Resistance to SARS-CoV-2 infection in camelid nasal organoids is associated with lack of ACE2 expression.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects a variety of animal species. Susceptibility to SARS-CoV-2 is primarily determined by the utilization of the viral receptor, ACE2. SARS-CoV-2 can utilize a broad range of animal ACE2 isoforms in vitro, including the ACE2 from various camelid species. However, experimental infection of these animals does not lead to productive infection or seroconversion. In this study, we investigate the susceptibility of camelids to SARS-CoV-2 using novel well-differentiated camelid nasal organoids. We show that camelid nasal organoids are highly susceptible to Middle East respiratory syndrome coronavirus (MERS-CoV) infection, but not to infection with different SARS-CoV-2 variants (614G, BA.1 or EG.5.1.1). All viruses efficiently infected human airway organoids. Immunohistochemistry analysis revealed the absence of ACE2 on camelid nasal organoids and dromedary camel upper respiratory tract. In contrast, DPP4 was expressed in both camelid nasal organoids and the camel upper respiratory tract, which correlates with MERS-CoV infection. This study indicates that the camelid upper respiratory tract lacks expression of ACE2, which is associated with resistance to SARS-CoV-2 infection.