Why Bats

Why do bats harbor so many nasty viruses? It's truly a list of horrors: Ebola, Marburg, and SARS like in Covid-19. Using data modeling, scientists found that bats have unique immune systems that allow them to co-exist with chronic viral infections.

The alarming result of this relationship is that these viruses are replicating in the bat's robust immune system, accumulating mutations that make them more virulent when they infect a secondary host like humans. In fact, bats are host to more zoonotic diseases than any other animal, diseases that can jump to humans.

Bats like all mammals have the Interferon alpha protein which is released after a viral infection alerting other cells to go into an anti-viral state. This limits viruses from entering nearby cells but creates an inflammation that can be damaging to mammals unless you're a bat. Bats are fine with it and constantly make Interferon alpha which puts them in a constant anti-viral state.

One result of this hyperactive antiviral immunity is that viruses don't make bats sick but rather linger. As the viruses reproduce, mutations occur and create swarms of viruses with minor genetic differences. This sets them up to dodge the immune systems of other animals when they make the leap.

These studies will help us prepare for future virulent zoonotic diseases when they make the jump to humans.