Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

SARS coronavirus 2 (SARS-CoV-2) isolates encoding a D614G mutation in the viral
spike (S) protein predominate over time in locales where it is found, implying that
this change enhances viral transmission. We therefore compared the functional
properties of the S proteins with aspartic acid (SD614) and glycine (SG614) at residue
614. We observed that retroviruses pseudotyped with SG614 infected ACE2-
expressing cells markedly more efficiently than those with SD614. This greater
infectivity was correlated with less S1 shedding and greater incorporation of the S
protein into the pseudovirion. Similar results were obtained using the virus-like
particles produced with SARS-CoV-2 M, N, E, and S proteins. However, SG614 did
not bind ACE2 more efficiently than SD614, and the pseudoviruses containing these S
proteins were neutralized with comparable efficiencies by convalescent plasma.
These results show SG614 is more stable than SD614, consistent with epidemiological
data suggesting that viruses with SG614 transmit more efficiently.

A particular mutation in one strain of the new SARS-CoV-2 coronavirus may have helped it infect more human cells and turn it into the dominant strain worldwide, new laboratory research shows.

Researchers at Scripps Research in Jupiter, Fla., stressed that their finding doesn't mean the virus is any more lethal. And because this was research conducted in a lab, it doesn't yet confirm that the mutation makes the strain more likely to spread among people, they added.

Still, "viruses with this mutation were much more infectious than those without the mutation in the cell culture system we used," study senior author and virologist Hyeryun Choe, said in a Scripps news release.

Does the D614G strain cause more severe disease?

Professor Seshadri Vasan, head of CSIRO's Dangerous Pathogens Team testing COVID-19 vaccine candidates at the Australian Centre for Disease Preparedness in Geelong, said:

"Even if a particular strain may be more transmissible, it does not mean it will cause a more severe form of disease. In fact, the authors of this pre-print have themselves said 'there was no significant correlation found between D614G status and hospitalisation status'.

"This virus is still adapting to its new human host. It is expected that, over time, different dominant strains will appear in different parts of the world. This is especially true where movement around the world is restricted.

"This should not cause undue alarm. While it is normal and anticipated for RNA viruses to mutate, the SARS-CoV-2 virus has a 'proof-reading' mechanism which limits the rate at which it can mutate.

"More research is required before we can separate out host and environmental factors to draw firm conclusions from this limited data.”