Low homology between 2019-nCoV Orf8 protein and its SARS-CoV counterparts questions their identical function

Abstract

SARS-CoV accessory protein Orf8b is involved in suppressing interferon-mediated immune response of the infected cell and this might lead to supposition that the corresponding protein 2019-nCoV Orf8 shares the same role. But the tertiary structures of these proteins are still unknown, and the primary structures demonstrate very low homology and different calculating parameters. This time they both are affected by stabilizing selection and in natural viral populations do not tend to be deleted. The question whether in this case very different proteins could share the same function rises from the present data.

Imaging Techniques: Essential Tools for the Study of SARS-CoV-2 Infection

“…As a consequence, MHC-I is expressed at lower levels on the cell surface and the infected cell cannot be eliminated by CTL in COVID-19 patients, hence the development of chronic disease (Zhang et al, 2021b). Down-regulation of MHC-I is not observed with SARS-CoV ORF8, probably because of the low homology of 26% between ORF8 of the two viruses (Iatsenko et al, 2021).…”