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.
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Thanks for watching, and I’ll see you next time.