The virologist said the newly identified viruses represent a potential risk and monitoring their evolution and transmission is vital to prevent the next pandemic.
“Most viruses do not infect humans, while viruses that can infect humans may not necessarily cause diseases. But some of the pathogenic ones could cause serious illness,” he said.
“We analysed a wide range of viruses that we found in the three orders of animals, instead of focusing on one particular virus or one particular animal. It is a way to track if viruses would fuse to form a hybrid pathogenic one, Zhang said.
“A full picture of viruses in nature would help us understand their evolution and better equip us to make predictions of when and where an infectious disease will occur in the future.”
The field survey conducted from late 2016 to early 2017 did not identify viruses related to Sars-CoV-2, which causes Covid-19. But the team did discover 13 other coronaviruses in eight bat species, five rodent species and one species of shrew.
09:02
How Covid-19 could transform our cities of the future
How Covid-19 could transform our cities of the future
Her team evaluated the human spillover risk of 40 coronavirus species and rated half of them as “highly risky”. The study published in July was based on an analysis of viral traits, including population, genetic diversity, host species and any previous history of zoonosis – diseases that jump from animals to humans.
One day after the release, his laboratory at the Shanghai Public Health Clinical Centre was ordered to close, hindering further research.
The Fudan team, along with scientists from other regional CDCs, and Zhang’s long-time collaborator Edward Holmes, an evolutionary virologist at the University of Sydney, published their findings in the peer-reviewed journal Cell last month.
To better understand the diversity, ecology and evolution of viruses of the animals selected by the study, the scientists captured thousands of them in four locations in the central Chinese province of Hubei and Zhejiang province on the east coast.
How Chinese red tape stopped US scientists getting early virus access
How Chinese red tape stopped US scientists getting early virus access
The rodents and shrews were captured using baited cages in agricultural and forested areas, while bats were caught in mountain caves.
When asked how far the sample areas were from human settlements, Zhang replied “the question should be ‘how close were they?’”
“We found them in mountainous areas, as well as near agricultural areas where they were in closer proximity to humans,” he said.
We were stunned to find that one species in Hubei harboured at least 150 viruses, which is a very high risk
“The closer they are to humans and the more exposure people have, the more likely it is for viruses to jump to humans, or to domestic and wild animals, increasing the chance for them to be transmitted to humans. This is how infectious diseases spread.”
Samples from internal organs and animal faeces were analysed for virus sequencing. The researchers identified 669 viruses, nearly 80 per cent of which had never been sequenced.
06:38
Sars 2003: The first coronavirus to spark a Hong Kong public health crisis
Sars 2003: The first coronavirus to spark a Hong Kong public health crisis
Cross-species transmission events had likely occurred between mammals, the scientists concluded, with 138 viruses identified in more than two species of mammals.
Shrews carried the most viruses and were particularly prevalent in a species called the Smith’s shrew, according to the study.
“Shrews are a less studied group of mammals. We were stunned to find that one species in Hubei harboured at least 150 viruses, which is a very high risk,” Zhang said.
“They mainly feed on insects and other arthropods which carry a lot of viruses. Shrews play a role in transferring viruses from invertebrates to mammals, intensifying the threat to humans.”
Zhang said the goal is to develop an early warning mechanism for infectious diseases, much like weather forecasts.
Why culling bats won’t wipe out the deadly viruses they might carry
Why culling bats won’t wipe out the deadly viruses they might carry
“If we could predict when and where an infectious disease would occur, we would become proactive in prevention and control,” he said.
To accomplish that, scientists first need to understand how viruses behave in nature and then, through genetic sequencing and experiments, determine which ones could cause diseases in humans.
“We should not be slow to act, only looking for a pathogen after an infectious disease emerges.
“If we study viruses in advance, we would be able to identify the pathogen in the shortest possible time once a disease surfaces and assess its public health risks to minimise the threat to human health,” Zhang said.
