Scrap bats. It may not have been the flying mammals, after all, that incubated the deadly new coronavirus that has already infected tens of thousands of people and caused hundreds of deaths in China and even outside the country.
A team of Chinese scientists say it seems possible that pangolins were the original source of the new coronavirus based on a genetic analysis of the virus.
Scientists have long suspected that the as yet little-understood virus, dubbed nCoV-2019, has leapt to people from a mammalian host. Bats have been highlighted as a likely candidate. The coronavirus that caused severe acute respiratory syndrome (SARS) during a similar outbreak in 2002-2003 spread from bats to humans via civet cats as an intermediary.
However, scientists at the South China Agricultural University have now found that the genome sequence of a virus in pangolins is 99% identical to that of the new human coronavirus nCoV-2019.
They have reached this conclusion after testing more than 1,000 metagenome samples taken from wild animals by isolating the virus and observing its structure under electron microscopes. Coronaviruses that live in pangolins use receptors with similar molecular structures to infect cells, which makes it likely that the scaly anteaters were the intermediaries for the new virus.
“This is an extremely interesting observation,” says Edward Holmes, an evolutionary virologist at the University of Sydney. “Although we need to see more details, it does make sense as there are now some other data emerging that pangolins carry viruses that are closely related to 2019-nCoV.”
Other scientists, however, have cast doubt on the findings. “The evidence for the potential involvement of pangolins in the outbreak has not been published, other than by a university press release. This is not scientific evidence,” cautioned James Wood, head of veterinary medicine at the University of Cambridge. “Simply reporting detection of viral RNA with sequence similarity of more than 99% is not sufficient. Could these results have been caused by contamination from a highly infected environment?”
What isn’t in doubt, however, is that if pangolins were indeed the source of 2019-nCoV, the virus would certainly have had plenty of chance to make the interspecies transition to humans in China. The placid animals, which curl up into a defensive ball at the first sight of trouble, have long been highly sought for their scales, which are used as ingredients in Chinese medicine. Their meat, too, has been widely consumed in exotic dishes in countries like China and Vietnam.
Demand for pangolins, which have been around for 80 million years, has been so high that all eight subspecies of the animals are now critically endangered throughout their ranges in Asia and Africa. Over the past decade alone as many as 1 million of the slow-breeding animals have been seized from the wild, which has earned them the dubious distinction of the world’s “most trafficked mammals.” Unless remaining wild populations are protected, pangolins could well go extinct within a few short years.
In the wake of the latest viral outbreak, experts have called on China’s government to move decisively against the thriving illegal wildlife trade in the country. China remains the world’s largest market for a variety of poached animals, including pangolins. Demand is driven largely by atavistic beliefs in Traditional Chinese Medicine that falsely attribute magically curative properties to rare and exotic animals and their parts.
