As a coronavirus spreads in China and around the world, scientists are scrambling to find out exactly where it came from. Now, a new study provides more clues to the virus’ origins, and points to bats as the most likely hosts. To learn more about the virus’ origins, the researchers compared the 2019-nCoV genetic sequence with those in a library of viral sequences, and found that the most closely related viruses were two coronaviruses that originated in bats; both of those coronaviruses shared 88% of their genetic sequence with that of 2019-nCoV. (When compared with two other coronaviruses known to infect people — SARS and MERS — 2019-nCoV shared about 79% of its genetic sequence with SARS and 50% with MERS.)
Based on these results, the authors said the 2019-nCoV likely originated in bats. However, no bats were sold at the Huanan seafood market, which suggests that another yet-to-be-identified animal acted as a steppingstone of sorts to transmit the virus to humans.
Bat soup is reported to be an unusual but popular dish particularly in Wuhan, where the virus is understood to have originated at an open air fish market.
The new study was carried out jointly by the Chinese Academy of Sciences, the People’s Liberation Army and Institut Pasteur of Shanghai.
It revealed that the virus has a “strong binding affinity” to a human protein called ACE2.
The researchers said that this binding protein had a high resemblance to that of SARS – which killed almost 800 and infected 8,000 people worldwide in 2002-2003.
They also traced the evolution of the new strain of coronavirus in a government database and found that on the evolutionary tree, it belonged to Betacoronavirus.
The two shared about 70 to 80 per cent of genes, less than the similarity between pigs and humans.
Their findings suggest that the danger posed by the new strain of coronavirus, named 2019-nCoV, may have been underestimated in the research community.
During the past two decades, three zoonotic coronaviruses have been identified as the cause of large-scale disease outbreaks–Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), and Swine Acute Diarrhea Syndrome (SADS).
SARS and MERS emerged in 2003 and 2012, respectively, and caused a worldwide pandemic that claimed thousands of human lives, while SADS struck the swine industry in 2017. They have common characteristics, such as they are all highly pathogenic to humans or livestock, their agents originated from bats, and two of them originated in China. Thus, it is highly likely that future SARS- or MERS-like coronavirus outbreaks will originate from bats, and there is an increased probability that this will occur in China. Therefore, the investigation of bat coronaviruses becomes an urgent issue for the detection of early warning signs, which in turn minimizes the impact of such future outbreaks in China.
The purpose of the review is to summarize the current knowledge on viral diversity, reservoir hosts, and the geographical distributions of bat coronaviruses in China, and eventually we aim to predict virus hotspots and their cross-species transmission potential.
Fifteen years after the first highly pathogenic human coronavirus caused the severe acute respiratory syndrome coronavirus (SARS-CoV) outbreak, another severe acute diarrhea syndrome coronavirus (SADS-CoV) devastated livestock production by causing fatal diseases in pigs. Both outbreaks began in China and were caused by coronaviruses of bat origin . This increased the urgency to study bat coronaviruses in China to understand their potential of causing another virus outbreak.
In this review, we collected information from past epidemiology studies on bat coronaviruses in China, including the virus species identified, their host species, and their geographical distributions. We also discuss the future prospects of bat coronaviruses cross-species transmission and spread in China.