Milad Zandi1,2, Emad Behboudi3, Saber Soltani4,5. 1. Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Miladzandi416@gmail.com. 2. Research Center for Clinical Virology, Tehran University of Medical Sciences, Tehran, Iran. Miladzandi416@gmail.com. 3. Department of Microbiology, Golestan University of Medical Sciences, Gorgan, Iran. 4. Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 5. Research Center for Clinical Virology, Tehran University of Medical Sciences, Tehran, Iran.
One and a half year has passed since the outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) the causative agent of coronavirus disease 2019 (COVID-19) pandemic. Nowadays information on SARS-CoV-2 and its receptors are increasing. It’s been showed that O-acetylated sialic acids (SAs) can interact with viral spike glycoprotein for the primary attachment of virus and its penetration into the host cells [1]. Most beta coronaviruses recognize 9-O-acetyl-SAs but it has changed to 4-O-acetyl-SA through the evolution of Coronaviruses [1]. Its viral ligand, the hemagglutinin esterase (HE) gene was transmitted to a beta coronavirus lineage A through horizontal gene adaption from a 9-O-acetyl-SA–specific HEF, as in influenza C [1, 2]. Adaption of HE occurs via cross-species transmission and HE evolution [1]. This fact demonstrates viral evolutionary compatibility to host glycans. Thus, studying emerging viruses like SARS-CoV-2 may result in better recognition of viral evolution process. For instance, as mentioned above, HE gene transfer is discovered in the beta coronaviruses, which choose 9-di-O-Ac-SAs. A more interesting example of such events happens in the murine CoVs, with attachment to two various subtypes of the canonical 9-O-Ac-SA (type I) and unique 4-O-Ac-SA (type II) [3]. But noticeably it must be mentioned that same as SARS-CoV-2, SARS-CoV genome has no HE gene [4]. Incorrectly a recent published article in the journal of stem cell reviews and reports states that SARS-CoV-2 has HE and hemagglutinin protein [5], also the authors has illustrated viral hemagglutinin glycoprotein on viral envelope. This is in contrast to previous studies which experimentally showed that SARS-CoV-2 lacks HE gene and glycoprotein. According to data from different full genome sequencing studies using next generation sequencing (NGS) and phylogenic analysis of SARS-CoV-2 virus has no HE gene and consequently HE glycoprotein [4]. Therefore this virus lacks HE gene and cannot carry HE protein (Fig. 1).
Fig. 1