In the quest to understand SARS-CoV-2 and its variants, researchers have developed ACE2-overexpressing human airway organoids as a reliable model. These organoids faithfully replicate viral infection dynamics while preserving the complex 3D structure and cellular diversity of the airway epithelium.

When infected with SARS-CoV-2 variants, these ACE2-overexpressing organoids revealed insights through single-cell RNA-sequencing. They found that cells with low-level infection upregulated Interferon-lambda, a key antiviral protein. Interestingly, infected cells consistently showed increased expression of the NF-kB inhibitor alpha gene (IkBa), which normally limits NF-kB activity.

However, confocal microscopy uncovered a surprising twist: despite elevated IkBa levels, infected cells also displayed nuclear translocation of NF-kB, a process typically blocked by IkBa. Further experiments with a nondegradable IkBa mutant confirmed that reducing NF-kB translocation decreased viral infection rates.

These findings highlight the ACE2-overexpressing organoids as a valuable tool for studying SARS-CoV-2 and underscore the critical role of the NF-kB pathway in regulating viral replication within infected cells.