Two novel coronaviruses that are closely related to SARS have been found in Chinese horseshoe bats. The results of research, published today in Nature, provide the strongest evidence to date that the viruses responsible for the 2002-2003 SARS pandemic and the on-going Middle East respiratory syndrome coronavirus may have originated in bats.
Our colleagues at the AusSMC collected the following expert commentary. Feel free to use these quotes in your reporting. If you would like to contact a New Zealand expert, please contact the SMC (04 499 5476; smc@sciencemediacentre.co.nz).
Gary Crameri is Stream Leader for Emerging Zoonotic Disease at CSIRO’s Australian Animal Health Laboratory and an author of this research. He comments:
“Our identification of these two new SARS-like coronaviruses from Chinese horseshoe bats is the key to resolving the continued speculation around bats as the origin of the SARS outbreaks. Unlike previously identified viruses, these two are identical to the SARS virus in the mechanism they use for infection and prove that SARS-like coronaviruses from bats have the potential to directly infect humans without the need for an intermediate host.
“Despite an enormous global effort by many groups this is the very first reported isolation of a bat coronavirus facilitating study of their mechanisms of infection. The work highlights the importance of pathogen discovery programs targeting high-risk wildlife groups in emerging disease hotspots as a strategy for pandemic preparedness.”
Associate Professor Sanjaya Senanayake, Associate Professor of Medicine at the Australian National University, comments:
“This study in Nature is important. It was already known that bats carried coronaviruses, the family from which SARS and MERS come. But to this point, no one had been able to find the SARS coronavirus in bats.
“The investigators here identified two viruses almost identical to SARS from these bats in Yunnan province. In addition, they were able to isolate a live virus which could directly invade human lung tissue using special receptors called ACE2. In other words, SARS-like viruses live in bats and can potentially directly infect humans. They don’t appear to need an intermediate host (like a civet cat) for the virus to mutate before becoming infectious to humans.
“While SARS cases in humans haven’t occurred for around 10 years, the MERS coronavirus is current and has made almost a hundred people sick and killed about 65% of them. The MERS virus has been isolated from a bat in a region of Saudi Arabia close to one of the cases. And of course, bats transmit a variety of serious infections to humans other than SARS or MERS.
“Of the forty or so new infections in humans discovered in the last forty years, most have come from animals. Now that animals, including bats, and humans live closer together as our population expands globally, the opportunity for direct transmission of these dangerous viruses becomes more and more of an issue. This increasingly intricate cohabitation becomes a long-term issue for pandemic planners e.g. policymakers, public health officials, vaccine developers and infectious diseases specialists. And while neither SARS or MERS have been found within Australia, the ease of global travel means that a case can easily enter here.”
Professor Charles Watson, John Curtin Distinguished Professor in the Faculty of Health Sciences at Curtin University, comments:
“The recent coronavirus outbreak in the Middle East (MERS) has reminded us that this family of viruses is still a potential cause of major human epidemics. The 2002 coronavirus pandemic, caused by the SARS coronavirus (SARS-CoV) was a serious public health threat, with over 8,000 cases worldwide. While the MERS (Middle East Respiratory Syndrome) outbreak has so far infected less than 200 individuals, it is clear that the coronavirus must be carefully watched.
“It was suspected, but never proven, that the SARS coronavirus originally came from bats, and a coronavirus almost identical to the MERS virus has been identified in bats in the Arabian Peninsula. It has been suggested that the bat MERS virus is transmitted to dromedary camels, and then secondarily passed on to humans in rural areas of Saudi Arabia.
“This extensive study of viruses in bats in China has shown that Chinese horseshoe bats are the natural reservoir of SARS-CoV. Because the bat virus had previously been shown to be unable to bind with a human entry receptor protein (ACEs), it had been assumed that the bat SARS-CoV could not be directly transmitted to humans. It was therefore supposed that SARS-CoV was first transmitted to civet cats, and secondarily passed on to humans. However, this new Chinese study shows that the horseshoe bat SARS-like coronavirus is capable of using human ACE2 as an entry receptor. This finding is important for the design of control strategies in future coronavirus outbreaks.”