Researchers at the CSIRO have uncovered a unique ability in bats which allows them to carry lethal diseases but not become sick.
The discovery could help stop the spread of diseases such as Ebola, SARS and the Nipah virus in humans.
For infectious disease researchers, bats are among some of the world's most perplexing carriers of lethal viruses.
More than a hundred viruses, including Ebola, Hendra, Marbug and SARS, have all been traced to bats.
But they can carry and transmit viruses without becoming sick or showing symptoms.
That is because their immune systems remain switched on constantly, it turns out, a finding scientists believe could hold the key to protecting people from deadly diseases.
A new study by the CSIRO has found bats have only a fraction of the number of interfurons, integral for promoting an immune response against viruses, that humans have.
However, despite that, bats still have a stronger immune system.
A bat immunologist at the CSIRO's Australian Animal Health Laboratory, Dr Michelle Baker, led the study.
She says the findings surprised her.
"We think bats are able to control viruses very efficiently, very early in their immune response, before the viruses have a chance to really start replicating and causing a problem. They've been co-evolving with viruses throughout their long period of co-evolution. So we think that they've kind of achieved an equilibrium with viruses so they can coexist quite happily together, and, because of this co-evolution, there's probably been changes that have occurred in their immune system to allow them to cohabitate quite happily together."
Dr Baker says, normally, it is unhealthy for an immune system to remain constantly active.
"A lot of the problems you see when you get infected with a virus are actually caused by the immune system. It's this overreaction of the immune system that causes a lot of the damage that we see during a viral infection. So, most of the time, most species try to regulate that response fairly closely. You don't want it to get out of control, which it often does with some of these really nasty viruses that the bats carry. But bats actually seem to have parts of their immune system switched on all of the time without any negative consequences at all, so that's one of the really interesting findings we've made."
Dr Baker says the super immunity of bats could help in protecting humans one day against deadly diseases, including Ebola, SARS and the Hendra virus.
She suggests it could help in redirecting immune responses.
"I think we need to do a little bit more work yet before we can transfer it into humans, but, hopefully, the goal is to eventually find something that can be translated so that we can redirect the immune system of other species, then some of these diseases might not be as much of a problem."
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