Representational Image

The latest study conducted by the team of international scientistsrevealed that the novel coronavirus could have transmitted from animals to humans years before the first case was detected in Wuhan, China.

The novel coronavirus, officially named SARS-CoV-2, has spread across more than 200 countries and territories across the globe. The infection COVID-19 has already claimed more than 43,000 lives since its outbreak back in December 2019 in Wuhan. Ever since the outbreak was reported, researchers have been trying to decode the origin of the novel coronavirus strain.

Origin of novel coronavirus

Using a comparative analysis of genomic datacollected from various genetic studies of the coronavirusan international team of researchers propose two possible hypotheses about the origin of this deadly virus.

Among the origin hypothesis, one theory suggests that novel coronavirus may have crossed from the animal barrier to settle in humansbefore it evolved into an active strain and started to induce the disease. It is possible that a progenitor of SARS-CoV-2 jumped into humans, acquiring the genomic features through adaptation during undetected human-to-human transmission, says the paper.

Another, far scarier scenario is that it evolved into the current strain in an animal host before transmission to humans. In this scenario, there is the risk of future re-emergence similar outbreaks, the study highlights.

The correspondence was published in Nature Medicine. The researchers compared the genetic code of the novel coronavirus from its ancestral strains, found in bats and pangolin, to understand the evolutionary history of the virus. The researchers from different institutes in the United States, Britain and Australia, also explain the notable features of the SARS-CoV-2 genome in this paper.

A bat or a pangolin?

In December end, when the suspicious cases of pneumonia emerged in Wuhan, it was linked to the Huanan Market in the province, which indicated the presence of an animal source for the spread of the virus.

Soon, an unknown strain of the virus was isolated by the team of researchers from the Wuhan Institute of Virology. The origin of the strain was traced to a bat virus found close to the China-Myanmar border. However, the bat coronavirus and the novel coronavirus strains were only 96 percent similarnot sufficient to attribute as the definite source. The bat virus did not showcase the presence of spike proteinrequired for the virus to bind in human cells.

The study also highlights the presence of the SARS-CoV-2-related coronavirus in the illegally imported Malayan pangolins. Further, the analyses showcased the presence of spike protein required to optimise the virus for transmission in humans among the coronaviruses found in pangolins.

However, the present study reveals that the novel coronavirus found responsible for the current outbreak had a mutation in its genes at the polybasic cleavage site, which was not found in both coronaviruses identified in bats and pangolins.

Evolution of coronavirus by natural selection

Analysing the research so far, the scientists say that the novel coronavirus had acquired both the polybasic cleavage site and mutations in the spike protein suitable for binding to humans naturally. The question, however, remains whether this natural selection occurred in humans or animals.

The spike protein interacts with furin, a widely distributed enzyme in the human body. This interaction mediates the fusion of virus and human cell membranes, which triggers the symptoms and makes it contagious. Some of the virus diseases like HIV and Ebola also have the furin-like cleavage site, which makes them contagious.

Moreover, the study also says an animal host to allow natural selection efficiently, there has to be a high population density. The dwindling population of pangolins is, therefore, may not be an ideal host for such a mutation to occur.

The study concludes that it is important to understand the properties of a virus to trace the origins of the pandemic. Scientists hope that a detailed understanding of how an animal virus-infected humans will help in the prevention of future zoonotic events.

See the original post:

Novel Coronavirus Could Have Entered and Evolved in Humans Much Before Outbreak in Wuhan: Study - The Weather Channel