There is no clarity on the natural origin of SARS CoV-2 as no intermediate host has been found yet that transmits it from bats to humans. On the other hand, there are circumstantial evidences to suggest a laboratory origin based on the fact that the gain of function research (that induces artificial mutations in the ویروس through repeated passaging of ویروس ها in human cell lines), was being carried out in the laboratory
COVID-19 disease caused by SARS CoV-2 ویروس has caused unprecedented damage to the entire سیاره not only economically but also has caused psychological impacts on people that will take a long time to recover. Since its outbreak in Wuhan in November/December 2019, a number of theories have been put forward regarding its origin. The most common one refers to the wet market in ووهان که در آن ویروس jumped species from bats to humans via an intermediate host, due to its zoonotic nature of transmission as was seen in SARS (bats to civets to humans) and MERS (bats to camels to humans) ویروس ها1,2. However, in the past year or so, there has been no clarity on the intermediate host for the SARS CoV2 ویروس. The other theory refers to the accidental leak of the virus from the Wuhan Institute of Virology (WIV) where the scientists were performing research on coronaviruses. In order to understand why the latter theory has gained significant popularity over the past year or so, one needs to dwell back into the events of the recent past, beginning 2011, to examine the nature of origin of such coronaviruses that could cause disease in humans.
در سال 2012، شش معدنچی که در یک معدن مس آلوده به خفاش در جنوب چین (استان یوننان) کار می کردند، به یک خفاش آلوده شدند. قرنطینه3, known as RaTG13. All of them developed symptoms exactly like COVID-19 symptoms and only three of them survived. The viral samples were taken from these miners and submitted to the Wuhan Institute of Virology, the only level 4 biosecurity lab in China that was studying bat ویروس های کرونا. Shi Zheng-Li and colleagues from the WIV have been researching on the SARS CoV ویروس ها از خفاش ها در تلاش برای درک بهتر منشاء این گونه ویروس ها4. پیش بینی می شود که WIV تحقیقات عملکردی را به دست آورد5, that involved serial passaging of these ویروس ها in vitro and in vivo in a bid to increase their pathogenicity, transmissibility, and antigenicity. This gain of function research is very different than genetically engineering the ویروس ها to be more deadly in terms of their disease-causing ability. The idea behind funding and performing gain of function research is to remain a step ahead of ویروس ها to understand their infectivity in humans so that we are better prepared as a human race should such eventuality arises.
Thus, it is likely that the virus SARS CoV-2 made an accidental escape when it appeared in late 2019 in the city of Wuhan, although there is no concrete evidence of the same. The closest relative of this ویروس was RaTG13 that was sampled from Yunnan miners. RaTG13 is not the backbone of SARS CoV-2 thereby refuting the theory that SARS-CoV-2 had been genetically engineered. However, the sampling of related SARS ویروس ها for performing research and subsequent gain of function research (leads to induced mutations) perhaps led to the development of SARS CoV-2. Gain of function does not involve genetic manipulation via genetic engineering. The genome sequencing of the new ویروس obtained from initial 5 patients that contracted COVID-19 showed that this virus was 79.6% identical to SARS virus6.
Initially, the scientific world thought that the SARS CoV-2 ویروس had jumped from animal species (bats) to an intermediate host and then to humans7 as was the case with SARS and MERS ویروس ها as mentioned above. However, the inability of finding an intermediate host for the past 18 months has led to the conspiracy theory8 که ویروس could have been accidentally leaked from the lab. It is also possible that the SARS CoV-2 ویروس came from the repository of ویروس ها already held in WIV9 عنوان ویروس was already well adapted to infect human cells. Had it been of a natural origin, it would have taken some time to cause the degree of transmissibility and lethality that it did.
It still remains uncertain as to whether SARS CoV-2 had a natural origin or was man-made (gain of function leading to artificially induced mutations) which accidentally escaped from the laboratory. There is no hard evidence to support either of the theories. However, based on the fact that we haven’t been able to find an intermediate host for zoonotic transmission of this ویروس coupled with the fact that the ویروس was well adapted already to cause infection in human cells to a great extent and the associated research at WIV in Wuhan where the ویروس originated, suggests that it is a product of gain of function research which escaped from the lab.
Further evidence and investigation are required to establish a conclusive evidence not only to understand the origin of SARS-CoV2 ویروس but also to ameliorate any such future accidents should they possibly arise in order to save mankind from the wrath of such viruses.
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منابع
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- راسموسن، آل در مورد منشا SARS-CoV-2. Nat Med شماره ۱۰۲۹، 9 (2021). https://doi.org/10.1038/s41591-020-01205-5.
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