Bats' immune systems make viruses more deadly

is no coincidence that some of the most serious viral diseases in recent years - SARS, MERS, Ebola, Marburg disease and the emerging new coronary pneumonia - have originated in bats. A new study published in eLife by the Cara E Brook team at the University of California, Berkeley, found that bats' strong immune response to the virus may prompt it to replicate more quickly, causing fatal damage when it spreads to mammals with normal immune systems, such as humans.
bats, including those believed to be the source of human infection, have an immune system that is always prepared to defend against viruses and can quickly isolate them from cells. While this may protect bats from high viral loads, it may also encourage them to multiply more quickly within the host body. This makes bats a unique host for rapid reproduction and highly transmitted viruses.
bats can withstand these viruses, when they enter other animals that lack a rapid-response immune system, they quickly knock down the new host, leading to a high fatality rate. Cara Brook, a postdoctoral student at the University of California, Berkeley and co-author of the study, said: "Some bats can produce this powerful antiviral response, but at the same time balance the anti-inflammatory response. If we try the same antiviral strategy, our immune system will produce widespread inflammation.
researchers point out that destroying bats' habitats appears to put pressure on them to release more viruses in saliva, urine and feces, infecting other animals.
, bats can be very special in 'storing' viruses," said Mike Boots, a disease ecologist at the university. Many viruses come from bats, which are not random. Bats are not closely related to us, so they don't carry many human viruses. But this study proves how bats' immune systems overcome toxicity. As
the only mammal that can fly, bats increase their metabolic rate during flight, twice as much as running rodents.
researchers say intense physical activity and high metabolic rates often lead to higher tissue damage due to the accumulation of active molecules, mainly free agents. But to be able to fly, bats seem to have evolved a physiological mechanism that effectively removes these harmful molecules. This may be why bats live longer. Some bats can live for 40 years, while rodents of the same size can live for only two years. This rapid suppression of inflammation may have another benefit: the suppression of inflammation associated with the antiviral immune response. A key trick of many bats' immune systems is to release a signaling molecule called interferon α, which tells other cells to "get ready for battle" before the virus invades.
Brook and Boots created a simple model of the bat's immune system to model their experiments on a computer. The researchers note that many bat viruses are transmitted to humans through animal vectors. SARS coronavirus is transmitted to humans through fruit beavers, MERS virus through camels, Ebola virus through gorillas and chimpanzees, Nipa virus through pigs, Hendra virus through horses, Marburg virus through African green monkeys. Despite this, these viruses are extremely toxic and deadly when they finally enter the human body.
are working on a more formal evolutionary model of bat disease to better understand the spread of the virus in other animals and humans. "In order to be able to predict the emergence and spread of infection, it is important to understand the evolutionary trajectory of infection." Brook said. (Source: Tang Erdu, China Science Daily)