horseshoe Unlucky. bats in Chinese horseshoe like this carry a virus similar to SARS can infect human cells.
Libiao Zhang / Guangdong Entomological Institute / South China Institute of Endangered Animals
In November 02, a new deadly virus suddenly appeared in southern China. In less than a year, the disease has caused, known as SARS spread to 33 countries, sickening more than 8,000 people and killing more than 700. Then he disappeared. Now, researchers say they first isolated a virus closely related bats in China that can infect human cells. "This shows, that at this time in China, there are bats with a virus that can infect people directly, and cause another SARS pandemic," says Peter Daszak, one of the authors and President of EcoHealth Alliance in New York.
scientists have long suspected bats to be the natural reservoir of coronaviruses such as that responsible for SARS (severe acute respiratory syndrome). the animals were identified as the source of many dangerous viruses such as Nipah and Hendra, and have also been linked to Ebola and new coronavirus causing SARS-like illness, called MERS. in 05, Daszak and others have found viral DNA closely resembling the SARS virus in three bat species in Chinese horseshoe. However, while the sequences of these viral genomes were 88% to 92% identical to the SARS coronavirus, they showed marked differences in a region encoding said protein peak. In the SARS virus, this protein binds to a receptor on the surface of human cells mediating its input. The difference means that the bat virus would not be able to infect human cells. And because some palm civets were carriers of a virus almost identical to the human SARS virus, most researchers have come to believe that SARS spread from bats to civets-probably in a Chinese market where these and other animals come into close contact and then to humans.
Now, new research suggests that civets may not be necessary to start a SARS pandemic. For more than a year, China's scientists, Australia and the United States gathered anal swabs or faecal samples of horseshoe bats in a cave in Kunming in southern China. They found coronavirus RNA in 27 of the 117 sampled animals. Among the viruses were two new coronavirus strains that resemble the SARS closer than those previously identified in bats, particularly in the part of the genome encoding the major spike protein. Scientists have also isolated the virus living in one of the animals. In the experiments, reported online today in Nature , they showed that the virus has infected pig kidney cells and bats, and perhaps more importantly, cells lining the human lung.
The new results can not solve if the original SARS virus moved directly from bats to humans or through an intermediate host, said Columbia University virologist Ian Lipkin, who was not involved the work. But it shows that a similar coronavirus "has the potential to infect people without an intermediate host."
This should be a warning to everyone, said Daszak. Although the SARS virus blew to humans by civet cats, this stopover was not necessary, he said. Bats are still hunted and eaten in large numbers in China, it is concerned. "I think people should stop chasing bats and stop eating bats."
But Michael Osterholm, director of the Center for Research on Infectious Diseases and politics at the University of Minnesota, Twin Cities, said that scientists must be careful to distinguish between what is possible and what which is likely in nature. Bat rabies, for example, easily infects human tissues, and many bats carry the virus, he said. "If it was sufficient for transmission that we should all be dying of bats in the US" But the virus can be transmitted if an infected bat bites a human. This rarely happens and there are very few cases of bats in the United States.
Christian Drosten, a coronavirus expert at the University of Bonn in Germany, also warns against over-interpretation of the results. Laboratory experiments do not necessarily mean that the virus can actually infect humans, he said. "Receptors and cell culture studies are not everything. You should take this virus and see in animal testing if it can, for example, infect a primate. "
What fascinates Drosten more on paper is a parallel to the coronavirus causing MERS, a disease that was reported the first in the Middle East in 2012 and killed 62 people to date. that the virus has also been shown to infect cells of various species in cell culture. "We thought it was a particular feature of MERS, but now this virus shows a similar trend, "said Drosten. This suggests that coronaviruses found in bats and other animals differ in a way that can make them more or less likely to jump to humans. In trying to predict future pandemics, such characteristics can guide virologists most likely pathogens to cause a pandemic, he hopes, and could one day help prevent another SARS pandemic to occur.
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