Fruit bats as natural reservoir of highly pathogenic henipaviruses: balance between antiviral defense and viral tolerance

Bats are the natural reservoir host for a number of zoonotic viruses, including Hendra and Nipah viruses of Henipavirus genus, which are highly pathogenic in humans and numerous other mammalian species. Despite being infected, bats present limited signs of disease but still retain the ability to transmit the infection to other susceptible hosts, presenting thus a permanent source of new viral outbreaks. Different mechanisms have evolved in fruit bats permitting them to efficiently control the Henipavirus infection. These mechanisms likely allow bats to establish an adequate equilibrium between viral tolerance and antiviral defense, enabling them thus to avoid both uncontrollable virus expansion as well as immunopathology linked to excessive antiviral responses.