The SARS-CoV-2 Alpha variant exhibits comparable fitness to the D614G strain in a Syrian hamster model.

Late 2020, SARS-CoV-2 Alpha variant emerged in United Kingdom and gradually replaced G614 strains initially involved in the global spread of the pandemic. In this study, we use a Syrian hamster model to compare a clinical strain of Alpha variant with an ancestral G614 strain. The Alpha variant succeed to infect animals and to induce a pathology that mimics COVID-19. However, both strains replicate to almost the same level and induced a comparable disease and immune response. A slight fitness advantage is noted for the G614 strain during competition and transmission experiments. These data do not corroborate the epidemiological situation observed during the first half of 2021 in humans nor reports that showed a more rapid replication of Alpha variant in human reconstituted bronchial epithelium. This study highlights the need to combine data from different laboratories using various animal models to decipher the biological properties of newly emerging SARS-CoV-2 variants.

Gastrointestinal symptoms of 95 cases with SARS-CoV-2 infection.

OBJECTIVE: To study the GI symptoms in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients. DESIGN: We analysed epidemiological, demographic, clinical and laboratory data of 95 cases with SARS-CoV-2 caused coronavirus disease 2019. Real-time reverse transcriptase PCR was used to detect the presence of SARS-CoV-2 in faeces and GI tissues. RESULTS: Among the 95 patients, 58 cases exhibited GI symptoms of which 11 (11.6%) occurred on admission and 47 (49.5%) developed during hospitalisation. Diarrhoea (24.2%), anorexia (17.9%) and nausea (17.9%) were the main symptoms with five (5.3%), five (5.3%) and three (3.2%) cases occurred on the illness onset, respectively. A substantial proportion of patients developed diarrhoea during hospitalisation, potentially aggravated by various drugs including antibiotics. Faecal samples of 65 hospitalised patients were tested for the presence of SARS-CoV-2, including 42 with and 23 without GI symptoms, of which 22 (52.4%) and 9 (39.1%) were positive, respectively. Six patients with GI symptoms were subjected to endoscopy, revealing oesophageal bleeding with erosions and ulcers in one severe patient. SARS-CoV-2 RNA was detected in oesophagus, stomach, duodenum and rectum specimens for both two severe patients. In contrast, only duodenum was positive in one of the four non-severe patients. CONCLUSIONS: GI tract may be a potential transmission route and target organ of SARS-CoV-2.

Intestinal viral infections of nSARS-CoV2 in the Indian community: Risk of virus spread in India.

In December 2019, novel severe acute respiratory syndrome coronavirus 2 (nSARS-CoV-2) virus outbreaks emerged from Wuhan, China, and spread all over the world, including India. Molecular diagnosis of Coronavirus Disease 2019 (COVID) 19 for densely and highly populated countries like India is time-consuming. A few reports have described the successful diagnosis of nSARS-CoV-2 virus from sewage and wastewater samples contaminated with fecal matter, suggesting the diagnosis of COVID 19 from the same to raise an alarm about the community transmission of virus for implementation of evacuation and lockdown strategies. So far, the association between the detection of virus and its concentration in stool samples with severity of the disease and the presence or absence of gastrointestinal symptoms have been rarely reported. We led the search utilizing multiple databases, specifically PubMed (Medline), EMBASE, and Google Scholar. We conducted a literature survey on gastrointestinal infection and the spread of this virus through fecal-oral transmission. Reports suggested that the existence and persistence of nSARS-CoV-2 in anal/rectal swabs and stool specimens for a longer period of time than in nasopharyngeal swabs provides a strong tenable outcome of gastrointestinal contamination and dissemination of this infection via potential fecal-oral transmission. This review may be helpful to conduct further studies to address the enteric involvement and excretion of nSARS-CoV-2 RNA in feces and control the community spread in both COVID-19 patients ahead of the onset of symptoms and in asymptomatic individuals through wastewater and sewage surveillance as an early indication of infection. The existence of the viral genome and active viral particle actively participate in genomic variations. Hence, we comprehended the enteric spread of different viruses amongst communities with special reference to nSARS-CoV-2.

Protein expression of transmembrane protease serine 4 in the gastrointestinal tract and in healthy, cancer, and SARS­CoV­2 infected lungs.

In addition to the angiotensin­converting enzyme 2 (ACE2), a number of host cell entry mediators have been identified for severe acute respiratory syndrome coronavirus­2 (SARS­CoV­2), including transmembrane protease serine 4 (TMPRSS4). The authors have recently demonstrated the upregulation of TMPRSS4 in 11 different cancers, as well as its specific expression within the central nervous system using in silico tools. The present study aimed to expand the initial observations and, using immunohistochemistry, TMPRSS4 protein expression in the gastrointestinal (GI) tract and lungs was further mapped. Immunohistochemistry was performed on tissue arrays and lung tissues of patients with non­small cell lung cancer with concurrent coronavirus disease 2019 (COVID­19) infection using TMPRSS4 antibody. The results revealed that TMPRSS4 was abundantly expressed in the oesophagus, stomach, small intestine, jejunum, ileum, colon, liver and pancreas. Moreover, the extensive TMPRSS4 protein expression in the lungs of a deceased patient with COVID­19 with chronic obstructive pulmonary disease and bronchial carcinoma, as well in the adjacent normal tissue, was demonstrated for the first time, at least to the best of our knowledge. On the whole, the immunohistochemistry data of the present study suggest that TMPRSS4 may be implicated in the broader (pulmonary and extra­pulmonary) COVID­19 symptomatology; thus, it may be responsible for the tropism of this coronavirus both in the GI tract and lungs.

SARS-CoV-2 pseudovirus infectivity and expression of viral entry-related factors ACE2, TMPRSS2, Kim-1, and NRP-1 in human cells from the respiratory, urinary, digestive, reproductive, and immune systems.

Infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a wide spectrum of syndromes involving multiple organ systems and is primarily mediated by viral spike (S) glycoprotein through the receptor-binding domain (RBD) and numerous cellular proteins including ACE2, transmembrane serine protease 2 (TMPRSS2), kidney injury molecule-1 (Kim-1), and neuropilin-1 (NRP-1). In this study, we examined the entry tropism of SARS-CoV-2 and SARS-CoV using S protein-based pseudoviruses to infect 22 cell lines and 3 types of primary cells isolated from respiratory, urinary, digestive, reproductive, and immune systems. At least one cell line or type of primary cell from each organ system was infected by both pseudoviruses. Infection by pseudoviruses is effectively blocked by S1, RBD, and ACE2 recombinant proteins, and more weakly by Kim-1 and NRP-1 recombinant proteins. Furthermore, cells with robust SARS-CoV-2 pseudovirus infection had strong expression of either ACE2 or Kim-1 and NRP-1 proteins. ACE2 glycosylation appeared to be critical for the infections of both viruses as there was a positive correlation between infectivity of either SARS-CoV-2 or SARS-CoV pseudovirus with the level of glycosylated ACE2 (gly-ACE2). These results reveal that SARS-CoV-2 cell entry could be mediated by either an ACE2-dependent or -independent mechanism, thus providing a likely molecular basis for its broad tropism for a wide variety of cell types.

Evaluation of serum total sialic acid in moderate COVID-19 patients with and without gastrointestinal tract manifestations.

BACKGROUND: It is known that SARS-CoV-2 mostly infects the respiratory system causing pneumonia; although it can also affect the gastrointestinal tract (GIT), which covered with a bi-layer of mucus rich in glycosylated proteins that terminated by sialic acid. Therefore; this study aimed to evaluate serum total sialic acid (TSA) in moderate COVID-19 patients with and without GIT manifestations. METHODS: A total of 161 moderate COVID-19 patients without and with GIT manifestations and 50 controls were enrolled into our study. Serum electrolytes levels were measured by using colorimetric or turbidmetric commercial assay kits, while the level of serum TSA was measured by using a commercial ELISA kit. RESULTS: Our results showed that serum TSA level was highly significantly increased in moderate COVID-19 patients with GIT manifestations (81.43 ± 8.91) when compared with controls (61.24 ± 6.41) or even moderate COVID-19 patients without GIT manifestations (69.46 ± 7.03). ROC curve analysis showed that AUC for TSA is 0.84 with 76.2 % sensitivity and 73.7 % specificity in discrimination between moderate COVID-19 patients with and without GIT manifestations. Serum potassium and sodium levels were highly significantly decreased in moderate COVID-19 patients with GIT manifestations when compared with controls or even moderate COVID-19 patients without GIT manifestations; while serum calcium level was found to be significantly decreased in moderate COVID-19 patients with GIT manifestations when compared with controls. CONCLUSION: Finally, we can conclude that SA plays a crucial role in the pathogenesis of GIT complications associated with COVID-19 and could be a potential biomarker for the COVID-19 gastrointestinal complications.

UK B.1.1.7 (Alpha) variant exhibits increased respiratory replication and shedding in nonhuman primates.

The continuing emergence of SARS-CoV-2 variants calls for regular assessment to identify differences in viral replication, shedding and associated disease. In this study, we compared African green monkeys infected intranasally with either the UK B.1.1.7 (Alpha) variant or its contemporary D614G progenitor. Both variants caused mild respiratory disease with no significant differences in clinical presentation. Significantly higher levels of viral RNA and infectious virus were found in upper and lower respiratory tract samples and tissues from B.1.1.7 infected animals. Interestingly, D614G infected animals showed significantly higher levels of viral RNA and infectious virus in rectal swabs and gastrointestinal tissues. Our results indicate that B.1.1.7 infection in African green monkeys is associated with increased respiratory replication and shedding but no disease enhancement similar to human B.1.1.7 cases.

Gastrointestinal manifestations of coronavirus disease 2019.

PURPOSE OF REVIEW: The ubiquitous expression of angiotensin-converting enzyme-2 receptors and its significance as the origin of viral entry have assisted in comprehending the pathophysiology of extrapulmonary manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this review, we focus on the clinical significance of gastrointestinal manifestations. RECENT FINDINGS: The global pandemic, a result of the widespread implications of SARS-CoV-2, remains a significant burden to current healthcare systems. Fever, dyspnea, and tussive symptoms have primarily been recognized as the most common presenting signs/symptoms. During the past one year our scope of practice has transcended beyond the management of the respiratory system to incorporate other varying systemic manifestations such as anorexia, nausea, vomiting, diarrhea, and abdominal pain. The outcomes reported by recent studies suggest an association between the presence of gastrointestinal symptoms and important clinical factors such as delay in presentation, disease severity, and mortality. SUMMARY: We provide a summarization of the most recent in-depth investigations of coronavirus disease 2019 with gastrointestinal manifestations and their conclusions. Although the pathophysiology remains an area of evolving interest, a better understanding of this disease process may allow for early recognition, efficient triage, and improved prognostication for those presenting with gastrointestinal manifestations of SARS-CoV-2.

Pathogenesis of the inflammatory bowel disease in context of SARS-COV-2 infection.

To date, the latest research results suggest that the novel severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) can enter host cells directly via the gastrointestinal tract by binding to the enterocyte-expressed ACE2 receptor, or indirectly as a result of infection of type II alveolar epithelial cells. At the same time, entry of SARS-CoV-2 through the gastrointestinal tract initiates the activation of innate and adaptive immune responses, the formation of an excessive inflammatory reaction and critical increase in the expression of proinflammatory cytokines, which, subsequently, can presumably increase inflammation and induce intestinal damage in patients suffering from inflammatory bowel disease (IBD). The aims of the present review were to reveal and analyze possible molecular pathways and consequences of the induction of an innate and adaptive immune response during infection with SARS-CoV-2 in patients with IBD. A thorough literature search was carried out by using the keywords: IBD, SARS-CoV-2, COVID-19. Based on the screening, a number of intracellular and extracellular pathways were considered and discussed, which can impact the immune response during SARS-CoV-2 infection in IBD patients. Additionally, the possible consequences of the infection for such patients were estimated. We further hypothesize that any virus, including the new SARS-CoV-2, infecting intestinal tissues and/or entering the host's body through receptors located on intestinal enterocytes may be a trigger for the onset of IBD in individuals with a genetic predisposition and/or the risk of developing IBD associated with other factors.

Cytomegalovirus as an Uninvited Guest in the Response to Vaccines in People Living with HIV.

In stark contrast to the rapid development of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an effective human immunodeficiency virus (HIV) vaccine is still lacking. Furthermore, despite virologic suppression and CD4 T-cell count normalization with antiretroviral therapy (ART), people living with HIV (PLWH) still exhibit increased morbidity and mortality compared to the general population. Such differences in health outcomes are related to higher risk behaviors, but also to HIV-related immune activation and viral coinfections. Among these coinfections, cytomegalovirus (CMV) latent infection is a well-known inducer of long-term immune dysregulation. Cytomegalovirus contributes to the persistent immune activation in PLWH receiving ART by directly skewing immune response toward itself, and by increasing immune activation through modification of the gut microbiota and microbial translocation. In addition, through induction of immunosenescence, CMV has been associated with a decreased response to infections and vaccines. This review provides a comprehensive overview of the influence of CMV on the immune system, the mechanisms underlying a reduced response to vaccines, and discuss new therapeutic advances targeting CMV that could be used to improve vaccine response in PLWH.

Critical appraisal of the mechanisms of gastrointestinal and hepatobiliary infection by COVID-19.

COVID-19 represents a novel infectious disease induced by SARS-CoV-2. It has to date affected 24,240,000 individuals and killed 2,735,805 people worldwide. The highly infectious virus attacks mainly the lung, causing fever, cough, and fatigue in symptomatic patients, but also pneumonia in severe cases. However, growing evidence highlights SARS-CoV-2-mediated extrarespiratory manifestations, namely, gastrointestinal (GI) and hepatic complications. The detection of 1) the virus in the GI system (duodenum, colon, rectum, anal region, and feces); 2) the high expression of additional candidate coreceptors/auxiliary proteins to facilitate the virus entry; 3) the abundant viral angiotensin-converting enzyme 2 receptor; 4) the substantial expression of host transmembrane serine protease 2, necessary to induce virus-cell fusion; 5) the viral replication in the intestinal epithelial cells; and 6) the primarily GI disorders in the absence of respiratory symptoms lead to increased awareness of the risk of disease transmission via the fecal-oral route. The objectives of this review are to provide a brief update of COVID-19 pathogenesis and prevalence, present a critical overview of its GI and liver complications that affect clinical COVID-19 outcomes, clarify associated mechanisms (notably microbiota-related), define whether gut/liver disorders occur more frequently among critically ill patients with COVID-19, determine the impact of COVID-19 on preexisting gut/liver complications and vice versa, and discuss the available strategies for prevention and treatment to improve prognosis of the patients. The novel SARS-CoV-2 can cause gastrointestinal and hepatobiliary manifestations. Metagenomics studies of virobiota in response to SARS-CoV-2 infection are necessary to highlight the contribution of bacterial microflora to COVID-19 phenotype, which is crucial for developing biomarkers and therapeutics.

Bioinformatics and system biology approaches to identify the diseasome and comorbidities complexities of SARS-CoV-2 infection with the digestive tract disorders.

Coronavirus Disease 2019 (COVID-19), although most commonly demonstrates respiratory symptoms, but there is a growing set of evidence reporting its correlation with the digestive tract and faeces. Interestingly, recent studies have shown the association of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection with gastrointestinal symptoms in infected patients but any sign of respiratory issues. Moreover, some studies have also shown that the presence of live SARS-CoV-2 virus in the faeces of patients with COVID-19. Therefore, the pathophysiology of digestive symptoms associated with COVID-19 has raised a critical need for comprehensive investigative efforts. To address this issue we have developed a bioinformatics pipeline involving a system biological framework to identify the effects of SARS-CoV-2 messenger RNA expression on deciphering its association with digestive symptoms in COVID-19 positive patients. Using two RNA-seq datasets derived from COVID-19 positive patients with celiac (CEL), Crohn's (CRO) and ulcerative colitis (ULC) as digestive disorders, we have found a significant overlap between the sets of differentially expressed genes from SARS-CoV-2 exposed tissue and digestive tract disordered tissues, reporting 7, 22 and 13 such overlapping genes, respectively. Moreover, gene set enrichment analysis, comprehensive analyses of protein-protein interaction network, gene regulatory network, protein-chemical agent interaction network revealed some critical association between SARS-CoV-2 infection and the presence of digestive disorders. The infectome, diseasome and comorbidity analyses also discover the influences of the identified signature genes in other risk factors of SARS-CoV-2 infection to human health. We hope the findings from this pathogenetic analysis may reveal important insights in deciphering the complex interplay between COVID-19 and digestive disorders and underpins its significance in therapeutic development strategy to combat against COVID-19 pandemic.

Gastrointestinal Pathology in Samples From Coronavirus Disease 2019 (COVID-19)-Positive Patients.

CONTEXT.­: Although primarily considered a respiratory illness, coronavirus disease 2019 (COVID-19) can cause gastrointestinal manifestations. OBJECTIVE.­: To evaluate histopathology and in situ hybridization for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in gastrointestinal samples from patients with recent and remote COVID-19. DESIGN.­: Patients with positive SARS-CoV-2 nasopharyngeal tests and a gastrointestinal tissue specimen were included. SARS-CoV-2 in situ hybridization (ISH) was performed on each sample. A subset had SARS-CoV-2 next-generation sequencing (NGS) performed. RESULTS.­: Twenty-five patients met inclusion criteria. Five had positive SARS-CoV-2 nasopharyngeal tests within 7 days of their gastrointestinal procedure. Two were ulcerative colitis patients on steroid therapy who lacked typical COVID-19 symptoms. Their colectomies showed severe ulcerative colitis; one demonstrated SARS-CoV-2 by NGS but a negative ISH. Another had an ischemic colon resected as a complication of the COVID-19 course; however, both ISH and NGS were negative. A fourth had a normal-appearing terminal ileum but positive ISH and NGS. The fifth patient had ileal ulcers with SARS-CoV-2 negativity by both modalities. The remaining 20 patients had positive nasopharyngeal tests an average of 53 days prior to procedure. None of their samples demonstrated SARS-CoV-2 ISH positivity, but one was positive on NGS despite a negative nasopharyngeal test. CONCLUSIONS.­: Gastrointestinal findings from SARS-CoV-2-infected patients ranged from normal with virus detected by ISH and NGS to bowel ischemia secondary to systemic viral effects without evidence of virus in the tissue. No distinct histologic finding was identified in those with gastrointestinal tissue specimens demonstrating SARS-CoV-2 positivity in this cohort.

Pathological findings in organs and tissues of patients with COVID-19: A systematic review.

BACKGROUND: Coronavirus disease (COVID-19) is the pandemic caused by SARS-CoV-2 that has caused more than 2.2 million deaths worldwide. We summarize the reported pathologic findings on biopsy and autopsy in patients with severe/fatal COVID-19 and documented the presence and/or effect of SARS-CoV-2 in all organs. METHODS AND FINDINGS: A systematic search of the PubMed, Embase, MedRxiv, Lilacs and Epistemonikos databases from January to August 2020 for all case reports and case series that reported histopathologic findings of COVID-19 infection at autopsy or tissue biopsy was performed. 603 COVID-19 cases from 75 of 451 screened studies met inclusion criteria. The most common pathologic findings were lungs: diffuse alveolar damage (DAD) (92%) and superimposed acute bronchopneumonia (27%); liver: hepatitis (21%), heart: myocarditis (11.4%). Vasculitis was common only in skin biopsies (25%). Microthrombi were described in the placenta (57.9%), lung (38%), kidney (20%), Central Nervous System (CNS) (18%), and gastrointestinal (GI) tract (2%). Injury of endothelial cells was common in the lung (18%) and heart (4%). Hemodynamic changes such as necrosis due to hypoxia/hypoperfusion, edema and congestion were common in kidney (53%), liver (48%), CNS (31%) and GI tract (18%). SARS-CoV-2 viral particles were demonstrated within organ-specific cells in the trachea, lung, liver, large intestine, kidney, CNS either by electron microscopy, immunofluorescence, or immunohistochemistry. Additional tissues were positive by Polymerase Chain Reaction (PCR) tests only. The included studies were from numerous countries, some were not peer reviewed, and some studies were performed by subspecialists, resulting in variable and inconsistent reporting or over statement of the reported findings. CONCLUSIONS: The main pathologic findings of severe/fatal COVID-19 infection are DAD, changes related to coagulopathy and/or hemodynamic compromise. In addition, according to the observed organ damage myocarditis may be associated with sequelae.

Fluid and Electrolyte Disturbances in COVID-19 and Their Complications.

The novel coronavirus disease 2019 (COVID-19) is the cause of an acute respiratory illness which has spread around the world. The virus infects the host by binding to the angiotensin-converting enzyme 2 (ACE2) receptors. Due to the presence of ACE2 receptors in the kidneys and gastrointestinal (GI) tract, kidneys and GI tract damage arising from the virus can be seen in patients and can cause acute conditions such as acute kidney injury (AKI) and digestive problems for the patient. One of the complications of kidneys and GI involvement in COVID-19 is fluid and electrolyte disturbances. The most common ones of these disorders are hyponatremia, hypernatremia, hypokalemia, hypocalcemia, hypochloremia, hypervolemia, and hypovolemia, which if left untreated, cause many problems for patients and even increase mortality. Fluid and electrolyte disturbances are more common in hospitalized and intensive care patients. Children are also at greater risk for fluid and electrolyte disturbances complications. Therefore, clinicians should pay special attention to the fluid and electrolyte status of patients. Changes in fluid and electrolyte levels can be a good indicator of disease progression.

Prevalence and Persistent Shedding of Fecal SARS-CoV-2 RNA in Patients With COVID-19 Infection: A Systematic Review and Meta-analysis.

INTRODUCTION: The prevalence and shedding of fecal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA indicate coronavirus disease 2019 (COVID-19) infection in the gastrointestinal (GI) tract and likely infectivity. We performed a systemic review and meta-analysis to evaluate the prevalence and the duration of shedding of fecal RNA in patients with COVID-19 infection. METHODS: PubMed, Embase, Web of Science, and Chinese databases Chinese National Knowledge Infrastructure and Wanfang Data up to June 2020 were searched for studies evaluating fecal SARS-CoV-2 RNA, including anal and rectal samples, in patients with confirmed COVID-19 infection. The pooled prevalence of fecal RNA in patients with detectable respiratory RNA was estimated. The days of shedding and days to loss of fecal and respiratory RNA from presentation were compared. RESULTS: Thirty-five studies (N = 1,636) met criteria. The pooled prevalence of fecal RNA in COVID-19 patients was 43% (95% confidence interval [CI] 34%-52%). Higher proportion of patients with GI symptoms (52.4% vs 25.9%, odds ratio = 2.4, 95% CI 1.2-4.7) compared with no GI symptoms, specifically diarrhea (51.6% vs 24.0%, odds ratio = 3.0, 95% CI 1.9-4.8), had detectable fecal RNA. After loss of respiratory RNA, 27% (95% CI 15%-44%) of the patients had persistent shedding of fecal RNA. Days of RNA shedding in the feces were longer than respiratory samples (21.8 vs 14.7 days, mean difference = 7.1 days, 95% CI 1.2-13.0). Furthermore, days to loss of fecal RNA lagged respiratory RNA by a mean of 4.8 days (95% CI 2.2-7.5). DISCUSSION: Fecal SARS-CoV-2 RNA is commonly detected in COVID-19 patients with a 3-fold increased risk with diarrhea. Shedding of fecal RNA lasted more than 3 weeks after presentation and a week after last detectable respiratory RNA.

SARS-CoV-2 Infection and Disease Modelling Using Stem Cell Technology and Organoids.

In this Review, we briefly describe the basic virology and pathogenesis of SARS-CoV-2, highlighting how stem cell technology and organoids can contribute to the understanding of SARS-CoV-2 cell tropisms and the mechanism of disease in the human host, supporting and clarifying findings from clinical studies in infected individuals. We summarize here the results of studies, which used these technologies to investigate SARS-CoV-2 pathogenesis in different organs. Studies with in vitro models of lung epithelia showed that alveolar epithelial type II cells, but not differentiated lung alveolar epithelial type I cells, are key targets of SARS-CoV-2, which triggers cell apoptosis and inflammation, while impairing surfactant production. Experiments with human small intestinal organoids and colonic organoids showed that the gastrointestinal tract is another relevant target for SARS-CoV-2. The virus can infect and replicate in enterocytes and cholangiocytes, inducing cell damage and inflammation. Direct viral damage was also demonstrated in in vitro models of human cardiomyocytes and choroid plexus epithelial cells. At variance, endothelial cells and neurons are poorly susceptible to viral infection, thus supporting the hypothesis that neurological symptoms and vascular damage result from the indirect effects of systemic inflammatory and immunological hyper-responses to SARS-CoV-2 infection.

Implications of SARS-CoV-2 infection for neurogastroenterology.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is associated with gastrointestinal and hepatic manifestation in up to one fifth of patients. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of COVID-19, infects gastrointestinal epithelial cells expressing angiotensin-converting enzyme 2 (ACE2) receptors triggering a cascade of events leading to mucosal and systemic inflammation. Symptomatic patients display changes in gut microbiota composition and function which may contribute to intestinal barrier dysfunction and immune activation. Evidence suggests that SARS-CoV-2 infection and related mucosal inflammation impact on the function of the enteric nervous system and the activation of sensory fibers conveying information to the central nervous system, which, may at least in part, contribute symptom generation such as vomiting and diarrhea described in COVID-19. Liver and pancreas dysfunctions have also been described as non-respiratory complications of COVID-19 and add further emphasis to the common view of SARS-CoV-2 infection as a systemic disease with multiorgan involvement. PURPOSE: The aim of this review was to highlight the current knowledge on the pathophysiology of gastrointestinal SARS-CoV-2 infection, including the crosstalk with the gut microbiota, the fecal-oral route of virus transmission, and the potential interaction of the virus with the enteric nervous system. We also review the current available data on gastrointestinal and liver manifestations, management, and outcomes of patients with COVID-19.