccination is uncertain, and may reduce the ability of antibodies to recognize the protein. Therefore, SSI scientists conducted experiments on the neutralization activity of the mutant ΔFVI-spike in the plasma of recovered patients and immunized rabbits/mouses. The effect of Spike protein mutations on different concentrations of neutralizing antibodies is unknown, so the researchers selected samples with different neutralizing titers for testing. The results showed that samples with high, middle and low titers were basically not affected by the mutant, but samples with low and medium titers were significantly affected by the mutant, and the neutralizing activity decreased. In the 9 plasma samples tested, the average neutralization activity was reduced by 3.58 times (0-13.5 times), and two plasma neutralization activities were reduced by more than 4 times. SSI scientists call these experiments preliminary studies and call for the need for more in-depth scientific verification.
China Yiqiao Shenzhou successfully expressed Y453F mutant protein in 9 days
In order to support scientific researchers in accelerating the research on the mutation of the new coronavirus in mink, Yiqiao Shenzhou successfully expressed the recombinant protein of the new coronavirus Y453F mutant strain (Cat. No.: 40592-V08H80) in only 9 days. The purity of the protein is more than 95% by SDS-PAGE electrophoresis. ELISA analysis showed that the protein has biological activity and can bind ACE2.
All mink sequences contain the D614G mutation
It is also mentioned in this working paper that all mink SARS-COV-2 sequences tested contain the D614G mutation. During the pandemic, the new coronavirus is constantly undergoing evolutionary mutations, especially the new coronavirus with the D614G mutation has become the main strain infecting the world. Recently, an article in Science magazine confirmed that in the new coronavirus infection model, the D614G mutation enhances the spread of the virus.
Yiqiao Shenzhou has established the world’s leading novel coronavirus mutant antigen library, and currently has 68 RBD mutant proteins and D614G mutant proteins verified by HPLC, supporting researchers in the transmission, clinical, diagnosis, and diagnosis of new coronaviruses by mutants. Research on the impact of vaccine and drug development.
(Source: China Sohu)