STUDY DECODES HOW SARS-COV-2 MUTATES, ESCAPES ANTIBODIES

NEW DELHI: The Sars-cov-2 evades antibody response due to deletions in its genetic structure, triggering minute changes in the spike protein that the virus uses to infect cells, according to a study published by researchers from University of Pittsburgh School of Medicine in the journal Science on Thursday.

The findings offer some clues on how the virus changes: the researchers found that much of the mutation occurred at the same spots in a sequence, “spots where the virus can tolerate a change in shape without losing its ability to invade cells and make copies of itself”.

The deletion occurs when the virus replicates and because the coronavirus has a faulty biological “proofreader”, the deletions are not caught. “You can’t fix what’s not there,” said study senior author Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh. “Once it’s gone, it’s gone, and if it’s gone in an important part of the virus that the antibody ‘sees,’ then it’s gone for good.”

The study was carried out by looking at the case of an immunocompromised patient, who had a recurrent infection for 74 days before ultimately succumbing to the disease. The authors say in the report that a “cat and mouse” game between the person’s immune system and the virus turns into a co-evolutionary dance that helps the fittest of mutations to eventually survive.

At least three variants of the virus, carrying a constellation of mutations, are of concern globally at the present. Among these, two carry a mutation known as E484K that lab tests and clinical trials suggest could lead to a decrease in potency of vaccines.

The researchers said it remains to be seen how much the virus will go on to mutate. “How far these deletions erode protection is yet to be determined,” said Kevin Mccarthy, assistant professor of molecular biology and molecular genetics at Pitt, and an expert on the influenza virus.