WASHINGTON, Feb. 22 (Xinhua) -- Chinese scientists have identified the secret of bats that harbor highly pathogenic viruses like Ebola, Marburg and SARS coronavirus but do not show clinical signs of disease.

In a paper published on Thursday in the journal Cell Host & Microbe, scientists at the Wuhan Institute of Virology in China find that in bats, an antiviral immune pathway called the STING-interferon pathway is dampened, so bats can maintain just enough defense against illness without triggering a heightened immune reaction.

"We believe there is a balance between bats and the pathogens they carry," said the paper's senior author Zhou Peng.

"This work demonstrated that in order to maintain a balance with viruses, bats may have evolved to dampen certain pathways," Zhou said.

According to researchers, in humans and other mammals, an immune-based over-response to one of these and other pathogenic viruses can trigger severe illness. For example, in humans, an activated STING pathway is linked with severe autoimmune diseases.

"In human history, we have been chasing infectious diseases one after another," said Zhou, "But bats appear to be a 'super-mammal' to these deadly viruses."

By identifying a weakened but not defunct STING pathway in bats, researchers have some new insight into how bats fine-tune antiviral defenses to balance an effective, but not an overt, response against viruses.

They hypothesize that this defense strategy evolved as part of three interconnected features of bat biology: they are flying mammals, have a long lifespan, and host a large viral reservoir.

"Adaptation to flight likely caused positive selection of multiple bat innate immune and DNA damage repair genes," Zhou said.

These adaptations may have shaped certain antiviral pathways including STING, interferon to make them good viral reservoir hosts and achieve a tolerable balance.

Zhou told Xinhua that the study has provided a possibility that people can learn from bats in combating virus although whether this mechanism can be directly used in humans is still unknown.