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SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

biorxiv.org

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Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#91

Post by nradov »

djsumdog wrote: post #26
packetlost wrote: post #16

Earlier quoted context omitted.

The h1n1 is a bit of a strange case though because it jumps species boundary very often and mutates very quickly. COVID-19 appears to evolve much, much slower. Based on my limited understanding of virology, I think this means it's unlikely to become a seasonal problem unless the general populations immune system does not retain immunity to the same strain for a significant period of time.

We already know CoV2 rarely causes any symptoms in children. I wonder if there was a time in prehistory where common Rhinoviruses and Coronaviruses wiped out larger populations of elderly. Even if our immune system memory doesn't last very long for these types of viruses, wouldn't young people getting exposed to it now likely reduce its impact long term? It also seems like >95% of people who die from this are over 55…

Yes that probably happened several times in human history. There are four other endemic coronaviruses. Most people catch them as children and build up some immunity, so even if they're reinfected later the symptoms are usually less severe. But they can be deadly to immunocompromised patients.

There is some strong circumstantial evidence that the 1889 "Russian flu" pandemic wasn't caused by influenza at all but rather by the emergence of HCoV-OC43. It killed about a million people worldwide.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252012/

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#92

Post by Fnoord »

CyanLite2 wrote: post #90
cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

If you look at the death rate compared to March, it is dramatically lower, even though we're having 2x the cases. This could be because of better treatment, or because the virus itself is getting milder.

Or because more people (with mild symptoms) get traced and tested. We had a shortage of tests and masks on start of pandemic.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#93

Post by Fnoord »

estebank wrote: post #56
davidf560 wrote: post #37

Earlier quoted context omitted.

I keep wondering what unintended consequences our nearly-unprecedented efforts on non-pharmaceutical interventions ("lockdown", social distancing, masks, etc.) might end up having on the virus - for example, could all our isolation and distancing be accidentally selecting for strains of the virus that transmit more readily over further distances?

The mitigations are effective in slowing the spread (to varying degrees, due to a multitude of factors), which in turn slow down the rate of mutation. In any case, I would expect the dispersion of the virus to follow a pattern similar to https://www.youtube.com/watch?v=plVk4NVIUh8

Don't know about your country/region but here the mitigations are put in effect because hospitals can't handle the pressure anymore.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#94

Post by TheGallopedHigh »

cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

In purely theoretical models virulence naturally evolved to a smaller value.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#95

Post by TheGallopedHigh »

backtoyoujim wrote: post #61
neuronic wrote: post #45

Earlier quoted context omitted.

No, but its effect on the virus population kind of does.

Are you saying that a virus population has a conscience or morality ?

No the person is speaking about the evolutionary nature of the virus

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#96

Post by titzer »

CyanLite2 wrote: post #90
cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

If you look at the death rate compared to March, it is dramatically lower, even though we're having 2x the cases. This could be because of better treatment, or because the virus itself is getting milder.

There are a lot of factors contributing, in particular the age distribution of those people getting infected.

One thing is "viral load", which has to do with how much of the virus is present at initial infection. Because immune system response takes time to ramp up, e.g. 10x more virus in the beginning means that it can do much more damage before the immune response. It's likely that social distancing and masks have reduced the average viral load at infection time.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#97

Post by Izkata »

throwaway2245 wrote: post #89
Izkata wrote: post #77

Earlier quoted context omitted.

> There's evidence for influenza virus existing thousands of years before 1918. As such, it seems to have evolved into a much more deadly strain at that point. Influenza refers to a class of viruses, not a single virus.

You seem to be suggesting that 1918 influenza occurred spontaneously and independently of other influenza? No.

"Occurred spontaneously" no. Independently, yes.

Just like SARS-CoV-2 wasn't a thing a year ago, but crossed over to humans late 2019, the 1918 Spanish flu virus did indeed only start infecting humans in 1918, independently of other viruses. 1918 just happens to be the year it (most likely) crossed over from an animal to a human.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#98

Post by a_imho »

alexktz wrote: post #73
a_imho wrote: post #55

Earlier quoted context omitted.

I'm getting old. Last 20 years maybe, but I can't name a technology advancement that happened in the last 10 years that I would really miss. To me it seems like most technology is now done for the sake of doing it and solutions are looking for problems. Not to mention all the dystopian surveillance we have now. Rose tinted glasses and all that, the start of the millennium was a much happier time period imo.

Have you used a 10 year old phone lately?

Yes, I use an old feature phone for voice calls. I'm fully aware I'm in a very small minority.

Indeed smart devices are the epitome of useless tech. In fact, I would argue they make life worse if one is conscious about their privacy and computing.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#99

Post by a_imho »

ollifi wrote: post #74
a_imho wrote: post #55

Earlier quoted context omitted.

I'm getting old. Last 20 years maybe, but I can't name a technology advancement that happened in the last 10 years that I would really miss. To me it seems like most technology is now done for the sake of doing it and solutions are looking for problems. Not to mention all the dystopian surveillance we have now. Rose tinted glasses and all that, the start of the millennium was a much happier time period imo.

How does your age map to this Douglas Adams quote: ”I've come up with a set of rules that describe our reactions to technologies: 1. Anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works. 2. Anything that's invented between when you’re fifteen and thirty-five is new and exciting and revolutionary and you can probably get a career in it. 3. Anything…

Yet to turn 35.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#100

Post by throwaway2245 »

Izkata wrote: post #97
throwaway2245 wrote: post #89

Earlier quoted context omitted.

You seem to be suggesting that 1918 influenza occurred spontaneously and independently of other influenza? No.

"Occurred spontaneously" no. Independently, yes. Just like SARS-CoV-2 wasn't a thing a year ago, but crossed over to humans late 2019, the 1918 Spanish flu virus did indeed only start infecting humans in 1918, independently of other viruses. 1918 just happens to be the year it (most likely) crossed over from an animal to a human.

Independently, no.

Assuming generously that you are right about this, why (for example) are viruses crossing over in the other direction - from humans to animals - never considered important?

We might only care about the part of viral evolution and epidemiology that we closely observe or are immediately impacted by, but that does not mean the other aspects of evolution are independent.

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