Membrane Condensation and Curvature Induced by SARS-CoV-2 Envelope Protein.

The envelope (E) protein of SARS-CoV-2 participates in virion encapsulation and budding at the membrane of the endoplasmic reticulum Golgi intermediate compartment (ERGIC). The positively curved membrane topology required to fit an 80 nm viral particle is energetically unfavorable; therefore, viral proteins must facilitate ERGIC membrane curvature alteration. To study the possible role of the E protein in this mechanism, we examined the structural modification of the host lipid membrane by the SARS-CoV-2 E protein using synchrotron-based X-ray methods. Our reflectometry results on solid-supported planar bilayers show that E protein markedly condenses the surrounding lipid bilayer. For vesicles, this condensation effect differs between the two leaflets such that the membrane becomes asymmetric and increases its curvature. The formation of such a curved and condensed membrane is consistent with the requirements to stably encapsulate a viral core and supports a role for E protein in budding during SARS-CoV-2 virion assembly.

Channel Formation in Cry Toxins: An Alphafold-2 Perspective.

Bacillus thuringiensis (Bt) strains produce pore-forming toxins (PFTs) that attack insect pests. Information for pre-pore and pore structures of some of these Bt toxins is available. However, for the three-domain (I-III) crystal (Cry) toxins, the most used Bt toxins in pest control, this crucial information is still missing. In these Cry toxins, biochemical data have shown that 7-helix domain I is involved in insertion in membranes, oligomerization and formation of a channel lined mainly by helix α4, whereas helices α1 to α3 seem to have a dynamic role during insertion. In the case of Cry1Aa, toxic against Manduca sexta larvae, a tetrameric oligomer seems to precede membrane insertion. Given the experimental difficulty in the elucidation of the membrane insertion steps, we used Alphafold-2 (AF2) to shed light on possible oligomeric structural intermediates in the membrane insertion of this toxin. AF2 very accurately (<1 Å RMSD) predicted the crystal monomeric and trimeric structures of Cry1Aa and Cry4Ba. The prediction of a tetramer of Cry1Aa, but not Cry4Ba, produced an 'extended model' where domain I helices α3 and α2b form a continuous helix and where hydrophobic helices α1 and α2 cluster at the tip of the bundle. We hypothesize that this represents an intermediate that binds the membrane and precedes α4/α5 hairpin insertion, together with helices α6 and α7. Another Cry1Aa tetrameric model was predicted after deleting helices α1 to α3, where domain I produced a central cavity consistent with an ion channel, lined by polar and charged residues in helix α4. We propose that this second model corresponds to the 'membrane-inserted' structure. AF2 also predicted larger α4/α5 hairpin n-mers (14 ≤n ≤ 17) with high confidence, which formed even larger (~5 nm) pores. The plausibility of these models is discussed in the context of available experimental data and current paradigms.

The Complex Proteolipidic Behavior of the SARS-CoV-2 Envelope Protein Channel: Weak Selectivity and Heterogeneous Oligomerization.

The envelope (E) protein is a small polypeptide that can form ion channels in coronaviruses. In SARS coronavirus 2 (SARS-CoV-2), the agent that caused the recent COVID-19 pandemic, and its predecessor SARS-CoV-1, E protein is found in the endoplasmic reticulum-Golgi intermediate compartment (ERGIC), where virion budding takes place. Several reports claim that E protein promotes the formation of "cation-selective channels". However, whether this term represents specificity to certain ions (e.g., potassium or calcium) or the partial or total exclusion of anions is debatable. Herein, we discuss this claim based on the available data for SARS-CoV-1 and -2 E and on new experiments performed using the untagged full-length E protein from SARS-CoV-2 in planar lipid membranes of different types, including those that closely mimic the ERGIC membrane composition. We provide evidence that the selectivity of the E-induced channels is very mild and depends strongly on lipid environment. Thus, despite past and recent claims, we found no indication that the E protein forms cation-selective channels that prevent anion transport, and even less that E protein forms bona fide specific calcium channels. In fact, the E channel maintains its multi-ionic non-specific neutral character even in concentrated solutions of Ca2+ ions. Also, in contrast to previous studies, we found no evidence that SARS-CoV-2 E channel activation requires a particular voltage, high calcium concentrations or low pH, in agreement with available data from SARS-CoV-1 E. In addition, sedimentation velocity experiments suggest that the E channel population is mostly pentameric, but very dynamic and probably heterogeneous, consistent with the broad distribution of conductance values typically found in electrophysiological experiments. The latter has been explained by the presence of proteolipidic channel structures.

The intrinsically disordered region of coronins fine-tunes oligomerization and actin polymerization.

Coronins play critical roles in actin network formation. The diverse functions of coronins are regulated by the structured N-terminal ß propeller and the C-terminal coiled coil (CC). However, less is known about a middle "unique region" (UR), which is an intrinsically disordered region (IDR). The UR/IDR is an evolutionarily conserved signature in the coronin family. By integrating biochemical and cell biology experiments, coarse-grained simulations, and protein engineering, we find that the IDR optimizes the biochemical activities of coronins in vivo and in vitro. The budding yeast coronin IDR plays essential roles in regulating Crn1 activity by fine-tuning CC oligomerization and maintaining Crn1 as a tetramer. The IDR-guided optimization of Crn1 oligomerization is critical for F-actin cross-linking and regulation of Arp2/3-mediated actin polymerization. The final oligomerization status and homogeneity of Crn1 are contributed by three examined factors: helix packing, the energy landscape of the CC, and the length and molecular grammar of the IDR.

The cytoplasmic N-terminal tail of Zika virus NS4A protein forms oligomers in the absence of detergent or lipids.

The non-structural (NS) NS4A protein in flaviviruses has three predicted transmembrane domains, is critical for virulence and participates in membrane morphogenesis. In Dengue virus (DENV), both hydrophylic N-terminal tail and its first transmembrane domain participate in the formation of oligomers which are important for pathogenicity. However, the relative importance of the N-terminal domain in oligomerization has been under debate. In particular, since in the absence of detergent or lipids, this domain (residues 1-48) in both DENV and Zika virus (ZIKV) NS4A, was found to be disordered. Recently, however, we reported preliminary data that showed that peptide ZIKV NS4A 4-58 adopts a defined secondary structure in aqueous solution and forms oligomers, signaling its importance for full length NS4A oligomerization. Herein we have performed detailed analytical ultracentrifugation experiments to further characterize the oligomerization of this peptide and also a shorter variant (residues 4-44). In both cases, sedimentation velocity produced a single species with concentration-dependent sedimentation coefficient, consistent with a fast equilibrium between at least two species. Combining sedimentation velocity and equilibrium experiments, data is best fitted to a monomer-dimer-trimer equilibrium. Possible models of NS4A oligomers obtained with AlphaFold-2 predict the stabilizing role for residues in this N-terminal domain, such as Arg20, Asn27, Ala44 and Glu50, all at highly conserved positions in flavivirus NS4A proteins. Our results are thus consistent with N-terminal domain interactions acting as one of the driving forces for NS4A homo-oligomerization.

Anomalous Oligomerization Behavior of E. coli Aquaporin Z in Detergent and in Nanodiscs.

Aquaporins are tetrameric integral membrane proteins that act as water channels, and can also permeabilize membranes to other solutes. The monomer appears to be the functional form despite all aquaporins being organized as tetramers, which therefore must provide a clear functional advantage. In addition to this quaternary organization, some aquaporins can act as adhesion molecules in membrane junctions, when tetramers located in opposing membranes interact via their extracellular domains. These stacked forms have been observed in a range of aquaporins, whether using lipidic membrane environments, in electron crystallography, or using detergent micelles, in single-particle cryo-electron microscopy (cryo-EM). In the latter technique, structural studies can be performed when the aquaporin is reconstituted into nanodiscs of lipids that are surrounded by a protein scaffold. During attempts to study E. coli Aquaporin Z (AqpZ), we have found that in some conditions these nanodiscs tend to form filaments that appear to be either thicker head-to-tail or thinner side-to-side stacks of nanodiscs. Nanodisc oligomerization was observed using orthogonal analytical techniques analytical ultra-centrifugation and mass photometry, although the nature of the oligomers (head-to-tail or side-to-side) could not be determined. Using the latter technique, the AqpZ tetramer itself formed oligomers of increasing size when solubilized only in detergent, which is consistent with multiple stacking of AqpZ tetramers. We observed images consistent with both of these filaments in negative staining EM conditions, but only thicker filaments in cryo-EM conditions. We hypothesize that the apparent nanodisc side-to-side arrangement that can only be visualized in negative staining conditions is related to artifacts due to the sample preparation. Filaments of any kind were not observed in EM when nanodiscs did not contain AqpZ, or after addition of detergent into the nanodisc cryo-EM preparation, at concentrations that did not disrupt nanodisc formation. To our knowledge, these filaments have not been observed in nanodiscs preparations of other membrane proteins. AqpZ, like other aquaporins has a charge asymmetry between the cytoplasmic (more positive) and the extracellular sides, which may explain the likely head-to-tail stacking observed, both in nanodisc preparations and also in detergent micelles.

The Cytoplasmic Domain of the SARS-CoV-2 Envelope Protein Assembles into a ß-Sheet Bundle in Lipid Bilayers.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) envelope (E) protein forms a pentameric ion channel in the lipid membrane of the endoplasmic reticulum Golgi intermediate compartment (ERGIC) of the infected cell. The cytoplasmic domain of E interacts with host proteins to cause virus pathogenicity and may also mediate virus assembly and budding. To understand the structural basis of these functions, here we investigate the conformation and dynamics of an E protein construct (residues 8-65) that encompasses the transmembrane domain and the majority of the cytoplasmic domain using solid-state NMR. 13C and 15N chemical shifts indicate that the cytoplasmic domain adopts a ß-sheet-rich conformation that contains three ß-strands separated by turns. The five subunits associate into an umbrella-shaped bundle that is attached to the transmembrane helices by a disordered loop. Water-edited NMR spectra indicate that the third ß-strand at the C terminus of the protein is well hydrated, indicating that it is at the surface of the ß-bundle. The structure of the cytoplasmic domain cannot be uniquely determined from the inter-residue correlations obtained here due to ambiguities in distinguishing intermolecular and intramolecular contacts for a compact pentameric assembly of this small domain. Instead, we present four structural topologies that are consistent with the measured inter-residue contacts. These data indicate that the cytoplasmic domain of the SARS-CoV-2 E protein has a strong propensity to adopt ß-sheet conformations when the protein is present at high concentrations in lipid bilayers. The equilibrium between the ß-strand conformation and the previously reported α-helical conformation may underlie the multiple functions of E in the host cell and in the virion.

Oligomerization-Dependent Beta-Structure Formation in SARS-CoV-2 Envelope Protein.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic. In SARS-CoV-2, the channel-forming envelope (E) protein is almost identical to the E protein in SARS-CoV, and both share an identical α-helical channel-forming domain. Structures for the latter are available in both detergent and lipid membranes. However, models of the extramembrane domains have only been obtained from solution NMR in detergents, and show no ß-strands, in contrast to secondary-structure predictions. Herein, we have studied the conformation of purified SARS-CoV-2 E protein in lipid bilayers that mimic the composition of ER-Golgi intermediate compartment (ERGIC) membranes. The full-length E protein at high protein-to-lipid ratios produced a clear shoulder at 1635 cm-1, consistent with the ß-structure, but this was absent when the E protein was diluted, which instead showed a band at around 1688 cm-1, usually assigned to ß-turns. The results were similar with a mixture of POPC:POPG (2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine/3-glycerol) and also when using an E-truncated form (residues 8-65). However, the latter only showed ß-structure formation at the highest concentration tested, while having a weaker oligomerization tendency in detergents than in full-length E protein. Therefore, we conclude that E monomer-monomer interaction triggers formation of the ß-structure from an undefined structure (possibly ß-turns) in at least about 15 residues located at the C-terminal extramembrane domain. Due to its proximity to the channel, this ß-structure domain could modulate channel activity or modify membrane structure at the time of virion formation inside the cell.

SARS-CoV-2 accessory protein 7b forms homotetramers in detergent.

A global pandemic is underway caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 genome, like its predecessor SARS-CoV, contains open reading frames that encode accessory proteins involved in virus-host interactions active during infection and which likely contribute to pathogenesis. One of these accessory proteins is 7b, with only 44 (SARS-CoV) and 43 (SARS-CoV-2) residues. It has one predicted transmembrane domain fully conserved, which suggests a functional role, whereas most variability is contained in the predicted cytoplasmic C-terminus. In SARS-CoV, 7b protein is expressed in infected cells, and the transmembrane domain was necessary and sufficient for Golgi localization. Also, anti-p7b antibodies have been found in the sera of SARS-CoV convalescent patients. In the present study, we have investigated the hypothesis that SARS-2 7b protein forms oligomers with ion channel activity. We show that in both SARS viruses 7b is almost completely α-helical and has a single transmembrane domain. In SDS, 7b forms various oligomers, from monomers to tetramers, but only monomers when exposed to reductants. Combination of SDS gel electrophoresis and analytical ultracentrifugation (AUC) in both equilibrium and velocity modes suggests a dimer-tetramer equilibrium, but a monomer-dimer-tetramer equilibrium in the presence of reductant. This data suggests that although disulfide-linked dimers may be present, they are not essential to form tetramers. Inclusion of pentamers or higher oligomers in the SARS-2 7b model were detrimental to fit quality. Preliminary models of this association was generated with AlphaFold2, and two alternative models were exposed to a molecular dynamics simulation in presence of a model lipid membrane. However, neither of the two models provided any evident pathway for ions. To confirm this, SARS-2 p7b was studied using Planar Bilayer Electrophysiology. Addition of p7b to model membranes produced occasional membrane permeabilization, but this was not consistent with bona fide ion channels made of a tetrameric assembly of α-helices.

Safety of Drugs Used during the First Wave of COVID-19: A Hospital-Registry-Based Study.

The emergency of the coronavirus disease 2019 (COVID-19) pandemic led to the off-label use of drugs without data on their toxicity profiles in patients with COVID-19, or on their concomitant use. Patients included in the COVID-19 Patient Registry of a tertiary hospital during the first wave were analyzed to evaluate the adverse drug reactions (ADRs) with the selected treatments. Twenty-one percent of patients (197 out of 933) had at least one ADR, with a total of 240 ADRs. Patients with ADRs were more commonly treated with multiple drugs for COVID-19 infection than patients without ADRs (p < 0.001). They were younger (median 62 years vs. 70.1 years; p < 0.001) and took less medication regularly (69.5% vs. 75.7%; p = 0.031). The most frequent ADRs were gastrointestinal (67.1%), hepatobiliary (10.8%), and cardiac disorders (3.3%). Drugs more frequently involved included lopinavir/ritonavir (82.2%), hydroxychloroquine (72.1%), and azithromycin (66.5%). Although most ADRs recovered without sequelae, fatal cases were described, even though the role of the disease could not be completely ruled out. In similar situations, efforts should be made to use the drugs in the context of clinical trials, and to limit off-label use to those drugs with a better benefit/risk profile in specific situations and for patients at high risk of poor disease prognosis.

Proteoliposome-Incorporated Seawater Reverse Osmosis Polyamide Membrane: Is the Aquaporin Water Channel Effect in Improving Membrane Performance Overestimated?

The water channel feature of the aquaporin (AQP) is considered to be the key in improving the permselectivity of AQP-based thin-film composite (TFC) polyamide (PA) membranes, yet much less attention has been paid to the physicochemical property changes of the PA layer induced by AQP-reconstituted proteoliposomes. This study systematically investigated the roles of proteoliposome constituents (liposome/detergent/AQP) in affecting the physicochemical properties and performance of the membranes. For the first time, we demonstrated that the constituents in the proteoliposome could facilitate the formation of a PA layer with enlarged protuberances and thinner crumples, resulting in a 79% increase in effective surface area and lowering of hydraulic resistance for filtration. These PA structural changes of the AQP-based membrane were found to contribute over 70% to the water permeability increase via comparing the separation performance of the membranes prepared with liposome, detergent, and proteoliposome, respectively, and one proteoliposome-ruptured membrane. The contribution from the AQP water channel feature was about 27% of water permeability increase in the current study, attributed to only ∼20% vesicle coverage in the PA matrix, and this contribution may be easily lost as a result of vesicle rupture during the real seawater reverse osmosis process. This study reveals that the changed morphology dominates the performance improvement of the AQP-based PA membrane and well explains why the actual AQP-based PA membranes cannot acquire the theoretical water/salt selectivity of a biomimetic AQP membrane, deepening our understanding of the AQP-based membranes.

Are Temporal Artery Biopsy Findings Related to PET/CT Findings in Giant Cell Arteritis?

BACKGROUND: Two clinical subsets of giant cell arteritis have been identified with different histological and CT findings. However, PET/CT findings have not been compared with temporal artery biopsy (TAB). OBJECTIVE: The aims of this study were to describe clinical and histological findings in patients with giant cell arteritis according to the presence or absence of aortitis in PET/CT at the disease diagnosis, and to identify independent factors related to aortic involvement. METHODS: Patients were included and followed prospectively. Clinical symptoms and TAB findings were recorded. PET/CT was performed in the first 10 days of steroid therapy. Aortitis was defined if a grade 3 uptake on visual analysis was present on arterial wall. Clinical and histological variables were compared according to the presence or absence of aortitis on PET/CT. Multivariate analysis was performed to identify independent factors related to the presence of aortitis. RESULTS: Twenty-seven patients (median age, 77.6 years) were included. PET/CT was performed with a median delay of 5.0 days. Aortitis was observed in 8 patients. Patients with aortitis were younger (69.9 vs 83.7 years, P = 0.04) and had less frequently ischemic manifestations (25.0% vs 84.2%, P = 0.006) than patients without aortitis. Giant multinucleated cells were more frequent on TAB from patients with aortitis (71.4% vs 16.7%), and its presence was an independent risk factor for the occurrence of aortic involvement on PET/CT (odds ratio, 12.2; P = 0.046). CONCLUSIONS: Our study shows that giant cells on TAB are associated with the presence of aortitis on PET/CT. Patients with aortic involvement are younger and show less frequently ischemic manifestations.

Síndrome de Sjögren y afectación pulmonar / Pulmonary involvement in Sjögren's syndrome

El síndrome de Sjögren es una enfermedad autoinmune que afecta a las glándulas exocrinas. Su sintomatología característica es el síndrome seco en forma de xeroftalmia y xerostomía, pero puede afectar a diversos órganos o sistemas y la afectación extraglandular es la que condiciona el pronóstico de la enfermedad. Típicamente se asocia con la presencia de anticuerpos antinucleares, que incluyen anti-Ro-60. La afectación pulmonar aparece en forma de bronquiectasias y/o neumopatía intersticial. Dada la alta prevalencia de esta complicación, su presencia debe descartarse en todos los pacientes con síntomas respiratorios mediante pruebas de función respiratoria y tomografía computarizada de alta resolución torácica. Se puede completar la valoración mediante biopsia transbronquial en aquellos casos en que existan dudas diagnósticas. El tratamiento incluye glucocorticoterapia, terapia inmunosupresora o antifibrótica, y terapia biológica. En caso de mala evolución se debe valorar el trasplante pulmonar.

Sjögren's syndrome is an autoimmune disease that involves exocrine glands. The most characteristic symptoms consist of the sicca syndrome (including xerostomia and dry eye – xerophtalmia), but can involve multiple organs. The extraglandular involvement determines the prognosis. It is typically associated with the presence of antinuclear antibodies, including Ro-60 antibodies. Pulmonary involvement appears as bronchiectasis and/or interstitial pneumonia. Considering its high prevalence, it must be ruled out in all patients with respiratory symptoms by performing pulmonary function tests and high-resolution computed tomography of the chest. Evaluation can be completed with a transbronchial biopsy if diagnostic doubts persist. Treatment includes steroid therapy, inmunosupressive or antifibrotic drugs, or biological therapy. In selected cases pulmonary transplantation must be considered. (AU)

[Pulmonary involvement in Sjögren's syndrome]. / Síndrome de Sjögren y afectación pulmonar.

Sjögren's syndrome is an autoimmune disease that involves exocrine glands. The most characteristic symptoms consist of the sicca syndrome (including xerostomia and dry eye - xerophtalmia), but can involve multiple organs. The extraglandular involvement determines the prognosis. It is typically associated with the presence of antinuclear antibodies, including Ro-60 antibodies. Pulmonary involvement appears as bronchiectasis and/or interstitial pneumonia. Considering its high prevalence, it must be ruled out in all patients with respiratory symptoms by performing pulmonary function tests and high-resolution computed tomography of the chest. Evaluation can be completed with a transbronchial biopsy if diagnostic doubts persist. Treatment includes steroid therapy, inmunosupressive or antifibrotic drugs, or biological therapy. In selected cases pulmonary transplantation must be considered.

Trimerization of the N-Terminal Tail of Zika Virus NS4A Protein: A Potential In Vitro Antiviral Screening Assay.

The nonstructural (NS) protein NS4A in flaviviruses is a membrane protein that is critical for virulence, and, among other roles, it participates in membrane morphogenesis. In dengue virus (DENV), the NS4A hydrophilic N-terminal tail, together with the first transmembrane domain, is involved in both homo-oligomerization and hetero-oligomerization with NS4B. In both DENV and Zika virus (ZIKV), this N-terminal tail (residues 1-48) forms a random coil in solution but becomes mostly α-helical upon interaction with detergents or lipid membranes. Herein, we show that a peptide from ZIKV NS4A that spans residues 4-58, which includes most of the N-terminal tail and a third of its first transmembrane domain, forms homotrimers in the absence of detergents or liposomes. After interaction with the latter, α-helical content increases, consistent with binding. The oligomeric size of NS4A is not known, as it has only been reported in SDS gels. Therefore, we propose that full-length NS4A forms homotrimers mediated by this region, and that disruption of the oligomerization of peptide ZIKV NS4A 4-58 in solution can potentially constitute the basis for an in vitro assay to discover antivirals.

Optimization of Aquaporin Loading for Performance Enhancement of Aquaporin-Based Biomimetic Thin-Film Composite Membranes.

The aquaporin-based biomimetic thin-film composite membrane (ABM-TFC) has demonstrated superior separation performance and achieved successful commercialization. The larger-scale production of the ABM membrane requires an appropriate balance between the performance and manufacturing cost. This study has systematically investigated the effects of proteoliposome concentration, protein-to-lipid ratio, as well as the additive on the separation performance of ABM for the purpose of finding the optimal preparation conditions for the ABM from the perspective of industrial production. Although increasing the proteoliposome concentration or protein-to-lipid ratio within a certain range could significantly enhance the water permeability of ABMs by increasing the loading of aquaporins in the selective layer, the enhancement effect was marginal or even compromised beyond an optimal point. Alternatively, adding cholesterol in the proteoliposome could further enhance the water flux of the ABM membrane, with minor effects on the salt rejection. The optimized ABM not only achieved a nearly doubled water flux with unchanged salt rejection compared to the control, but also demonstrated satisfactory filtration stability within a wide range of operation temperatures. This study provides a practical strategy for the optimization of ABM-TFC membranes to fit within the scheme of industrial-scale production.

Usefulness of PCR Screening in the Initial Triage of Trauma Patients During COVID-19 Pandemic.

BACKGROUND: Hospitals worldwide have postponed all nonessential surgery during the COVID-19 pandemic, but non-COVID-19 patients are still in urgent need of care. Uncertainty about a patient's COVID-19 status risks infecting health care workers and non-COVID-19 inpatients. We evaluated the use of quantitative reverse transcription polymerase chain reaction (RT-qPCR) screening for COVID-19 on admission for all patients with fractures. METHODS: We conducted a retrospective cohort study of patients older than 18 years admitted with low-energy fractures who were tested by RT-qPCR for SARS-CoV-2 at any time during hospitalization. Two periods based on the applied testing protocol were defined. During the first period, patients were only tested because of epidemiological criteria or clinical suspicion based on fever, respiratory symptoms, or radiological findings. In the second period, all patients admitted for fracture treatment were screened by RT-qPCR. RESULTS: We identified 15 patients in the first period and 42 in the second. In total, 9 (15.8%) patients without clinical or radiological findings tested positive at any moment. Five (33.3%) patients tested positive postoperatively in the first period and 3 (7.1%) in the second period (P = 0.02). For clinically unsuspected patients, postoperative positive detection went from 3 of 15 (20%) during the first period to 2 of 42 (4.8%) in the second (P = 0.11). Clinical symptoms demonstrated high specificity (92.1%) but poor sensitivity (52.6%) for infection detection. CONCLUSIONS: Symptom-based screening for COVID-19 has shown to be specific but not sensitive. Negative clinical symptoms do not rule out infection. Protocols and separated areas are necessary to treat infected patients. RT-qPCR testing on admission helps minimize the risk of nosocomial and occupational infection. LEVEL OF EVIDENCE: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.