Through serum tests of 218 villagers in Yunnan Province, Shi Zhenglis team suggested that SARS coronavirus has a high potential to directly infect people without intermediate host. It is also predicted that when the SARS related coronavirus in bats spills into human body, it may cause diseases similar to SARS. It is suggested to strengthen surveillance in relevant areas.
Serum samples of 218 villagers in Yunnan Province, 6 positive
In recent reports, Professor Richard ebright, director of the Waxman Institute of Microbiology in the United States, was quoted as explaining that the similarity between ACE2 receptor of Chinese Rhinolophus and that of human body is the same as that of other potential intermediate hosts, indicating that the source of the epidemic, which infected tens of thousands of people, may be directly from bats.
The report points directly to the research done two years ago by Shi Zhengli, a researcher at the Wuhan Institute of Virology, Chinese Academy of Sciences. From the end of November 2017 to February 2018, Shi Zhenglis team published three consecutive papers (release platform, Chinese and English names see notes at the end of the paper), revealing the consistent research results of SARS related coronaviruses in bats sampled in Yunnan Province.
According to the relevant evidence, the paper identified bat as the source host of SARS virus. At the same time, it was found that SARS coronavirus has high potential to infect human directly without intermediate host.
In order to detect the human sera infected with SARS related coronavirus in bats, in October 2015, Shi Zhenglis team collected serum samples from 218 residents in 4 villages (patio, Dafengkou, lvxi, lvxi New Village) of Xiyang Yi Township, Jinning District, Kunming City, Yunnan Province. There are two bat caves (Swallow Cave and stone cave) nearby, which are 1.1-6.0km away from four villages. Since 2011, Shi Zhenglis team has been conducting longitudinal molecular surveillance on bats with coronavirus in these caves, and has found a large number of bats living in them, including the chrysanthemum head bat, which has been proved to be the main host of SARS related virus (the virus sample closest to the new coronavirus found by Shi Zhenglis team is also taken from the chrysanthemum head bat).
There was no SARS outbreak in this area in 2002-2003, and no subjects showed any obvious respiratory diseases during the sampling process. Of these samples, 139 were women and 79 were men, with a median age of 48. Career data were provided by 208 people (95.4%): 85.3% of them were farmers and 8.7% were students. Most of the respondents (81.2%) had livestock or pets, and most of the respondents (97.2%) had contact with livestock or wildlife. Among them, 20 participants (9.1%) witnessed bats flying near the house, and one of them disposed of the dead bats.
Six of the 218 were positive for SARS related coronavirus, but none of them were positive for viral nucleic acids in their oral and fecal swabs or blood cells.
In the paper, Shi Zhenglis team said their research provided the first serological evidence that bats may be infected with SARS r-cov or a potentially related virus.
How to identify the source of infection?
Six people have not been exposed to SARS patients, one has been to Shenzhen
The paper introduces the demographic statistics and travel history of six positive samples (four males and two females).
Among them, there are two men (jn162, 45, jn129, 51) in Dafengkou village, two men (jn117, 49, jn059, 57) in lvxi village, and two women (jn053, jn041, 55) from Tianjing village. In the 12 months before the sampling, jn041 was the only one with a history of travel outside Yunnan. She had been to Shenzhen, 1400km from her hometown. Jn053 and jn059 have only been 1.4 km from their villages. Jn162 has traveled 63 kilometers to Kunming, the capital of Yunnan Province. Jn129 and jn117 never left the village. All six mentioned seeing bats flying in their villages.
The six respondents had no contact with SARS patients, nor had they been to the severe epidemic area during the outbreak of SARS. Moreover, the detectable antibodies in the body of the convalescent patients infected with SARS decreased rapidly within 2-3 years, which also showed that these positive results were not caused by previous SARS infection.
At the time of the interview, all six people indicated that they had no clinical symptoms in the 12 months prior to the investigation. Based on the study of cell and humanized mouse infection, these viruses are not as toxic as SARS virus. Shi Zhenglis team said that considering that these people are likely to have direct contact with bat secretions in the village, their research shows that some bats can directly infect humans with SARS related coronaviruses without passing through intermediate hosts.
Do viruses in bats evolve frequently?
There are many kinds of bats in the cave, and virus recombination often occurs
In another paper, Shi Zhenglis team said they studied caves about 60 kilometers from Kunming. In addition to many chrysanthemum head bats and foot bats that have already detected SARS related viruses, there are other bats, such as the mouse ear bat. The temperature of the cave is about 22 u2103 u2013 25 u2103, and the humidity is about 85% - 90%. The physical nature of the cave is not unique, but it does contain a particularly dense bat population during the breeding season. In other areas of Yunnan, similar caves inhabited by bat populations of different species are not uncommon.
Data show that there are frequent recombination events among SARS related coronaviruses in the same cave. Shi Zhenglis team proved that SARS virus is most likely produced by recombination of SARS related coronavirus in Rhinolophus. In addition, they found that various SARS related coronaviruses that bind to human ACE2 cross infect bats in this area. Therefore, it is possible for the coronavirus in bats to overflow to humans and develop SARS like diseases.
The bat cave investigated by Shi Zhengli is only 1.1km away from the nearest village. Local residents may be exposed to bats. They suggested that we should continue to monitor the evolution of SARS related virus in this site and other sites, check the risk of human infection and carry out serological investigation on villagers to determine whether these sites have been infected and develop intervention strategies to avoid future disease.
What is the risk of human transmission of bat coronavirus?
Shi Zhenglis team also conducted longitudinal monitoring of two beta coronaviruses in fruit bat samples collected in Yunnan and Guangdong Province in 2009-2016.
Bats are the only mammals that can fly, accounting for about 20% of all mammals, the paper said. According to the difference of diet, bats are divided into insectivores and fruit eaters. Because of its large size and plump flesh, fruit bats are regarded as delicious by people in Africa and some parts of Southeast Asia.
Fruit bats in Africa and the Pacific are host to many viruses, such as Marburg virus, Hendra virus and Nipah virus. Hendra virus, Nipah virus, Ebola virus and rabies virus related to the immune system have been detected in fruit bats in China. In addition, respiratory enteroviruses, adenoviruses and coronaviruses with various genetic materials were detected or isolated from fruit bats.
Two closely related but distinct beta coronaviruses (SARS and CNV) were found in Guangdong Province and Yunnan Province, respectively. u2014u2014Press note). Both are found in black fruit bats in China, where coronavirus can infect the host through the respiratory system and gut. Shi Zhenglis team found that intestinal tissue is the main target of two beta coronaviruses. However, one of the beta coronaviruses has also been detected in the kidneys and lungs, indicating that the beta coronavirus has a wide range of tissue tropism and may be transmitted through feces and respiratory tract, thus infecting other animals.
There are at least five species of fruit bats in China, all located in the tropics, Shis team said in the paper. These fruit bats feed on fruits and flowers and are in frequent contact with farmers and farms, thus increasing the risk of bat virus transmission to livestock and humans.
Are researchers at risk of infection?
Collection of bat feces
In May 2017, Wuhan Evening News reported that Tian Junhua, Wuhan Center for Disease Control and prevention, risked being infected to catch bats in the field for scientific research.
According to the report, the environment for collecting bat samples is extremely bad. There is a stench in bat cave, and it is extremely dangerous on cliffs; bats carry a large number of viruses, and they are at risk of infection if they are not careful.
Tian Junhua found that he used the fireworks and noise to alarm the bats to make them move and pull the net again, and most bats were caught. But during the operation, Tian Junhua forgot to take protective measures, and the bat urine dripped on him like raindrops from the top of his head. the wings of the bat carry sharp claws. When catching the bat, a clamp is needed, and the big bat is easy to spray blood after being hurt by the clamp; several times, the bat blood directly sprayed on Tian Junhuas skin..
Tian Junhua knows that there is a risk of infection, and he will take the initiative to keep a distance with his wife and children after returning home and isolate himself for 14 days. According to previous research by Shi Zhenglis team, contact with bat secretions has a high probability of being infected with coronavirus.
A paper published in 2013 on emerging infectious dis (new infectious diseases) showed that beta coronavirus was positive in bat feces samples collected in Thailand. It was suggested that workers collecting bat feces should use personal hygiene precautions and improve barrier protection to reduce the possibility of exposure to zoonoses.
Kevin olival, an American ecologist who has collected bat samples in China and other parts of Asia, said in an interview with the National Geographic that the coronavirus is not only transmitted through the air and respiratory tract, but also through feces. Bats are not very clean. If a fruit is polluted by bat feces and falls to the ground, it may cross infect the breeding animals (if the beavers).
From the end of November 2017 to February 2018, Shi Zhenglis team published three papers in the American Biological journal PLoS patterns (etiology) and the English journal virological Sinica (Chinese Virology) of the Wuhan Institute of Virology, which are respectively the discovery of the genetic pool of batsars related coronavirus (SARS related coronavirus in bats) The discovery of abundant gene pool provides new insights for the study of the origin of SARS virus), digital surveillance of betacoronavirus in fruit batsin Yunnan Province, China during 2009-2016 (longitudinal surveillance of beta coronavirus in fruit bats in Yunnan Province from 2009-2016), serial evidence of batsars related coronavirus infection in humans, China (serological evidence of human infection with SARS related coronavirus in bats).
The first study on the characteristics of critical patients with new crown: organ dysfunction in most patients
In 52 severe patients, most of them had organ dysfunction, including acute respiratory distress syndrome in 35 cases (67%), acute renal injury in 15 cases (29%), heart injury in 12 cases (23%), liver dysfunction in 15 cases (29%) and pneumothorax in 1 case (2%). Hospital acquired infection occurred in 7 patients (13.5%).
The viral load of novel coronavirus pneumonia reached peak at the early stage (5-6 days), which was different from the peak time of SARS (the tenth day of symptom onset). The viral load of sputum in patients with new crown was higher than that of throat swab. At the same time, patients may have been infectious before symptoms.