Pangolin-derived sarbecoviruses show attenuated pathogenicity and transmissibility than SARS-CoV-2 in human ACE2 transgenic hamsters

ABSTRACT Genetic diversity of sarbecoviruses phylogenetically related to SARS-CoV-2 has been identified in Malayan pangolins. However, their potential pathogenicity and risk of cross-species transmission to humans remain largely unknown. In the present study, we performed comparative characterization of SARS-CoV-2 and two pangolin SARS-CoV-2-related viruses, named MpCoV-GD and MpCoV-GX, respectively, in human cell lines and organoids and human ACE2 (hACE2) transgenic hamsters. The cell-to-cell fusion assay showed that the Spike (S) protein of MpCoV-GD induces a stronger membrane fusion than the MpCoV-GX S protein, though weaker than the SARS-CoV-2 S protein. In human cells and organoids, both MpCoV-GX and MpCoV-GD replicated well but less efficiently than SARS-CoV-2. In K18-hACE2 hamsters, MpCoV-GD induced lung pathology comparable to SARS-CoV-2 by showing extensive damage to the alveolar parenchyma, while MpCoV-GX mainly caused alveolar wall thickening due to mild inflammatory cell infiltration. Similar to SARS-CoV-2, the two pangolin coronaviruses were capable of transmitting through direct contact and aerosol exposure, but their infectivity was largely attenuated during aerosol transmission. This study expands our understanding of the biological and infection features of the pangolin-derived sarbecoviruses. It demonstrates that current SARS-CoV-2-related therapeutics and pre-existing immunity can elicit cross-protection against the pangolin sarbecoviruses. Although their pathogenicity and transmissibility are relatively low, our findings suggest the necessity of continuing sarbecovirus surveillance in pangolins and other wildlife for prevention of future disease emergence. IMPORTANCE Pangolin-derived sarbecoviruses capable of infecting human cells underscore the role of wildlife as reservoirs for potential zoonotic emergence. MpCoV-GD induces lung pathology comparable to SARS-CoV-2 in hACE2 hamsters, highlighting the need for proactive assessment of novel coronaviruses. Although aerosol transmission of MpCoV-GD and MpCoV-GX is attenuated, their ability to spread via direct contact and airborne routes indicates a tangible risk of cross-species transmission. Importantly, cross-neutralizing activity or inhibition conferred by existing SARS-CoV-2 immunity and therapeutics suggests that current preparedness strategies may help mitigate their impact. These findings reinforce the necessity of sustained surveillance of sarbecoviruses in pangolins and other wildlife to enable early detection and prevention of future outbreaks with significant public health consequences.