SARS-CoV-2 productively infects human gut enterocytes

Feline infectious peritonitis (FIP) and coronavirus disease 19 (COVID-19): Are they similar?

SARS‐CoV‐2 has radically changed our lives causing hundreds of thousands of victims worldwide and influencing our lifestyle and habits. Feline infectious peritonitis (FIP) is a disease of felids caused by the feline coronaviruses (FCoV). FIP has been considered irremediably deadly until the last few years. Being one of the numerous coronaviruses that are well known in veterinary medicine, information on FCoV could be of interest and might give suggestions on pathogenic aspects of SARS‐CoV‐2 that are still unclear. The authors of this paper describe the most important aspects of FIP and COVID‐19 and the similarities and differences between these important diseases. SARS‐CoV‐2 and FCoV are taxonomically distant viruses, and recombination events with other coronaviruses have been reported for FCoV and have been suggested for SARS‐CoV‐2. SARS‐CoV‐2 and FCoV differ in terms of some pathogenic, clinical and pathological features. However, some of the pathogenic and immunopathogenic events that are well known in cats FIP seem to be present also in people with COVID‐19. Moreover, preventive measures currently recommended to prevent SARS‐CoV‐2 spreading have been shown to allow eradication of FIP in feline households. Finally, one of the most promising therapeutic compounds against FIP, GS‐441524, is the active form of Remdesivir, which is being used as one therapeutic option for COVID‐19.

Presentation, Treatment Response and Short-Term Outcomes in Paediatric Multisystem Inflammatory Syndrome Temporally Associated with SARS-CoV-2 (PIMS-TS)

The novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the pathogen responsible for Coronavirus Disease 2019 (COVID-19). Whilst most children and young people develop mild symptoms, recent reports suggest a novel paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS). Case definition and classification are preliminary, treatment is empiric and disease-associated outcomes are unclear. Here, we report 29 patients with PIMS-TS who were diagnosed, admitted and treated in the English North West between March and June 2020. Consistent with patterns observed internationally, cases peaked approximately 4 weeks after the initial surge of COVID-19-like symptoms in the UK population. Clinical symptoms included fever (100%), skin rashes (72%), cardiovascular involvement (86%), conjunctivitis (62%) and respiratory involvement (21%). Some patients had clinical features partially resembling Kawasaki disease (KD), toxic shock syndrome and cytokine storm syndrome. Male gender (69%), black, Asian and other minority ethnicities (BAME, 59%) were over-represented. Immune modulating treatment was used in all, including intravenous immunoglobulin (IVIG), corticosteroids and cytokine blockers. Notably, 32% of patients treated with IVIG alone went into remission. The rest required additional treatment, usually corticosteroids, with the exception of two patients who were treated with TNF inhibition and IL-1 blockade, respectively. Another patient received IL-1 inhibition as primary therapy, with associated rapid and sustained remission. Randomized and prospective studies are needed to investigate efficacy and safety of treatment, especially as resources of IVIG may be depleted secondary to high demand during future waves of COVID-19.

Sewage as a Possible Transmission Vehicle During a Coronavirus Disease 2019 Outbreak in a Densely populated Community: Guangzhou, China, April 2020

Background

SARS-CoV-2 has been identified in the fecal matter of COVID-19 patients. However, sewage transmission has never been shown. In April 2020, a COVID-19 outbreak occurred in a densely populated community in Guangzhou, China. We investigated this outbreak to identify the mode of transmission.

Method

A home quarantined order was issued in the community. We collected throat swab samples from the residents and environmental samples from the surfaces inside and around the houses, and conducted RT-PCR testing and genome sequencing. We defined a case as a resident in this community with a positive RT-PCR test, with or without symptoms. We conducted a retrospective cohort study of all residents living in the same buildings as the cases to identify exposure risk factors.

Result

We found eight cases (four couples) in this community of 2888 residents (attack rate=2.8/1000), with onset during April 5–21, 2020. During their incubation periods, Cases 1-2 frequented market T with an ongoing outbreak. Cases 3-8 never visited market T during incubation period, lived in separate buildings from, and never interacted with, Cases 1-2. Retrospective cohort study showed that working as cleaners or waste picker (RR=13, 95% CI_exact: 2.3-180), not changing to clean shoes after returning home (RR=7.4, 95% CI_exact: 1.8-34), collating and cleaning dirty shoes after returning home (RR=6.3, 95% CI_exact: 1.4-30) were significant exposure risk factors. Of 63 samples collected from street-sewage puddles and sewage-pipe surfaces, 19% tested positive for SARS-CoV-2. Of 50 environmental samples taken from cases’ apartments, 24% tested positive. Viral genome sequencing showed that the viruses identified from the squat toilet and shoe-bottom dirt inside the apartment of Cases 1-2 were homologous with those from Cases 3-8 and those identified from sewage samples. The sewage pipe leading from the apartment of Cases 1-2 to the drainage had a large hole above ground. Rainfalls after the onset of Cases 1-2 flooded the streets.

Conclusion

Our investigation has for the first time pointed to the possibility that SARS-CoV-2 might spread by sewage. This finding highlighted the importance of sewage management, especially in densely-populated places with poor hygiene and sanitation measures, such as urban slums and other low-income communities in developing countries.

Robust and persistent SARS-CoV-2 infection in the human intestinal brush border expressing cells

Studies on patients with the coronavirus disease-2019 (COVID-19) have implicated that the gastrointestinal (GI) tract is a major site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We established a human GI tract cell line model highly permissive to SARS-CoV-2. These cells, C2BBe1 intestinal cells with a brush border having high levels of transmembrane serine protease 2 (TMPRSS2), showed robust viral propagation, and could be persistently infected with SARS-CoV-2, supporting the clinical observations of persistent GI infection in COVID-19 patients. Ectopic expression of viral receptors revealed that the levels of angiotensin-converting enzyme 2 (ACE2) expression confer permissiveness to SARS-CoV-2 infection, and TMPRSS2 greatly facilitates ACE2-mediated SARS-CoV-2 dissemination. Interestingly, ACE2 but not TMPRSS2 expression was significantly promoted by enterocytic differentiation, suggesting that the state of enterocytic differentiation may serve as a determining factor for viral propagation. Thus, our study sheds light on the pathogenesis of SARS-CoV-2 in the GI tract.

Coronavirus infection and PARP expression dysregulate the NAD Metabolome: an actionable component of innate immunity

Poly-ADP-ribose polymerase (PARP) superfamily members covalently link either a single ADP-ribose (ADPR) or a chain of ADPR units to proteins using nicotinamide adenine dinucleotide (NAD) as the source of ADPR. While the well-known poly-ADP-ribosylating (PARylating) PARPs primarily function in the DNA damage response, many non-canonical mono-ADP-ribosylating (MARylating) PARPs are associated with cellular antiviral responses. We recently demonstrated robust upregulation of several PARPs following infection with Murine Hepatitis Virus (MHV), a model coronavirus. Here we show that SARS-CoV-2 infection strikingly upregulates MARylating PARPs and induces the expression of genes encoding enzymes for salvage NAD synthesis from nicotinamide (NAM) and nicotinamide riboside (NR), while downregulating other NAD biosynthetic pathways. We show that overexpression of PARP10 is sufficient to depress cellular NAD and that the activities of the transcriptionally induced enzymes PARP7, PARP10, PARP12 and PARP14 are limited by cellular NAD and can be enhanced by pharmacological activation of NAD synthesis. We further demonstrate that infection with MHV induces a severe attack on host cell NAD+ and NADP+. Finally, we show that NAMPT activation, NAM and NR dramatically decrease the replication of an MHV virus that is sensitive to PARP activity. These data suggest that the antiviral activities of noncanonical PARP isozyme activities are limited by the availability of NAD, and that nutritional and pharmacological interventions to enhance NAD levels may boost innate immunity to coronaviruses.

Sampling manholes to home in on SARS-CoV-2 infections

About 50% of individuals infected with the novel Coronavirus (SARS-CoV-2) suffer from intestinal infection as well as respiratory infection. They shed virus in their stool. Municipal sewage systems carry the virus and its genetic remnants. These viral traces can be detected in the sewage entering a wastewater treatment plant (WTP). Such virus signals indicate community infections but not locations of the infection within the community. In this paper, we frame and formulate the problem in a way that leads to algorithmic procedures homing in on locations and/or neighborhoods within the community that are most likely to have infections. Our data source is wastewater sampled and real-time tested from selected manholes. Our algorithms dynamically and adaptively develop a sequence of manholes to sample and test. The algorithms are often finished after 5 to 10 manhole samples, meaning that-in the field-the procedure can be carried out within one day. The goal is to provide timely information that will support faster more productive human testing for viral infection and thus reduce community disease spread. Leveraging the tree graph structure of the sewage system, we develop two algorithms, the first designed for a community that is certified at a given time to have zero infections and the second for a community known to have many infections. For the first, we assume that wastewater at the WTP has just revealed traces of SARS-CoV-2, indicating existence of a "Patient Zero" in the community. This first algorithm identifies the city block in which the infected person resides. For the second, we home in on a most infected neighborhood of the community, where a neighborhood is usually several city blocks. We present extensive computational results, some applied to a small New England city.

Tracking Mechanisms of Viral Dissemination In Vivo

Dissemination and replication of viruses into hosts is a multistep process where viral particles infect, navigate, and indoctrinate various cell types. Viruses can reach tissues that are distant from their infection site by subverting subcellular mechanisms in ways that are, sometimes, disruptive. Modeling these steps, at appropriate resolution and within animal models, is cumbersome. Yet, mimicking these strategies in vitro fails to recapitulate the complexity of the cellular ecosystem. Here, we will discuss relevant in vivo platforms to dissect the cellular and molecular programs governing viral dissemination and briefly discuss organoid and ex vivo alternatives. We will focus on the zebrafish model and will describe how it provides a transparent window to unravel new cellular mechanisms of viral dissemination in vivo.

The zebrafish model allows in vivo investigations of virus-induced molecular processes at subcellular resolution.

Viruses have evolved multiple strategies for disseminating over long distance, including by indoctrinating host cell types with high migration potential.

Organoids derived from stem cells emerge as powerful alternatives to unravel new molecular mechanisms of viral dissemination.

Modeling the viral dynamics of SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19), an infectious disease caused by the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is spreading and causing the global coronavirus pandemic. The viral dynamics of SARS-CoV-2 infection have not been quantitatively investigated. In this paper, we use mathematical models to study the pathogenic features of SARS-CoV-2 infection by examining the interaction between the virus, cells and immune responses. Models are fit to the data of SARS-CoV-2 infection in patients and non-human primates. Data fitting and numerical simulation show that viral dynamics of SARS-CoV-2 infection have a few distinct stages. In the initial stage, viral load increases rapidly and reaches the peak, followed by a plateau phase possibly generated by lymphocytes as a secondary target of infection. In the last stage, viral load declines due to the emergence of adaptive immune responses. When the initiation of seroconversion is late or slow, the model predicts viral rebound and prolonged viral persistence, consistent with the observation in non-human primates. Using the model we also evaluate the effect of several potential therapeutic interventions for SARS-CoV-2 infection. Model simulation shows that anti-inflammatory treatments or antiviral drugs combined with interferon are effective in reducing the duration of the viral plateau phase and diminishing the time to recovery. These results provide insights for understanding the infection dynamics and might help develop treatment strategies against COVID-19.

On the whereabouts of SARS-CoV-2 in the human body: A systematic review

Since SARS-CoV-2 appeared in the human population, the scientific community has scrambled to gather as much information as possible to find good strategies for the containment and treatment of this pandemic virus. Here, we performed a systematic review of the current (pre)published SARS-CoV-2 literature with a focus on the evidence concerning SARS-CoV-2 distribution in human tissues and viral shedding in body fluids. In addition, this evidence is aligned with published ACE2 entry-receptor (single cell) expression data across the human body to construct a viral distribution and ACE2 receptor body map. We highlight the broad organotropism of SARS-CoV-2, as many studies identified viral components (RNA, proteins) in multiple organs, including the pharynx, trachea, lungs, blood, heart, vessels, intestines, brain, male genitals and kidneys. This also implicates the presence of viral components in various body fluids such as mucus, saliva, urine, cerebrospinal fluid, semen and breast milk. The main SARS-CoV-2 entry receptor, ACE2, is expressed at different levels in multiple tissues throughout the human body, but its expression levels do not always correspond with SARS-CoV-2 detection, indicating that there is a complex interplay between virus and host. Together, these data shed new light on the current view of SARS-CoV-2 pathogenesis and lay the foundation for better diagnosis and treatment of COVID-19 patients.

First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan

Wastewater-based epidemiology is a powerful tool to understand the actual incidence of coronavirus disease 2019 (COVID-19) in a community because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, can be shed in the feces of infected individuals regardless of their symptoms. The present study aimed to assess the presence of SARS-CoV-2 RNA in wastewater and river water in Yamanashi Prefecture, Japan, using four quantitative and two nested PCR assays. Influent and secondary-treated (before chlorination) wastewater samples and river water samples were collected five times from a wastewater treatment plant and three times from a river, respectively, between March 17 and May 7, 2020. The wastewater and river water samples (200-5000 mL) were processed by using two different methods: the electronegative membrane-vortex (EMV) method and the membrane adsorption-direct RNA extraction method. Based on the observed concentrations of indigenous pepper mild mottle virus RNA, the EMV method was found superior to the membrane adsorption-direct RNA extraction method. SARS-CoV-2 RNA was successfully detected in one of five secondary-treated wastewater samples with a concentration of 2.4 × 103 copies/L by N_Sarbeco qPCR assay following the EMV method, with sequence confirmation of the qPCR product, whereas all the influent samples were tested negative for SARS-CoV-2 RNA. This result could be attributed to higher limit of detection for influent (4.0 × 103-8.2 × 104 copies/L) with a lower filtration volume (200 mL) compared to that for secondary-treated wastewater (1.4 × 102-2.5 × 103 copies/L) with a higher filtration volume of 5000 mL. None of the river water samples tested positive for SARS-CoV-2 RNA. Comparison with the reported COVID-19 cases in Yamanashi Prefecture showed that SARS-CoV-2 RNA was detected in the secondary-treated wastewater sample when the cases peaked in the community. This is the first study reporting the detection of SARS-CoV-2 RNA in wastewater in Japan.

Making waves: Wastewater surveillance of SARS-CoV-2 for population-based health management

Worldwide, clinical data remain the gold standard for disease surveillance and tracking. However, such data are limited due to factors such as reporting bias and inability to track asymptomatic disease carriers. Disease agents are excreted in the urine and feces of infected individuals regardless of disease symptom severity. Wastewater surveillance - that is, monitoring disease via human effluent - represents a valuable complement to clinical approaches. Because wastewater is relatively inexpensive and easy to collect and can be monitored at different levels of population aggregation as needed, wastewater surveillance can offer a real-time, cost-effective view of a community's health that is independent of biases associated with case-reporting. For SARS-CoV-2 and other disease-causing agents we envision an aggregate wastewater-monitoring system at the level of a wastewater treatment plant and exploratory or confirmatory monitoring of the sewerage system at the neighborhood scale to identify or confirm clusters of infection or assess impact of control measures where transmission has been established. Implementation will require constructing a framework with collaborating government agencies, public or private utilities, and civil society organizations for appropriate use of data collected from wastewater, identification of an appropriate scale of sample collection and aggregation to balance privacy concerns and risk of stigmatization with public health preservation, and consideration of the social implications of wastewater surveillance.

SARS-CoV-2 Induces a More Robust Innate Immune Response and Replicates Less Efficiently Than SARS-CoV in the Human Intestines: An Ex Vivo Study With Implications on Pathogenesis of COVID-19

BACKGROUND AND AIMS

Besides prominent respiratory involvement, gastrointestinal manifestations are commonly reported in Coronavirus Disease 2019 (COVID-19) patients. We compared infection of ex vivo human intestinal tissues by SARS-CoV-2 and SARS-CoV with respect to their replication kinetics and immune activation profile.

METHODS

Human intestinal tissues were obtained from patients while undergoing surgical operations at Queen Mary Hospital, Hong Kong. Upon surgical removal, the tissues were immediately processed and infected with SARS-CoV-2 or SARS-CoV. Replication kinetics were determined with immunohistochemistry, qRT-PCR, and plaque assays. Immune activation in the infected intestinal tissues was assessed by detecting the gene expression of interferons and representative pro-inflammatory cytokines and chemokines.

RESULTS

SARS-CoV-2 could infect and productively replicate in the ex vivo human intestinal tissues with release of infectious virus particles, but not in ex vivo human liver and kidney tissues. Importantly, SARS-CoV-2 replicated less efficiently than SARS-CoV, induced less cytopathology in the human intestinal epithelium, and induced a more robust innate immune response including the activation of both type I and type III interferons, than SARS-CoV in human intestinal tissues.

CONCLUSION

Using the ex vivo human intestinal tissues as a physiologically relevant model, our data indicated that SARS-CoV-2 could productively replicate in the human gut and suggested that the gastrointestinal tract might serve as an alternative route of virus dissemination. SARS-CoV-2 replicated less efficiently and induced less cytopathology than SARS-CoV in keeping with the clinical observations reported for COVID-19 and SARS, which might be the result of a more robust immune activation by SARS-CoV-2 than SARS-CoV in the human intestine.

First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan

Wastewater-based epidemiology is a powerful tool to understand the actual incidence of coronavirus disease 2019 (COVID-19) in a community because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, can be shed in the feces of infected individuals regardless of their symptoms. The present study aimed to assess the presence of SARS-CoV-2 RNA in wastewater and river water in Yamanashi Prefecture, Japan, using four quantitative and two nested PCR assays. Influent and secondary-treated (before chlorination) wastewater samples and river water samples were collected five times from a wastewater treatment plant and three times from a river, respectively, between March 17 and May 7, 2020. The wastewater and river water samples (200-5000 mL) were processed by using two different methods: the electronegative membrane-vortex (EMV) method and the membrane adsorption-direct RNA extraction method. Based on the observed concentrations of indigenous pepper mild mottle virus RNA, the EMV method was found superior to the membrane adsorption-direct RNA extraction method. SARS-CoV-2 RNA was successfully detected in one of five secondary-treated wastewater samples with a concentration of 2.4 × 10³ copies/L by N_Sarbeco qPCR assay following the EMV method, with sequence confirmation of the qPCR product, whereas all the influent samples were tested negative for SARS-CoV-2 RNA. This result could be attributed to higher limit of detection for influent (4.0 × 10³-8.2 × 10⁴ copies/L) with a lower filtration volume (200 mL) compared to that for secondary-treated wastewater (1.4 × 10²-2.5 × 10³ copies/L) with a higher filtration volume of 5000 mL. None of the river water samples tested positive for SARS-CoV-2 RNA. Comparison with the reported COVID-19 cases in Yamanashi Prefecture showed that SARS-CoV-2 RNA was detected in the secondary-treated wastewater sample when the cases peaked in the community. This is the first study reporting the detection of SARS-CoV-2 RNA in wastewater in Japan.

First environmental surveillance for the presence of SARS-CoV-2 RNA in wastewater and river water in Japan

Wastewater-based epidemiology is a powerful tool to understand the actual incidence of coronavirus disease 2019 (COVID-19) in a community because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, can be shed in the feces of infected individuals regardless of their symptoms. The present study aimed to assess the presence of SARS-CoV-2 RNA in wastewater and river water in Yamanashi Prefecture, Japan, using four quantitative and two nested PCR assays. Influent and secondary-treated (before chlorination) wastewater samples and river water samples were collected five times from a wastewater treatment plant and three times from a river, respectively, between March 17 and May 7, 2020. The wastewater and river water samples (200-5000 mL) were processed by using two different methods: the electronegative membrane-vortex (EMV) method and the membrane adsorption-direct RNA extraction method. Based on the observed concentrations of indigenous pepper mild mottle virus RNA, the EMV method was found superior to the membrane adsorption-direct RNA extraction method. SARS-CoV-2 RNA was successfully detected in one of five secondary-treated wastewater samples with a concentration of 2.4 × 10³ copies/L by N_Sarbeco qPCR assay following the EMV method, with sequence confirmation of the qPCR product, whereas all the influent samples were tested negative for SARS-CoV-2 RNA. This result could be attributed to higher limit of detection for influent (4.0 × 10³-8.2 × 10⁴ copies/L) with a lower filtration volume (200 mL) compared to that for secondary-treated wastewater (1.4 × 10²-2.5 × 10³ copies/L) with a higher filtration volume of 5000 mL. None of the river water samples tested positive for SARS-CoV-2 RNA. Comparison with the reported COVID-19 cases in Yamanashi Prefecture showed that SARS-CoV-2 RNA was detected in the secondary-treated wastewater sample when the cases peaked in the community. This is the first study reporting the detection of SARS-CoV-2 RNA in wastewater in Japan.

Increased Risk of COVID-19 Among Users of Proton Pump Inhibitors

INTRODUCTION

Proton pump inhibitors (PPIs) increase the risk for enteric infections that is likely related to PPI-induced hypochlorhydria. Although the impact of acid suppression on severe acute respiratory syndrome coronavirus 2 is unknown thus far, previous data revealed that pH ≤3 impairs the infectivity of the similar severe acute respiratory syndrome coronavirus 1. Thus, we aimed to determine whether use of PPIs increases the odds for acquiring coronavirus disease 2019 (COVID-19) among community-dwelling Americans.

METHODS

From May 3 to June 24, 2020, we performed an online survey described to participating adults as a "national health survey." A multivariable logistic regression was performed on reporting a positive COVID-19 test to adjust for a wide range of confounding factors and to calculate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

Of 53,130 participants, 3,386 (6.4%) reported a positive COVID-19 test. In regression analysis, individuals using PPIs up to once daily (aOR 2.15; 95% CI, 1.90-2.44) or twice daily (aOR 3.67; 95% CI, 2.93-4.60) had significantly increased odds for reporting a positive COVID-19 test when compared with those not taking PPIs. Individuals taking histamine-2 receptor antagonists were not at elevated risk.

DISCUSSION

We found evidence of an independent, dose-response relationship between the use of antisecretory medications and COVID-19 positivity; individuals taking PPIs twice daily have higher odds for reporting a positive test when compared with those using lower-dose PPIs up to once daily, and those taking the less potent histamine-2 receptor antagonists are not at increased risk. These findings emphasize good clinical practice that PPIs should only be used when indicated at the lowest effective dose, such as the approved once-daily label dosage of over-the-counter and prescription PPIs. Further studies examining the association between PPIs and COVID-19 are needed.

Human intestinal models to study interactions between intestine and microbes

Implementations of suitable in vitro cell culture systems of the human intestine have been essential tools in the study of the interaction among organs, commensal microbiota, pathogens and parasites. Due to the great complexity exhibited by the intestinal tissue, researchers have been developing in vitro/ex vivo systems to diminish the gap between conventional cell culture models and the human intestine. These models are able to reproduce different structures and functional aspects of the tissue. In the present review, information is recapitulated on the most used models, such as cell culture, intestinal organoids, scaffold-based three-dimensional models, and organ-on-a-chip and their use in studying the interaction between human intestine and microbes, and their advantages and limitations are also discussed.

Severe Acute Respiratory Distress Syndrome Secondary to Coronavirus 2 (SARS-CoV-2)

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and has created a worldwide pandemic. Many patients with this infection have an asymptomatic or mild illness, but a small percentage of patients require hospitalization and intensive care. Patients with respiratory tract involvement have a spectrum of presentations that range from scattered ground-glass infiltrates to diffuse infiltrates with consolidation. Patients with the latter radiographic presentation have severe hypoxemia and usually require mechanical ventilation. In addition, some patients develop multiorgan failure, deep venous thrombi with pulmonary emboli, and cytokine storm syndrome. The respiratory management of these patients should focus on using low tidal volume ventilation with low intrathoracic pressures. Some patients have significant recruitable lung and may benefit from higher positive end-expiratory pressure (PEEP) levels and/or prone positioning. There is no well-established anti-viral treatment for this infection; the United States Food and Drug Administration (FDA) has provided emergency use authorization for convalescent plasma and remdesivir for the treatment of patients with COVID-19. In addition, randomized trials have demonstrated that dexamethasone improves outcomes in patients on mechanical ventilators or on oxygen. There are ongoing trials of other drugs which have the potential to moderate the acute inflammatory state seen in some of these patients. These patients often need prolonged high-level intensive care. Hospitals are confronted with significant challenges in patient management, supply management, health care worker safety, and health care worker burnout.

Shelter from the cytokine storm: pitfalls and prospects in the development of SARS-CoV-2 vaccines for an elderly population

The SARS-CoV-2 pandemic urgently calls for the development of effective preventive tools. COVID-19 hits greatly the elder and more fragile fraction of the population boosting the evergreen issue of the vaccination of older people. The development of a vaccine against SARS-CoV-2 tailored for the elderly population faces the challenge of the poor immune responsiveness of the older population due to immunosenescence, comorbidities, and pharmacological treatments. Moreover, it is likely that the inflammaging phenotype associated with age could both influence vaccination efficacy and exacerbate the risk of COVID-19-related "cytokine storm syndrome" with an overlap between the factors which impact vaccination effectiveness and those that boost virulence and worsen the prognosis of SARS-CoV-2 infection. The complex and still unclear immunopathological mechanisms of SARS-CoV-2 infection, together with the progressive age-related decline of immune responses, and the lack of clear correlates of protection, make the design of vaccination strategies for older people extremely challenging. In the ongoing effort in vaccine development, different SARS-CoV-2 vaccine candidates have been developed, tested in pre-clinical and clinical studies and are undergoing clinical testing, but only a small fraction of these are currently being tested in the older fraction of the population. Recent advances in systems biology integrating clinical, immunologic, and omics data can help to identify stable and robust markers of vaccine response and move towards a better understanding of SARS-CoV-2 vaccine responses in the elderly.

Covid-19 pandemic and pregnancy

At the end of 2019, a new coronavirus disease, COVID-19, emerged and quickly spread around the world. Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), the causative virus of this disease, belongs to the β-coronavirus family, together with SARS and middle east respiratory syndrome, and has similar biological characteristics to these viruses. For obstetricians, the susceptibility and prognoses of pregnant women and the effects of the infection on the fetus have been the focus of attention; however, at present, the seriousness of the disease in pregnant women is not apparent, and COVID-19 does not increase the rate of miscarriage, stillbirth, preterm labor or teratogenicity. Even so, carriers might transmit SARS-CoV-2 to pregnant women. Thus, we must keep in mind that all medical personnel must understand and maintain standard precautions in their clinical and laboratory practices.

The Mitochondrial Outer Membrane Protein Tom70-Mediator in Protein Traffic, Membrane Contact Sites and Innate Immunity

Tom70 is a versatile adaptor protein of 70 kDa anchored in the outer membrane of mitochondria in metazoa, fungi and amoeba. The tertiary structure was resolved for the Tom70 of yeast, showing 26 α-helices, most of them participating in the formation of 11 tetratricopeptide repeat (TPR) motifs. Tom70 serves as a docking site for cytosolic chaperone proteins and co-chaperones and is thereby involved in the uptake of newly synthesized chaperone-bound proteins in mitochondrial biogenesis. In yeast, Tom70 additionally mediates ER-mitochondria contacts via binding to sterol transporter Lam6/Ltc1. In mammalian cells, TOM70 promotes endoplasmic reticulum (ER) to mitochondria Ca2+ transfer by association with the inositol-1,4,5-triphosphate receptor type 3 (IP3R3). TOM70 is specifically targeted by the Bcl-2-related protein MCL-1 that acts as an anti-apoptotic protein in macrophages infected by intracellular pathogens, but also in many cancer cells. By participating in the recruitment of PINK1 and the E3 ubiquitin ligase Parkin, TOM70 can be implicated in the development of Parkinson's disease. TOM70 acts as receptor of the mitochondrial antiviral-signaling protein (MAVS) and thereby participates in the corresponding system of innate immunity against viral infections. The protein encoded by Orf9b in the genome of SARS-CoV-2 binds to TOM70, probably compromising the synthesis of type I interferons.

Functional Landscape of SARS-CoV-2 Cellular Restriction

A deficient interferon response to SARS-CoV-2 infection has been implicated as a determinant of severe COVID-19. To identify the molecular effectors that govern interferon control of SARS-CoV-2 infection, we conducted a large-scale gain-of-function analysis that evaluated the impact of human interferon stimulated genes (ISGs) on viral replication. A limited subset of ISGs were found to control viral infection, including endosomal factors that inhibited viral entry, nucleic acid binding proteins that suppressed viral RNA synthesis, and a highly enriched cluster of ER and Golgi-resident ISGs that inhibited viral translation and egress. These included the type II integral membrane protein BST2/tetherin, which was found to impede viral release, and is targeted for immune evasion by SARS-CoV-2 Orf7a protein. Overall, these data define the molecular basis of early innate immune control of viral infection, which will facilitate the understanding of host determinants that impact disease severity and offer potential therapeutic strategies for COVID-19.

Analysis of the intestinal microbiota in COVID-19 patients and its correlation with the inflammatory factor IL-18

The ongoing global pandemic of COVID-19 disease, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mainly infect lung epithelial cells, and spread mainly through respiratory droplets. However, recent studies showed potential intestinal infection of SARS-CoV-2, implicated the possibility that the intestinal infection of SARS-CoV-2 may correlate with the dysbiosis of gut microbiota, as well as the severity of COVID-19 symptoms. Here, we investigated the alteration of the gut microbiota in COVID-19 patients, as well as analyzed the correlation between the altered microbes and the levels of intestinal inflammatory cytokine IL-18, which was reported to be elevated in the serum of in COVID-19 patients. Comparing with healthy controls or seasonal flu patients, the gut microbiota showed significantly reduced diversity, with increased opportunistic pathogens in COVID-19 patients. Also, IL-18 level was higher in the fecal samples of COVID-19 patients than in those of either healthy controls or seasonal flu patients. Moreover, the IL-18 levels were even higher in the fecal supernatants obtained from COVID-19 patients that tested positive for SARS-CoV-2 RNA than those that tested negative in fecal samples. These results indicate that changes in gut microbiota composition might contribute to SARS-CoV-2-induced production of inflammatory cytokines in the intestine and potentially also to the onset of a cytokine storm.

SARS-CoV-2, an Underestimated Pathogen of the Nervous System

Numerous clinical studies have reported neurological symptoms in COVID-19 patients since the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), apart from the atypical signs of pneumonia. Angiotensin-converting enzyme-2 (ACE-2), a potential receptor for SARS-CoV-2 entry, is expressed on various brain cells and cerebral parts, i.e., subfornical organ, paraventricular nucleus, nucleus of the tractus solitarius, and rostral ventrolateral medulla, as well as in non-cardiovascular areas such as the motor cortex and raphe. The resident CNS cells like astrocytes and microglia also express ACE-2, thus highlighting the vulnerability of the nervous system to SARS-CoV-2 infection. Additionally, transmembrane serine protease 2 (TMPRSS2) and furin facilitate virus entry into the host. Besides, the probable routes of virus entry into the nervous system include the hematogenic pathway, through the vagus, the olfactory nerve, or the enteric nervous system. However, the trajectory of SARS-CoV-2 to the brain needs investigation. Furthermore, a Th17-mediated cytokine storm is seen in COVID-19 cases with higher levels of IL-1β/2/7/8/9/10/17, GM-CSF, IFN-γ, TNF-α, CXCL-10, MCP1, and MIP1α/β. Some cytokines can cross the blood-brain barrier and activate the brain's immune cells to produce neural cytokines, leading to neuronal dysfunctions. Nonetheless, most of the neurological conditions developed due to viral infections may not have effective and registered treatments. Although, some antivirals may inhibit the virus-mediated pathogenesis and prove to be suitable in COVID-19 treatment. Therefore, clinicians' and researchers' collective expertise may unravel the potential of SARS-CoV-2 infection to prevent short-term and long-term CNS damage.

Vitamin D sufficiency, a serum 25-hydroxyvitamin D at least 30 ng/mL reduced risk for adverse clinical outcomes in patients with COVID-19 infection

BACKGROUND

To investigate the association between serum 25-hydroxyvitamin D levels and its effect on adverse clinical outcomes, and parameters of immune function and mortality due to a SARS-CoV-2 infection.

STUDY DESIGN

The hospital data of 235 patients infected with COVID-19 were analyzed.

RESULTS

Based on CDC criteria, among our study patients, 74% had severe COVID-19 infection and 32.8% were vitamin D sufficient. After adjusting for confounding factors, there was a significant association between vitamin D sufficiency and reduction in clinical severity, inpatient mortality serum levels of C-reactive protein (CRP) and an increase in lymphocyte percentage. Only 9.7% of patients older than 40 years who were vitamin D sufficient succumbed to the infection compared to 20% who had a circulating level of 25(OH)D< 30 ng/ml. The significant reduction in serum CRP, an inflammatory marker, along with increased lymphocytes percentage suggest that vitamin D sufficiency also may help modulate the immune response possibly by reducing risk for cytokine storm in response to this viral infection.

CONCLUSION

Therefore, it is recommended that improving vitamin D status in the general population and in particular hospitalized patients has a potential benefit in reducing the severity of morbidities and mortality associated with acquiring COVID-19.

An Asymptomatic SARS-CoV-2-Infected Infant With Persistent Fecal Viral RNA Shedding in a Family Cluster: A Rare Case Report

An outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become pandemic worldwide. A better understanding of asymptomatic infections is crucial to prevent and control this epidemic. Here, we report the epidemiological and clinical characteristics of a family cluster with SARS-CoV-2 infection. In the family cluster, a 32-year-old male (case 1) and a 53-year-old female (case 2, the mother-in-law of case 1) exhibited clinical symptoms of COVID-19, while case 1's 32-year-old wife (case 3) and their 11-month-old daughter (case 4) were both asymptomatic. Notably, case 4's nasopharyngeal swab samples was negative for nearly 80 days, and her immune system has been boosted for at least 57 days, but the fecal samples have tested positive for 100 days (May 13, 2020), suggesting SARS-CoV-2 may invade enterocytes and may exist in individuals with low antiviral immunity for a long term. This report highlights that asymptomatic infections should be managed with caution and vigilance. For SARS-CoV-2 testing of asymptomatic cases, besides the normally used nasopharyngeal swab, fecal sample testing is also needed.

SARS-CoV-2 targets neurons of 3D human brain organoids

COVID‐19 pandemic caused by SARS‐CoV‐2 infection is a public health emergency. COVID‐19 typically exhibits respiratory illness. Unexpectedly, emerging clinical reports indicate that neurological symptoms continue to rise, suggesting detrimental effects of SARS‐CoV‐2 on the central nervous system (CNS). Here, we show that a Düsseldorf isolate of SARS‐CoV‐2 enters 3D human brain organoids within 2 days of exposure. We identified that SARS‐CoV‐2 preferably targets neurons of brain organoids. Imaging neurons of organoids reveal that SARS‐CoV‐2 exposure is associated with altered distribution of Tau from axons to soma, hyperphosphorylation, and apparent neuronal death. Our studies, therefore, provide initial insights into the potential neurotoxic effect of SARS‐CoV‐2 and emphasize that brain organoids could model CNS pathologies of COVID‐19.

Consensus transcriptional regulatory networks of coronavirus-infected human cells

Establishing consensus around the transcriptional interface between coronavirus (CoV) infection and human cellular signaling pathways can catalyze the development of novel anti-CoV therapeutics. Here, we used publicly archived transcriptomic datasets to compute consensus regulatory signatures, or consensomes, that rank human genes based on their rates of differential expression in MERS-CoV (MERS), SARS-CoV-1 (SARS1) and SARS-CoV-2 (SARS2)-infected cells. Validating the CoV consensomes, we show that high confidence transcriptional targets (HCTs) of MERS, SARS1 and SARS2 infection intersect with HCTs of signaling pathway nodes with known roles in CoV infection. Among a series of novel use cases, we gather evidence for hypotheses that SARS2 infection efficiently represses E2F family HCTs encoding key drivers of DNA replication and the cell cycle; that progesterone receptor signaling antagonizes SARS2-induced inflammatory signaling in the airway epithelium; and that SARS2 HCTs are enriched for genes involved in epithelial to mesenchymal transition. The CoV infection consensomes and HCT intersection analyses are freely accessible through the Signaling Pathways Project knowledgebase, and as Cytoscape-style networks in the Network Data Exchange repository.

A Single-Cell RNA Expression Map of Human Coronavirus Entry Factors

To predict the tropism of human coronaviruses, we profile 28 SARS-CoV-2 and coronavirus-associated receptors and factors (SCARFs) using single-cell transcriptomics across various healthy human tissues. SCARFs include cellular factors both facilitating and restricting viral entry. Intestinal goblet cells, enterocytes, and kidney proximal tubule cells appear highly permissive to SARS-CoV-2, consistent with clinical data. Our analysis also predicts non-canonical entry paths for lung and brain infections. Spermatogonial cells and prostate endocrine cells also appear to be permissive to SARS-CoV-2 infection, suggesting male-specific vulnerabilities. Both pro- and anti-viral factors are highly expressed within the nasal epithelium, with potential age-dependent variation, predicting an important battleground for coronavirus infection. Our analysis also suggests that early embryonic and placental development are at moderate risk of infection. Lastly, SCARF expression appears broadly conserved across a subset of primate organs examined. Our study establishes a resource for investigations of coronavirus biology and pathology.

Common genetic variation in humans impacts in vitro susceptibility to SARS-CoV-2 infection

The host response to SARS-CoV-2, the etiologic agent of the COVID-19 pandemic, demonstrates significant inter-individual variability. In addition to showing more disease in males, the elderly, and individuals with underlying comorbidities, SARS-CoV-2 can seemingly render healthy individuals with profound clinical complications. We hypothesize that, in addition to viral load and host antibody repertoire, host genetic variants also impact vulnerability to infection. Here we apply human induced pluripotent stem cell (hiPSC)-based models and CRISPR-engineering to explore the host genetics of SARS-CoV-2. We demonstrate that a single nucleotide polymorphism (rs4702), common in the population at large, and located in the 3'UTR of the protease FURIN, impacts alveolar and neuron infection by SARS-CoV-2 in vitro. Thus, we provide a proof-of-principle finding that common genetic variation can impact viral infection, and thus contribute to clinical heterogeneity in SARS-CoV-2. Ongoing genetic studies will help to better identify high-risk individuals, predict clinical complications, and facilitate the discovery of drugs that might treat disease.

Single-cell RNA sequencing analysis of SARS-CoV-2 entry receptors in human organoids

Coronavirus disease‐2019 (COVID‐19) is a global pandemic and caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), which has resulted in millions of deaths worldwide. Reports denote SARS‐CoV‐2 uses angiotensin‐converting enzyme 2 (ACE2), transmembrane serine protease 2 (TMPRSS2) as its primary entry point into the host cell. However, understanding the biology behind this viral replication, disease mechanism and drug discovery efforts are limited due to the lack of a suitable experimental model. Here, we used single‐cell RNA sequencing data of human organoids to analyze expressions of ACE2 and TMPRSS2, in addition to an array of RNA receptors to examine their role in SARS‐CoV‐2 pathogenesis. ACE2 is abundant in all organoids, except the prostate and brain, and TMPRSS2 is omnipresent. Innate immune pathways are upregulated in ACE2(+) cells of all organoids, except the lungs. Besides this, the expression of low‐density lipoprotein receptor is highly enriched in ACE2(+) cells in intestinal, lung, and retinal organoids, with the highest expression in lung organoids. Collectively, this study demonstrates that the organoids can be used as an experimental platform to explore this novel virus disease mechanism and for drug development.

Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients

Objectives

Because the detection of SARS-CoV-2 RNA in aerosols but failure to isolate viable (infectious) virus are commonly reported, there is substantial controversy whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be transmitted through aerosols. This conundrum occurs because common air samplers can inactivate virions through their harsh collection processes. We sought to resolve the question whether viable SARS-CoV-2 can occur in aerosols using VIVAS air samplers that operate on a gentle water vapor condensation principle.

Methods

Air samples collected in the hospital room of two coronavirus disease-2019 (COVID-19) patients, one ready for discharge and the other newly admitted, were subjected to RT-qPCR and virus culture. The genomes of the SARS-CoV-2 collected from the air and isolated in cell culture were sequenced.

Results

Viable SARS-CoV-2 was isolated from air samples collected 2 to 4.8 m away from the patients. The genome sequence of the SARS-CoV-2 strain isolated from the material collected by the air samplers was identical to that isolated from the newly admitted patient. Estimates of viable viral concentrations ranged from 6 to 74 TCID₅₀ units/L of air.

Conclusions

Patients with respiratory manifestations of COVID-19 produce aerosols in the absence of aerosol-generating procedures that contain viable SARS-CoV-2, and these aerosols may serve as a source of transmission of the virus.

Central Nervous System Targets and Routes for SARS-CoV-2: Current Views and New Hypotheses

As the coronavirus disease 2019 (COVID-19) pandemic unfolds, neurological signs and symptoms reflect the involvement of targets beyond the primary lung effects. The etiological agent of COVID-19, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), exhibits neurotropism for central and peripheral nervous systems. Various infective mechanisms and paths can be exploited by the virus to reach the central nervous system, some of which bypass the blood-brain barrier; others alter its integrity. Numerous studies have established beyond doubt that the membrane-bound metalloprotease angiotensin-converting enzyme 2 (ACE2) performs the role of SARS-CoV-2 host-cell receptor. Histochemical studies and more recently transcriptomics of mRNA have dissected the cellular localization of the ACE2 enzyme in various tissues, including the central nervous system. Epithelial cells lining the nasal mucosae, the upper respiratory tract, and the oral cavity, bronchoalveolar cells type II in the pulmonary parenchyma, and intestinal enterocytes display ACE2 binding sites at their cell surfaces, making these epithelial mucosae the most likely viral entry points. Neuronal and glial cells and endothelial cells in the central nervous system also express ACE2. This short review analyzes the known entry points and routes followed by the SARS-CoV-2 to reach the central nervous system and postulates new hypothetical pathways stemming from the enterocytes lining the intestinal lumen.

Implications of Sex Differences in Immunity for SARS-CoV-2 Pathogenesis and Design of Therapeutic Interventions

Men present more frequently with severe manifestations of coronavirus disease 2019 (COVID-19) and are at higher risk for death. The underlying mechanisms for these differences between female and male individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are insufficiently understood. However, studies from other viral infections have shown that females can mount stronger immune responses against viruses than males. Emerging knowledge on the basic biological pathways that underlie differences in immune responses between women and men needs to be incorporated into research efforts on SARS-CoV-2 pathogenesis and pathology to identify targets for therapeutic interventions aimed at enhancing antiviral immune function and lung airway resilience while reducing pathogenic inflammation in COVID-19.

SARS-CoV-2 infection of human iPSC-derived cardiac cells predicts novel cytopathic features in hearts of COVID-19 patients

Although COVID-19 causes cardiac dysfunction in up to 25% of patients, its pathogenesis remains unclear. Exposure of human iPSC-derived heart cells to SARS-CoV-2 revealed productive infection and robust transcriptomic and morphological signatures of damage, particularly in cardiomyocytes. Transcriptomic disruption of structural proteins corroborated adverse morphologic features, which included a distinct pattern of myofibrillar fragmentation and numerous iPSC-cardiomyocytes lacking nuclear DNA. Human autopsy specimens from COVID-19 patients displayed similar sarcomeric disruption, as well as cardiomyocytes without DNA staining. These striking cytopathic features provide new insights into SARS-CoV-2 induced cardiac damage, offer a platform for discovery of potential therapeutics, and raise serious concerns about the long-term consequences of COVID-19.

Occult Colonic Perforation in a Patient With Coronavirus Disease 2019 After Interleukin-6 Receptor Antagonist Therapy

Background

Interleukin-6 blockade (IL-6) has become a focus of therapeutic investigation for the coronavirus disease 2019 (COVID-19).

Methods

We report a case of a 34-year-old with COVID-19 pneumonia receiving an IL-6 receptor antagonist (IL-6Ra) who developed spontaneous colonic perforation. This perforation occurred despite a benign abdominal exam and in the absence of other known risk factors associated with colonic perforation.

Results

Examination of the colon by electron microscopy revealed numerous intact severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virions abutting the microvilli of the colonic mucosa. Multiplex immunofluorescent staining revealed the presence of the SARS-CoV-2 spike protein on the brush borders of colonic enterocytes that expressed angiotensin-converting enzyme 2. However, no viral particles were observed within the enterocytes to suggest direct viral injury as the cause of colonic perforation.

Conclusions

These data and absence of known risk factors for spontaneous colonic perforation implicate IL-6Ra therapy as the potential mediator of colonic injury in this case. Furthermore, this report provides the first in situ visual evidence of the virus in the colon of a patient presenting with colonic perforation adding to growing evidence that intact infectious virus can be present in the stool.

Expression of ACE2 and a viral virulence-regulating factor CCN family member 1 in human iPSC-derived neural cells: implications for COVID-19-related CNS disorders

It has been reported that coronavirus disease 2019 (COVID-19) causes not only pneumonia but also systemic inflammations including central nervous system (CNS) disorders. However, little is known about the mechanism that triggers the COVID-19-associated CNS disorders, due to the lack of appropriate experimental systems. Our present study showed that angiotensin-converting enzyme-2 (ACE2), a cellular receptor for SARS-CoV-2, is expressed in human induced pluripotent stem cell (iPSC)-derived neural stem/progenitor cells (hiPSC-NS/PCs) and young neurons. Furthermore, together with database analysis, we found that a viral virulent factor CCN family member 1 (CCN1), which is known to be induced by SARS-CoV-2 infection, is expressed in these cells at basal levels. Considering the role of CCN1 which is known to be involved in viral toxicity and inflammation, hiPSC-NS/PCs could provide an excellent model for COVID-19-associated CNS disorders from the aspect of SARS-CoV-2 infection-ACE2-CCN1 axis. In addition, we identified compounds that reduce CCN1 expression. Collectively, our study using hiPSC-NS/PCs may aid in the development of a therapeutic target for COVID-19-related CNS disorders.

Intestinal Receptor of SARS-CoV-2 in Inflamed IBD Tissue Seems Downregulated by HNF4A in Ileum and Upregulated by Interferon Regulating Factors in Colon

BACKGROUND

Patients with inflammatory bowel disease [IBD] are considered immunosuppressed, but do not seem more vulnerable for COVID-19. Nevertheless, intestinal inflammation has shown to be an important risk factor for SARS-CoV-2 infection and prognosis. Therefore, we investigated the role of intestinal inflammation on the viral intestinal entry mechanisms, including ACE2, in IBD.

METHODS

We collected inflamed and uninflamed mucosal biopsies from Crohn's disease [CD] [n = 193] and ulcerative colitis [UC] [n = 158] patients, and from 51 matched non-IBD controls for RNA sequencing, differential gene expression, and co-expression analysis. Organoids from UC patients were subjected to an inflammatory mix and processed for RNA sequencing. Transmural ileal biopsies were processed for single-cell [sc] sequencing. Publicly available colonic sc-RNA sequencing data, and microarrays from tissue pre/post anti-tumour necrosis factor [TNF] therapy, were analysed.

RESULTS

In inflamed CD ileum, ACE2 was significantly decreased compared with control ileum [p = 4.6E-07], whereas colonic ACE2 was higher in inflamed colon of CD/UC compared with control [p = 8.3E-03; p = 1.9E-03]. Sc-RNA sequencing confirmed this ACE2 dysregulation and exclusive epithelial ACE2 expression. Network analyses highlighted HNF4A as key regulator of ileal ACE2, and pro-inflammatory cytokines and interferon regulating factors regulated colonic ACE2. Inflammatory stimuli upregulated ACE2 in UC organoids [p = 1.7E-02], but not in non-IBD controls [p = 9.1E-01]. Anti-TNF therapy restored colonic ACE2 regulation in responders.

CONCLUSIONS

Intestinal inflammation alters SARS-CoV-2 coreceptors in the intestine, with opposing dysregulations in ileum and colon. HNF4A, an IBD susceptibility gene, seems an important upstream regulator of ACE2 in ileum, whereas interferon signalling might dominate in colon.

Gastrointestinal involvement of COVID-19 and potential faecal transmission of SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was found initially in Wuhan, China in early December 2019. The pandemic has spread to 216 countries and regions, infecting more than 23310 000 people and causing over 800 000 deaths globally by Aug. 24, 2020, according to World Health Organization (https://www.who.int/emergencies/diseases/ novel-coronavirus-2019). Fever, cough, and dyspnea are the three common symptoms of the condition, whereas the conventional transmission route for SARS-CoV-2 is through droplets entering the respiratory tract. To date, infection control measures for COVID-19 have been focusing on the involvement of the respiratory system. However, ignoring potential faecal transmission and the gastrointestinal involvement of SARS-CoV-2 may result in mistakes in attempts to control the pandemic.

Human norovirus exhibits strain-specific sensitivity to host interferon pathways in human intestinal enteroids

Human noroviruses (HuNoVs) are the leading cause of viral gastroenteritis worldwide; yet currently, no vaccines or FDA-approved antiviral drugs are available to counter these pathogens. To understand HuNoV biology and the epithelial response to infection, we performed transcriptomic analyses, RT-qPCR, CRISPR-Cas9 modification of human intestinal enteroid (HIE) cultures, and functional studies with two virus strains (a pandemic GII.4 and a bile acid-dependent GII.3 strain). We identified a predominant type III interferon (IFN)-mediated innate response to HuNoV infection. Replication of both strains is sensitive to exogenous addition of IFNs, suggesting the potential of IFNs as therapeutics. To obtain insight into IFN pathway genes that play a role in the antiviral response to HuNoVs, we developed knockout (KO) HIE lines for IFN alpha and lambda receptors and the signaling molecules, MAVS, STAT1, and STAT2 An unexpected differential response of enhanced replication and virus spread was observed for GII.3, but not the globally dominant GII.4 HuNoV in STAT1-knockout HIEs compared to parental HIEs. These results indicate cellular IFN responses restrict GII.3 but not GII.4 replication. The strain-specific sensitivities of innate responses against HuNoV replication provide one explanation for why GII.4 infections are more widespread and highlight strain specificity as an important factor in HuNoV biology. Genetically modified HIEs for innate immune genes are useful tools for studying immune responses to viral or microbial pathogens.

Infection of Brain Organoids and 2D Cortical Neurons with SARS-CoV-2 Pseudovirus

Since the global outbreak of SARS-CoV-2 (COVID-19), infections of diverse human organs along with multiple symptoms continue to be reported. However, the susceptibility of the brain to SARS-CoV-2, and the mechanisms underlying neurological infection are still elusive. Here, we utilized human embryonic stem cell-derived brain organoids and monolayer cortical neurons to investigate infection of brain with pseudotyped SARS-CoV-2 viral particles. Spike-containing SARS-CoV-2 pseudovirus infected neural layers within brain organoids. The expression of ACE2, a host cell receptor for SARS-CoV-2, was sustained during the development of brain organoids, especially in the somas of mature neurons, while remaining rare in neural stem cells. However, pseudotyped SARS-CoV-2 was observed in the axon of neurons, which lack ACE2. Neural infectivity of SARS-CoV-2 pseudovirus did not increase in proportion to viral load, but only 10% of neurons were infected. Our findings demonstrate that brain organoids provide a useful model for investigating SARS-CoV-2 entry into the human brain and elucidating the susceptibility of the brain to SARS-CoV-2.

Activation of the SARS-CoV-2 Receptor Ace2 through JAK/STAT-Dependent Enhancers during Pregnancy

ACE2 binds the coronavirus SARS-CoV-2 and facilitates its cellular entry. Interferons activate ACE2 expression in pneumocytes, suggesting a critical role of cytokines in SARS-CoV-2 target cells. Viral RNA was detected in breast milk in at least seven studies, raising the possibility that ACE2 is expressed in mammary tissue during lactation. Here, we show that Ace2 expression in mouse mammary tissue is induced during pregnancy and lactation, which coincides with the activation of intronic enhancers. These enhancers are occupied by the prolactin-activated transcription factor STAT5 and additional regulatory factors, including RNA polymerase II. Deletion of Stat5a results in decommissioning of the enhancers and an 83% reduction of Ace2 mRNA. We also demonstrate that Ace2 expression increases during lactation in lung, but not in kidney and intestine. JAK/STAT components are present in a range of SARS-CoV-2 target cells, opening the possibility that cytokines contribute to the viral load and extrapulmonary pathophysiology.

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Ace2 expression is induced in the mammary glands of pregnant and lactating mice

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Gene enhancers are activated by the prolactin-activated transcription factors STAT5A/B

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Deletion of the Stat5a gene mitigates enhancer formation and Ace2 expression

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Ace2 levels also increase in lung tissue during lactation

Neurological injuries in COVID-19 patients: direct viral invasion or a bystander injury after infection of epithelial/endothelial cells

A subset of patients with coronavirus 2 disease (COVID-19) experience neurological complications. These complications include loss of sense of taste and smell, stroke, delirium, and neuromuscular signs and symptoms. The etiological agent of COVID-19 is SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), an RNA virus with a glycoprotein-studded viral envelope that uses ACE2 (angiotensin-converting enzyme 2) as a functional receptor for infecting the host cells. Thus, the interaction of the envelope spike proteins with ACE2 on host cells determines the tropism and virulence of SARS-CoV-2. Loss of sense of taste and smell is an initial symptom of COVID-19 because the virus enters the nasal and oral cavities first and the epithelial cells are the receptors for these senses. Stroke in COVID-19 patients is likely a consequence of coagulopathy and injury to cerebral vascular endothelial cells that cause thrombo-embolism and stroke. Delirium and encephalopathy in acute and post COVID-19 patients are likely multifactorial and secondary to hypoxia, metabolic abnormalities, and immunological abnormalities. Thus far, there is no clear evidence that coronaviruses cause inflammatory neuromuscular diseases via direct invasion of peripheral nerves or muscles or via molecular mimicry. It appears that most of neurologic complications in COVID-19 patients are indirect and as a result of a bystander injury to neurons.

Virological Characterization of the First 2 COVID-19 Patients Diagnosed in Italy: Phylogenetic Analysis, Virus Shedding Profile From Different Body Sites, and Antibody Response Kinetics

Background

The pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains unclear. We report the detection of viral RNA from different anatomical districts and the antibody profile in the first 2 COVID-19 cases diagnosed in Italy.

Methods

We tested for SARS-CoV-2 RNA clinical samples, either respiratory and nonrespiratory (ie, saliva, serum, urine, vomit, rectal, ocular, cutaneous, and cervico-vaginal swabs), longitudinally collected from both patients throughout the hospitalization. Serological analysis was carried out on serial serum samples to evaluate IgM, IgA, IgG, and neutralizing antibody levels.

Results

SARS-CoV-2 RNA was detected since the early phase of illness, lasting over 2 weeks in both upper and lower respiratory tract samples. Virus isolate was obtained from acute respiratory samples, while no infectious virus was rescued from late respiratory samples with low viral RNA load, collected when serum antibodies had been developed. Several other specimens came back positive, including saliva, vomit, rectal, cutaneous, cervico-vaginal, and ocular swabs. IgM, IgA, and IgG were detected within the first week of diagnosis, with IgG appearing earlier and at higher titers. Neutralizing antibodies developed during the second week, reaching high titers 32 days after diagnosis.

Conclusions

Our longitudinal analysis showed that SARS-CoV-2 RNA can be detected in different body samples, which may be associated with broad tropism and different spectra of clinical manifestations and modes of transmission. Profiling antibody response and neutralizing activity can assist in laboratory diagnosis and surveillance actions.