Airborne Virus Transmission: Increased Spreading due to Particle Inflation (preprint)

The globally supported social distancing rules to prevent airborne transmission of COVID-19 assume small saliva droplets evaporate fast and large ones, which contain most viral copies, fall fast to the ground. However, during evaporation, solutes distribute non-uniformly within the droplets. We developed a numerical model to predict saliva droplet drying in different environments until the solutes effloresce at the droplets' surface. In a hot and dry ambiance, the solutes form a shell on the droplets' surface, producing light, hollow particles. These inflated particles can float longer and travel farther in the air than their solid counterparts. Considering the droplets' lifetimes, traveling distances, virus infectivities, and virus loads, droplets of a size of 60 {\mu}m to 80 {\mu}m are probably the most dangerous for airborne virus transmission. In hot, dry air, they can carry many highly infectious viral copies over longer distances than expected.

Merkel Cell Polyomavirus Large T Antigen Induces Cellular Senescence for Host Growth Arrest and Viral Genome Persistence through Its Unique Domain.

Senescent cells accumulate in the host during the aging process and are associated with age-related pathogeneses, including cancer. Although persistent senescence seems to contribute to many aspects of cellular pathways and homeostasis, the role of senescence in virus-induced human cancer is not well understood. Merkel cell carcinoma (MCC) is an aggressive skin cancer induced by a life-long human infection of Merkel cell polyomavirus (MCPyV). Here, we show that MCPyV large T (LT) antigen expression in human skin fibroblasts causes a novel nucleolar stress response, followed by p21-dependent senescence and senescence-associated secretory phenotypes (SASPs), which are required for MCPyV genome maintenance. Senolytic and navitoclax treatments result in decreased senescence and MCPyV genome levels, suggesting a potential therapeutic for MCC prevention. Our results uncover the mechanism of a host stress response regulating human polyomavirus genome maintenance in viral persistency, which may lead to targeted intervention for MCC.

Comprehensive analysis of nasal IgA antibodies induced by intranasal administration of the SARS-CoV-2 spike protein (preprint)

Intranasal vaccination is an attractive strategy for preventing COVID-19 disease as it stimulates the production of multimeric secretory immunoglobulin A (IgAs), the predominant antibody isotype in the mucosal immune system, at the target site of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry. Currently, the evaluation of intranasal vaccine efficacy is based on the measurement of polyclonal antibody titers in nasal lavage fluid. However, how individual multimeric secretory IgA protects the mucosa from SARS-CoV-2 infection remains to be elucidated. To understand the precise contribution and molecular nature of multimeric secretory IgAs induced by intranasal vaccines, we developed 99 monoclonal IgAs from nasal mucosa and 114 monoclonal IgAs or IgGs from nonmucosal tissues of mice that were intranasally immunized with the SARS-CoV-2 spike protein. The nonmucosal IgAs exhibited shared origins and both common and unique somatic mutations with the related nasal IgA clones, indicating that the antigen-specific plasma cells in the nonmucosal tissues originated from B cells stimulated at the nasal mucosa. Comparing the spike protein binding reactivity, angiotensin-converting enzyme-2-blocking and SARS-CoV-2 virus neutralization of monomeric and multimeric IgA pairs recognizing different epitopes showed that even nonneutralizing monomeric IgA, which represents 70% of the nasal IgA repertoire, can protect against SARS-CoV-2 infection when expressed as multimeric secretory IgAs. Our investigation is the first to demonstrate the function of nasal IgAs at the monoclonal level, showing that nasal immunization can provide effective immunity against SARS-CoV-2 by inducing multimeric secretory IgAs at the target site of virus infection.

Longitudinal SARS-CoV-2 neutralization of Omicron BA.1, BA.5 and BQ.1.1 after four vaccinations and the impact of break-through infections in hemodialysis patients (preprint)

Background Individuals on hemodialysis are more vulnerable to SARS-CoV-2 infection than the general population due to end-stage kidney disease-induced immunosuppression. Methods 26 hemodialysis patients experiencing SARS-CoV-2 infection after 3rd vaccination were matched 1:1 to 26 out of 92 SARS-CoV-2 naives by age, sex, dialysis vintage and immunosuppressive drugs receiving a 4th vaccination with an mRNA-based vaccine. A competitive surrogate neutralization assay was used to monitor vaccination success. To determine infection neutralization titers, Vero-E6 cells were infected with SARS-CoV-2 variants of concern (VoC), Omicron sub-lineage BA.1, BA.5, and BQ.1.1. 50% inhibitory concentration (IC50, serum dilution factor 1:x) was determined before, four weeks after and 6 months after the 4th vaccination. Results 52 hemodialysis patients received four COVID-19 vaccinations and were followed up for a median of 6.3 months. Patient characteristics did not differ between the matched cohorts. Patients without a SARS-CoV-2 infection had a significant reduction of real virus neutralization capacity for all Omicron sub-lineages after six months (p<0.001 each). Those patients with a virus infection did not experience a reduction of real virus neutralization capacity after six months. Compared to the other Omicron VoC the BQ.1.1 sub-lineage had the lowest virus neutralization capacity. Conclusions SARS-CoV-2-naive hemodialysis patients had significantly decreased virus neutralization capacity six months after the 4th vaccination whereas patients with a SARS-CoV-2 infection had no change in neutralization capacity. This was independent of age, sex, dialysis vintage and immunosuppression. Therefore, in infection-naive hemodialysis patients a fifth COVID-19 vaccination might be reasonable 6 months after the 4th vaccination.

Impaired potency of neutralizing antibodies against cell-cell fusion mediated by SARS-CoV-2 (preprint)

The SARS-CoV-2 Omicron subvariants have dominated the pandemic due to their high transmissibility and immune evasion conferred by the spike mutations. The Omicron subvariants can spread by cell-free virus infection and cell-cell fusion, the latter of which is more effective but has not been extensively investigated. In this study, we developed a simple and high-throughput assay that provides a rapid readout to quantify cell-cell fusion mediated by the SARS-CoV-2 spike proteins without using live or pseudotyped virus. This assay can be used to identify variants of concern and to screen for prophylactic and therapeutic agents. We further evaluated a panel of monoclonal antibodies (mAbs) and vaccinee sera against D614G and Omicron subvariants, finding that cell-cell fusion is substantially more resistant to mAb and serum inhibition than cell-free virus infection. Such results have important implications for the development of vaccines and antiviral antibody drugs against cell-cell fusion induced by SARS-CoV-2 spikes.

Integrated analyses of single-cell RNA-seq public data reveal the gene regulatory network landscape of respiratory epithelial and peripheral immune cells in COVID-19 patients (preprint)

Introduction: Infection with SARS-CoV-2 leads to coronavirus disease 2019 (COVID-19), which can result in acute respiratory distress syndrome and multiple organ failure. However, its comprehensive influence on pathological immune responses in the respiratory epithelium and peripheral immune cells is not yet fully understood. Methods: In this study, we integrated multiple public scRNA-seq datasets of nasopharyngeal swab and peripheral blood results to investigate the gene regulatory networks (GRNs) of healthy individuals and COVID-19 patients with mild/moderate and severe disease, respectively. Similar and dissimilar regulons were identified within or between epithelial and immune cells during COVID-19 severity progression. The relative transcription factors (TFs) and their targets were used to construct GRNs among different infection sites and conditions. Results: Between respiratory epithelial and peripheral immune cells, different TFs tended to be used to regulate the activity of a cell between healthy individuals and COVID-19 patients, although they had some TFs in common. For example, XBP1, FOS, STAT1, and STAT2 were activated in both the epithelial and immune cells of virus-infected individuals. In contrast, severe COVID-19 cases exhibited activation of CEBPD in peripheral immune cells, while CEBPB was exclusively activated in respiratory epithelial cells. Moreover, in patients with severe COVID-19, CEBPD upregulated S100A8 and S100A9 in CD14 and CD16 monocytes, while S100A9 genes were co-upregulated by different regulators (SPEDEF and ELF3) in goblet and squamous cells. The cell-cell communication analysis suggested that epidermal growth factor receptor signaling among epithelial cells contributes to mild/moderate disease, and chemokine signaling among immune cells contributes to severe disease. Conclusions: This study identified cell type- and condition-specific regulons in a wide range of cell types from the initial infection site to the peripheral blood, and clarified the diverse mechanisms of maladaptive responses to SARS-CoV-2 infection.

Generation of a SARS-CoV-2 reverse genetics system and novel human lung cell lines that exhibit high virus-induced cytopathology (preprint)

The global COVID-19 pandemic continues with an increasing number of cases worldwide and the emergence of new SARS-CoV-2 variants. In our study, we have developed novel tools with applications for screening antivirals, identifying virus-host dependencies, and characterizing viral variants. Using reverse genetics, we rescued SARS-CoV-2 Wuhan1 (D614G variant) wild type (WTFL) and reporter virus (NLucFL) using molecular BAC clones. The replication kinetics, plaque morphology and titers were comparable between rescued molecular clones and a clinical isolate (VIDO strain), thus providing confidence that the rescued viruses can be used as effective replication tools. Furthermore, the reporter SARS-CoV-2 NLucFL virus exhibited robust luciferase values over the time course of infection and was used to develop a rapid antiviral assay using remdesivir as proof-of-principle. In addition, as a tool to study lung-relevant virus-host interactions, we established novel human lung cell lines that support SARS-CoV-2 infection with high virus-induced cytopathology. Six lung cell lines (NCI-H23, A549, NCI-H1703, NCI-H520, NCI-H226, and HCC827) and HEK293T cells, were transduced to stably express ACE2 and tested for their ability to support virus infection. A549ACE2 B1 and HEK293TACE2 A2 cell lines exhibited more than 70% virus-induced cell death and a novel lung cell line NCI-H23ACE2 A3 showed about ~99% cell death post-infection. These cell lines are ideal for assays relying on live-dead selection and are currently being used in CRISPR knockout and activation screens in our lab.

Impact of COVID-19 pandemic on the etiology and characteristics of community-acquired pneumonia among children requiring bronchoalveolar lavage in northern China (preprint)

Background: To investigate the etiology and clinical characteristics of community-acquired pneumonia (CAP) among children requiring bronchoalveolar lavage (BAL) and analyze the impact of the coronavirus disease 2019 (COVID-19) pandemic on the pathogen spectrum and clinical manifestations. Methods: Children <14 years old hospitalized with CAP requiring BLA were enrolled between February 2019 to January 2020 and August 2021 to July 2022. Multiplex reverse transcription polymerase chain reaction (mRT-PCR) was used for pathogen detection. The demographic and clinical characteristics were compared between different pathogen-type infection groups, and before and during the COVID-19 pandemic. Results: Pathogen was detected in 91.66% (1363/1487) children. Mycoplasma pneumoniae, adenovirus and human rhinovirus were the most frequently detected pathogens. The frequency of detection of virus infections and co-infections was decreased during the pandemic, but the detection of atypical bacterial infections was increased. The clinical manifestations and the results of CT scans and fiberoptic bronchoscopy showed a significant difference between different types of pathogen infection, and lung inflammation was reduced during the COVID-19 pandemic compared with before the pandemic. Conclusions: M. pneumoniae infection might be the greatest pediatric disease burden leading to CAP in northern China. Wearing masks and social distancing in public places during the COVID-19 pandemic effectively reduced the transmission of respiratory viruses, but it did not reduce the infection rate of M. pneumoniae. In addition, these interventions significantly reduced lung inflammation in children compared with before the pandemic.

Machine learning on large scale perturbation screens for SARS-CoV-2 host factors identifies β-catenin/CBP inhibitor PRI-724 as a potent antiviral (preprint)

Expanding antiviral treatment options against SARS-CoV-2 remains crucial as the virus evolves rapidly and drug resistant strains have emerged. Broad spectrum host-directed antivirals (HDA) are promising therapeutic options, however the robust identification of relevant host factors by CRISPR/Cas9 or RNA interference screens remains challenging due to low consistency in the resulting hits. To address this issue, we employed machine learning based on experimental data from knockout screens and a drug screen. As gold standard, we assembled perturbed genes reducing virus replication or protecting the host cells. The machines based their predictions on features describing cellular localization, protein domains, annotated gene sets from Gene Ontology, gene and protein sequences, and experimental data from proteomics, phospho-proteomics, protein interaction and transcriptomic profiles of SARS-CoV-2 infected cells. The models reached a remarkable performance with a balanced accuracy of 0.82 (knockout based classifier) and 0.71 (drugs screen based classifier), suggesting patterns of intrinsic data consistency. The predicted host dependency factors were enriched in sets of genes particularly coding for development, morphogenesis, and neural related processes. Focusing on development and morphogenesis-associated gene sets, we found {beta}-catenin to be central and selected PRI-724, a canonical {beta}-catenin/CBP disruptor, as a potential HDA. PRI-724 limited infection with SARS-CoV-2 variants, SARS-CoV-1, MERS-CoV and IAV in different cell line models. We detected a concentration-dependent reduction in CPE development, viral RNA replication, and infectious virus production in SARS-CoV-2 and SARS-CoV-1-infected cells. Independent of virus infection, PRI-724 treatment caused cell cycle deregulation which substantiates its potential as a broad spectrum antiviral. Our proposed machine learning concept may support focusing and accelerating the discovery of host dependency factors and the design of antiviral therapies.

A robust Platform for Integrative Spatial Multi-omics Analysis to Map Immune Responses to SARS-CoV-2 infection in Lung Tissues (preprint)

The SARS-CoV-2 (COVID-19) virus has caused a devastating global pandemic of respiratory illness. To understand viral pathogenesis, methods are available for studying dissociated cells in blood, nasal samples, bronchoalveolar lavage fluid, and similar, but a robust platform for deep tissue characterisation of molecular and cellular responses to virus infection in the lungs is still lacking. We developed an innovative spatial multi-omics platform to investigate COVID-19-infected lung tissues. Five tissue-profiling technologies were combined by a novel computational mapping methodology to comprehensively characterise and compare the transcriptome and targeted proteome of virus infected and uninfected tissues. By integrating spatial transcriptomics data (Visium, GeoMx and RNAScope) and proteomics data (CODEX and PhenoImager HT) at different cellular resolutions across lung tissues, we found strong evidence for macrophage infiltration and defined the broader microenvironment surrounding these cells. By comparing infected and uninfected samples, we found an increase in cytokine signalling and interferon responses at different sites in the lung and showed spatial heterogeneity in the expression level of these pathways. These data demonstrate that integrative spatial multi-omics platforms can be broadly applied to gain a deeper understanding of viral effects on cellular environments at the site of infection and to increase our understanding of the impact of SARS-CoV-2 on the lungs.

LINE1-mediated reverse transcription and genomic integration of SARS-CoV-2 mRNA detected in virus-infected but not in viral mRNA-transfected cells (preprint)

SARS-CoV-2 sequences can be reverse-transcribed and integrated into the genomes of virus-infected cells by a LINE1-mediated retrotransposition mechanism. Whole genome sequencing (WGS) methods detected retrotransposed SARS-CoV-2 subgenomic sequences in virus-infected cells overexpressing LINE1, while an enrichment method (TagMap) identified retrotranspositions in cells that did not overexpress LINE1. LINE1 overexpression increased retrotranspositions about 1,000-fold as compared to non-overexpressing cells. Nanopore WGS can directly recover retrotransposed viral and flanking host sequences but its sensitivity depends on the depth of sequencing (a typical 20-fold sequencing depth would only examine 10 diploid cell equivalents). In contrast, TagMap enriches for the host-virus junctions and can interrogate up to 20,000 cells and is able to detect rare viral retrotranspositions in LINE1 non-overexpressing cells. Although Nanopore WGS is 10 - 20-fold more sensitive per tested cell, TagMap can interrogate 1,000 - 2,000-fold more cells and therefore can identify infrequent retrotranspositions. When comparing SARS-CoV-2 infection and viral nucleocapsid mRNA transfection by TagMap, retrotransposed SARS-CoV-2 sequences were only detected in infected but not in transfected cells. Retrotransposition in virus-infected in contrast to transfected cells may be facilitated because virus infection in contrast to viral RNA transfection results in significantly higher viral RNA levels and stimulates LINE1-expression which causes cellular stress.

The natural tannins oligomeric proanthocyanidins and punicalagin are potent inhibitors of infection by SARS-CoV-2 in vitro (preprint)

The COVID-19 pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against SARS-CoV-2 infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention.

Severity Tomographic Score as a Predictor of Mortality in Patients With Covid-19 Pneumonia From a Third-level Hospital in Peru (preprint)

Objective: Determine whether the tomographic characteristics of patients with COVID-19 pneumonia at the hospital admission and the initial tomographic severity score (TSS) as well as some laboratory tests or clinical characteristics predict mortality. Methods: Retrospective analytical study that included patients with a clinical diagnosis of SARSCoV2 virus infection, performed by reverse transcriptase polymerase chain reaction (RT-PCR), serologic reactive test (IgM/IgG) and/or thoracic computed tomography (CT). Patients were divided into two groups: recovered and deceased. Two radiologists (blind evaluators) described the tomographic findings. TSS, clinical and laboratory parameters in relation to mortality were analyzed. Mortality predictions were made by binary logistic regression. Results: Hypertension was the most frequent associated disease, the most common clinical presentation included cough, discomfort, fever, and dyspnea. The ground glass opacity pattern was the most frequent, followed by consolidation and distortion of the architecture; however, they were not associated with higher mortality. The pattern of pleural effusion and bronchial dilation showed a significant difference from mortality (p <0.05). The binary logistic regression model showed that a moderate and high TSS (≥ 8), as well as a higher degree of lymphopenia, history of asthma and age were associated with an increased risk of death (p< 0.05). Conclusions: TSS is useful in the initial and comprehensive diagnostic evaluation of COVID-19 pneumonia, in conjunction with markers such as lymphopenia that can predict a poor short-term outcome. A high TSS score is a predictor of mortality.

Validation of a MALDI-TOF MS method for SARS-CoV-2 detection on the Bruker Biotyper and nasopharyngeal swabs. A Brazil - UK collaborative study. (preprint)

We had developed a MALDI-TOF mass spectrometry method for detection of SARS-CoV-2 virus in saliva-gargle samples using Shimadzu MALDI-TOF mass spectrometers in the UK. This was validated in the USA to CLIA-LDT standards for asymptomatic infection detection remotely via sharing protocols, shipping key reagents, video conference and data exchange. In Brazil, more so than in the UK and USA, there is a need to develop non-PCR dependent rapid affordable SARS-CoV-2 infection screening tests, which also identify variant SARS-CoV-2 and other virus infections. Travel restrictions necessitated remote collaboration with validation on the available Clinical MALDI-TOF - the Bruker Biotyper (microflex LT/SH) - and on nasopharyngeal swab samples, as salivary gargle samples were not available. The Bruker Biotyper was shown to be almost log10^3 more sensitive at detection of high molecular weight spike proteins. A protocol for saline swab soaks out was developed and duplicate swab samples collected in Brazil were analysed by MALDI-TOF MS. The swab collected sample spectra varied from that of gargle-saliva in three additional mass peaks in the mass region expected for IgG heavy chains and human serum albumin. A subset of clinical samples with additional high mass, probably Spike-related proteins, were also found. Spectral data comparisons and analysis, subjected to machine learning algorithms in order to resolve RT-qPCR positive from RT-qPCR negative swab samples, showed a 78% agreement with RT-qPCR scoring for SARS-CoV-2 infection.

SARS-CoV-2 accessory proteins ORF3a and ORF7a modulate autophagic flux and Ca2+ homeostasis in yeast (preprint)

Virus infection involves the manipulation of key host cell functions by specialized virulence proteins. The SARS-CoV-2 small accessory proteins ORF3a and ORF7a have been implicated in favoring virus replication and spreading by inhibiting the autophagic flux within the host cell. Here, we apply yeast models to gain insights into the physiological functions of both SARS-CoV-2 small ORFs. ORF3a and ORF7a can be stably overexpressed in yeast cells, producing a decrease in cellular fitness. Both proteins show a distinguishable intracellular localization. ORF3a specifically localizes to the vacuolar membrane, whereas ORF7a targets the endoplasmic reticulum. Overexpression of ORF3a and ORF7a leads to the accumulation of Atg8 specific autophagosomes. However, the underlying mechanism is different for each viral protein as assessed by the quantification of the autophagic degradation of Atg8-GFP fusion proteins, which is inhibited by ORF3a and stimulated by ORF7a. Overexpression of both SARS-CoV-2 ORFs decreases cellular fitness upon starvation conditions, where autophagic processes become essential. These data are in agreement with a model where both small ORFs have synergistic functions in stimulating intracellular autophagosome accumulation, ORF3a by inhibiting autophagosome processing at the vacuole and ORF7a by promoting autophagosome formation at the ER. ORF3a has an additional function in Ca2+ homeostasis. The overexpression of ORF3a confers calcineurin-dependent Ca2+ tolerance and activates a Ca2+ sensitive FKS2-luciferase reporter, suggesting a possible ORF3a-mediated Ca2+ efflux from the vacuole. Taken together, we show that viral accessory proteins can be functionally investigated in yeast cells and that SARS-CoV-2 ORF3a and ORF7a proteins interfere with autophagosome formation and processing as well as with Ca2+ homeostasis from distinct cellular targets.

Quantitative multi-organ proteomics of fatal COVID-19 uncovers tissue-specific effects beyond inflammation (preprint)

SARS-CoV-2 directly damages lung tissue via its infection and replication process and indirectly due to systemic effects of the host immune system. There are few systems-wide, untargeted studies of these effects on the different tissues of the human body and nearly all of them base their conclusions on the transcriptome. Here we developed a parallelized mass spectrometry (MS)-based proteomics workflow allowing the rapid, quantitative analysis of hundreds of virus-infected and FFPE preserved tissues. The first layer of response in all tissues was dominated by circulating inflammatory molecules. To discriminated between these systemic and true tissue-specific effects, we developed an analysis pipeline revealing that proteome alterations reflect extensive tissue damage, mostly similar to non-COVID diffuse alveolar damage. The next most affected organs were kidney and liver, while the lymph-vessel system was also strongly affected. Finally, secondary inflammatory effects of the brain correlated with receptor rearrangements and the degradation of neuronal myelin. Our results establish MS-based tissue proteomics as a promising strategy to inform organ-specific therapeutic interventions following COVID-19 infections.

Novel genetic association of the Furin gene polymorphism rs1981458 with COVID-19 severity among Indian populations (preprint)

Background SARS CoV-2, the causative agent for the ongoing COVID-19 pandemic, enters the host cell by activating the ACE2 receptor with the help of two proteases, i.e., Furin and TMPRSS2. Therefore, variations in these genes may account for differential susceptibility and severity between populations. Our previous studies have shown that ACE2 and TMPRSS2 gene variants are essential in understanding COVID-19 susceptibility among Indian populations. However, there is a knowledge gap regarding Furin gene variants and their phylogenetic structure among diverse Indian and South Asian ethnic groups and their impact on disease vulnerability, which needs to be investigated.Material and methods Considering the role of the Furin gene in the pathogenesis of SARS-CoV-2. We have used 450 samples from diverse Indian states and performed linear regression to analyse the Furin gene variant's allele frequency with COVID-19 CFR that could be epidemiologically associated with disease severity outcomes among populations. Associated genetic variants were further evaluated for their expression and regulatory potential through various Insilco analyses. Additionally, we examined the Furin gene architecture using next-generation sequencing (NGS) data from 393 diverse global samples, with a particular emphasis on South Asia, to investigate its phylogenetic makeup and the distribution of haplotypes among distinct global populations.Results We found a significant positive association for the rs1981458 with COVID-19 CFR among diverse Indian populations. Further QTL and other regulatory analyses showed various significant associations and positive regulatory roles of this SNP and Furin gene, mainly in Immune cells and virus infection process, highlighting their role in host immunity and viral assembly and processing. The Furin protein-protein interaction suggested that COVID-19 may contribute to Pulmonary arterial hypertension via a typical inflammation mechanism. The phylogenetic architecture of the Furin gene demonstrated a closer genetic affinity between West Eurasian and South Asians. Therefore, it is worth proposing that in the context of the Furin gene, the COVID-19 susceptibility of South Asians will be more similar to the West Eurasian population. Our previous studies on the ACE2 and TMPRSS2 genes showed a contrasting genetic affinity of South Asian with East Eurasians and West Eurasians, respectively. Therefore, we modelled COVID-19 susceptibility for susceptibility of South Asia in between these two major ancestries with an inclination towards West Eurasians.Conclusion In conclusion, this study, for the first time, concluded the role of rs1981458 in COVID-19 severity among the Indian population and outlined its regulatory potential in COVID-19 and genetic structure and susceptibility for COVID-19 susceptibility of South Asia is inclined to West Eurasian population. We believe this insight may well be utilised as a genetic biomarker to identify vulnerable populations, which might be directly relevant for developing policies and allocating resources more effectively during an epidemic.

Ultrasound treatment inhibits SARS-CoV-2 in vitro infectivity (preprint)

Background: COVID-19 (coronavirus disease 2019) is a disease caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), affecting millions of people worldwide, with a high rate of deaths. The present study aims to evaluate ultrasound (US) as a physical method for virus inactivation. Materials and methods: The UV-transductor was exposed to the SARS-CoV-2 viral solution for 30 minutes. Vero-E6 cells were infected with medium exposure or not with the US, using 3-12, 5-10, or 6-18MHz as frequencies applied. We performed confocal microscopy to determine virus infection and replicative process. Moreover, we detected the virus particles with a titration assay. Results: We observed an effective infection of SARS-CoV-2 Wuhan, Delta, and Gamma strains in comparison with mock, an uninfected experimental group. The US treatment was able to inhibit the Wuhan strain in all applied frequencies. Interestingly, 3-12 and 6-18MHz did not inhibit SARS-CoV-2 delta and gamma variants infection, on the other hand, 5-10MHz was able to abrogate infection and replication in all experimental conditions. Conclusions: These results show that SARS-CoV-2 is susceptible to US exposure at a specific frequency 5-10MHz and could be a novel tool for reducing the incidence of SARS-CoV-2 infection. Keywords: Ultrasound, SARS-CoV-2, virucidal effect, COVID-19

Human Early Syncytiotrophoblasts Are Highly Susceptible to SARS-CoV-2 Infection (preprint)

The ongoing and devastating pandemic of coronavirus disease 2019 (COVID-19) has led to a global public health crisis. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and can potentially pose a serious risk to maternal and neonatal health. Cases of abnormal pregnancy and vertical transmission of SARS-CoV-2 from mother to foetus have been reported but no firm conclusions are drawn. Trophoblasts are the major constituents of the placenta to protect and nourish the developing foetus. However, direct in vivo investigation of trophoblast susceptibility to SARS-CoV-2 and of COVID-19 and pregnancy is challenging. Here we report that human early syncytiotrophoblasts (eSTBs) are highly susceptible to SARS-CoV-2 infection in an angiotensin-converting enzyme 2 (ACE2)-dependent manner. From human expanded potential stem cells (hEPSCs), we derived bona fide trophoblast stem cells (TSCs) that resembled those originated from the blastocyst and the placenta in generating functional syncytiotrophoblasts (STBs) and extravillus trophoblasts (EVTs) and in low expression of HLA-A/B and amniotic epithelial (AME) cell signature. The EPSC-TSCs and their derivative trophoblasts including trophoblast organoids could be infected by SARS-CoV-2. Remarkably, eSTBs were highly susceptible to SARS-CoV-2. They expressed high levels of ACE2 and produced substantially higher amounts of virion than Vero E6 cells which are widely used in SARS-CoV-2 research and vaccine production. These findings provide experimental evidence for the clinical observations that opportunistic SARS-CoV-2 infection during pregnancy can occur. At low concentrations, two well characterized antivirals, remdesivir and GC376, effectively eliminated infection of eSTBs by SARS-CoV-2 and middle east respiratory syndrome-related coronavirus (MERS-CoV), and rescued their developmental arrest caused by the virus infection. Several human cell lines have been used in coronavirus research. However, they suffer from genetic and/or innate immune defects and have some of the long-standing technical challenges such as cell transfection and genetic manipulation. In contrast, hEPSCs are normal human stem cells that are robust in culture, genetically stable and permit efficient gene-editing. They can produce and supply large amounts of physiologically relevant normal and genome-edited human cells such as eSTBs for isolation, propagation and production of coronaviruses for basic research, antiviral drug tests and safety evaluation.

Long-term temporal trends in incidence rate and case fatality of sepsis and COVID-19-related sepsis: nationwide registry study (preprint)

Importance: Sepsis is one of the leading causes of morbidity and mortality. The majority of sepsis cases is attributed to bacterial infections, but virus infections can also induce sepsis. Conflicting results in incidence rates and case fatality trends of sepsis is reported, and how the COVID-19 pandemic influenced these trends are unknown. Objective: To estimate temporal trends in incidence rate and case fatality during a 14-year period from 2008 through 2021, and to assess possible shifts in these trends during the COVID-19 pandemic. Design: A nationwide longitudinal registry study using ICD-10 discharge codes to identify sepsis. Setting: All Norwegian hospitals from 2008 through 2021. Participants: All sepsis cases included 317.705 patients and of these, 222.832 had a first sepsis episode. Main outcomes and measures: Annual age-standardized incidence rates with 95% confidence intervals (CI). Poisson regression was used to estimate changes in incidence rates across time, and logistic regression was used to estimate odds ratios for in-hospital death. Results: Among 12.619.803 adult hospitalizations, 317.705 (2.5%) patients met the sepsis criteria and 222.832 (70.0%) had a first sepsis episode. In the period 2009-2019, the annual incidence rate for a first sepsis episode was stable (incidence rate ratio per year, 0.999; 95% CI, 0.994-1.004), whereas for all sepsis the incidence rate increased by 15.5% during the period (annual incidence rate ratio, 1.013; 95% CI 1.007-1.019). During the COVID-19 pandemic, the incidence rate ratio for a first sepsis was 0.877 (95% CI, 0.829-0.927) in 2020 and 0.929 (95% CI, 0.870-0.992) in 2021, and for all sepsis it was 0.870 (95% CI, 0.810-0.935) in 2020 and 0.908 (95% CI, 0.840-0.980) in 2021, compared to the previous 11-year period. In-hospital deaths declined in the period 2009-2019 (odds ratio per year, 0.954 [95% CI,0.950-0.958]), whereas deaths increased during the COVID-19 pandemic in 2020 (odds ratios, 1.061 [95% CI 1.001-1.124] and in 2021 odds ratio (1.164 [95% CI, 1.098-1.233]). Conclusion and relevance: We found a stable incidence rate of a first sepsis episode during the years 2009-2019. However, the increasing burden of all sepsis admissions indicates that sepsis awareness with updated guidelines and education must continue.