Why bats frequently contact with infectious disease but seldom being infected?

New research concludes that the bat's immune system works in a fundamentally different way from other animals. The research about mastiff bats was conducted by scientists from the Max Planck Institute for Ornithology. It can also help fighting against viral diseases that can be transmitted from animals to humans.
There are very little researches has been conducted about bats'immune system till now. Researchers mentioned above are now trying to bridge this gap. Their findings show the difference between the immune system of bats and other animals. The bats seem to be able to fight off the pathogens without becoming ill themselves. But what makes their immune system so special?
The scientists studied the immune responses of Pallas's mastiff bats (Molossus molossus) in Panama. Those bats live a specific life: during the day they reduce their energy consumption in their roosts in order to save energy. During this period, the bats rest motionless and their body temperature drops. They come to life only at sunset when the mastiff bats set out for the hunt. Then their body temperature rises to more than 40 degrees Celsius as their muscles need to work to keep flying.
However, the high temperature could activate the immune response against pathogens as a type of daily fever. On the contrary, the daily slowdown in their metabolic rate could also inhibit the proliferation of existing pathogens in the body.
The researchers administered a lipopolysaccharide (LPS) to the bats to test the hypothesis. LPS is a compound which is harmless in itself and made up of lipid and sugar components. It is also found on the outer membrane of many pathogens, then the  bat's immune system assumes a bacterial attack and switches to defence mode.
However, the daily temperature fluctuations turned out to remain unchanged even after the administration of LPS. The material therefore does not trigger a fever in the bats. What's more, the number of white blood cells in the blood, which is an indicator of the strength of the immune defence, did not increase. But the bats did lose a significant amount of mass within 24 hours meaning that the bats mobilise energy reserves for the immune defence decrease.
The findings indicate that the bats' immune system is switched on but works in a different way. Know more about the difference can help us learn more about the danger of human diseases.
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