While research is currently working on the development of a vaccine against SARS-CoV-2, it is also important to trace its origin. Recently, an international team announced that the virus has been circulating in bats for at least four decades.
In recent months, several debates took place regarding the SARS-CoV-2 coronavirus. Which animal transmitted it to humans? When did the epidemic really start? What about dubious theories that the coronavirus was made from the AIDS virus or that it escaped from the Wuhan Institute of Virology?
Science is now certain, the original carriers of the coronavirus are indeed bats. A study published in the journal Nature Microbiology on July 28, 2020 estimates that SARS-CoV-2 has been circulating between these animals for more than forty years ! Chinese, American, Belgian and British researchers have done meticulous work to reconstruct the evolutionary history of the virus.
Recall that coronaviruses have highly recombinant genetic material . In other words, several parts of their genome can come from different sources. In order to reconstruct the evolutionary history of SARS-CoV-2, scientists identified all of these regions that recombined. Next, they reconstructed the phylogenetic histories of the non-recombinant regions. After that, they made a comparison of these regions in order to identify which specific viruses were involved in these famous recombinations.
After these observations, the scientists concluded that the SARS-CoV-2 lineage differentiated itself from the others between forty and seventy years ago . The directors of the study confirm all the same that this coronavirus is close to 96% of RaTG13, identified in 2013 in the province of Yunnan (China). However, SARS-CoV-2 deviated from RaTG13 in 1969 ! In addition, the researchers made another discovery. One of the oldest common traits of SARS-CoV-2 and other members of its lineage is the ability to recognize and attach to receptors on the surface of human cells. This therefore suggests that other viruses have been circulating for a very long time in bats.
However, we are talking about viruses that can potentially infect humans. However, the question of an intermediary arises again. Since the beginning of the crisis, some have thought that the pangolin could be this intermediate host. However, there is currently no evidence that such an intermediate host is essential for the infection of humans by bats.
