A plethora of information has been spread throughout the world in an attempt to keep people informed during the coronavirus pandemic. The conspiracy theory that coronavirus was created in a laboratory has caused speculations that it might be true despite scientists claiming that it came from animals.
A vast majority of the scientists who have studied the virus agree that the virus evolved naturally and crossed from an animal, most likely a bat, into humans.
But how exactly do they know that the SARS-CoV-2 virus has a zoonotic animal original and does not come from a laboratory? According to the scientists, the answer lies in the genetic material and evolutionary history of the virus, as well as the ecology of the bats.
Zoonotic animal origin of SARS-CoV-2
Approximately 60% of the known infectious diseases and 75% of the new emerging or re-emerging diseases infecting humans came from animals. SARS-CoV-2 is the latest addition to the seven coronaviruses found in humans, and experts said that all of these viruses either came from bats, mice, or domestic animals.
More so, bats are the source of the Ebola virus, rabies, Nipah ad Hendra virus infections, Marburg virus disease, and influenza A virus.
The whole world probably knows the genetic makeup or "genome" of SARS-CoV-2 as it was repeatedly shared with the public. If the virus had ever been engineered in the lab, there would be signs that it was manipulated.
Science Alert reports that evidence of an existing viral sequence as the backbone for the new virus would have been used to be engineered in a laboratory. Moreover, there would also be an obvious, targeted inserted or deleted genetic elements to the virus.
However, no such evidence exists in the novel coronavirus' genome. It is very unlikely that it would not leave a genetic signature like identifiable pieces of DNA code.
Scientists found that the genome of SARS-CoV-2 is the same as the coronavirus found in bats and pangolins. Differences in these genomes show that it results from natural coronavirus evolution, which suggests that it came from a previous wild coronavirus.
The SARS-CoV-2 virus differs from other coronaviruses because its spike protein binds well with another protein on the ACE2 of human cells, enabling them to hook onto it and infect a variety of human cells.
Coronavirus from bats are constantly evolving to evade the bat immune system, and so bats too evolve to withstand the infections caused by a coronavirus.
Recombination of coronavirus genome
The recombination of specific coronavirus genomes in nature is one of the mechanisms that brought the novel coronavirus. New evidence was found that this process could have been involved in the generation of SARS-CoV-2.
SARS-CoV-2 appears to have involved in two strains since the pandemic began. This could have occurred because of the selective sweep, a mechanism wherein beneficial mutations help a virus infect more hosts, so it becomes more common in the viral population.
This mechanism is a natural process that reduces the genetic variation between individual viral genomes. A similar mechanism would account for the lack of diversity observed in earlier SARS-CoV-2 genomes that have been sequenced.
That indicates that its ancestors may have circulated in the bat populations for some time, which would have acquired mutations that allowed to spill from bats into other animals and then to humans.