Covid may have originated from recombined bat

NEW DELHI A new study has suggested that the Sars-CoV-2, the virus that causes Covid-19, might have originated from a recombination of coronaviruses in a bat and pangolin. The findings strengthen the theory that pangolins could be the intermediate host for transmission of SarsCoV-2 to humans.

The paper, published in the journal Nature by researchers from College of Veterinary Medicine, South China Agricultural University, also flags that pangolins, being the most trafficked mammal in the world, could be a future threat to public health if wildlife trade is not controlled because they harbour Sars-CoV2-like viruses. A coronavirus isolated from Malayan pangolins by a team of Chinese scientists showed 100%, 98.6%, 97.8% and 90.7% amino acid identity with Sars-CoV-2 in 4 genes.

The Malayan pangolin coronavirus was found to be particularly identical to Sars-CoV-2 in its receptor binding domain of the spike protein (which SARSCoV-2 uses to bind to its host’s cells). Genome sequencing found that the pangolin-CoV was very similar to both SARS-CoV-2 and

Bat Sars-CoV RaTG13 (from which SARS-CoV-2 is suspected to have originated) but the only difference was the spike or S gene.

Further analysis of S gene sequences has suggested recombination events on May 8.

For this study, the team used lung tissues from four Chinese pangolins and 25 Malayan pangolins in a wildlife rescue center during March-August 2019. RNA from 17 of the 25 Malayan pangolins were found to be positive for Sars-CoV-2 like viruses and they gradually showed signs of respiratory disease, including shortness of breath, emaciation, inactivity, and crying. Out of 17, 14 pangolins later died.

Generally, a natural reservoir host does not show severe disease, while an intermediate host may have clinical signs of infection, the authors said. Pangolins and bats are both nocturnal animals, eat insects, and share overlapping ecological niches which make pangolins the ideal intermediate host for some Sars-related coronaviruses.

“Of particular interest here is that the entire genome of the pangolin coronavirus is not similar to the Sars-CoV-2 but they’re almost identical in the receptor-binding area (which the virus uses to bind to its host’s cells).

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