Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 7, 2020; 26(41): 6335-6345
Published online Nov 7, 2020. doi: 10.3748/wjg.v26.i41.6335
Origin and genomic characteristics of SARS-CoV-2 and its interaction with angiotensin converting enzyme type 2 receptors, focusing on the gastrointestinal tract
Michail Galanopoulos, Aris Doukatas, Maria Gazouli
Michail Galanopoulos, Department of Gastroenterology, 401 General Military Hospital of Athens, Athens 11525, Attiki, Greece
Aris Doukatas, Medical Office of Hellenic Army General Staff, 401 General Military Hospital of Athens, Athens 11525, Attiki, Greece
Maria Gazouli, Laboratory of Biology, School of Medicine, National and Kapodistrian University of Athens, Athens 11527, Attiki, Greece
Author contributions: Galanopoulos M designed the review; Galanopoulos M, Doukatas A analyzed and interpreted the data; Galanopoulos M drafted the manuscript; Gazouli M critically revised the paper. All authors have read and approved the final manuscript.
Conflict-of-interest statement: There is no conflict of interest associated with the senior author or other coauthors in relation to their efforts in this manuscript.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Michail Galanopoulos, FEBG, MD, PhD, Doctor, Department of Gastroenterology, 401 General Military Hospital of Athens, 138 Mesogeion Avenue and Katechaki Street, Athens 11525, Attiki, Greece.
Received: July 22, 2020
Peer-review started: July 22, 2020
First decision: August 8, 2020
Revised: August 10, 2020
Accepted: September 25, 2020
Article in press: September 25, 2020
Published online: November 7, 2020

The emergence of coronavirus disease-2019 induced by a newly identified b-coronavirus, namely severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has constituted a public health emergency. Even though it was considered a zoonotic disease, the virus has also spread among humans via respiratory secretions. The expression and distribution of angiotensin converting enzyme type 2 (ACE2) in various human organs might also show other possible infection routes. High ACE2 ribonucleic acid expression has been identified in the gastrointestinal tract (GI) indicating its importance as a possible infection pathway of SARS-CoV-2. ACE2 induces viral entry into the host and most importantly has been found to be associated with the function of the gut. Its deficiency has been implicated in several pathologies such as colorectal inflammation. The renin-angiotensin system (RAS) is an essential regulatory cascade operating both at a local tissue level and at the systemic or circulatory level. The RAS may be important in the pathogenesis of chronic liver disease and is associated with the up-regulation of ACE2. Thus, the aim of this review is firstly, the analysis of some important general and genome characteristics of SARS-CoV-2 and secondly, and most importantly, to focus on the utility of ACE2 receptors in both SARS-CoV-2 replication and pathogenesis, especially in the GI tract.

Keywords: SARS-CoV-2, COVID-19, Gastrointestinal tract, Angiotensin converting enzyme type 2, Angiotensin converting enzyme type 2 receptor, Renin-angiotensin system, Angiotensin converting enzyme

Core Tip: Although the main route of spread and symptomatology of coronavirus disease 2019 is closely related to the respiratory tract, the gastrointestinal tract could be an alternative and potential route of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and manifestation, most probably as a result of the overexpression of angiotensin converting enzyme type 2 (ACE2) receptors in the digestive system. Thus, this review primarily focuses on the analysis of some critical elements regarding the SARS-CoV-2 genome and its general characteristics, but most importantly, intends to highlight the role of ACE2 receptors in both SARS-CoV-2 replication and pathogenesis, especially in the gastrointestinal tract.