nature | "Therefore, to examine the emergence potential (that is, the potential to infect humans) of circulating bat CoVs, we built a chimeric virus
encoding a novel, zoonotic CoV spike protein—from the RsSHC014-CoV
sequence that was isolated from Chinese horseshoe bats1—in the context
of the SARS-CoV mouse-adapted backbone. The hybrid virus allowed us to
evaluate the ability of the novel spike protein to cause disease
independently of other necessary adaptive mutations in its natural
backbone. Using this approach, we characterized CoV infection mediated
by the SHC014 spike protein in primary human airway cells and in vivo,
and tested the efficacy of available immune therapeutics against
SHC014-CoV"
So they create a "chimeric" SARS-CoV virus that can cause disease (in humans)?
They continue:
"we synthesized the SHC014 spike in the context of the
replication-competent, mouse-adapted SARS-CoV backbone (we hereafter
refer to the chimeric CoV as SHC014-MA15) to maximize the opportunity
for pathogenesis and vaccine studies in mice (Supplementary Fig. 2a).
Despite predictions from both structure-based modeling and pseudotyping
experiments, SHC014-MA15 was viable and replicated to high titers in
Vero cells"
So they "maximize the opportunity for pathogenesis". Very interesting...
And then they continue saying:
"To test the ability of the SHC014 spike to mediate infection of the
human airway, we examined the sensitivity of the human epithelial airway
cell line Calu-3 2B4 (ref. 9) to infection and found robust SHC014-MA15
replication, comparable to that of SARS-CoV Urbani (Fig. 1c). To extend
these findings, primary human airway epithelial (HAE) cultures were
infected and showed robust replication of both viruses"
So in the last paragraph they have found that the new chimeric virus
they have created (they called it SHC014-MA15) "show robust replication"
in human cells. A great success I guess...
But they continue with the research and say:
"We next analyzed infection in more susceptible, aged (12-month-old)
animals. SARS-MA15–infected animals rapidly lost weight and succumbed to
infection"
So they test the new chimeric virus (they call it SARS-MA15 and also
SCH014-MA15) in mice and they saw a high pathogenicity in the lungs of
the animals, more acute in older ones
Then they continue with the trials of the SHC014-MA15 chimeric virus:
"Similarly, antibodies 230.15 and 227.14, which were derived from
memory B cells of SARS-CoV–infected patients13, also failed to block
SHC014-MA15 replication (Fig. 2b,c). For all three antibodies,
differences between the SARS and SHC014 spike amino acid sequences
corresponded to direct or adjacent residue changes found in SARS-CoV
escape mutants (fm6 N479R; 230.15 L443V; 227.14 K390Q/E), which probably
explains the absence of the antibodies' neutralizing activity against
SHC014. Finally, monoclonal antibody 109.8 was able to achieve 50%
neutralization of SHC014-MA15, but only at high concentrations (10
μg/ml) (Fig. 2d). Together, the results demonstrate that broadly
neutralizing antibodies against SARS-CoV may only have marginal efficacy
against emergent SARS-like CoV strains such as SHC014."
So it seems that the new chimeric virus they created is quite resilient to the antibodies normally used to treat SARS
Still more about the risks of chimeric virus:
"the creation of chimeric viruses such as SHC014-MA15 was not
expected to increase pathogenicity. Although SHC014-MA15 is attenuated
relative to its parental mouse-adapted SARS-CoV, similar studies
examining the pathogenicity of CoVs with the wild-type Urbani spike
within the MA15 backbone showed no weight loss in mice and reduced viral
replication23. Thus, relative to the Urbani spike–MA15 CoV, SHC014-MA15 shows a gain in pathogenesis
(Fig. 1). On the basis of these findings, scientific review panels may
deem similar studies building chimeric viruses based on circulating
strains too risky to pursue, as increased pathogenicity in mammalian
models cannot be excluded"
So they recognize they have created a very dangerous chimeric virus
with a high pathogenesis, easily transmitted in human cells and hard to
fight by antibodies, and they said at the end "building chimeric
viruses based on circulating strains too risky to pursue, as increased
pathegenicity in mammalian models cannot be excluded"
Say What?
At the end of the article they finally said:
"Coupled with restrictions on mouse-adapted strains and the
development of monoclonal antibodies using escape mutants, research into
CoV emergence and therapeutic efficacy may be severely limited moving
forward. Together, these data and restrictions represent a crossroads of
GOF research concerns; the potential to prepare for and mitigate future
outbreaks must be weighed against the risk of creating more dangerous
pathogens. In developing policies moving forward, it is important to
consider the value of the data generated by these studies and whether these types of chimeric virus studies warrant further investigation versus the inherent risks involved "
So I have some questions:
a) What are the probabilities that an strange new SARS virus, never
seen before, very easily transmitted and very pathogenic, started
exactly some hundred meters from the same research lab where theses
people were creating chimeric viruses one day and the following?
b) What are the probabilities that a new "wild" virus be so similar
to this chimeric virus created in 2015 for this study? Could it be a
self-fulfilling prophecy?
c) What are the probabilities that the Wuhan Virology Instute have
developed a very accurate test for the brand "new" virus in just some
days after the outbreak? Do they have some knowledge in advance of what
kind of virus it was?
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