The seventh human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is described as the causative agent of coronavirus infectious disease (COVID-19) [1]. Since the first detection of SARS-CoV-2 in late December 2019 [2], the virus and ongoing COVID-19 pandemic have spread across the globe, killing more than 4 million individuals in the past 18 months. Highly efficacious vaccines generated by biotech and pharma remain the only solution to this international crisis.
The SARS-CoV-2 harbors a positive-sense single-stranded RNA in order of 5′-replicase (ORF1a/b)-S-E-M-N-poly(A)-3′, also the SARS-CoV-2 genome contains several ORFs at its 3′ portion which encodes accessory proteins including ORF3a, ORF3b, ORF6, ORF7a, ORF7b, ORF8, ORF9b, ORF9c as well as ORF10 [3,4]. The scientific evidence shows that the genome of SARS-CoV-2 lacks ORF8a [[5], [6], [7], [8]].
Indeed, both ORF8a and ORF8b are absent in SARS-CoV-2 because of a 29-nucleotide deletion that inactivates the formation ORF8ab tandem [9], while ORF8a and ORF8b are present in SARS-CoV [5,10]. In SARS-CoV, ORF8 splitting into two separated ORFs (ORF8a and ORF8b) [11]. In addition, ORF3b of SARS-CoV is longer than its ortholog in SARS-CoV-2 [8,12].
The SARS-CoV-2 encodes an intact ORF8, which among all the viral proteins of SARS-CoV-2 and SARS-CoV shares the least homology [13]. The ORF8 protein, one of the accessory proteins of SARS-CoV-2, can downregulate surface and total levels of MHC-1 by direct binding and can also degrade MHC-1 by the autophagy pathway [13]. In addition, the ORF8 protein prevents antigen presentation system and CTL-mediated killing of cells that infected with SARS-CoV-2 [14,15].
I have recently read with interest an article by Ni Zhao et al. the authors reported that SARS-CoV-2 can encode a set of accessory proteins, including two ion-channel proteins known as viroporins (open reading frame 3a (ORF3a) and ORF8a) [16], while according to scientific evidence, SARS-CoV-2 lacks ORF8a, and this protein (ORF8a) has no role in SARS-CoV-2 infection.
Declaration of Competing Interest
The author reports no declarations of interest.
Biography
Milad Zandi is a Ph.D. candidate in medical virology at Tehran University of Medical Sciences. He received his Master of Science in virology from the Ahvaz Jundishapur University of Medical Sciences. He is currently pursuing a Ph.D. in department virology at Tehran University of Medical Sciences and plans to graduate in September of 2021. Since August 2018, he has been involved in Pasteur Institute of Iran and studied the using cerium nanoparticles as adjuvant in rabies vaccine. His current research interests focus on two topics: Emerging Viral Diseases and Viral Vaccines. To this end, Milad has published over 30 research papers.
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