ORF3b is a gene found in coronaviruses of the subgenus Sarbecovirus, encoding a short non-structural protein. It is present in both SARS-CoV (which causes the disease SARS) and SARS-CoV-2 (which causes COVID-19), though the protein product has very different lengths in the two viruses. The encoded protein is significantly shorter in SARS-CoV-2,...