France detects a new mutant strain of the new coronavirus B.1.640.2 with 46 mutations

Recently, scientists from France reported a new strain of new coronavirus mutation B.
1.
640.
2, which has 46 mutations
.

At present, 12 people in southern France have been detected to be infected with the B.
1.
640.
2 mutant strain
.

The research was published on the medical preprint website medRxiv and has not been peer-reviewed
.

The research unit is the Institute of Infectious Diseases (IHU) of the Affiliated Hospital of the Mediterranean University of Marseilles, France, and they tentatively named the mutant strain IHU
.

Since the current number of cases is not clear, its transmissibility, toxicity, and immune evasion ability also need to be studied
.

Analysis by French scientists revealed that B.
1.
640.
2 possesses 46 mutations and 37 deletions
.

Among them, there are 14 amino acid substitutions in the spike protein (S protein), including N501Y and E484K, and 9 deletions
.

This genotype pattern makes it the B.
1.
640.
2 lineage, a phylogenetic sister group to the old B.
1.
640 lineage
.

The two lineages differed by 25 nucleotide substitutions and 33 deletions
.

Having both the N501Y and E484K mutations on the spike protein is noteworthy because the spike protein plays a key role in entering human cells: the spike protein binds to the ACE2 receptor in human cells and is a major target for mRNA vaccine manufacturing
.

Previous studies have shown that E484A or N501Y mutations in the S protein of the new coronavirus suggest enhanced immune evasion ability
.

The researchers said they first discovered the mutant strain in a person infected with the new coronavirus in Forcalquier, Alpes-Haute-Provence
.

The patient was diagnosed after traveling from Cameroon, so it is suspected that the mutant strain may have originated in Africa
.

Jiang Shibo, director of the Institute of Pathogenic Microbiology of Fudan University, said in an interview with The Paper ( that the new coronavirus, as an RNA virus, is more prone to mutation
.

According to the classification of viruses proposed by American virologist and Nobel Prize winner in physiology or medicine David Baltimore, coronaviruses including 2019-nCoV belong to positive-strand RNA viruses, which means that the genomic RNA of the virus can be directly used as mRNA for the translation of viral proteins Synthesis, the viral genome first synthesizes the negative-strand RNA, and then uses it as a template to synthesize the positive-strand genomic RNA of the progeny
.

It is worth mentioning that viral polymerase (polymerase) plays a central role in viral genome replication and transcription, while RNA viruses utilize RNA-dependent RNA polymerase (RdRp) to replicate and transcribe their genomes
.

The reason why RNA is easy to mutate is that RdRp does not have nuclease proofreading activity, so the nucleotide mismatch rate of its genome during replication is relatively high
.

In the book "General Virology" edited by Hu Zhihong and Chen Xinwen, the two directors of the Wuhan Institute of Virology, Chinese Academy of Sciences, the mutation rate of a virus is usually defined as the number of nucleotides produced in the genome of the virus progeny during each replication cycle of the virus.
The average number of mutations
.

They mentioned that viruses have a high mutation rate compared to other organisms
.

Generally speaking, RNA viruses will have one wrong base every 10^3-10^7 nucleotides, while DNA viruses have a relatively low mutation rate, and no 10^9-10^10 nucleotides will occur.
One such mistake
.

Professor Zhang Linqi of Tsinghua University School of Medicine and Vanke School of Public Health and Health previously said in an interview with The Paper that in fact, as a type of RNA (ribonucleic acid) virus, people should not be surprised by the mutation of the new coronavirus, "It is It is a 'nature' of RNA viruses that their own replication machinery during replication is not as accurate as human gene replication
.

"