SARS-CoV-2 Omicron variant is attenuated for replication in a polarized human lung epithelial cell model

Human alveolar epithelial lentivirus immortalized cells are very permissive for human coronaviruses and influenza A viruses, provided a suitable model for such infections of the lower respiratory tract as shown by reduced propagation of the SARS-CoV-2 Omicron variant. SARS-CoV-2 and its emerging variants of concern remain a major threat for global health. Here we introduce an infection model based upon polarized human Alveolar Epithelial Lentivirus immortalized (hAELVi) cells grown at the air-liquid interface to estimate replication and epidemic potential of respiratory viruses in the human lower respiratory tract. hAELVI cultures are highly permissive for different human coronaviruses and seasonal influenza A virus and upregulate various mediators following virus infection. Our analysis revealed a significantly reduced capacity of SARS-CoV-2 Omicron BA.1 and BA.2 variants to propagate in this human model compared to earlier D614G and Delta variants, which extends early risk assessments from epidemiological and animal studies suggesting a reduced pathogenicity of Omicron.