The outbreak was caused by at least two different strains of 2019-nCoV.
Scientists from China and Canada analyzed the evolution of the 2019-nCoV virus, which gave rise to an outbreak of pneumonia in China and several other countries, and concluded that it was caused not by one, but two strains of this pathogen write the website bioRxiv.
“It probably started a few months before it was known and officially reported by health authorities,” the researchers said.
The scientists came to this conclusion by studying sets of small mutations in two dozen complete genomes of the 2019-nCoV virus, whose samples were extracted from the blood of patients in hospitals in Wuhan and other cities of China.
Geneticists compared these data and compared them with similar RNA fragments in other coronaviruses, including SARS pneumonia and Middle Eastern MERS fever. This allowed the researchers to reconstruct the tree of evolution of the virus 2019-nCoV and understand when the common ancestor of all existing strains of this pathogen appeared today.
Scientists have made two unexpected discoveries. First, it turned out that the virus did not originate in early or mid-December, but much earlier – about three months or even six months before.
Second, biologists have found a unique set of mutations in the RNA of one of the 2019-nCoV samples collected in Wuhan. This clearly indicates that this outbreak of viral pneumonia had at least two ancestors.
So far, the researchers note, it’s unclear whether this separation occurred before the virus began to infect humans or after the outbreak of pneumonia in Wuhan.
The very existence of two different versions of this pathogen, they say, calls into question the theory that the market for exotic food in this city was the only source of the virus.
As reported, the hypothesis that the original source of coronavirus 2019-nCoV was a wholesale seafood market in Wuhan in China, may not be quite true.