According to Science Alert, there is evidence that SARS-CoV-2 is a combination of two different viruses. Bats and pangolins are thought to be not infectious hosts.
Over the past few weeks, scientists around the world have deciphered many facts about the Covid-19 disease and the virus that causes it, SARS-CoV-2.
While there are many rumors and validated scientific reports, there is still much to be known about this disease. In particular, the question of which animals have transmitted SARS-CoV-2 virus to humans? A bat, a pangolin or another animal? Where does this disease come from? From the forest market in Hubei or from a cave?
These questions are still challenging scientists because no evidence has been accepted yet.
According to Science Alert, there is evidence that SARS-CoV-2 is a combination of two different viruses. Bats and pangolins are thought to be not infectious hosts. However, the animal that actually carried the Covid-19 pathogen has yet to be discovered.
In December 2019, 27 of the first 41 people infected with Covid-19 said they had passed through the central market in Wuhan City, Hubei Province, China. But according to a study done at Wuhan Hospital, the first person with Covid-19 did not often go to this market.
Instead, an evolutionary event age estimate based on the SARS-CoV-2 genome indicates that the virus dates back to November 2019. This raises the question that Covid-19 virus is related to wildlife.
The SARS-CoV-2 genome data was quickly decoded by Chinese researchers.
It is an RNA molecule consisting of about 30,000 base pairs containing 15 genes, including the S gene that encodes a protein located on the surface of the virus envelope.
Gene analyzes indicate that SARS-CoV-2 belongs to the Betacoronaviruses group. It is very close to SARS-CoV, the virus that caused the acute pneumonia epidemic in November 2002 in Guangdong province, China and then spread to 29 countries in 2003.
In the past, the SARS pandemic had infected 8,098 people, including 774 deaths. The bat of the genus Rhinolophus is the parasitic unit of this virus. Besides, civets, a small carnivore is said to be the first to spread the disease to humans.
Since then, many types of Betacoronavirus have been detected, mainly in bats and others in humans.
Including RaTG13, a variant virus from a bat of the species Rhinolophus affinis in China’s Yunnan province. Recently, scientists realized that the virus on this animal has a sequence of genome codes that is 96% similar to SARS-CoV-2.
Thus, these findings indicate that the bat species of the genus Rhinolophus have become host hosts for SARS-CoV and SARS-CoV-2 viruses.
On February 7, scientists discovered that SARS-CoV-2 was even more closely related to the virus on pangolin than the species in previous studies. Their genomes are 99% similar. This suggests that pangolin may be the more ideal host for infection than bats. However, a new study shows that the genome of the corona virus isolated from Malaysian pangolin is only 90% similar to SARS-CoV-2. Thus, virus isolation on pangolin is not the cause of Covid-19.
However, the corona virus isolated from pangolin is 99% similar to the S protein region that allows direct transmission to humans. In contrast, the RaTG13 virus isolated from bats is not likely to infect humans.
In addition, comparisons of this genome indicate that SARS-Cov-2 virus is the result of a recombination of two different viruses, one close to RaTG13 and the other close to the virus on pangolin.
In other words, SARS-CoV-2 is a combination of two viruses found in bats and pangolin.
It is important now to find out that a new host species capable of carrying the SARS-CoV-2 virus is a combination of the two. And above all, scientists need to know the environment that promotes the combination that creates the Covid-19 virus.