3.9. Orf8
The identity and similarity or orf8 of the SARS-CoV-2 and orf8a of the
SARS-CoV are 38.9 and 77.8 respectively. The orf8 of SARS-CoV-2 is
44.4% identical and 66.7% similar to the orf8b of SARS-CoV
[Fig.10]. The identity and similarity percentage of orf8 of the
SARS-CoV-2 and the BatCoV RaTG13 are 95% and 95.9%, respectively
(Table.2). However, the number of amino acids of the orf8 of SARS-CoV-2
is 121 amino acids compared to 39 amino acids for the orf8a of the
SARS-CoV, 84 amino acids for the orf8b of the SARS-CoV, and 121 amino
acids for the orf8 of the BatCoV RaTG13 (Table.1).
The orf8a and orf8b of SARS-CoV are not needed for viral replication. In
the host cells, they are localized in vesicle like structures in the
mitochondria, endoplasmic reticulum, cytosol and nucleus of host cells.
The orf8a and orf8b of SARS-CoV stimulates cellular DNA synthesis and
caspase-dependent apoptosis [48].