Thread by @NavroopSingh_

Cambridge University medical team Analysis of samples from the patient showed that the virus evolved rapidly after the plasma therapy, developing mutations that changed how it could infect cells and resist antibodies. nature.com/articles/s4158…

Last summer, as the second wave of COVID-19 cases was sweeping the United Kingdom, a man in his 70s was admitted to his local hospital where he tested positive for SARS-CoV-2.

He was sent home, but a month later he checked into the hospital at Cambridge University, unable to shake the virus.

Doctors gave him remdesivir, an antiviral drug used to treat COVID-19, but he showed little improvement. Two months after his illness began, as the patient continued to worsen, his medical team opted to treat him with convalescent plasma,

a therapy derived from the blood of patients who have recovered from COVID-19, which contains antibodies to fight off the virus.

Sadly, he succumbed to the virus 102 days after testing positive, but what doctors learned from him and similar patients “has been transformative of our understanding of what’s going on in this disease,” says Ravindra Gupta, a member of the Cambridge University medical team

He was sent home, but a month later he checked into the hospital at Cambridge University, unable to shake the virus. Like many people who develop severe COVID-19, the man was immunocompromised

Analysis of samples from the patient showed that the virus evolved rapidly after the plasma therapy, developing mutations that changed how it could infect cells and resist antibodies. The conditions turned out to be ripe for viral evolution

The plasma treatments did not rid the man of the virus, and in fact had little impact on the amount of virus detected. But the plasma had a remarkable effect on the genetic makeup of the viral population that the patient harbored

Seemingly in response to the antibodies contained within the plasma, the virus produced “escape mutations,” changes in the genetic code that helped it to evade detection by the sticky antibodies. Such mutations can make the virus more contagious or vaccines less effective

Random changes in any viral genetic sequence are normal over the course of an infection, but a striking pattern emerged in Gupta’s patient. After the plasma infusions, viruses containing multiple new mutations appeared and quickly dominated, but not for long.

Two weeks later, when antibody levels were expected to have diminished, the mutant virus population vanished. But then the patient received a final plasma treatment. Remarkably, the mutant strain came roaring back.

Gupta’s team conjectured that the genetic changes appear to have occurred in response to the plasma treatment. This phenomenon, called selective pressure, may have occurred when viruses with mutations resistant to the antibodies survived.

post-plasma virus strain carried two particular mutations: one, called D796H, has been only rarely documented b4.The other, resulting in the deletion of two amino acids, called ∆H69/∆V70, “has gained notoriety, because it’s one of the defining mutations in the B.1.1.7 lineage.

Gupta believes that the B.1.1.7 strain likely emerged from an immunocompromised patient who was given Plasma Therapy, but the data show it did not originate in this specific patient.

COVID Variants May Arise in People with Compromised Immune Systems specially those given Plasma Therapy-
scientificamerican.com/article/covid-…