The Corner


New Study: The Human Version of SARS-CoV-2 Is Closer to the One in Bats than the One in Pangolins

This scanning electron microscope image shows SARS-CoV-2 (round blue objects), also known as novel coronavirus, emerging from the surface of cells cultured in the lab which was isolated from a U.S. patient. (NIAID-RML/Reuters)

Earlier this week, the Morning Jolt newsletter examined a study that contended the virus SARS-CoV-2 has certain features indicating it evolved through a considerable period of natural selection, and those traits are just too similar to coronaviruses from pangolins for the virus to have jumped straight from bats to humans, a scenario that made the researchers conclude that an accidental release from a laboratory was unlikely.

But scientists are always learning more. And Matt Ridley, a science journalist and author in the United Kingdom, offers significant news in the Wall Street Journal today:

RaTG13 is the name, rank and serial number of an individual horseshoe bat of the species Rhinolophus affinis, or rather of a sample of its feces collected in 2013 in a cave in Yunnan, China. The sample was collected by hazmat-clad scientists from the Institute of Virology in Wuhan that year. Stored away and forgotten until January this year, the sample from the horseshoe bat contains the virus that causes Covid-19

The role of pangolins in the spread of Sars-CoV-2, the virus that causes Covid-19, remains unclear. A closer look at more of the Sars-CoV-2 genome, published last week by Maciej Boni at Penn State University and David Robertson at Glasgow University, together with Chinese and European colleagues, finds that human versions of the virus are more closely related to the RaTG13 horseshoe bat sample from the cave than they are to the known pangolin versions. It is not yet possible to tell whether the virus went from bat to pangolin to people, or from bat to pangolin and bat to people in parallel.

Significantly, the same analysis shows that the most recent common ancestor of the human virus and the RaTG13 virus lived at least 40 years ago. So it is unlikely that the cave in Yunnan (a thousand miles from Wuhan) is where the first infection happened or that the culprit bat was taken from that cave to Wuhan to be eaten or experimented on.

Rather, it is probable that somewhere much closer to Wuhan, there is another colony of bats carrying the same kind of virus. Unless other evidence emerges, it thus looks like a horrible coincidence that China’s Institute of Virology, a high-security laboratory where human cells were being experimentally infected with bat viruses, happens to be in Wuhan, the origin of today’s pandemic.

Bats are sold in markets and supplied directly to restaurants throughout China and southeast Asia, but no direct evidence of their sale in Wuhan’s wet market has come to light. Also, horseshoe bats, which are much smaller than the tastier fruit bats, are generally not among the species eaten. The significance of the Yunnan cave sample is that it shows the bat virus didn’t need to recombine with viruses in other species in a market to be infectious to people. The role of the wet markets may be that other animals get infected there and produce much higher loads of virus than the bats would, amplifying the infection.

The accidental-release scenario cannot yet be proven — and it may forever be impossible to prove — but it seems to be dismissed a little too quickly in some circles, at least for my tastes. The accidental-release scenario would require one of the several hundred bats being used for research on coronaviruses in either the Wuhan Institute of Virology or Wuhan Center for Disease Control to have developed SARS-CoV-2 and for it to have accidentally infected someone at the lab through blood, urine, or feces, and then for that lab employee to have unknowingly passed it to others. Alternatively, some biological material containing the virus could have been improperly disposed of, leading to an accidental infection of someone outside the lab.

Lab accidents happen, even in the very best laboratories, as discussed in the newsletter this week. Terrifying examples abound. Russia’s State Research Center of Virology and Biotechnology — one of the two centers in the world housing samples of live smallpox virus — suffered an explosion in September 2019. In 2016, a lab worker at the University of Pittsburgh became infected with Zika virus after accidentally sticking herself with a needle. In 1979, a Soviet bioweapons lab in Sverdlovsk accidentally released a puff of anthrax spores into the sky, killing about sixty-four people. The Soviet government blamed bad meat; the KGB confiscated all of the hospital records. In 2007, the CDC shut down all research on dangerous pathogens at Texas A&M University after two accidents went unreported for too long: “The first exposure at TAMU occurred in February 2006, when a lab worker cleaning a chamber containing brucella bacteria in a biosafety level-3 lab developed brucellosis; she recovered after treatment with antibiotics. One month later, three other workers tested positive for antibodies to Coxiella burnetii, the bacterium that causes Q fever, but didn’t become sick.” In the United Kingdom, the Health and Safety Executive “held formal investigations into more than 40 mishaps at specialist laboratories between June 2015 and July 2017, amounting to one every two to three weeks.”

Just this week, a courier carrying coronavirus samples to a lab for testing was involved in a car crash on Interstate 195 in Massachusetts.

I do not understand why so many people insist that an accident at either Wuhan Institute of Virology or Wuhan Center for Disease Control is so unthinkable.


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