3.8. Orf7b
The orf7b of both SARS-CoV-2 and BatCoV RaTG13 contains 43 amino acids while the orf7b of the SARS-CoV contains 44 amino acids (Table.1). The orf7b proteins of SARS-CoV-2 and SARS-CoV are characterized by identity percentage of 85.4 and similarity percentage of 90.2. On the other hand, the identity and similarity percentages of the orf7b proteins of SARS-CoV-2 and BatCoV RaTG13 are 97.7% each (Table.2).
The orf7b contains three domains; N-terminal domain (to the outside), C-terminal domain (to the cytoplasm), and a trans-membrane hydrophobic domain [43].
It is reported that the orf7b is not involved in the virus replication [43-46]. The anti orf7b antibody concentration increases in SARS-CoV patients which shows that it is highly immunogenic and it can be used in vaccination trials [46,47].