Chinese scientists are hunting for the next viral disease threat to humans before it emerges

In China, a group of virologists are conducting research to identify potential viral threats to humans before they emerge. They are focusing on animals such as bats, rodents, and shrews, which are known to be significant sources of human infectious diseases. The team has identified over 500 novel viruses in these animals, some of which are related to pathogens that cause diseases in humans or domestic animals. The lead author of the study, Zhang Yongzhen, who was also the first to share the genome sequence of the Covid-19 coronavirus with the world, emphasizes the importance of understanding these viruses to provide early warnings of future infectious diseases. He explains that while most viruses do not infect humans, those that can may not necessarily cause diseases. However, some pathogenic ones could lead to serious illness. The team's approach involves analyzing a wide range of viruses found in different animals, rather than focusing on a single virus or animal. This method allows them to track the potential fusion of viruses to form a hybrid pathogenic one. They believe that a comprehensive understanding of viruses in nature would equip us better to predict when and where an infectious disease might occur in the future. Despite their extensive field survey conducted from late 2016 to early 2017, the team did not identify viruses related to Sars-CoV-2, the virus that causes Covid-19. However, they did discover 13 other coronaviruses in various species of bats, rodents, and shrews. Another Chinese virologist, Shi Zhengli, also warns of the likelihood of future coronavirus outbreaks. Her team evaluated the human spillover risk of 40 coronavirus species and rated half of them as 'highly risky'. This assessment 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. Zhang and his research team were the first to share the genome sequence of the coronavirus that led to the Covid-19 pandemic with the rest of the world. This data was instrumental in helping researchers elsewhere identify infections, develop test kits, and design vaccines. However, his laboratory was ordered to close a day after the release of this information, hindering further research. Zhang is now an adjunct professor at Fudan University’s school of life sciences. His team, along with scientists from other regional CDCs, and his long-time collaborator Edward Holmes, an evolutionary virologist at the University of Sydney, published their findings in the peer-reviewed journal Cell. To better understand the diversity, ecology, and evolution of viruses in 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. The rodents and shrews were captured using baited cages in agricultural and forested areas, while bats were caught in mountain caves. The researchers identified 669 viruses, nearly 80 per cent of which had never been sequenced. They concluded that cross-species transmission events had likely occurred between mammals, 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. Zhang said the goal is to develop an early warning mechanism for infectious diseases, much like weather forecasts. 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. Researchers would then need to study the ecological and environmental factors that contribute to the spread of viruses across species to assess their risks. Zhang emphasizes the importance of proactive research, stating that 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 minimize the threat to human health.