Did This New Coronavirus Come From Bats? Here’s What We Know

By now, you’ve probably heard of the coronavirus
that’s traveling the globe. The disease it’s causing, known as COVID-19,
and the virus itself, known as SARS-COV-2, know no borders. And we’re still trying to grasp where it
will end up next. So far, we know that the outbreak originated
in Wuhan, China—but as of yet, how the outbreak began hasn’t been solved. We’ve heard seafood, snakes, and a whole
host of conspiracy theories surrounding the virus’s origin, but it seems that preliminary
evidence may be pointing to an all-too-familiar source: bats. When you look at the genetic sequence of the
virus, you can line it up against every other known coronavirus and say, ‘what are its closest
relatives?’ It turns out that there are two viruses, one
in particular that we found in China a few years ago, that’s extremely closely related:
about 96% of the genetic sequence lines up with this new virus. That virus came from bats. So that’s really why people believe it’s a
bat-origin virus. And this isn’t the first time bats have
been identified as the potential source of an outbreak. In fact, studies have found that bats host
a much higher proportion of zoonotic viruses than any other mammal, making them disease
reservoirs. Viruses that cause Ebola, SARS, and MERS are
all zoonotic, meaning they can cross from animals to humans. To better understand these zoonotic viruses,
Daszak and his team have worked to sample more than 10,000 bats in Southern China and
most significantly, detected over 500 new coronaviruses in the past ten years. Now, in order to understand how SARS-COV-2
could potentially cross between species, researchers are looking at it on a cellular level. When we find Coronaviruses in bats in China,
we analyze the proteins on the surface of those viruses and say, ‘are they able to bind
to human cells?’, and humans have cell surface receptors that viruses need to be able to
bind to get in. And some of these bat viruses don’t; some
of them do. So probably this novel coronavirus, already
had that protein that could bind. Then it needs to successfully replicate. So how exactly can bats harbor all these viruses
and not be affected? The answer could be in how bats evolved to
fly. Bats are the only mammal capable of flying
long distances, and use a tremendous amount of energy to do so. But a byproduct of these high energy demands
is believed to be an increased number of free radicals in cells, which in turn can damage
a bat’s DNA. So to overcome these harmful effects, it seems
that bats have evolved genes to dampen their immune response, so they don’t over-react
to free radical damage caused by flight. Bats have a unique adaptation of their immune
system which allows them to harbor viruses without these viruses causing any diseases.There’s
a lot of influenza viruses out there. And we harbor a quite a few of them. They cause us no harm. And bats do exactly the same. And is only after spillover to humans that
some of these viruses can cause illness in us. So while the bats may not get sick, when viruses
make the jump to species without the same immune strength, like say, a human, mortality
rates can be high. Environmental threats like deforestation could
add to the animals’ stress levels, causing them to shed more virus through their saliva,
urine, and feces, which can later infect other mammals. So in these spillover events like the current
coronavirus, a lot of focus often gets driven towards which species is responsible. But really, really important is to understand
that it’s about the construct that we’ve created an environment where humans are suddenly in
contact with a lot of wildlife species in close quarters. And so this creates an environment where viruses
can spill over. Bats may be the hosts to these viruses, but
we can’t forget the crucial role that they play in regulating insect populations and
as important pollinators, with many plants depending on them for their survival and propagation. Some of your favorite fruits like mangos,
bananas, or guava wouldn’t exist if bats weren’t here. I really hope people don’t start getting a
more negative view of bats, but just because they’re unlucky enough to carry some of these
viruses. Remember, our relationship with wildlife is
what allows those viruses to get in. So let’s think about that and change our relationship
with wildlife. If you want to learn more about COVID-19,
check out our video here. And if there’s another aspect of COVID-19
that you want to see us cover, let us know in the comments below. Make sure to subscribe to Seeker for all your
viral news. Thanks for watching, and I’ll see you next