A study published in the British Science Report has experimentally verified the hypothesis that bat cells can coexist with viruses for a long time. The researchers infected the cells of a big brown bat with MERS coronavirus 126 days, and analyzed the infected cells by detecting protein, transcripts and genes. Studies have found that although MERS coronavirus will kill human cells after entering the human body, it can "live in peace" with the host in bat cells for a long time.
According to the researchers, once exposed to the virus, the bat's "super" immune system will maintain its natural antiviral response, which has been "turned off" in many species, including humans. Studies have shown that compared with normal cells, the basic level of type I interferon in bat cells infected for a long time is very high, which may inhibit the continuous replication of the virus.
At the same time, MERS coronavirus itself rapidly produces specific gene mutations to adapt to bat cells. Infected bat cells also have the ability to resist repeated virus infection. For the above reasons, the big brown bat can carry MERS virus for several months without getting sick.
However, vikram Misra, a microbiologist at the University of Saskatchewan, said that if bats are forced to leave their habitats due to some stress, such as being infected with other diseases, the balance between their immune systems and viruses may be upset, leading to virus reproduction and possibly spreading to other species.
Bats are the natural reservoirs of thousands of viruses, and some studies believe that each bat carries an average of 17.22 viruses that may make people sick. The researchers analyzed a database containing 2805 mammalian viruses and found that bats have the largest number of viruses that may threaten humans, twice as many as the second-ranked mammalian primates, and rodents rank third. Bats can directly transmit the virus to humans, or they may infect other animals such as primates first, and then transmit it to humans.
Researchers from Wuhan Institute of Virology, Chinese Academy of Sciences, China Academy of Sciences and other institutions published a paper in the British journal Nature, saying that they found that the gene sequence of TG 13 coronavirus strain in COVID-19 and bats was as high as 96%. TG 13 is the closest known strain to COVID-19 gene, which indicates that bat is probably the natural host of COVID-19.
Although bats can carry a variety of viruses, researchers also stressed that people should not regard them as "enemies". The Spanish newspaper Le Monde recently quoted Simon Ripperger, a researcher at Ohio State University, as saying that bats are far away from our enemies, and they also help to maintain the health of human beings and ecosystems in some ways. For example, some bats in the tropical rain forest feed on fruits and nectar, thus helping flowers pollinate and sow. Insect-eating bats in Europe will prey on a large number of insects that may cause insect disasters.