As the article points out close to the end, bats are really inefficient flyers. When bats fly they run really hot and consume lots of energy. Very high body temperature (above 40C) slows down many virus proteins.
Not mentioned in the article is idea that bats may have very weak immune response because they don't have energy for it. They need all the energy for flying.
Not mentioned in the article is idea that bats may have very weak immune response because they don't have energy for it. They need all the energy for flying.