The identification and characterization of a novel coronavirus associated with the recent outbreak of respiratory illness in China, published online in Nature, reveals similarities with severe acute respiratory syndrome (SARS) coronaviruses. The analysis uncovers evidence that the coronavirus has an origin in bats, although the animal source of this outbreak has not been confirmed.
Coronaviruses have been a source of infectious disease epidemics in humans, such as SARS and Middle East respiratory syndrome (MERS). SARS-related coronaviruses are mainly found in mammals, such as bats, and are a potential threat to public health. As of December 2019, an outbreak of respiratory illness has been reported, originating in a seafood market in Wuhan, Hubei province, China. Symptoms include fever, shortness of breath and pneumonia. The outbreak has since spread to other regions of China and overseas, and at time of writing over 14,000 cases have been identified and more than 300 deaths have been reported.
Zheng-Li Shi and colleagues analysed samples from seven patients with severe pneumonia, six of whom were identified as workers from the seafood market in Wuhan, China, where the cases were first reported in December 2019. Full-length genome sequences obtained from five of these patients are found to be almost (over 99.9%) identical to each other, and share 79.5% sequence identity with SARS coronaviruses. Moreover, the researchers find that the virus sequence is 96% identical at the whole-genome level to a bat coronavirus, suggesting that bats are a probable source of this coronavirus.
The identification and sequencing of seven non-structural proteins also found in SARS coronaviruses demonstrates that this virus is a SARS-related coronavirus, which the authors provisionally name novel coronavirus 2019 (2019-nCoV). They determine that 2019-nCoV enters cells through the same route as SARS coronaviruses, via the ACE2 cell receptor. Antibodies isolated from patients infected with 2019-nCoV are shown to have the potential to neutralize the virus. A previously identified horse antibody against SARS-CoV also neutralizes the virus at a low serum dilution, but whether or not anti-SARS-CoV antibodies cross-react with 2019-nCoV needs to be confirmed using serum from humans who have convalesced from SARS-CoV infection.
The authors developed a test that can differentiate 2019-nCoV from all other human coronaviruses; they show that 2019-nCoV was detected in initial oral swab samples, but that subsequent samples (taken around 10 days later) did not have a positive viral result. This finding suggest that the most likely route of transmission is through the airways of individuals, although the authors note that other possible routes may be possible, and more patient data is needed to investigate the transmission routes further.
Sequence data that support the findings of this study have been deposited in GISAID with the accession no. EPI_ISL_402124 and EPI_ISL_402127-402130, and EPI_ISL_402131.
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