Virology: Omicron's altered infectivity and immune escape

 
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Omicron mutants The mutations in the peplomer alter the process by which the virus infects cells, reducing susceptibility to therapeutic and vaccine-inducing antibodies. It became clear that he had done it.It was also found that booster vaccination with the mRNA vaccine strengthened the virus-neutralizing activity, and that the antiviral drugs (remdesivir and molnupiravir) retained their efficacy against the Omicron strain.A paper reporting these research findings will be published in Nature.

It is the spike protein that helps SARS-CoV-2 invade the host cell, and there are about 36 mutations in the spike protein of the Omicron strain.Now, Ravindra Gupta and colleagues have identified changes that can affect the process by which the virus binds to the host's receptor (ACE2).In addition, Gupta et al. Reduced the infectivity of the Omicron mutant strain in several types of cells compared to the previous Delta mutant strains, for example, suppressed replication in airway organoids and enterocytes. I also made it clear.In addition, Gupta et al. Showed that the dependence of the Omicron strain on a type II transmembrane serine protease (TMPRSS2), a cell membrane protein, was reduced.Previous mutants required TMPRSS2 to efficiently infect cells.The data obtained in this study show that mutations in the peplomer of the Omicron mutant suppress the efficient infection of TMPRSS2-expressing lower respiratory tract cells (eg, alveolar cells), but TMPRSS2. It has been shown that efficient infection of non-expressing cells (eg, cells found in the upper respiratory tract) is not suppressed.

Gupta and colleagues found clinically recognized antibodies in both live and pseudoviral particles to elucidate how the Omicron strain responds to existing coronavirus infection (COVID-19) treatments. And analyzed the interaction between the antibody and the peplomer of the Omicron strain.Casilibimab and imdevimab have been shown to be particularly effective in neutralizing delta strains, but Gupta et al. It was revealed that all the harmony activities were lost, and that the antiviral drugs remdesivir and molnupiravir had similar activities to the Delta strain and the Omicron strain.

To evaluate the efficacy of existing vaccines against the Omicron strain, Gupta et al. Created viral particles expressing spike proteins from the Omicron or Delta strains, Pfizer-Biontech vaccine and Oxford-AstraZeneca. Serums collected from subjects inoculated with any of the company's vaccines were exposed to the virus particles.As a result, it was observed that the effect of neutralizing the Omicron strain was less than 2/10 of that of the Delta strain after two doses of either vaccine, and each time after the second dose, it was observed. The response was even weaker.In addition, no neutralization of the Omicron strain was detected in most of the subjects who received the Oxford-AstraZeneca vaccine twice.In addition, a study of sera collected from people in the above-mentioned group of subjects who received a third booster vaccination with the Pfizer-Biontech vaccine revealed an enhanced neutralizing effect.In experiments with live viruses, similar results were observed with two doses of the Pfizer-Biontech vaccine.

 
* This article is reprinted from "Nature Japan Featured Highlights".
Reprinted from: "Virology: Changes in Infectivity and Antigenic Jailbreak in Omicron Strains'