The ramifications of the emerging coronavirus epidemic have been felt all across the world. While this virus (known as SARS-CoV-2) is one of several coronaviruses known to cause disease in humans, it is one of the few found to produce disastrous effects. As there have been three coronavirus outbreaks in the past decade, understanding where they originate from is imperative so that better preventative and diagnostic measures can be taken.
SARS-CoV-2 is believed to be a zoonotic viral disease, meaning that it originated in an animal host and at some point was transferred to infect and spread in humans. There are two possible methods the virus could have evolved to target human cells: it either developed random mutations before entering a human host or it adapted after entering a human host. Addressing rumors of potential viral tampering and genetic manipulation, there appears to be no evidence that indicates this was a viable origin for SARS-CoV-2.
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Pangolins are commonly trafficked for their ivory and are under suspicion for being the original host for the virus that started the COVID-19 pandemic.
Image Source: GP232
Many of the earlier confirmed COVID-19 cases were located at a meat market in Wuhan, China, where scientists believe the original zoonotic transfer occurred. Most likely, SARS-CoV-2 originated in bats, similar to their SARS predecessor. In order to test this, researchers analyzed the genome of a coronavirus found in bats and compared it to SARS-CoV-2. This bat coronavirus (called RaTG13) was found to be 96% similar to SARS-CoV-2; however, SARS-CoV-2 had one region in its genome that was unique and not found in the bat coronavirus. Even though a large majority of their genetic code is the same, if RaTG13 is indeed the animal coronavirus origin, it is unlikely that SARS-CoV-2 is a direct descendent of it.
There have also been reports of a pangolin coronavirus that could potentially be an origin for SARS-CoV-2, which many suspect due to the large number of pangolins being trafficked in Asia. From doing a genomic analysis of the pangolin coronavirus, scientists found that it was less similar to the human coronavirus compared to the bat coronavirus. However, the pangolin virus did show similarity in the region that allows SARS-CoV-2 to infect humans. Still, this evidence isn’t entirely indicative of a relationship between the two viruses, and there is far more work to be done to identify the exact origins of the virus. If an evolutionary map of SARS-CoV-2 development eventually becomes available, scientists could build better models and more accurately predict future pandemics. By discovering the origins of this coronavirus pandemic, we can also identify geographic regions of risk and subsequently take steps to mitigate those risks.
Featured Image Source: Romolo Tavani
