AsianScientist (Feb. 25, 2020) – Scientists in China have sequenced the genome of the COVID-19 virus demonstrating that it is a completely new virus, albeit closely related to the coronavirus (CoV) responsible for severe acute respiratory syndrome (SARS). Their findings are published in the journal Chinese Medical Journal.
In early December 2019, people in the city of Wuhan in the Hubei province of China began falling sick after going to a local seafood market. They experienced symptoms like cough, fever, shortness of breath and complications related to acute respiratory distress syndrome. The immediate diagnosis was pneumonia, but the exact cause was unexplained.
In the present study, researchers led by Dr. Wang Jianwei at the Chinese Academy of Medical Sciences, Institute of Pathogen Biology, China, used next generation sequencing (NGS) to definitively identify the pathogen causing illness in Wuhan. They focused on five patients admitted to Jin Yin-tan Hospital in Wuhan, most of whom were workers in the Huanan Seafood Market in Wuhan.
The scientists first obtained bronchoalveolar lavage (BAL) fluid samples taken from the patients, isolated the DNA and RNA, then sequenced the genetic material. Most of the viral sequences belonged to the CoV family of viruses, which includes the SARS-CoV and the Middle East respiratory syndrome-related (MERS) CoV.
The researchers then constructed the whole genomic sequence of the new virus—now known as COVID-19—and found that its genome sequence is 79 percent similar to the SARS-CoV, about 51.8 percent similar to the MERS-CoV, and about 87.6-87.7 percent similar to other SARS-like CoVs from Chinese horseshoe bats (called ZC45 and ZXC21). These findings clearly suggest that the virus originated from bats.
This study paves the way for future studies to understand the virus and its sources better, said the researchers. Although four of the five patients from whom this virus was identified were associated with a seafood market in Wuhan, the exact origin of infection is unknown. The CoV could have been transmitted to humans through an intermediate carrier, such as in the case of SARS-CoV (palm civet meat) or MERS-CoV (camel).
“All human CoVs are zoonotic, and several human CoVs have originated from bats, including the SARS- and MERS-CoVs. Our study clearly shows the urgent need for regular monitoring of the transmission of bat-origin CoVs to humans,” Wang said.
“The emergence of this virus is a massive threat to public health, and therefore, it is of critical importance to understand the source of this virus and decide the next steps before we witness a larger scale outbreak,” he added.