The SARS-CoV-2 ORF10 is not essential in vitro or in vivo in humans

Ten open reading frames (ORFs) are encoded in SARS-CoV-2 genome, of which the last ORF10 is positioned downstream of the N gene. ORF10 is a hypothetical gene speculated to encode an only 38 amino acids protein. The authors identified two strains of SARS-CoV-2 in Poland, whose ORF10 gene was prematurely terminated. However, the viruses possessing deleted ORF10 did not show an attenuated phenotype in the patients, as well as not exhibit a declined viral growth in the inoculated culture cells. Thus, the authors propose that the ORF10 should not be treated as the protein-coding gene.