File photo: Xinhua

The novel coronavirus appears to have originated in horseshoe bats and the possibility cannot be ruled out that it may have come from outside China from Southeast Asian countries, according to study results recently revealed by a research team led by Chinese virologist Shi Zhengli from the Wuhan Institute of Virology (WIV).

The study was jointly conducted by the WIV and some foreign research institutes, including EcoHealth Alliance in the US; School of Veterinary Science, the University of Queensland, Australia; and Duke-NUS Medical School, Singapore.

In a paper recently released on the preprint server for biology BioRvix, the team said they found that the novel coronavirus likely derived from a clade of viruses originating in horseshoe bats after analyzing all known bat-CoVs in China.

The virus' full genome was 96 percent similar to a viral sequence reported from Rhinolophus affinis. Closely related sequences were also identified in Malayan pangolins, read the article.

The geographic location of horseshoe bat samples the team used appears to be from Southwest China's Yunnan Province. However, the paper noted that many of their sampling sites were close to China's borders with Myanmar and Lao and most of the bats sampled in Yunnan also live in those countries.

For these reasons, the possibility cannot be ruled out that an origin for the clade of viruses that are progenitors of the novel coronavirus, which caused the deadly COVID-19 pandemic, is outside China, and within Myanmar, Lao, Vietnam or another Southeast Asian country, according to the paper.

During the study, researchers generated 630 partial sequences of the RNA-dependent RNA polymerase gene from 79 bat rectal swabs collected in China and added 608 bat-CoV and eight pangolin CoV sequences from available data in GenBank, a genetic sequence database under the US National Institutes of Health, according to the paper.

Analysis shows that a significant amount of cross-species transmission has occurred among bat hosts over time.

Analysis also identifies the host taxa and geographic regions that define hotspots of CoV evolutionary diversity in China that could help target bat-CoV discovery for proactive zoonotic disease surveillance, according to the paper.