As scientists race to develop vaccines against SARS-CoV-2, tracing its origins remains crucial. A recent international study reveals the virus has been circulating in bats for at least four decades.
Intense debates have surrounded SARS-CoV-2 in recent months: What animal transmitted it to humans? When did the outbreak truly begin? Theories ranging from lab leaks to engineered origins have been debunked by evidence.
Experts now confirm bats as the original reservoir. Published in Nature Microbiology on July 28, 2020, a collaborative study by Chinese, American, Belgian, and British researchers estimates SARS-CoV-2 has circulated among bats for more than 40 years. Their rigorous analysis reconstructed the virus's evolutionary history.
Coronaviruses feature highly recombinant genomes, where segments derive from diverse sources. Researchers pinpointed recombination sites, reconstructed phylogenies for non-recombinant regions, and compared them to identify ancestral viruses.
Findings indicate the SARS-CoV-2 lineage diverged from relatives 40 to 70 years ago. It's 96% similar to RaTG13, a bat virus found in China's Yunnan province in 2013, but diverged from it in 1969. Notably, the ability to bind human cell receptors is an ancient trait shared across the lineage, hinting at long-circulating human-infective potential in bats.
While pangolins were once suspected as intermediates, no conclusive evidence requires one for bat-to-human transmission.
