SARS CoV-2ウイルスは実験室で発生しましたか？

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 ウイルス through repeated passaging of ウイルス in human cell lines), was being carried out in the laboratory 

COVID-19 disease caused by SARS CoV-2 ウイルス has caused unprecedented damage to the entire 惑星 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 武漢 どこ ウイルス 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) ウイルス^1,2. However, in the past year or so, there has been no clarity on the intermediate host for the SARS CoV2 ウイルス. 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. 

2012年、中国南部（雲南省）のコウモリが蔓延している銅山で働くXNUMX人の鉱山労働者がコウモリに感染しました。 コロナウイルス³, 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 コロナウイルス. Shi Zheng-Li and colleagues from the WIV have been researching on the SARS CoV ウイルス そのようなコロナウイルスの起源をよりよく理解するための努力でコウモリから⁴。 WIVが機能獲得研究を実施したことが想定される⁵, that involved serial passaging of these ウイルス 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 ウイルス 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 ウイルス 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 ウイルス 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 ウイルス 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 ウイルス 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 ウイルス had jumped from animal species (bats) to an intermediate host and then to humans⁷ as was the case with SARS and MERS ウイルス as mentioned above. However, the inability of finding an intermediate host for the past 18 months has led to the conspiracy theory⁸ その ウイルス could have been accidentally leaked from the lab. It is also possible that the SARS CoV-2 ウイルス came from the repository of ウイルス already held in WIV⁹ として ウイルス 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 ウイルス coupled with the fact that the ウイルス was well adapted already to cause infection in human cells to a great extent and the associated research at WIV in Wuhan where the ウイルス 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 ウイルス 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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参考文献 

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