On January 24, 2020, the French Ministry of Health announced three cases of the 2019-nCoV coronavirus in France. On January 29, a team of researchers from the Institut Pasteur successfully grew 2019-nCoV in cell culture and sequenced its whole genome after taking samples from the patients.
A cell layer with a visible cytopathic effect; the cells infected by the 2019-nCoV coronavirus were destroyed. Image credit: National Reference Center for Respiratory Viruses, Institut Pasteur.
“Sequencing the genome of pathogens is crucial for the development of specific diagnostic tests and the identification of potential treatment options,” said Dr. Sylvie van der Werf, director of the National Reference Center for Respiratory Viruses at the Institut Pasteur.
“On January 24, we received samples of three suspected cases: two patients in Paris and one in Bordeaux,” said Dr. Sylvie Behillil, deputy director of the National Reference Center for Respiratory Viruses at the Institut Pasteur.
“Using the samples taken from these patients, we detected the novel coronavirus.”
“We performed data analysis and then corroborated the results with counter analysis. The whole sequence was confirmed in just three days,” said Dr. Vincent Enouf, deputy director of the National Reference Center for Respiratory Viruses at the Institut Pasteur.
The sequences were identical in all three samples, according to the scientists.
“One member of the couple must have contaminated the other, as the virus is the same,” they said.
“Around twenty other sequences of the novel coronavirus genome have been obtained worldwide, and if we compare them with ours, we can see that they are all very close,” Dr. Enouf said.
“There is not much diversity in the viruses analyzed, which suggests that coronavirus 2019-nCoV did not need to mutate in order to adapt and spread.”
The whole genome sequence of the 2019-nCoV coronavirus isolated from a patient in France. Image credit: National Reference Center for Respiratory Viruses, Institut Pasteur.
The team also successfully grew 2019-nCoV in cell culture, which is necessary for further studies.
“On January 24, 2020, we began the process of culturing the samples that had tested positive for the virus,” they explained.
“Using detection methods, we had observed a high viral load in the samples taken from the patients in hospital in Paris.”
“This enabled us to identify which samples should be cultured first,” Dr. Behillil said.
“We didn’t think that it would grow so quickly,” she added.
“The rapid growth of the culture may be explained by the high viral load in the samples, but also by the quality of the samples,” Dr. Enouf said.
“We could see the cells becoming damaged and then grouping together, which can indicate that they have been infected.”
“But we did not observe this cytopathic effect for all the inoculated samples; that reassured us that we had managed to isolate the strains, and this was then confirmed by additional analyses.”
