This is also why bats are viral reservoirs and likely sources for mammalian pandemics - their immune system simply doesn't clear infections. My understanding i

This is also why bats are viral reservoirs and likely sources for mammalian pandemics - their immune system simply doesn't clear infections. My understanding is it's because they're constantly damaging their own dna from high operating temps (flying mammals). So the immune system must tolerate foreign looking dna at all times, constantly repairing cell damage instead of aggressively attacking foreigners.