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Japanese and Thai scientists from the Institute of Medical Science, The University of Tokyo in Japan and Chulalongkorn University in Thailand respectively have identified a novel group of coronaviruses closely related to SARS-CoV-2 circulating in horseshoe bats in Thailand. These viruses have the potential to infect humans, according to a statement by the University of Tokyo.
Horseshoe bats are the main host of coronaviruses related to SARS-CoV-2, the causative agent of the recent COVID-19 pandemic. Yet, the diversity and properties of bat SARS-CoV-2-related viruses remain unexplored, especially in Southeast Asia that harbours the largest number of horseshoe bat species.
The international team of researchers led by Japanese and Thai scientists discovered the new group of these viruses sampled in acuminate horseshoe bats (Rhinolophus acuminatus) and compared their virological characteristics to those of SARS-CoV-2.
The study revealed important insights into the features that make these viruses capable of jumping onto humans by combining wildlife virus surveillance, laboratory molecular virology experiments and computational methods to trace the geographic movement and history of the viruses.
The paper, published by the team in the journal Cell on May 6, 2026, is the first work of a new international research consortium, the Genotype to Phenotype Asia (G2P-Asia) Consortium1, in collaboration with Chulalongkorn University, formed as a continuation of the Genotype to Phenotype Japan (G2P-Japan) Consortium2, led by Kei Sato of the Division of Systems Virology at The Institute of Medical Science, The University of Tokyo.
“The new group of SARS-CoV-2-related viruses, referred to by the researchers as Clade B, is the second type of coronaviruses found in bats inhabiting the same artificial cave in Thailand’s Chachoengsao Province. The first group, Clade A3, was also found co-circulating with the newly discovered Clade B, even infecting the same individual bat. The difference between the two clades is that, unlike Clade A, Clade B viruses can engage the same human receptor that SARS-CoV-2 uses to infect humans, called angiotensin-converting enzyme 2 - or ACE2 for short,” noted the university statement.
According to Spyros Lytras, one of the study’s co-first authors, this is clear evidence that SARS-CoV-2-related viruses which utilise different entry receptors co-circulate in and co-infect the same bat populations, opening up the possibility that they can swap parts of their genome through recombination and readily change their receptor usage.
The researchers were able to synthetically produce a representative Clade B virus, called RacCS20637, to study virological properties beyond receptor usage. All experiments involving these viruses, were conducted in a Biosafety Level 3 laboratory at the Institute of Medical Science, The University of Tokyo, with approval from Japan’s Minister of Education, Culture, Sports, Science and Technology and the University of Tokyo Research Microbial Safety Committee.
These results indicated that, compared to SARS-CoV-2, RacCS20637 also binds the human ACE2 receptor efficiently but replicates much slower in human cells. Furthermore, RacCS20637 infection in hamsters caused little to no pathology and the virus was not capable of transmitting between individual hamsters.
“Although we cannot know how RacCS20637 infection behaves in horseshoe bats, this virus is much worse at replicating in human cells than SARS-CoV-2, while showing no pathology or transmission in the animal systems we use to study SARS-CoV-2,” said Wilaiporn Saikruang, another co-first author of the study.
Reassuringly, the RacCS20637 virus is neutralised by sera from people who had received three doses of the COVID-19 vaccine, while also being effectively targeted by available antiviral drugs used for SARS-CoV-2.
Kei Sato, the co-senior author of the study, commented that “Despite their close relatedness to SARS-CoV-2, this particular group of coronaviruses poses no threat to humans. However, our findings highlight how SARS-CoV-2-related coronaviruses can readily alter their virological properties with only few changes in their genomes”.
The team further analysed the recent geographic movement of both Clade A and Clade B viruses that led them to infect the same bat population at the time of sampling. Their results show a complex network of virus movement across overlapping horseshoe bat host ranges in Southeast Asia with Clade B likely making its way to Eastern Thailand from northern parts of the peninsula, near Laos.
According to Sato, during the course of the study, the team expanded the research consortium The Genotype to Phenotype Japan (G2P-Japan) Consortium into an international collaborative research consortium with teams from Asian countries, known as The Genotype to Phenotype Asia (G2P-Asia) Consortium.
“Both G2P-Japan and G2P-Asia are conducting basic virological research aimed at establishing systems to prepare for the ‘next pandemic’. By focusing on Southeast Asia—where, as in this study, a large number of SARS-CoV-2-related coronaviruses have been detected—we are promoting research to investigate and identify high-risk viruses and experimentally elucidate their virological characteristics. Through such research, we aim to discover the scientific insights necessary to establish better infectious disease control systems before the ‘next pandemic’ occurs and to share these findings with the global community,” said Sato.
