Coronavirus Mutates To Escape Immune System

Live Science

The virus often mutates by simply deleting small pieces of its genetic code. The mutations "disguise" the virus from antibodies.

Transcript

00:00The novel coronavirus has recently developed a number of worrisome mutations,

00:04resulting in multiple new variants popping up around the world.

00:08A new study sheds light on how the virus mutates so easily

00:12and why these mutations help it escape the body's immune system.

00:20The beauty of this story is it's quite complex but it's really rather simple.

00:26The study researchers found that SARS-CoV-2, the virus that causes COVID-19,

00:32often mutates by simply deleting small pieces of its genetic code.

00:37Although the virus has its own proofreading mechanism that fixes errors as it replicates,

00:42the deletions get around this.

00:45So what deletions do is not only alter one site but they can alter

00:48a string of sequential letters in a row and so you can't proofread against that

00:54and you can alter a number of amino acids that build up that protein

00:58and so it does represent a way that the virus can quickly adapt.

01:02Oh it's devilishly clever.

01:05For their study, the researchers used a database to analyze

01:09nearly 150,000 genetic sequences of SARS-CoV-2.

01:13They found that these deletions frequently show up in similar spots on the genome.

01:19And these deletions started to line up to very distinct sites and so that's why

01:22we've called them recurrent deletion regions because we kept seeing them over and over and

01:26over again from viruses from different places at different times in genetically distinct viruses.

01:33Possibly these deletions were leading to the escape or the evolution away from

01:37antibodies that are binding it.

01:39This would be a way to get around that because the antibodies won't be able to recognize.

01:43Yeah because remember the key thing in biology is shape and precise little changes in shape

01:50even in a big molecule can have really really big effects right so perfectly attuned to recognize

01:58shape small movement and this thing doesn't see this anymore.

02:03I mean one missing building block out of about 1200 can knock out the binding of antibodies

02:09that are potently neutralizing so you're looking at you know less than a one percent

02:13you know change there.

02:14Small changes in biology can have massive effects and that's why we have to think about

02:21antibiotic resistance and anti-viral drug resistance and that's where it's really hard

02:28whenever you're trying to describe this because it's hard to show something which is gone right.

02:34Absence is hard to show but these tiny little absences have a big big effect.

02:43Does it seem like the the main goal for the evolution perspective is to sort of escape

02:48the immune system and this transmissibility might be like a secondary factor or we don't

02:53like a beneficial side effect but we don't really.

02:56The virus has evolved to replicate efficiently

02:59and it'll evolve around anything that gets in its way or go extinct.

03:03Evolution finds these sweet spots and this is a pretty good virus right what it's doing is

03:09every single time it's replicating think of the millions of people viruses replicating in the

03:13world each day right because anything that we can do to dampen the number of times

03:19it replicates just like Kevin said will buy us a little bit of time.

03:24Coming up with the tools now that we know that they're important and that they can alter the

03:28immunogenicity of the molecule the way that some antibodies bind it and understand if there's

03:34clinical changes that are associated with that and that's in some ways what happened with the

03:39discovery of the variants from from South Africa and from the United Kingdom both of which have

03:44deletions. Will we see something happen like we do with flu vaccines that these need to be

03:50reformulated frequently? You know it's not going to be an all or nothing where one day

03:56you know the virus can be blocked by a vaccine and the next day it's gone it's a continuum

04:01but you still have something that's 90 or 85 percent efficacious which I think at the start

04:06of this pandemic we'd all sign up for. It's not just going to be this virus it'll be the next

04:10virus and the next virus and the next virus and the next virus they will continue to emerge

04:15they will continue to evolve and we continually have to play cat and mouse and stay one step ahead

04:22of them. The results underscore the importance of closely monitoring the virus's evolution

04:27by tracking these deletions and other mutations. The findings also show why it's important to wear

04:33a mask and implement other measures to prevent the virus from spreading.

04:38The more people it infects the more chances it has to replicate and potentially mutate.

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