Since the
early days of the COVID-19 epidemic, theories have circulated about the origin
of the novel coronavirus causing the disease, SARS-CoV-2. One prominent rumor
is that it first escaped from a lab in Wuhan studying bat coronaviruses and
then spread to the public. This theory has also evolved into claims that the
virus was genetically engineered to be a bioweapon. But scientists say that
while there’s not enough information to pinpoint where the virus came from, there
is no evidence that it was created in a lab.
The
lab-escape theory had been circulating on social media and various blogs for
weeks, but gained considerable visibility in a New York Post article in late
February. In it, Steven Mosher, a social scientist and the president of the
Population Research Institute in Front Royal, Virginia, summarizes why he
believes SARS-CoV-2 may have been accidentally spread by China’s National
Biosafety Laboratory at the Wuhan Institute of Virology, where researchers have
studied bat coronaviruses.
In the
article, Mosher describes several lines of reasoning, namely, that the lab is
less than 10 miles away from the seafood market where a cluster of COVID-19
cases was first discovered, and that after the 2003 SARS outbreak, the SARS-CoV
virus escaped from virology labs multiple times in China. He also describes how
Chinese virologist and bioweapons expert Major General Chen Wei went to the
Wuhan Institute of Virology with military scientists in January to study thenew virus, which Mosher sees as a form of damage control.
“The
circumstantial evidence surrounding it is pretty compelling. . . . The idea
that the epicenter of this epidemic would be just a few miles from the
Institute of Virology in Wuhan, which is where we know that dangerous pathogens
are being kept and looked at as potential bioweapons, I think the odds against
that are just astronomical,” Mosher tells The Scientist.
Dimitrios Paraskevis, an epidemiologist at the National and Kapodistrian University of
Athens in Greece, tells The Scientist that while it’s not possible to rule out
the idea of lab escape, he believes that it is unlikely. “Any person who works
in a lab must follow very strict safety regulations. It sounds to me very
extraordinary that something happened and nobody took care about such an
accident,” he says. The World Health Organization updated SARS surveillance guidelines in 2004 after the lab-based outbreaks, urging labs to follow proper
biosafety procedures, and China replaced the director of its Center for Disease
Control and Prevention.
One problem
leading to a lot of apprehension and speculation about the new coronavirus is
that scientists “don’t know what the actual source of the virus was,” Anthony Fehr, a coronavirus researcher at the University of Kansas, tells The
Scientist. Additionally, researchers don’t know if SARS-CoV-2 immediately
started to spread in humans after a single transmission from an animal, or if
it took multiple zoonotic events between an infected animal population and
humans.
Despite the
question mark around the exact source of the disease, it does appear to have
originally come from wildlife, according to a team of international public
health scientists who wrote a statement published in The Lancet. An analysis of
SARS-CoV-2 by scientists at the Wuhan Institute of Virology suggests that the
virus’s genome is 96 percent similar to a coronavirus found in bats.
Mosher
agrees that animals were the likely origin. “That doesn’t mean [the virus]
wasn’t collected, brought to the lab, and was being tested on in various ways,
and escaped from the lab,” he says. Mosher also does not claim that China
genetically engineered the virus. “I’m not saying this has been genetically
engineered to be a bioweapon that’s escaped from the lab. . . . I’m just saying
that [China is] collecting dangerous pathogens, [and] they have a history of
letting them escape from the lab,” he says.
Transmission
from an animal, with no lab experiment or genetic manipulation involved, fits
best with what scientists know about how other coronaviruses have made the jump
to humans. In the past, these viruses have spread through wild bats that infect
another type of animal—an intermediate host—that then spreads it to humans.
SARS-CoV, for example, was transmitted from bats to civets to humans, while
camels were an intermediate host in MERS, according to Quanta. The civet
version of SARS-CoV was 99.8 percent similar to the one found in humans—much
more closely related than the bat and human varieties of SARS-CoV-2—so
researchers believe the new coronavirus also infected another type of animal on
its way from bats to humans. But they have not found a candidate so far,
according to Nature.
This
ability to move in between different animal hosts is a characteristic feature
of coronaviruses, according to Paul McCray, a pulmonologist at the University
of Iowa Carver College of Medicine whose lab studies coronaviruses. “It’s
exactly what we’ve learned in studies of SARS in 2002 and 2003, and MERS in
2012. . . . So the concept that this is happening again should come as no
surprise,” he says. “For people that work with these viruses, this is
completely unsurprising. We don’t need to come up with farfetched theories when
the genome sequences and the characteristics of these viruses support what
we’re seeing.”
No signs of
engineering in SARS-CoV-2 genome
In addition
to the claim that a naturally evolved virus escaped from a lab by mistake, some
conspiracy theories have posited that SARS-CoV-2 was genetically engineered. In
fact, researchers throughout the world, including in the US and China, have
conducted research involving the creation of experimentally engineered hybrid
coronaviruses. But there is no evidence that SARS-CoV-2 was genetically
engineered, says Paraskevis, whose genomic analysis of the new virus was reported
as a preprint in January.
RNA
viruses, which include coronaviruses, “accumulate mutations at a rate one
million times faster than human DNA [does]. . . . It gives them the ability to
survive against an immune response,” Paraskevis says. While the new coronavirus
does have some genetic differences to other known viruses due to mutations,
“there’s no evidence that this is the result of a human experiment,” he says,
adding that if the virus were engineered, scientists would expect to see
additional genetic material in its genome. For example, an early bioRxiv
preprint on SARS-CoV-2 found HIV-like genetic sequences, but online commenters
pointed out that “the findings were at most a coincidence” and that research
has since been retracted, reports STAT.
As there
are still many unknowns about SARS-CoV-2, researchers worldwide are trying to
uncover as much as they can about the virus. Chinese researchers “released the
genomic sequence incredibly rapidly online. . . . They were very public in
sharing the most important first piece of information” about it, McCray tells
The Scientist. “The fact that scientists all over the world had access to that
genomic sequence” made a lot of early research possible, he says.
Emily
Makowski is a freelance writer based in Boston. Find her on Twitter
@EmilyRMakowski.
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