Air pollution is a major global environment and health concern. Recent studies have suggested an association between air pollution and COVID-19 mortality and morbidity. In this context, a close association between increased levels of air pollutants such as particulate matter ≤2.5 to 10 µM, ozone and nitrogen dioxide and SARS-CoV-2 infection, hospital admissions and mortality due to COVID 19 has been reported. Air pollutants can make individuals more susceptible to SARS-CoV-2 infection by inducing the expression of proteins such as angiotensin converting enzyme (ACE)2 and transmembrane protease, serine 2 (TMPRSS2) that are required for viral entry into the host cell, while causing impairment in the host defence system by damaging the epithelial barrier, muco-ciliary clearance, inhibiting the antiviral response and causing immune dysregulation. The aim of this review is to report the epidemiological evidence on impact of air pollutants on COVID 19 in an up-to-date manner, as well as to provide insights on in vivo and in vitro mechanisms.

The constant mutation of SARS-CoV-2 has led to the continuous appearance of viral variants and their pandemics and has improved the development of vaccines with a broad spectrum of antigens to curb the spread of the virus. The work described here suggested a novel vaccine with a virus-like structure (VLS) composed of combined mRNA and protein that is capable of stimulating the immune system in a manner similar to that of viral infection. This VLS vaccine is characterized by its ability to specifically target dendritic cells and/or macrophages through S1 protein recognition of the DC-SIGN receptor in cells, which leads to direct mRNA delivery to these innate immune cells for activation of robust immunity with a broad spectrum of neutralizing antibodies and immune protective capacity against variants. Research on its composition characteristics and structural features has suggested its druggability. Compared with the current mRNA vaccine, the VLS vaccine was identified as having no cytotoxicity at its effective application dosage, while the results of safety observations in animals revealed fewer adverse reactions during immunization.

Over the past two decades, various coronaviruses have posed a severe threat to human life and health, with the spike protein (S protein) being a critical protein for infecting host cells. Glycyrrhizic acid (GA), as a natural drug, can inhibit the infection of coronaviruses by binding to the receptor-binding domain (RBD) of the S protein. However, issues like poor water solubility and weak binding affinity with the S protein have hindered its further application. Therefore, drawing inspiration from the biological structure of centipedes, a ROS-responsive multi-branched drug conjugate (ODPAG) was constructed through a "polymer-drug linkage" strategy using dextran as the backbone and GA as the active "claw". ODPAG exhibited drug loading of 22.0 ± 0.2% (OD40kPAG) and 19.7 ± 0.1% (OD450kPAG), showing ROS responsiveness with a half-life 6.4 times that of GA (OD40kPAG) and 5.4 times longer (OD450kPAG). In in vitro antiviral experiments, ODPAG exhibited an enhanced binding affinity to the S protein, with IC50 values of 1.33 μM (OD40kPAG) and 0.89 μM (OD450kPAG) against SARS-CoV-2 pseudovirus, demonstrating exceptional antiviral efficacy. These results collectively indicate that ODPAG can block coronavirus infection by binding to the S protein, exhibiting significant potential in addressing the current challenges posed by the novel coronavirus. Additionally, the "polymer-drug conjugate" strategy employed in this process is efficient, cost-effective, and offers new insights for combating future emergent coronaviruses.

Coronaviruses have emerged as a significant challenge to human health. While earlier outbreaks of coronaviruses such as SARS-CoV and MERS-CoV posed serious threats, the recent SARS-CoV-2 pandemic has heightened interest in coronavirus research due to its pulmonary pathology, in addition to its neurological manifestations. In addition, the patients who have recovered from SARS-CoV-2 infection show long-term symptoms such as anosmia, brain fog and long COVID. A major hurdle in studying these viruses is the limited availability of specialized research facilities, emphasizing the need for prototype virus-based models to investigate the pathophysiology. The mouse hepatitis virus (MHV), a member of the β-coronavirus family, serves as an excellent model to unravel the mechanisms underlying virus-induced pathogenesis. This review highlights two decades of research efforts aimed at understanding the pathophysiological mechanism of coronavirus-induced diseases, focusing on the development of targeted recombinant strains to identify the minimal essential motif of the spike protein responsible for fusogenicity and neuropathogenicity. By synthesizing findings from these studies, the review identifies the most promising therapeutic targets against coronaviruses, paving the way for the development of pan-coronavirus antivirals.

SARS-CoV-2 is the virus responsible for the COVID-19 pandemic, which caused over 6.7 million deaths worldwide. The Spike protein plays a crucial role in the infection process, mediating the binding of the virus to its cellular receptor, angiotensin-converting enzyme 2 (ACE2), and its subsequent entry into target cells. Previous studies identified, through virtual screening, several natural products capable of binding to two distinct pockets of the Spike protein: triterpenoids binding to pocket 1 and bile acid derivatives binding to pocket 5. Building on these findings, our study advances the field by developing bivalent compounds 1-4 that through a spacer combine a triterpenoid (betulinic acid or glycyrrhetinic acid) with a semisynthetic bile acid derivative (obeticholic acid). These bivalent compounds are designed to simultaneously bind both pockets of the Spike protein, offering significant advantages over single molecules or the combination of the two natural products. In vitro cell assays using pseudotyped recombinant lentiviral particles with selected SARS-CoV-2 Spike proteins demonstrated that 1 and 2 exhibit enhanced activity in reducing viral entry into target cells compared to individual natural products, thus highlighting their potential as superior antiviral agents with reduced side effects.

The antibody-mediated immune response is crucial for the development of protective immunity against SARS-CoV-2, the virus responsible for the COVID-19 pandemic. Understanding the interaction between SARS-CoV-2 and the immune system is critical because new variants emerge as a result of the virus's ongoing evolution. Understanding the function of B cells in the SARS-CoV-2 infection process is critical for developing effective and long-lasting vaccines against this virus. Triggered by the innate immune response, B cells transform into memory B cells (MBCs). It is fascinating to observe how MBCs provide enduring immune defence, not only eradicating the infection but also safeguarding against future reinfection. If there is a lack of B cell activation or if the B cells are not functioning properly, it can lead to a serious manifestation of the disease and make immunisation less effective. Individuals with disruptions in the B cells have shown increased production of cytokines and chemokines, resulting in a poor prognosis for the disease. Therefore, we have developed an updated review article to gain insight into the involvement of B cells in SARS-CoV-2 infection. The discussion has covered the generation, functioning, and dynamics of neutralising antibodies (nAbs). Furthermore, we have emphasised immunotherapeutics that rely on nAbs.

SARS-CoV-2 viral infection is regulated by the host cell receptors ACE2 and TMPRSS2, and therefore the effect of various natural and synthetic compounds on these receptors has recently been the subject of investigations. Cyclodextrins, naturally occurring polysaccharides derived from starch, are soluble in water and have a hydrophobic cavity at their center enabling them to accommodate small molecules and utilize them as carriers in the food, supplements, and pharmaceutical industries to improve the solubility, stability, and bioavailability of target compounds. In the current study, computational molecular simulations were used to investigate the ability of α-, β- and γ-Cyclodextrins on human cell surface receptors. Cell-based experimental approaches, including expression analyses at mRNA and protein levels and virus replication, were used to assess the effect on receptor expression and virus infection, respectively. We found that none of the three CDs could dock effectively to human cell surface receptor ACE2 and viral protease Mpro (essential for virus replication). On the other hand, α- and β-CD showed strong and stable interactions with TMPRSS2, and the expression of both ACE2 and TMPRSS2 was downregulated at the mRNA and protein levels in cyclodextrin (CD)-treated cells. A cell-based virus replication assay showed ∼20% inhibition by β- and γ-CD. Taken together, the study suggested that (i) downregulation of expression of host cell receptors may not be sufficient to inhibit virus infection (ii) activity of the receptors and virus protein Mpro may play a critical and clinically relevant role, and hence (iii) newly emerging anti-Covid-19 compounds warrant multimodal functional analyses.

This study evaluates the pathogenesis of COVID-19 and the therapeutic efficacy of sitagliptin in diabetic and obese mice. Using a novel double-transgenic mouse model (db/db and K18-hACE2), the findings demonstrates that SARS-CoV-2 infection (Delta variant) causes severe multi-organ damage, glucose metabolism abnormalities, insulin resistance, and pancreatic islet cell damage in diabetic mice. Infected diabetic mice displayed higher mortality, inflammation (elevated TNF-α, IL-6, IL-1β), and fibrinolytic activity (PAI-1), alongside dysregulated diabetes-related hormones (GLP-1, leptin, ghrelin, resistin) compared to non-diabetic controls. Sitagliptin treatment reduced organ injury, hyperglycemia, inflammation, and fibrinolytic activity while improving insulin resistance and glucose metabolism. This was evidenced by decreased fasting blood glucose levels, improved insulin sensitivity, and elevated insulin and GLP-1 levels. These findings suggest sitagliptin is a promising therapeutic strategy to mitigate the severity of COVID-19 in experimental diabetes by modulating inflammation and improving metabolic syndrome. Further mechanistic investigations revealed that the level of hACE2 expression, along with the activation of NF-κB and IRS-1, play critical roles in the development of SARS-CoV-2-induced diabetes, the exacerbation of pre-existing diabetes, and the therapeutic efficacy of sitagliptin.

Various pattern recognition receptors (PRRs), including toll-like receptors (TLRs), play a crucial role in recognizing invading pathogens as well as damage-associated molecular patterns (DAMPs) released in response to infection. The resulting signaling cascades initiate appropriate immune responses to eliminate these pathogens. Current evidence suggests that SARS-CoV-2-driven activation of TLR4, whether through direct recognition of the spike glycoprotein (alone or in combination with endotoxin) or by sensing various TLR4-activating DAMPs or alarmins released during viral infection, acts as a critical mediator of antiviral immunity. However, TLR4 exerts a dual role in COVID-19, demonstrating both beneficial and deleterious effects. Dysregulated TLR4 signaling is implicated in the proinflammatory consequences linked to the immunopathogenesis of COVID-19. Additionally, TLR4 polymorphisms contribute to severity of the disease. Given its significant immunoregulatory impact on COVID-19 immunopathology and host immunity, TLR4 has emerged as a key target for developing inhibitors and immunotherapeutic strategies to mitigate the adverse effects associated with SARS-CoV-2 and related infections. Furthermore, TLR4 agonists are also being explored as adjuvants to enhance immune responses to SARS-CoV-2 vaccines.

In May 2023 the World Health Organization (WHO) declared the end of COVID-19 as a public health emergency. Seroprevalence studies performed in African countries, such as Cameroon, depicted a much higher COVID-19 burden than reported by the WHO. To better understand humoral responses kinetics following infection, we enrolled 333 participants from Yaoundé, Cameroon between March 2020 and January 2022. We measured the levels of antibodies targeting the SARS-CoV-2 receptor-binding-domain (RBD) and the Spike glycoproteins of Delta, Omicron BA.1 and BA.4/5 and the common cold coronavirus HCoV-OC43. We also evaluated plasma capacity to neutralize authentic SARS-CoV-2 virus and to mediate Antibody-Dependent Cellular Cytotoxicity (ADCC). Most individuals mounted a strong antibody response against SARS-CoV-2 Spike. Plasma neutralization waned faster than anti-Spike binding and ADCC. We observed differences in humoral responses by age and circulating variants. Altogether, we show a global overview of antibody dynamics and functionality against SARS-CoV-2 in Cameroon.

Inflammation is a pathology implicated in a wide range of human diseases. Recent years have seen tremendous progress in developing new types of anti-inflammatory agents for the treatment of inflammation of various origins. However, each has its own strengths and weaknesses. The very fact that there needs to have multiple types of anti-inflammatory agents underlines the complexity of inflammatory diseases and conditions, their molecular origins, and their treatment. Such complexity dictates the need to search for new approaches with improved potency and efficacy as well as reduced side effects. For these reasons, we are interested in exploring the possibility of generating synergy between carbon monoxide (CO), an endogenously produced cytoprotective agent, and known anti-inflammatory agents. Herein, we report the potentiating actions of CO on the anti-inflammatory effects of cortisone and dexamethasone as demonstrated in their ability to suppress the expression of TNF-α and IL-6 induced by either LPS or the S protein of SARS-CoV-2. Such effects are reflected in the substantially increased potency as well efficacy, when the efficacy of the corticosteroid alone does not allow for complete suppression of the expression of these cytokines. Further, increased attenuation of p65 phosphorylation is at least part of the molecular mechanism for the observed potentiating effects. We hope our work will stimulate a high level of activity along the same direction, leading to anti-inflammatory strategies with improved potency and efficacy and reduced side effects.

The outbreak of COVID-19 pandemic has caused substantial health loss worldwide, and the long-term sequelae of COVID, resulting from repeated coronavirus infection, have emerged as a new public health concern. We report the widespread presence of abnormal metallomic profiles in the sera of patients who have recovered from SARS-CoV-2 coronavirus infection, even after 6 months post-discharge from hospital. We measured the concentrations of Fe, Cu, Zn, Se, Cr, Mn, Ba, Ni, Pb, Ag, As, Cd, Co, and V in the sera of 25 recovered participants and 38 healthy controls in the cross-sectional study. Higher concentrations of Cu, Ag, As, Ba, Cd, Ni, Pb, Cr and V were observed in the recovered participants, whereas lower concentrations of Fe and Se were obtained in these participants. Except for Zn, Mn, and Co, all other elements showed significant differences (p < 0.05) between the two groups, with variations dependent on age and gender. Further correlation analysis between metallome and metabolome indicated that SARS-CoV-2 infection continues to disrupt metallic homeostasis and affect metabolic processes, such as lipid metabolism and cell respiration, as well as the functions of certain organs (e.g., liver, kidney, and heart), even after 6 months recovery. Our findings provide novel insights into the potential long-term effect of COVID-19 on the human body from a new perspective of metallomics.

One of the approaches for treatment of COVID-19 is a use of neutralizing antibodies (nAbs). The study of the mechanisms by which nAbs recognize different strains of SARS-CoV-2 may facilitate the development of new drugs and vaccines against the coronavirus infection. In this work, we present the 3.1 Å resolution cryo-electron microscopy structure of a full-length trimeric spike-protein (S-protein) of the SARS-CoV-2 Alpha (B.1.1.7) variant in complex with the Fab of the REGN10987 nAb. In the complex, two receptor-binding domains (RBDs) of the S-protein were observed in the 'up' state, whereas third RBD was in the 'down' state. This distinguishes the obtained structure from the complex of Delta (B.1.617.2) S-protein with REGN10987-Fab, where only one RBD was in the 'up' state. Probably some of the substituted residues (K478T, A570D, and S982A) located at the interprotomer interfaces are responsible for the greater Alpha S-protein opening upon the REGN10987-Fab binding. The Fab identically binds to the RBD in the both 'up' and 'down' conformations. The RBD-Fab interaction interface was refined to a resolution of 3.6 Å. The antibody binds to the receptor-binding motif (RBM), which prevents the S-protein from the binding to its receptor, angiotensin-converting enzyme 2 (ACE-2). Comparison with the structures of the Wuhan (wild type) and Delta RBD variants in complex with REGN10987-Fab revealed that the N501Y and T478K/L452R mutations presented in the RBM of the Alpha and Delta variants, respectively, do not affect the mode of the RBD-Fab interaction.

COVID-19 infection shows variant symptoms apart from respiratory symptoms, including the orofacial pain. We aim to research the morbidity, characteristics and potential risk factors of orofacial pain associated with COVID-19 pandemic in China from December 2022 to early 2023.

A cross-sectional survey was conducted in Fujian Province, China. The demographic and characteristic data of the subjects were collected and analysed.

A total of 1526 subjects responded to the survey. The morbidity of orofacial pain increased significantly before and after COVID-19 infection. (42.26% vs. 46.52%, P < .001) A total of 217 (14.22%) subjects with orofacial pain before COVID-19 infection reported the phenomenon of "COVID-19 infection with orofacial pain" (CIOP). Univariate and multivariate logistic regression showed that male (OR = 1.761, P < .001) and other symptoms of COVID-19 (OR = 1.494, P < .001) may be the risk factors for the aggravation of CIOP, while the time of first infection (OR = 0.580, P = .004) and preference for drinking tea or coffee (OR = 0.610, P = .003) may be the protective factors for the aggravation of CIOP. While, the subjects who did not concern about the spread of COVID-19 in oral treatment (OR = 0.639, P = .001), female (OR = 0.749, P = .03), education level (OR = 1.687, P < .001) and income level (OR = 1.796, P < .001), higher PSS-10 score (OR = 1.076, P < .001), and more drugs taken for infection (OR = 1.330, P < .001) were more willing to seek medical treatment.

The morbidity of orofacial pain appears to have increased significantly due to the COVID-19 epidemic; a number of factors can influence the CIOP including gender, infection period, and beverage preference' psychological factors, gender, education and income level can also influence the intent to seek a dentist.

Booster doses are crucial against severe COVID-19, as rapid virus mutations and variant emergence prolong the pandemic crisis. The virus's quick evolution, short generation-time, and adaptive changes impact virulence and evolvability, helping predictions about variant of concerns' (VOCs') landscapes. Here, in this study, we used a new computational algorithm, to predict the mutational pattern in SARS-CoV-2 ssRNA, proteomics, structural identification, mutation stability, and functional correlation, as well as immune escape mechanisms. Interestingly, the sequence diversity of SARS Coronavirus-2 has demonstrated a predominance of G- > A and C- > U substitutions. The best validation statistics are explored here in seven homologous models of the expected mutant SARS-CoV-2 spike ssRNA and employed for hACE2 and IgG interactions. The interactome profile of SARS-CoV-2 spike with hACE2 and IgG revealed a strong correlation between phylogeny and divergence time. The systematic adaptation of SARS-CoV-2 spike ssRNA influences infectivity and immune escape. Data suggest higher propensity of Adenine rich sequence promotes MHC system avoidance, preferred by A-rich codons. Phylogenetic data revealed the evolution of SARS-CoV-2 lineages' epidemiology. Our findings may unveil processes governing the genesis of immune-resistant variants, prompting a critical reassessment of the coronavirus mutation rate and exploration of hypotheses beyond mechanical aspects.

The coronavirus disease 2019 (COVID-19) pandemic presents heightened risks for cancer patients, who are more susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe outcomes due to immunosuppression from both the malignancy and anticancer therapies. This review investigates the dual roles of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in SARS-CoV-2 infection among cancer patients. ACE2, the vital entry receptor for SARS-CoV-2, is overexpressed in certain tumors such as colon adenocarcinoma, renal carcinomas, pancreatic adenocarcinoma, and lung adenocarcinoma, potentially increasing viral susceptibility. Paradoxically, ACE2 also exhibits tumor-suppressive properties by inhibiting angiogenesis and modulating the tumor microenvironment, leading to improved patient prognoses in some cancers like breast cancer. TMPRSS2, essential for viral entry, shows decreased expression in several tumors but acts as a prognostic biomarker in prostate and lung cancers. This review illustrates the complexity of therapeutically targeting ACE2 and TMPRSS2 due to their contrasting roles in cancer progression and viral entry. We analyze the expression levels of ACE2 and TMPRSS2 in relation to immune cell infiltration and patient outcomes, and propose personalized therapeutic strategies. Furthermore, we underscore the necessity for multidisciplinary approaches, integrating antiviral treatments with cancer therapies and tailoring interventions based on individual molecular profiles. This approach to personalized medicine seeks to enhance treatment results and better manage cancer patients who have contracted SARS-CoV-2.

Accurate diagnosis and effective antiviral strategies are critical to combat acute infection and to avoid damage to the host. Due to their restricted radiation range and energy, Auger electron emitters have shown potential as a RNA-destructing radionuclide therapy in oncology and infection. Focusing on the process of angiotensin-converting enzyme 2 (ACE2)-mediated endocytosis, Technetium-99m-labeled DX600 (99mTc-DX600) was synthesized as an Auger electron vector to specifically bind to surface-expressed ACE2 proteins on 293T-hACE2 cells (293T cells stably expressing human ACE2), and Technetium-99m-loaded microvesicles (99mTc-MVs) served as an antiviral tracer and effector in pseudovirus infection. The whole-body ACE2 expression evaluation was non-invasive, meanwhile, the enhanced green fluorescent protein expression of pseudoviruses was substantially inhibited as a result of the 99mTc-DX600 loading of microvesicles, though the mitochondrial and DNA stabilities of the host cells were not affected. Furthermore, the in vivo distribution of 99mTc-DX600 in humanized ACE2 mice was demonstrated to be both ACE2-specific and long-lasting, and an antiviral effect was fully exhibited with two cycles of intravenous injection at a dosage of 37 MBq. Taking advantage of the ACE2-mediated interaction and natural trigger mechanism of virus-induced endocytosis, 99mTc-MV represents a theranostic biosensor of Auger electrons that can expose viral RNA to lethal amounts of radiation, with the host cells receiving no detrimental radiation.

A cytokine storm is marked by excessive pro-inflammatory cytokine release, and has emerged as a key factor in severe COVID-19 cases - making it a critical therapeutic target. However, its pathophysiology was poorly understood, which hindered effective treatment. SARS-CoV-2 initially disrupts angiotensin signalling, promoting inflammation through ACE-2 downregulation. Some patients' immune systems then fail to shift from innate to adaptive immunity, suppressing interferon responses and leading to excessive pyroptosis and neutrophil activation. This amplifies tissue damage and inflammation, creating a pro-inflammatory loop. The result is the disruption of Th1/Th2 and Th17/Treg balances, lymphocyte exhaustion, and extensive blood clotting. Cytokine storm treatments include glucocorticoids to suppress the immune system, monoclonal antibodies to neutralize specific cytokines, and JAK inhibitors to block cytokine receptor signalling. However, the most effective treatment options for mitigating SARS-CoV-2 infection remain vaccines as a preventive measure and antiviral drugs for the early stages of infection. This article synthesizes insights into immune dysregulation in COVID-19, offering a framework to better understand cytokine storms and to improve monitoring, biomarker discovery, and treatment strategies for COVID-19 and other conditions involving cytokine storms.

Genetic factors, including polymorphisms in the TNFRSF13B gene, which regulates humoral immunity, can influence susceptibility to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aims to investigate the association between two polymorphisms, rs12603708 and rs3751987, and SARS-CoV-2 susceptibility, disease severity, and humoral immune responses in a Moroccan population.

A total of 303 unvaccinated COVID-19 patients (151 severe cases and 152 asymptomatic/moderate cases) and 150 individuals from a SARS-CoV-2-negative group were included in the analysis. Genotyping was performed using TaqMan SNP assays. SARS-CoV-2 antibodies targeting the nucleocapsid protein and IgG antibodies specific to the receptor-binding domain (RBD) were quantified using chemiluminescence microparticles immunoassay. Complete blood counts and C-reactive protein levels were evaluated using an automated platform.

Our analysis revealed that the A/A genotype of rs12603708 significantly increased the risk of SARS-CoV-2 infection in both codominant (p = 0.0055; OR = 3.74; adjusted p value = 0.022) and recessive (p = 0.0049; OR = 3.17; adjusted p value = 0.022) models, as well as the risk of severe disease (p = 0.014; OR = 3.43; adjusted p value = 0.049). For rs3751987, the G/G genotype was linked to higher susceptibility to infection (p = 0.0011; OR = 2.91; adjusted p value = 0.008), while the G/A genotype appeared protective (p = 0.0007; OR = 0.45; adjusted p value = 0.008). No association was found between rs3751987 and disease severity. Analysis of IgG anti-N and anti-RBD levels revealed no significant associations with either polymorphism (p > 0.05).

These findings highlight the role of TNFRSF13B polymorphisms in SARS-CoV-2 susceptibility and severity, while their impact on humoral immune responses appears limited.

Angiotensin-converting enzyme 2 (ACE2) is a transmembrane protein known for its physiological role in the renin-angiotensin system that also serves as a receptor for entry of SARS-CoV-1, SARS-CoV-2, and the seasonal human coronavirus NL63 (hCoV-NL63). ACE2 contains seven N-linked glycosylation sites. Molecular simulation and binding analyses suggest that some of them are involved in the interaction with the Spike (S) proteins of hCoVs, but their relevance in S-mediated fusion and viral entry is poorly investigated. To address this, we determined the impact of all seven N-linked glycosylation sites in ACE2 on S-mediated SARS-CoV-2 and hCoV-NL63 infection as well as cell-to-cell fusion. We found that all mutant ACE2 proteins are expressed and localized at the cell surface, albeit ACE2 lacks all glycans at decreased levels. On average, changes in T92I, N322A, and N690A, as well as combined mutation of all N-linked glycosylation sites increased endocytic VSVpp infection mediated by early HU-1 as well as Omicron BA.2, BA.5, and XBB.1.5 SARS-CoV-2 S proteins. In comparison, only the lack of glycan at N322 in ACE2 enhanced syncytia formation and only in the case of HU-1 and XBB.1.5 S proteins. Changes in N90A, T92I, and N322A increased infection by the early SARS-CoV-2 HU-1 strain about twofold to threefold but had lesser effects on infection by genuine Omicron variants. Despite reduced cell surface expression of ACE2, elimination of all N-linked glycosylation sites usually enhanced SARS-CoV-2 infection via the endocytic pathway while having little effect on entry at the cell surface in the presence of TMPRSS2. Our results provide insights into the role of N-linked glycans in the ability of human ACE2 (hACE2) to serve as receptors for coronavirus infection.

Several human coronaviruses use angiotensin-converting enzyme 2 (ACE2) as a primary receptor for infection of human cells. ACE2 is glycosylated at seven distinct positions, and the role of glycans for the entry of SARS-CoV-2 and hCoV-NL63 into their target cells is incompletely understood. Here, we examined the impact of individual and combined mutations in hACE2 glycosylation sites on Spike-mediated VSV-pseudoparticle and genuine SARS-CoV-2 and hCoV-NL63 infection and cell-to-cell fusion. Our results provide new information on the role of glycans in hACE2 for infection by highly pathogenic and seasonal coronaviruses.

The epidemiological patterns of respiratory tract infections (RTIs) have experienced substantial changes due to the influence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with a particular focus on acute respiratory infections (ARIs). Challenges in early diagnosis, inadequate triage strategies, and the inappropriate use of antimicrobials or antivirals have compounded the difficulties in accurately diagnosing and managing ARIs in the post-pandemic context. This study aimed to investigate the efficacy of fever clinics equipped with nucleic acid testing capabilities in the precise triage of ARIs. In a cohort of 604 individuals presenting with symptoms of ARIs, we utilized real-time reverse transcription polymerase chain reaction (RT-PCR) technology available in the fever clinic to perform nucleic acid testing for SARS-CoV-2, influenza A virus (Flu A), influenza B virus (Flu B), respiratory syncytial virus, adenovirus, human rhinovirus, and Mycoplasma pneumoniae. Subsequently, statistical methods were employed to analyze the distribution and types of ARIs associated with these pathogens. In fever clinics, most patients presenting with respiratory pathogen infections were diagnosed with non-SARS-CoV-2 respiratory pathogens, with a higher incidence noted among pediatric patients compared to adults. In contrast, SARS-CoV-2 primarily affected the adult population and was linked to more severe clinical outcomes. Consequently, the swift triage of patients exhibiting ARI symptoms in a fever clinic equipped with nucleic acid testing enables the rapid identification and precise treatment of pathogens. This approach alleviates patient discomfort and enhances the efficiency of healthcare resource utilization.

In the life cycle of a virus, host cell entry represents the first step that a virus needs to undertake to gain access to the cell interior for replication. Once a virus attaches itself to its target cell receptor, it activates endogenous cellular responses and exploits host cell factors for its internalization, fusion, and genome release. Among the host factors that critically contribute to the viral entry processes are cathepsins, which are the most abundant endo/lysosomal proteases with diverse physiological functions. This review summarizes previous findings on how different cathepsins contribute to the host cell entry of human pathogenic viruses, focusing on their specific roles in the entry processes of both enveloped and non-enveloped RNA viruses. A comprehensive knowledge of the functions of different cathepsins in viral entry will provide valuable insights into the molecular mechanisms underlying viral infections and can be useful in the development of new antiviral strategies.

The COVID-19 pandemic remains an ongoing global health threat, yet effective treatments are still lacking. This has led to a high demand for complementary/alternative medicine, such as Chinese herbal medicines for curbing the COVID-19 pandemic. Given the dual anticancer and antiviral activities of many herbal drugs, they may hold a multifaceted potential to tackle both cancer and SARS-CoV-2. Triptolide is the major bioactive compound isolated from Tripterygium wilfordii Hook F (TwHF), a traditional Chinese medicinal herb recognized for its beneficial pharmacological properties in many diseases, including cancer and viral infection. However, its application in the clinic has been greatly limited due to its toxicity and poor water solubility. Here, from a screen of a natural compound library of Chinese Pharmacopoeia, we identified triptolide as a top candidate to inhibit cell entry of SARS-CoV-2. We demonstrated that triptolide robustly blocked viral entry at nanomolar concentrations in cellular models, with broad range activity against emerging Omicron variants of SARS-CoV-2. Mechanistically, triptolide disrupted the interaction of SARS-CoV-2 spike protein with its receptor ACE2. Furthermore, we synthesized water-soluble, triptolide-derived carbon quantum dots. Compared to triptolide, these highly biocompatible nanomaterials exhibited prominent antiviral capabilities against Omicron variants of SARS-CoV-2 with less cytotoxicity. Finally, we showed that triptolide-derived carbonized materials excelled in their anticancer properties compared to triptolide and Minnelide, a water-soluble analog of triptolide. Together, our results provide a rationale for the potential development of triptolide-carbonized derivatives as a promising antiviral candidate for the current pandemic and future outbreaks, as well as anticancer agents.

The Syrian hamster (Mesocricetus auratus) has shown promise as a human diseases model, recapitulating features of different human diseases including COVID-19. However, the landscape of its genome and transcriptome has not been systematically dissected, restricting its potential applications.

Here we provide a complete analysis of the genome and transcriptome of the Syrian hamster and found that its lineage diverged from that of the Chinese hamster (Cricetulus griseus) around 29.4 million years ago. 21,387 protein-coding genes were identified, with 90.03% of the 2.56G base pair sequence being anchored to 22 chromosomes. Further comparison of the transcriptomes from 15 tissues of the Syrian hamster revealed that the Syrian hamster shares a pattern of alternative splicing modes more similar to humans, compared to rats and mice. An integrated genomic-transcriptomic analysis revealed that the Syrian hamster also has genetic and biological advantages as a superior animal model for cardiovascular diseases. Strikingly, several genes involved in SARS-COV-2 infection, including ACE2, present a higher homology with humans compared to other rodents and show the same function as their human counterparts.

The detailed molecular characterisation of the Syrian hamster in the present study opens a wealth of fundamental resources from this small rodent for future research into human disease pathology and treatment.

The coronavirus disease 2019 (COVID-19) outbreak revealed the susceptibility of elderly patients to respiratory virus infections, showing cell senescence or subclinical persistent inflammatory profiles and favoring the development of severe pneumonia.

In our study, we evaluated the potential influence of lung aging on the efficiency of replication of influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as determining the pro-inflammatory and antiviral responses of the distal lung tissue.

Using precision-cut lung slices (PCLS) from donors of different ages, we found that pandemic H1N1 and avian H5N1 IAV replicated in the lung parenchyma with high efficacy. In contrast to these IAV strains, SARS-CoV-2 Early isolate and Delta variant of concern (VOC) replicated less efficiently in PCLS. Interestingly, both viruses showed reduced replication in PCLS from older compared to younger donors, suggesting that aged lung tissue represents a suboptimal environment for viral replication. Regardless of the age-dependent viral loads, PCLS responded to H5N1 IAV infection by an induction of IL-6 and IP10/CXCL10, both at the mRNA and protein levels, and to H1N1 IAV infection by induction of IP10/CXCL10 mRNA. Finally, while SARS-CoV-2 and H1N1 IAV infection were not causing detectable cell death, H5N1 IAV infection led to more cytotoxicity and induced significant early interferon responses.

In summary, our findings suggest that aged lung tissue might not favor viral dissemination, pointing to a determinant role of dysregulated immune mechanisms in the development of severe disease.

Coronavirus disease 2019 (COVID-19) survivors are concerned about the likelihood of developing further diseases. This study examines the global trends in scientific research on diabetes associated with COVID-19 from several perspectives. Bibliometric analyses are used to undertake a scientific review of the literature. The Web of Science Core Collection (WoSCC) database was used to acquire bibliographic information on diabetes related to COVID-19 from Jan 2020 to Dec. 2023. The visual map was built via advanced CiteSpace 6.2.R6. 7,348 papers were found. Khunti Kamlesh and Rizzo-Manfredi are the most well-known high-yield authors in this area, and the top ten authors collaborate extensively. Most of these papers came from universities. Harvard Medical School has the most publications, followed by Wuhan University and Huazhong University of Science and Technology. China and the United States are the countries with the most publications. Angiotensin-converting enzymes, chronic disease, intensive care unit, viral infection, and gestational diabetes mellitus were scored 0-11, 2, 3, and 4, respectively. Zhou et al.'s work on this topic, which appeared in the prominent medical journal The Lancet, was cited 1,366 times, highlighting its importance. "clinical characteristics," "diabetes mellitus," "metabolic syndrome," and "angiotensin-converting enzyme" were used as keywords for reference co-citation and clustering data identify. Over the last four years, related investigations have focused primarily on observing clinical aspects. This report is important for developing treatment strategies, directing future research, and guiding clinical practice.

Vaccination or infection by SARS-CoV-2 elicits a protective immune response against severe outcomes. It has been reported that SARS-CoV-2 infection or vaccination elicits cross-reactive antibodies against other betacoronaviruses. While plasma neutralizing capacity was studied in great detail, their Fc-effector functions remain understudied. Here, we analyzed Spike recognition, neutralization and antibody-dependent cellular cytotoxicity (ADCC) against D614G, a recent Omicron subvariant of SARS-CoV-2 (JN.1) and SARS-CoV-1. Plasma from individuals before their first dose of mRNA vaccine, and following their second, third and sixth doses were analyzed. Despite poor neutralization activity observed after the second and third vaccine doses, ADCC was readily detected. By the sixth dose, individuals could neutralize and mediate ADCC against JN.1 and SARS-CoV-1. Since previous reports have shown that Fc-effector functions were associated with survival from acute infection, these results suggest that ADCC could help in combating future SARS-CoV-2 variants as well as closely related coronaviruses.

Medical treatments using potent neutralizing SARS-CoV-2 antibodies have achieved remarkable improvements in clinical symptoms, changing the situation for the severity of COVID-19 patients. We previously reported an antibody, NT-108 with potent neutralizing activity. However, the structural and functional basis for the neutralizing activity of NT-108 has not yet been understood. Here, we demonstrated the therapeutic effects of NT-108 in a hamster model and its protective effects at low doses. Furthermore, we determined the cryo-EM structure of NT-108 in complex with SARS-CoV-2 spike. The single-chain Fv construction of NT-108 improved the cryo-EM maps because of the prevention of preferred orientations induced by Fab orientation. The footprints of NT-108 illuminated how escape mutations such as E484K evade from class 2 antibody recognition without ACE2 affinity attenuation. The functional and structural basis for the potent neutralizing activity of NT-108 provides insights into the rational design of therapeutic antibodies.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is an enveloped RNA virus that caused the Coronavirus Disease 2019 (COVID-19) pandemic. The SARS-CoV-2 Spike glycoprotein binds to angiotensin converting enzyme 2 (ACE2) on host cells to facilitate viral entry. However, the presence of SARS-CoV-2 in nearly all human organs - including those with little or no ACE2 expression - suggests the involvement of alternative receptors. Recent studies have identified several cellular proteins and molecules that influence SARS-CoV-2 entry through ACE2-dependent, ACE2-independent, or inhibitory mechanisms. In this review, we explore how these alternative receptors were identified, their expression patterns and roles in viral entry, and their impact on SARS-CoV-2 infection. Additionally, we discuss therapeutic strategies aimed at disrupting these virus-receptor interactions to mitigate COVID-19 pathogenesis.

Site-directed exogenous gene knock-in for stable cell line generation remains a multi-step procedure that heavily relies on expertise. Therefore, there is a need for a competent and easily manageable method, particularly when there is an urgent demand for cell lines, especially for emerging infection research. We present here a universal construct called CutIn that expresses the Cas9 protein and dual sgRNAs targeting a host cell genome locus and the ampicillin resistance (AmpR) gene of a cotransfected donor plasmid commercially available. This construct specifically induces double-strand breaks (DSBs) in cotransfected plasmids and host cell genomes, thereby facilitating whole plasmid integration through nonhomologous end joining (NHEJ) repair mechanisms. As pilot tests, adeno-associated virus integration site 1 (AAVS1) or hypoxanthine phosphoribosyl transferase (HPRT) locus was selected as host genome target, commonly used human cell lines 293T, HeLa and HCT116 were employed. CutIn was subjected for reporter plasmid knock-in in all three cell lines, either AAVS1 and AmpR or HPRT and AmpR loci were efficiently targeted. Fluorescent protein, human angiotensin-converting enzyme 2 (ACE2) and dengue virus (DENV) infection reporter transgenic cells were rapidly obtained via CutIn-mediated whole expression vector integration. This method is designed to be user-friendly and shows potential for supporting the investigation of emerging/re-emerging infectious diseases. Further validation in diverse research contexts will be necessary to fully assess its applicability and effectiveness.

SARS-CoV-2, the third major coronavirus of the 21st century, causing COVID-19 disease, profoundly impacts public health and workforces worldwide. Identifying individuals at heightened risk of SARS-CoV-2 infection is crucial for targeted interventions and preparedness. This study investigated 35 SNVs within viral infection-associated genes in SARS-CoV-2 patients and uninfected controls from the Basque Country (March 2020-July 2021). Its primary aim was to uncover genetic markers indicative of SARS-CoV-2 susceptibility and explore genetic predispositions to infection. Association analyses revealed previously unreported associations between SNVs and susceptibility. Haplotype analyses uncovered novel links between haplotypes and susceptibility, surpassing individual SNV associations. Descriptive modelling identified key susceptibility factors, with rs11246068-CC (IFITM3), rs5742933-GG (ORMDL1), rs35337543-CG (IFIH1), and GGGCT (rs2070788, rs2298659, rs17854725, rs12329760, rs3787950) variation in TMPRSS2 emerging as main infection-susceptibility indicators for a COVID-19 pandemic situation. These findings underscore the importance of integrated SNV and haplotype analyses in delineating susceptibility to SARS-CoV-2 and informing proactive prevention strategies. The genetic markers profiled in this study offer valuable insights for future pandemic preparedness.

DPP4 was considered a canonical receptor for merbecoviruses until the recent discovery of African bat-borne MERS-related coronaviruses using ACE2. The extent and diversity of ACE2 utilization among merbecoviruses and their receptor species tropism remain unknown. Here, we reveal that HKU5 enters host cells utilizing Pipistrellus abramus (P.abr) and several non-bat mammalian ACE2s through a binding mode distinct from that of any other known ACE2-using coronaviruses. We defined the molecular determinants of receptor species tropism and identified a single amino acid mutation enabling HKU5 to utilize human ACE2, providing proof of principle for machine-learning-assisted outbreak preparedness. We show that MERS-CoV and HKU5 have markedly distinct antigenicity and identified several HKU5 inhibitors, including two clinical compounds. Our findings profoundly alter our understanding of coronavirus evolution, as several merbecovirus clades independently evolved ACE2 utilization, and pave the way for developing countermeasures against viruses poised for human emergence.

Our research is driven by the need to design an advanced multi-epitope vaccine construct (MEVC) using the S-protein of SARS-CoV-2 to combat the emergence of new variants. Through rigorous computational screening, we have identified linear and discontinuous B-cell epitopes, CD8 + and CD4 + T-cell epitopes, ensuring extensive MEVC coverage across 90.03% of the global population. The MEVC, featuring four CD4 + and four CD8 + T-cell epitopes connected linearly with two adjuvant proteins on both ends, has been carefully designed to elicit robust immune response. Our in-silico analysis has confirmed the construct's antigenicity, non-allergenicity, and non-toxicity with optimized codon sequences for enhanced expression in E. coli K12. Furthermore, molecular docking and dynamics analyses have demonstrated its strong binding affinity with TLR-3 and TLR 4, and in-silico immune simulation yielded promising results on heightened B-cell and T-cell-mediated immunity. However, wet lab experiments are essential to validate computational findings to revolutionize the development of vaccines against SARS-CoV-2.

The angiotensin-converting enzyme 2 (ACE2) receptor is shared by various coronaviruses with distinct receptor-binding domain (RBD) architectures, yet our understanding of these convergent acquisition events remains elusive. Here, we report that two bat MERS-related coronaviruses (MERSr-CoVs) infecting Pipistrellus nathusii (P.nat)-MOW15-22 and PnNL2018B-use ACE2 as their receptor, with narrow ortholog specificity. Cryoelectron microscopy structures of the MOW15-22/PnNL2018B RBD-ACE2 complexes unveil an unexpected and entirely distinct binding mode, mapping >45 Å away from that of any other known ACE2-using coronaviruses. Functional profiling of ACE2 orthologs from 105 mammalian species led to the identification of host tropism determinants, including an ACE2 N432-glycosylation restricting viral recognition, and the design of a soluble P.nat ACE2 mutant with potent viral neutralizing activity. Our findings reveal convergent acquisition of ACE2 usage for merbecoviruses found in European bats, underscoring the extraordinary diversity of ACE2 recognition modes among coronaviruses and the promiscuity of this receptor.