The Take Away: Paper explores the origin and evolution of SARS-CoV-2

Sign up for Scientific Inquirer’s Steady State Newsletter for the week’s top stories, exclusive interviews, and weekly giveaways. Plenty of value added but without the tax.  http://bit.ly/2VEF06u

This is only a bullet point summary of a longer and more in-depth paper in the National Science Review, “On the origin and continuing evolution of SARS-CoV-2”. We suggest reading the paper in full on the publisher’s website for a better understanding of the points made here.

  • Coronaviruses are naturally hosted and evolutionarily shaped by bats.
  • The whole-genome sequence identity of the novel virus has 96.2% similarity to a bat.
  • SARS-related coronavirus (SARSr-CoV; RaTG13) collected in Yunnan province, China, but is not very similar to the genomes of SARS-CoV (about 79%) or MERS-CoV (about 50%).
  • We found that the nucleotide divergence at synonymous sites between SARS-CoV-2 and other viruses was much higher than previously anticipated.
  • Both SARS-CoV and SARS-CoV-2 bind to ACE2 through the RBD of spike protein in order to initiate membrane fusion and enter human cells
  • Although several ancient recombination events have been described in spike [27, 28], it also seems likely that the identical functional sites in SARS-CoV-2 and GD Pangolin-CoV may actually the result of coincidental convergent evolution.
  • It seems very unlikely that SARS-CoV-2 originated from the GD Pangolin-CoV due to a very recent recombination event.
  • Although we defined the L and S types based on two tightly linked SNPs, strikingly, the separation between the L (blue) and S (red) types was maintained when we reconstructed the haplotype networks using all the SNPs in the SARS-CoV-2 genomes.
  • We propose that, although the L type newly evolved from the ancient S type, it transmits faster or replicates faster in human populations, causing it to accumulate more mutations than the S type.
  • Thus, our results suggest the L might be more aggressive than the S type due to the potentially higher transmission and/or replication rates.
  • One possible explanation [of the prevalence of S type] is that, since January 2020, the Chinese central and local governments have taken rapid and comprehensive prevention and control measures.
  • Our analyses of molecular evolution and population genetics suggested that some amino acid changes might be favored by natural selection during the evolution of SARS-CoV-2 and other related viruses.
  • In summary, our analyses of 103 sequenced SARS-CoV-2 genomes suggest that the L type is more aggressive than the S type and that human interference may have shifted the relative abundance of L and S type soon after the SARS-CoV-2 outbreak.

Read the study in full here.

IMAGE SOURCE: Creative Commons

Words matter. Images matter. The Scientific Inquirer needs your support. Help us pay our contributors for their hard work. Visit our Patreon page and discover ways that you can make a difference. http://bit.ly/2jjiagi

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: