Wuhan and Shanghai - The genome analyzes of the first novel coronaviruses detected in China (2019-nCoV) confirm the relationship with coronaviruses that were previously detected in bats. According to two reports in Nature (2010; doi: and), 2019-nCoV can infect humans thanks to change in the receptor binding site that has approximated the SARS-CoV.
2019-nCoV became first detected in 41-year-old man who was employed in shop at the seafood market in Wuhan. Live animals were sold in the market, not in the shop where the man worked. These included hedgehogs, badgers, snakes and lovebirds, but no bats.
The man was admitted to the Wuhan Central Hospital 6 days after the onset of symptoms (fever, chest pain, unproductive cough and general complaints) on December 26th. Bilateral pneumonia was diagnosed there. When this continued to deteriorate despite treatment with antibiotics and the flu drug oseltamivir and all tests for known pathogens were negative, samples were sent to laboratory of biological protection level (BSL) 3 in Shanghai.
Test detected the genes of coronaviruses. After the test was positive, the entire genome of "WH-Human 1 coronavirus" was sequenced, which is now generally referred to as 2019-nCoV.
The 29,903 nucleotides were compared with the sequences of known coronaviruses. According to the data presented by team led by Yong-Zhen Zhang from China CDC in Beijing, the greatest agreement was with the coronavirus "bat-SL-CoVZC45" or ZC45 for short.
The agreement was 89.1%. ZC45 is common in bats, but it is not infectious to humans. Therefore, there had to be differences between 2019-nCoV and ZC45, which enables 2019-nCoV to infect number of people that is now growing every day.
It was obvious that these differences in the genes for the spike proteins to look for with which the virus binds to the cells. The researchers found great deal of agreement with the SARS-CoV in the receptor binding site.
Further investigations showed that the 3D structure of the binding sites of the two viruses is largely identical. This means that 2019-nCoV uses the same entry gate as the SARS-CoV. It is the ACE2 protein that is present on the epithelial cells of the human respiratory tract.
The Researchers initially suspected that the bat virus obtained the binding site of the SARS pathogen through an exchange of genes (recombination).This would be possible with the simultaneous infection of cell with the two viruses, which could possibly have occurred in the as yet unidentified intermediate host, which may have been traded on the market in Wuhan. However, the analysis with computer program that can recognize recombinations turned out to be negative. How 2019-nCoV acquired the binding properties of SARC-CoV is therefore still unknown.
In the second publication, team led by Zheng-Li Shi from the Institute of Virology in Wuhan reports on the viruses that it found in 7 early patients, 6 of whom were employed in the seafood market. The researchers found the greatest agreement with “BatCoV RaTG13” or TG13, which had previously been detected in the bat species Rhinolophus affinis.
The sequences were 96.2% in agreement. The virologists from Wuhan also found differences in the spikes protein, where the receptor binding site more closely matched the SARS-CoV. The virologists also found that 2019-nCoV binds to the ACE2 of horseshoe bat (a species of bat), but also to the ACE2 of civets and pigs.
The latter two animals are also sold in markets , would therefore be considered as intermediate hosts. However, there is currently no confirmation of this assumption. "Civets" are considered to be the intermediate hosts of SARS-CoV in the epidemic of 2002/03.
The virologists have developed an antibody test with which the immune response to the infection can be observed. IgM antibodies were already detectable in the first sample, which was taken 7 days after the symptoms began. The titer rose up to the 9th day and then fell again, as usually happens with virus infections.
On the 9th day, IgG antibodies were already detectable, which were then strong on further examination 18 days after the onset of symptoms had increased. At this point there were hardly any viruses in the oral mucosa, anal swab and in the blood. This shows that the immune system reacts to the virus and quickly gets the infection under control - if the patient survives the critical phase of the disease.