SARS-Cov-2 Has Already Mutated Once

October 26, 2020 12:45 PM

It was clear from gene sequencing that D614G had overtaken the "original" variant but wasn't clear whether this was the result of some meaningful difference or statistical anomalies such as "founder effect." Now new research shows that the D614G variant that quickly became dominant in Europe in the Spring is more highly transmissible because it replicates at a higher rate in the upper respiratory tract. The fear in a situation like this is that the virus is unstable and we'll need more than one vaccine, but the good news in this article is that the antibodies appear to be backwards compatible.
posted by diva_esq (9 comments total)

The use of "backwards compatible" in a non-tech context blows my mind right now.
posted by ipsative at 12:58 PM on October 26, 2020 [12 favorites]

Are these the anitbodies that nobody has? I've lost track.
posted by krisjohn at 3:45 PM on October 26, 2020 [2 favorites]

Does backwards compatible in this contest bother you more or less than using mutate to describe something that isn't alive?
posted by Kid Charlemagne at 5:39 PM on October 26, 2020 [1 favorite]

If I'm understanding them correctly (probably not), they're saying that SARS viruses are fairly resistant to mutation, except in the spike protein they use to get into cells. It's that spike protein that has changed between the two variants here, but that's not the part of the virus the immune system needs to recognize for antibodies to work.
posted by Kevin Street at 6:51 PM on October 26, 2020 [4 favorites]

This has been pretty well studied and documented since spring and early summer. It's not the only study looking at the mutation, but it adds weight to other research that the mutation makes the virus more transmissible but doesn't cause more severe infection (thankfully). Also, based on how they observed the muted virus to react to antibodies produced in response to the original virus, the study provides evidence that the vaccines will work against this mutation as well.

And yeah, coronaviruses do not mutate nearly as quickly as, for example, influenza viruses, which from what I've learned are considered fairly "sloppy" viruses. That also hopefully will make it easier to develop a vaccine against SARS COV 2 compared to seasonal flu.
posted by eagles123 at 8:52 PM on October 26, 2020 [4 favorites]

Kevin Street: It's that spike protein that has changed between the two variants here, but that's not the part of the virus the immune system needs to recognize for antibodies to work.

Actually, mild cases show higher levels of anti-spike IgG antibodies compared to anti-nucleocapsid IgG, and the opposite is true for severe cases. And all the major vaccine candidates carry or generate full or part of the spike protein to prime the immune system.
posted by Gyan at 3:40 AM on October 27, 2020 [2 favorites]

I agree with Gyan that the spike protein is a key part of the vaccine approach to date, which is why the prospect of mutation has been so concerning.
posted by diva_esq at 9:15 AM on October 27, 2020

I'm only going by a shaky understanding of the paper in the top link, so I'm probably wrong. But what you're saying seems to contradict what they're saying.
posted by Kevin Street at 9:33 AM on October 27, 2020

Alright, for those who don't have access to that paper, or would like something that is more easily read by a lay audience (As a chemist most of it went over my head), Derek Lowe has a very good breakdown on vaccine mutations and re-infection.

Basically: The vaccines target the spike protein. D614G is something we've known about for a long time, and doesn't change the spike protein enough to matter to a vaccine (vaccines don't care about gene sequence, they care about shape, and the shape changes are mild). Most of the mutations are in the other part of the virus, which shouldn't matter for the vaccine. Reinfection does happen, but at a very, VERY low rate, which if normal for any virus due to the human immune system being inconsistent. There does not appear to be any trend indicating that one set of mutations can get past the bodies defences once you've built them: Best guess is this handful of people over the whole world didn't build good defences the first time.
posted by Canageek at 9:57 AM on October 27, 2020 [2 favorites]