Why is it easier for new variants like Omicron to spread?

NSUsed virus Those that survive and thrive are called variants.in the case of SARS――――NSOV-2, the virus that causes covid-19, these began to spread in earnest in November 2020, and the Alpha variant that was first discovered in the United Kingdom appeared. The major global lineage, the delta mutant, was first detected in India in late 2020. The latest Omicron was first detected in South Africa in November 2021.

There is still much to know about Omicron. Early evidence suggests that this variant actually spreads very quickly, but more work is needed before anyone knows if it will replace Delta. Omicron has about 30 mutations in peplomer, a structure that is studded with the surface of the virus and allows its genome to be fixed and inserted into human cells. An additional about 20 mutations act on other parts of the virus: some of them may also be dangerous. How do mutations increase transmission?

Viruses, like all living things, have a life cycle. They are parasites and begin when the parent virus infects another organism and hijacks its cells to make a copy of itself.in the case of SARS――――NSOV-2, this happens when you latch on an enzyme called AceSitting on the membrane of some human cells 2. SARS――――NSOV-2 slides its genome into the cell. This cell infiltration is aided by peplomer. Some parts of the virus’s structure can tolerate mutations. Spikes are the most resistant to change.

Virus variability is rooted in the randomness inherent in the process of making a copy of an object, and errors are unavoidable.Host cell SARS――――NSOV-2, an error will occur. The majority of viruses cannot tolerate these errors in replication. However, some viruses can overcome ancestral viruses, spread more efficiently across the host population, and thrive as a result of change. In order for the new variant to become the predominant form of the virus, it must retain some advantages over the old variant. The benefits can be obtained in a variety of ways, but for respiratory diseases like covid-19, one of the most important factors is contagiousness, that is, how easily the virus is transmitted from person to person. is.

One of the first mutations to increase infectivity NS501When, Also known as “Nelly,” is one of the eight mutations that characterize the alpha mutant peplomer, and is also found in Omicron. “501” means that the 501st amino acid in the 1,273 chain that makes up the spike is changing. The sequence and composition of these amino acids is determined by the matching genomic sequence, so “501” refers to both genomic and amino acid chain positions. “N” is an abbreviation for asparagine, NS501When It is exchanged for the tyrosine “Y”.

This exchange affects the structure of peplomers, as different amino acids have slightly different chemistries. This is because the way the charge is distributed throughout changes. It slightly changes the shape of the protein, as the positively charged region attracts the negatively charged region. Thanks to these dynamics NS501When The key parts of the spikes can be twisted about 20 degrees for a better fit. Ace2 receptors. The result is better binding. That is, a copy of a variant that goes into the body is more likely to find its target and start replicating. This improves the transmission rate. Other mutations perform similar tricks, releasing different parts of the spike in different ways, allowing them to bind more effectively. Ace2.2.

Changing the shape of the spiked protein is not the only way to increase transmission. Ravindra Gupta, a molecular virologist at the University of Cambridge, and his colleagues argued that the increased transmission rate of Delta was partly due to mutations at site 681. Ace2. The protein is split in two. Dr. Gupta, above all NS681NSMakes it easier for the virus to inject its genome into host cells with the help of two reshaping mutations elsewhere.

Yet other mutations make the virus more contagious by helping the immune system evade the antibodies that the immune system throws at the virus to protect the body from infection.Just as a peaplomer is shifted by a series of mutations and binds better. Ace2. In return, other mutations can also make it difficult for the antibody to bind to the spikes. If so, they are not very effective in stopping the infection.

One of the reasons scientists are worried about Omicron is that Omicron appears to have all three mutations and has many mutations that are not yet understood. Only more data shows how well their fears are substantiated.■■