香港大學最新研究發(fā)現(xiàn)：菊頭蝙蝠或攜SARS病毒 http://www.biotech.org.cn/news/news/show.php?id=26708
More evidence links SARS to bats http://www.biotech.org.cn/news/news/show.php?id=27300
以中國科學院科學家為主進行的聯(lián)合研究調查結果表明，蝙蝠攜帶有類SARS病毒,。該項研究結果發(fā)表在9月29日出版的美國《科學》雜志上,。中國科學院武漢病毒研究所石正麗研究員和動物研究所張樹義研究員等科學家組成的聯(lián)合研究小組在研究中關注到，蝙蝠近年來已被證實是一些重要動物源傳染病病毒病原(既可以感染人又可以感染動物)的自然宿主,，而這些被病毒感染的蝙蝠基本不出現(xiàn)臨床癥狀,。因此，聯(lián)合研究小組將SARS病毒溯源集中在蝙蝠身上,。
從2004年3月開始,，聯(lián)合研究小組在廣西、廣東,、湖北和天津四個地區(qū)采集3個科6個屬9個種共408只蝙蝠的血清,、咽拭子和肛拭子樣本。在武漢的病毒學國家重點實驗室和澳大利亞Geelong的動物健康研究室(AAHL)同時對這些樣本進行了SARS病毒抗體和基因的檢測,，結果在菊頭蝠屬的4個種里發(fā)現(xiàn)SARS病毒抗體和基因,，其中大耳菊頭蝠顯示70%以上的抗體陽性率,。基因序列分析表明,，蝙蝠類SARS病毒與人SARS病毒基因組序列同源性達92%,。但是二者之間的差異對于蝙蝠類SARS病毒是否能夠跨物種傳播起關鍵作用，也就是說,，目前科學家在蝙蝠體內檢測到的類SARS病毒還不會直接感染人類,。
在研究中，科學家們在采樣過程中嚴格遵循國際保護動物的準則,，盡量減少對蝙蝠的傷害?？茖W家們指出：包括蝙蝠在內的野生動物攜帶各種病毒是自然進化的結果,，是正常現(xiàn)象,。包括菊頭蝠在內的食蟲蝙蝠是很多農,、林業(yè)害蟲的重要天敵，對維護生態(tài)系統(tǒng)平衡發(fā)揮著重要作用,。我國很多地區(qū)的蟲災泛濫與蝙蝠數量急劇下降密切相關,。我們切不可因為此項研究結果的公布而對蝙蝠開殺戒。蝙蝠數量少了,，蚊子攜帶的登革熱等流行病暴發(fā)的可能性便會大大增加,。
9月27日在美國國家科學院院報(PNAS)上也發(fā)表了香港科學家類似的研究結果。
該項研究成果獲得了國家科技部和歐盟等項目的資助,。參加研究的單位有中國科學院武漢病毒研究所,、中國科學院動物研究所、澳大利亞科工委組織(CSIRO)的動物健康研究室(AAHL),、澳大利亞昆士蘭主要工業(yè)和漁業(yè)部,、美國保護醫(yī)學中心和中國科學院廣州生物醫(yī)藥與健康研究院。
中國,、澳大利亞和美國科學家通過對野生蝙蝠的廣泛調查表明,，野生蝙蝠可能才是非典病毒的源頭宿主，而先前廣受懷疑的果子貍不過是將病毒從野外傳染到人類身上的中間宿主,。
香港大學袁國勇教授等人在中國香港特別行政區(qū)的野外調查中發(fā)現(xiàn),，當地的野生魯氏菊頭蝠身上帶有一種非常像果子貍非典病毒的冠狀病毒，并將其命名為“蝙蝠非典病毒”,，并懷疑野生蝙蝠才是非典病毒的源頭宿主,。中國科學院動物研究所李文東等與澳大利亞、美國科學家合作的最新研究成果,，為上述猜測提供了更多支持,。他們的論文將發(fā)表在３０日出版的新一期《科學》雜志網絡版上,。
研究人員在中國廣東、廣西,、湖北和天津地區(qū),，捕捉了４０８只野生蝙蝠，涵蓋了蝙蝠的３個科,、６個屬,、９個種。他們采集了蝙蝠的血樣,、糞便,、咽喉分泌物,，并分別在武漢和澳大利亞吉朗的病毒實驗室用不同方法檢驗,。結果發(fā)現(xiàn)，其中采集自廣西和湖北的３個種的菊頭蝠攜帶“類非典冠狀病毒”,。
蝙蝠是“漢塔”病毒,、“尼帕”病毒等引起人畜傳染病的病毒的野生宿主，它們能攜帶多種病毒而不顯示任何癥狀,，而且一些地區(qū)的人們把蝙蝠當作野味或藥材在市場上銷售，增加了蝙蝠與人類接觸的機會。
李文東等發(fā)現(xiàn),，“類非典冠狀病毒”基因與非典冠狀病毒平均有９２％的相似度,，因此非典冠狀病毒是屬于“類非典冠狀病毒”這一大類的，可以統(tǒng)稱為“冠狀病毒非典群”,。而香港大學科學家發(fā)現(xiàn)的“蝙蝠非典病毒”，與它們的差異相對大一些,，反而是這一群病毒的“親戚”,。
中國、澳大利亞和美國科學家最新的研究表明,，野生蝙蝠可能是非典病毒的源頭宿主,，而先前廣受懷疑的果子貍不過是將病毒從野外傳染到人類身上的中間宿主。
研究人員在中國廣東,、廣西、湖北和天津地區(qū),，捕捉了４０８只野生蝙蝠，并采集了蝙蝠的血樣,、糞便,、咽喉分泌物，并分別在武漢和澳大利亞吉朗的病毒實驗室用不同方法檢驗,。結果發(fā)現(xiàn),，其中采集自廣西和湖北的蝙蝠攜帶“類非典冠狀病毒”,這種“類非典冠狀病毒”基因與非典冠狀病毒平均有９２％的相似度。
一項新的研究表明,，一種名為蹄鼻蝠的蝙蝠可能是導致薩斯(SARS)的罪魁禍首,。
研究人員在中國三個地區(qū)生活的蝙蝠身上發(fā)現(xiàn)了，與薩斯冠狀病毒極為相似的病毒,。
研究人員在《科學》雜志上發(fā)表的文章中指出,，這些病毒在通過蹄鼻蝠最終感染人類之前，很有可能先被傳染給了果子貍,。
有關專家建議,，在病毒傳播途徑尚未了解清楚之前，應暫時禁止蹄鼻蝠在市場上的流通,。
誰是真兇,？
2003年5月曾有跡象表明，人們可能是由于食用了果子貍肉才感染了薩斯,。于是,，中國政府下令屠殺了近10,000只果子貍,。
然而，一些科學家們卻認為果子貍并不是薩斯的元兇,，因為果子貍對薩斯病毒的抵抗力極弱,。
倘若果子貍真是病毒的源頭，那么它的身體應該已在某種程度上適應了病毒,，并具備更強的抵抗力,。
另一種理論則認為，鳥類是薩斯病毒的元兇,。但香港大學的研究人員本月在蝙蝠的身上發(fā)現(xiàn)了一種與薩斯病毒極其相似的病毒,。
揭開謎團
目前，中國,、澳大利亞和美國的科學家正在攜手合作,，力圖確認并搞清在蝙蝠身發(fā)現(xiàn)的薩斯疑似病毒。
相關的基因分析專家指出,，在蝙蝠身上發(fā)現(xiàn)的病毒,，和在果子貍以及在人身上發(fā)現(xiàn)的病毒是有密切聯(lián)系的。
專家們還說,，可以確定的是,，蝙蝠身上的這種病毒是不會直接感染人類的。
所以,，最大的問題就是弄清,，病毒究竟是如何從蝙蝠傳染給人類的？但專家們目前還尚未找到答案,。
Two Teams Identify Chinese Bat as SARS Virus Hiding Place
By LAWRENCE K. ALTMAN（The New York Times）
The SARS virus, which has killed 774 people worldwide, has long been known to come from an animal. Now two scientific teams have independently identified the Chinese horseshoe bat as that animal and as a hiding place for the virus in nature.
The bats apparently are healthy carriers of SARS, which caused severe economic losses, particularly in Asia, as it spread to Canada and other countries. In Asia, many people eat bats or use bat feces in traditional medicine for asthma, kidney ailments and general malaise.
The Chinese horseshoe bat does not exist in the United States.
The finding is important in preventing outbreaks of SARS and similar viruses carried by bats because it provides an opportunity for scientists to break the transmission chain.
One team from China, Australia and the United States reported its findings yesterday in the online version of Science. The other team, from the University of Hong Kong, reported its findings on Tuesday in The Proceedings of the National Academy of Sciences.
"It's pretty pleasant to see two teams that did not know each other reach similar findings," Dr. Lin-Fa Wang, a virologist at the Australian Animal Health Laboratory, said in a telephone interview. After collecting hundreds of bats from the wild and from Chinese markets, each team reported identifying different viruses from the coronavirus family that are very closely related to the SARS virus.
SARS, or sudden acute respiratory syndrome, first appeared in China in 2002. It spread widely in early 2003 to infect at least 8,098 people in 26 countries, according to the World Health Organization. The disease died out later in 2003, and no cases have been reported since.
SARS now appears to join a number of other infectious agents that bats can transmit. Over the last decade, bats have been found as the source of two newly discovered human infections caused by the Nipah and Hendra viruses that can produce encephalitis and respiratory disease. In the SARS outbreak, attention focused on the role of Himalayan palm civets in transmitting it after scientists identified the virus in this species and in a raccoon dog sold in markets in Guangdong. But W.H.O. officials and scientists elsewhere cautioned that these species were most likely only intermediaries in the transmission, largely because no widespread infection could be found in wild or farmed civets. So, the teams assembled a variety of specialists, including veterinarians, zoologists, virologists and ecologists.
Dr. Wang said his group focused on bats largely because of the team members' earlier pioneering work on the Hendra and Nipah viruses. One member, Dr. Jonathan H. Epstein, a veterinary epidemiologist at the Consortium for Conservation Medicine in Manhattan, led the scientists in gathering bats from the wild and market places.
After obtaining fecal and blood samples, the scientists released the bats into the wild or returned them to the markets. The specimens were tested for a variety of viruses that infect animals.
Laboratory analysis of the coronaviruses' makeup provided strong genetic evidence of the close relationship between those found in the bats and the SARS virus.
Although it is logical to assume that the bat viruses infected the animals in the live markets to cause the outbreak, the studies were not planned to prove that point.
"The genetic relationships do not tell you anything mechanistically about if or how the virus moved from the bats to civets and from the civets to the humans," said Dr. Donald S. Burke, a virologist and professor at Johns Hopkins. "It's not a perfect story yet. But until I see otherwise, the working assumption will be that this is the reservoir species."
Dr. Wang said that "there is no rule" to establish proof that a certain species is the reservoir, or hiding place, of a virus, but that scientists make the judgment based on criteria like how widely the infectious agent is distributed in a species, the absence of symptoms among the animals and finding high levels of antibody but low amounts of virus in the animal.
The Chinese horseshoe bat fits those criteria and the civets do not, Dr. Wang said. The bat feeds on moths and other insects and generally does not bite animals. It was highly unlikely that insects transmitted the SARS viruses to bats, because the viruses do not grow in insect cells in the laboratory, Dr. Wang said.
Most civets that are sold in China as a delicacy are farmed, Dr. Wang said, and the government should ensure civet farms are distant from bat colonies, monitor farmed civets for SARS-like viruses and allow just noninfected animals to go to market.
Bats found to carry SARS-related virus : study
Agence France Presse
Bats have been found to be natural hosts of so-called coronaviruses closely related to those responsible for deadly outbreaks of SARS among humans, according to a study published this week.
Severe Acute Respiratory Syndrome (SARS) triggered a global health crisis after emerging in China's southern Guangdong province in November 2002, causing nearly 800 deaths worldwide, including 349 in China.
Scientists are vying to unravel the origins of its etiological agent, the SARS coronavirus (SARS-CoV), which sparks the full-blown SARS virus.
A team of international researchers work have found that bats are a natural host of these coronaviruses. Their findings were published in the journal Science on Wednesday.
The researchers hope the finding will give them new insights into SARS and its potentially lethal origins.
The viruses, termed SARS-like coronaviruses (SL-CoV), display greater genetic variations than SARS-CoV isolated from humans or some carnivorous mammals, according to the team's findings.
The team includes researchers in China, Australia and the United States.
The human and mammal isolates of SARS-CoV "nestle phylogenetically within the spectrum of SL-CoVs," suggesting that the virus responsible for the SARS outbreak was a member of the coronavirus group, the study said.
"Without knowledge of the reservoir host distribution and transmission routes of SARS-CoV, it will be difficult to prevent and control future outbreaks of SARS," the study's authors noted.
They said that bats "may be persistently infected with many viruses but rarely display clinical symptoms."
The researchers said such characteristics and the increasing presence of bats and bat products in food and traditional medicine markets in southern China and elsewhere in Asia led them to focus on bats the search for the origin of the SARS virus.
The study was conducted between March and December 2004, and involved 408 bats of nine different species.
Researchers from the Institute of Zoology of Chinese Academy of Sciences in Beijing, China, the Australian Animal Health Laboratory in Geelong, Australia, and The Consortium for Conservation Medicine in New York, among other centers, supported the research.
SARS probably originated in bats
By Anna Salleh for ABC Science Online
Bats are highly likely to be the original source of the deadly severe acute respiratory syndrome (SARS), scientists say.
An international team of scientists report evidence of a SARS-like virus in wild Chinese horseshoe bats in today's issue of the journal Science.
The findings into the origins of the virus that causes SARS support those in a recent issue of the Proceedings of the National Academy of Sciences.
"We're looking here at two independent observations," said the Australian co-author of the Science paper, Dr Bryan Eaton.
"There's a high likelihood that the origin of SARS coronavirus is this particular genus of bats."
Last year, researchers found that although civet cats in Chinese markets were infected with the SARS virus, animals bred on farms were free of antibodies to the virus.
"So the source was somewhere else," Dr Eaton, a virologist with CSIRO's Australian Animal Health Laboratory (AAHL) in Geelong, Victoria, which was also involved in the cat research, said.
Bats prime suspects
Dr Eaton says bats were a prime suspect as the virus host because they can carry a large number of viruses and not become ill.
"Some 40 different viruses have been isolated from bats ever since rabies in 1934," he said, noting the association of bats with Hendra virus and lyssavirus in Australia, and Nipah virus in Malaysia.
Bats are used for medicinal purposes in China.
For the research published in Science, researchers at the Chinese Academy of Sciences' Wuhan Institute of Virology trapped a large number of species of bats from caves and tested their serum.
They found that antibodies in three species of horseshoe bats cross-reacted with the SARS virus.
But the bat antibodies could not kill the SARS virus, which suggests the animals had actually formed in response to a SARS-like virus.
Bat poo clues
The researchers then examined the bat faeces. Here they found fragments of viral DNA they stitched together to form a complete sequence of a virus that was 90 per cent genetically similar to SARS.
"These bats were infected with a virus that was closely related to SARS," Dr Eaton said.
"It's close enough for us to be very highly suspicious that [the bats were] the source of the SARS virus."
This bat virus differed genetically from the human SARS virus in the area of the virus responsible for binding to human cells.
The researchers also found fragments of several other viruses that all differed only slightly from human SARS.
"There is a whole family of SARS-like viruses and they're all subtly different," Dr Eaton said.
He says the human SARS virus sits in the middle of this family in terms of its genetic make-up.
And a recombination of DNA from such viruses could easily have led to the virus that binds to human cells.
The three species of horseshoe bats identified by the Science researchers as carrying SARS-like viruses are Rhinolophus pearsoni from Guangxi and R. macrotis and R. ferrumequinum from Hubei.
The PNAS study carried out by Hong Kong researchers found a SARS-like virus in another species, R. sinicus.
SARS came from bats, say researchers
Friday Sep 30 08:40 AEST AAP
Australian researchers have helped identify bats as the likely source of the SARS epidemic that killed hundreds of people around the world.
A collaborative research project involving scientists in Australia, China and the United States has found that bats are highly likely to be the natural host of the virus responsible for Severe Acute Respiratory Syndrome.
SARS emerged in China's southern province of Guangdong in 2002. It spread across the world, killing 774 people and infecting another 8,000 by July 2003.
Initial studies indicated that the civet, a cat-sized mammal found in Asia, was probably the natural host of the previously unrecorded coronavirus.
But SARS research team leader Linfa Wang, from the CSIRO Livestock Industries' Australian Animal Health Laboratory in Geelong, said further research showed no widespread infection in wild or farmed civets.
"Bats are known reservoir hosts of an increasing number of zoonotic viruses but they rarely display clinical signs of infection," he said.
"It was these characteristics and the fact that bats are present in Asian food markets that led us to survey them."
Zoonotic viruses are those capable of infecting both animals and people.
The research, for which scientists sampled more than 400 bats from four areas of China, has been published in the journal Science.
The team collected blood, faecal and respiratory swabs which were analysed at the Geelong laboratories and the Chinese Academy of Sciences' Wuhan Institute of Virology.
More than 70 per cent of types of horseshoe bats sampled from China had SARS coronavirus antibodies in their blood.
Genetic analysis of the faecal samples supported the findings.
"The viruses detected from bats show greater genetic variation than those SARS coronaviruses which cause disease in humans and other animals," Dr Wang said.
"This variation suggest it's highly likely that the 2002-03 SARS outbreak originated from bats."
Research team member Hume Field, from the Queensland Department of Primary Industries, said discovering how the virus jumps from bats to other animals and humans will be the next step.
"This is crucial if we are to manage the risk of future outbreaks," Dr Field said.
Another research team, including scientists from the University of Hong Kong, published similar findings in the Proceedings of the National Academy of Sciences earlier this week.
