COVID-19 affects some people more than others: Know why

Researchers claim to have found clues as to why the COVID-19 virus affects different groups in dissimilar ways and think the answer may lie in the proteins initiating infection.

By: Jahnavi Sarma | | Published: December 4, 2020 9:14 am

The virus's protein spikes attach to a protein receptor on the surface of the host cell called ACE2, fusing the membranes around the cell and the virus together.

Since the beginning of the COVID-19 pandemic, we have seen that the virus responsible for the deadly disease affects some people more than others. The elderly and people with underlying health conditions are more vulnerable to infection and also severe complications. Now a new study from McGill University says that there may be clues as to why this happens. They say the answer may lie in the proteins involved in initiating infection, as the virus binds to host cells of different animals. Greater cellular oxidation with aging and sickness may explain why the elderly and people with chronic illness get infected more often and more severely. Also Read - Delhi health workers suffer mild reaction post COVID-19 vaccine: What you should expect

Till now, more than 60 million people have been infected by the novel coronavirus and around 1.5 million have died from this infection. The virus is also responsible for the disruption of economies and food supply chains across the world. Researchers say that understanding why some animals get infected and others do not could be the key to unlocking new treatments and therapies. In this study, which is published in Computational and Structural Biotechnology Journal, researchers analyzed available protein sequences of the virus and host cell receptors across different species to find out why. Also Read - Rapid blood test predicts COVID-19 patients at high risk of severe disease: Study

Understanding the virus

Scientists know that the virus causing the pandemic can infect humans, cats, dogs and ferrets. But it does not seem to have any effect on bovine and swine. It also hits the elderly and people with underlying conditions like diabetes and hypertension more severely than the young and healthy ones. Once inside a host cell, the virus hijacks the cell’s metabolic machinery to replicate and spread. The virus’s protein spikes attach to a protein receptor on the surface of the host cell called ACE2, fusing the membranes around the cell and the virus together. This process allows the virus to enter the cell and co-opt its protein-making machinery to make new copies of itself. The copies then go on to infect other healthy cells. Also Read - ‘Contagious’ UK strain could become dominant COVID-19 variant by March 2021, warns CDC

Greater cellular oxidation may be a cause

While analyzing the proteins and their amino acid building blocks, the researchers saw that the animals susceptible to the virus have certain things in common. Humans, cats and dogs have two cysteine amino acids that form a special disulfide bond held together by an oxidizing cellular environment. This disulfide bond creates an anchor for the virus. This suggests that greater cellular oxidation in the elderly or those with underlying health conditions could predispose them to more vigorous infection, replication and disease. In animals resistant to the virus, like pigs and cows, one of these two cysteine amino acids is missing, and the disulfide bond cannot be formed. As a result, the virus cannot anchor on to the cell.

Antioxidants may interfere with entry of the virus into host cells

According to the researchers, preventing the anchor from forming could be the key to unlocking new treatments for COVID-19. One strategy, they suggest, could be to disrupt the oxidizing environment that keeps the disulfide bonds intact. Antioxidants could decrease the severity of COVID-19 by interfering with entry of the virus into host cells and its survival afterwards in establishing further infection. According to researchers, the CRISPR technology could be used to edit protein sequences and test out their theory. They are also looking into other proteins near the ACE2 receptor that may facilitate entry of the virus to see if they behave the same way.

(With inputs from Agencies)

Published : December 4, 2020 9:14 am

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