Respiratory viruses: their importance and lessons learned from COVID-19

Intestinal microbiota and respiratory system diseases: Relationships with three common respiratory virus infections

In recent years, the role of the intestinal microbiota in regulating host health and immune balance has attracted widespread attention. This study provides an in-depth analysis of the close relationship between the intestinal microbiota and respiratory system diseases, with a focus on three common respiratory virus infections, including respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and influenza virus. The research indicates that during RSV infection, there is a significant decrease in intestinal microbial diversity, suggesting the impact of the virus on the intestinal ecosystem. In SARS-CoV-2 infection, there are evident alterations in the intestinal microbiota, which are positively correlated with the severity of the disease. Similarly, influenza virus infection is associated with dysbiosis of the intestinal microbiota, and studies have shown that the application of specific probiotics exhibits beneficial effects against influenza virus infection. Further research indicates that the intestinal microbiota exerts a wide and profound impact on the occurrence and development of respiratory system diseases through various mechanisms, including modulation of the immune system and production of short-chain fatty acids (SCFAs). This article comprehensively analyzes these research advances, providing new perspectives and potential strategies for the prevention and treatment of future respiratory system diseases. This study not only deepens our understanding of the relationship between the intestinal microbiota and respiratory system diseases but also offers valuable insights for further exploring the role of host-microbiota interactions in the development of diseases.

Analysis of respiratory RNA virus detection in the laboratory of a teaching hospital in Shanghai from 2017 to 2023

OBJECTIVE

The aim of this study was to analyze the detection and epidemiological characteristics of common influenza viruses (IVA/IVB) and respiratory syncytial virus (RSV) in a teaching hospital in Shanghai from 2017 to 2023, and to investigate the impact of the COVID-19 epidemic on the transmission and detection rates of these viruses.

METHODS

Retrospective analysis of IVA/IVB and RSV cases detected in hospitals from 2017 to 2023. Data was categorized into pre, during and post outbreaks based on the timing of the COVID-19 outbreak and further subdivided by season and age group. PCR and colloidal gold methods were used for virus detection and statistical analyses were performed accordingly.

RESULTS

Positive detection rates of pathogens were statistically different by age, period, season and detection method employed. Before the epidemic, the pathogen infections showed obvious seasonality but disappeared after 2019. Positive detection rates of influenza were higher in adolescents and young and middle-aged people while RSV detection was highest in adolescents. Detection by Gene Xpert real-time fluorescent PCR was superior in terms of timeliness and efficiency.

CONCLUSION

The COVID-19 pandemic and the massive public health intervention campaign have led to widespread changes in human behavior, significantly affecting the spread and activity of other seasonal respiratory viruses. Further, advances in detection methods have contributed to increased pathogen detection rates.

Trends of respiratory viruses and factors associated with severe acute respiratory infection in patients presenting at a university hospital: a 6-year retrospective study across the COVID-19 pandemic

Background

The COVID-19 pandemic significantly disrupted the epidemiology of respiratory viruses, altering seasonal patterns and reducing circulation. While recovery trends have been observed, factors associated with severe acute respiratory infections (SARIs) during pre- and post-pandemic periods remain underexplored in middle-income countries.

Objective

This study aimed to analyze the trends in respiratory virus circulation and identify factors associated with SARI in patients attending a tertiary care university hospital in western Mexico over a six-year period spanning the pre-pandemic, pandemic, and post-pandemic phases.

Methods

A retrospective study was conducted using data from 19,088 symptomatic patients tested for respiratory viruses between 2018 and 2024. Viral trends were analyzed through interrupted time series (ITS) modeling, incorporating locally estimated scatterplot smoothing (LOESS) and raw positivity rates. Additionally, ITS analysis was performed to evaluate temporal changes in SARI proportions across different phases of the pandemic. Multivariate logistic regression models were applied to determine independent risk factors for SARI across different time periods.

Results

During the pandemic (2020-2021), respiratory virus positivity rates significantly declined, particularly for influenza, which experienced a sharp reduction but rebounded post-2022. Respiratory syncytial virus (RSV) demonstrated a delayed resurgence, whereas other respiratory viruses exhibited heterogeneous rebound patterns. ITS modeling of SARI proportions revealed a significant pre-pandemic increasing trend, followed by a slower rise during the pandemic, and a sharp post-pandemic drop in early 2022, before resuming an upward trajectory. Among older adults (>65 years), a marked increase in SARI was observed at the beginning of the pandemic, while younger groups showed more stable patterns. Logistic regression identified advanced age, male sex, cardiovascular disease, obesity, and immunosuppression as major risk factors for SARI, while vaccination consistently showed a protective effect across all periods and subgroups.

Conclusion

The COVID-19 pandemic induced persistent shifts in respiratory virus circulation, disrupting seasonal dynamics and modifying the burden of SARI. The findings underscore the importance of continuous surveillance, targeted vaccination programs, and early diagnostics to mitigate severe outcomes. These results highlight the need for adaptive public health strategies in middle-income countries to address evolving respiratory disease threats.

The next viral pandemic-where do we stand?

The world is presently undergoing a recovery phase following the unexpected challenges posed by the coronavirus disease 2019 (COVID-19) pandemic. The loss of lives and the economic setbacks experienced by the global population will require considerable time to address. It is clear that future outbreaks, epidemics, or even pandemic caused by unknown bacterial, fungal, or viral pathogens are inevitable. In this context, public health front-liners will be essential in minimizing the impact of such incidents. This mini-review briefly discusses sociocultural issues, diagnostic capacities, surveillance, and screening strategies for potential future viral pandemic - referred to as Pandemic X. Additionally, it addresses treatment responses, vaccine development efforts, scientific advancements, policy considerations, and prospects for science communication related to forthcoming viral pandemics. While this review does not encompass all scientific approaches available on these topics, it aims to serve as a guideline for informing public health sectors about appropriate measures that should be undertaken.

Autophagy and Respiratory Viruses: Mechanisms, Viral Exploitation, and Therapeutic Insights

Respiratory viruses, such as influenza virus, rhinovirus, coronavirus, and respiratory syncytial virus (RSV), continue to impose a heavy global health burden. Despite existing vaccination programs, these infections remain leading causes of morbidity and mortality, especially among vulnerable populations like children, older adults, and immunocompromised individuals. However, the current therapeutic options for respiratory viral infections are often limited to supportive care, underscoring the need for novel treatment strategies. Autophagy, particularly macroautophagy, has emerged as a fundamental cellular process in the host response to respiratory viral infections. This process not only supports cellular homeostasis by degrading damaged organelles and pathogens but also enables xenophagy, which selectively targets viral particles for degradation and enhances cellular defense. However, viruses have evolved mechanisms to manipulate the autophagy pathways, using them to evade immune detection and promote viral replication. This review examines the dual role of autophagy in viral manipulation and host defense, focusing on the complex interplay between respiratory viruses and autophagy-related pathways. By elucidating these mechanisms, we aim to highlight the therapeutic potential of targeting autophagy to enhance antiviral responses, offering promising directions for the development of effective treatments against respiratory viral infections.

RNA aptamer-mediated RNA nanotechnology for potential treatment of cardiopulmonary diseases

Ribonucleic acid (RNA) aptamers are single-stranded RNAs that bind to target proteins or other molecules with high specificity and affinity, modulating biological functions through distinct mechanisms. These aptamers can act n as antagonists to block pathological interactions, agonists to activate signaling pathways, or delivery vehicles for therapeutic cargos such as siRNAs and miRNAs. The advances in RNA nanotechnology further enhances the versatility of RNA aptamers, offering scalable platforms for engineering. In this review, we have summarized recent developments in RNA aptamer-mediated RNA nanotechnology and provide an overview of its potential in treating cardiovascular and respiratory disorders, including atherosclerosis, acute coronary syndromes, heart failure, lung cancer, pulmonary hypertension, asthma, chronic obstructive pulmonary disease (COPD), acute lung injury, viral respiratory infections, and pulmonary fibrosis. By integrating aptamer technologies with innovative delivery systems, RNA aptamers hold the potential to revolutionize the treatment landscape for cardiopulmonary diseases.

Pulmonary microbiology and microbiota in adults with non-cystic fibrosis bronchiectasis: a systematic review and meta-analysis

BACKGROUND

Non-cystic fibrosis bronchiectasis is associated with frequent and diverse microbial infections, yet an overall understanding of microbial presence across different disease stages is lacking.

METHODS

A meta-analysis assessed lung microbes in adults with non-CF bronchiectasis, collecting data using both culture-based and sequencing approaches through three international databases and three Chinese databases. Subgroups were categorized by disease stage: the stable group (S), the exacerbation group (E), and unclassified data consolidated into the undetermined group (U). Culture data were analysed in random-effects meta-analyses while sequencing data were processed using QIIME 2.

RESULTS

A total of 98 studies were included with data from 54,384 participants worldwide. Pseudomonas aeruginosa was the most frequently isolated bacterium (S: 26[19-34]%, E: 23[20-25]%, U: 20[16-25]%), while not specified Mycobacterium avium complex exhibited the highest mycobacterial prevalence (S: 3[1-5]%, E: 4[2-5]%, U: 15[3-27]%). Aspergillus spp. (S: 15[-10-39]%, E: 2[1-3]%, U: 10[5-15]%) and Candida spp. (S: not applicable, E: 11[2-20]%, U: 10[-8-27]%) were predominant in fungi culture with variable distributions among groups. Rhinovirus was the most commonly detected virus with varying prevalence across airway sample types rather than disease stages (S-sputum: 18[-16-53]%, S-nasopharyngeal: 4[-1-9]%, E-sputum: 22[16-29]%, E-nasopharyngeal: 6[4-8]%). Sequencing results revealed notable antibiotic persistence of Pseudomonas in 16S, and significant domination of Candida in ITS.

CONCLUSION

Our findings indicate consistent bacterial patterns throughout bronchiectasis stages in both culture and sequencing results. Viruses are extensively detected in stable patients but vary across different airway sample types. Lower bacterial diversity and higher fungal diversity may be associated with exacerbation risks.

Adult vaccinations against respiratory infections

INTRODUCTION

Lower respiratory infections have a huge impact on global health, especially in older individuals, immunocompromised people, and those with chronic comorbidities. The COVID-19 pandemic highlights the importance of vaccination. However, there are lower rates of vaccination in the adult population that are commonly due to a missed opportunity to vaccinate. Vaccination offers the best strategy to prevent hospitalization, complications, and death caused by lower respiratory infections.

AREAS COVERED

In this review, the authors provide an overview of the vaccines for lower respiratory infections in the adult population. The review highlights the available data about the impact of vaccines on preventing respiratory infections, focusing on the pneumococcal vaccine, influenza vaccine, COVID-19 vaccines, and respiratory syncytial virus (RSV) vaccines. The authors discuss the currently available scientific evidence on the role of vaccines against respiratory infections. Finally, the authors review the current recommendations for vaccines in the adult population.

EXPERT OPINION

Scientific evidence on the effectiveness of vaccines against respiratory infections is important. An efficient implementation of adult immunization strategies will provide an opportunity to decrease the global burden of lower respiratory infections. Recognizing the existing vaccines and their recommendations for the adult population is essential to achieve a high vaccination rate in the population.

[Effectiveness of riamilovir in preventing respiratory viral infection among young people from organized collectives]

AIM

To evaluate the efficacy of the antiviral drug riamilovir (trade name - «Triazavirin®») for the prevention of SARS-CoV-2 infection (COVID-19) and other acute respiratory viral infections in young people from organized groups.

MATERIALS AND METHODS

The study involved 386 individuals aged 18-22 years: 199 received riamilovir at a daily dose of 250 mg for 15 days, while 187 did not receive prophylactic drugs. For 30 days, disease occurrence was monitored among volunteers. In case of illness, the duration, severity of clinical manifestations, complications, and pathogen elimination dynamics were assessed via PCR from nasopharyngeal and oropharyngeal swabs.

RESULTS

During riamilovir administration, a statistically significant reduction in cases of acute respiratory viral infections of non-coronavirus etiology was observed, with no COVID-19 cases reported, confirmed by the absence of SARS-CoV-2 RNA in this group. The shortest duration of acute respiratory viral infections was noted in patients taking the prophylactic drug.

CONCLUSION

Riamilovir (trade name - «Triazavirin®») showed statistically significant prophylactic efficacy during its administration in an organized group. Its use decreased the frequency of detection of viral pathogens and resulted in milder acute respiratory disease, likely due to reduced viral load in individuals.

The Role of Inflammation in the Pathogenesis of Viral Respiratory Infections

Viral respiratory infections (VRIs) are a leading cause of morbidity and mortality worldwide, making them a significant public health concern. During infection, respiratory viruses, including Influenza virus, SARS-CoV-2, and respiratory syncytial virus (RSV), trigger an antiviral immune response, specifically boosting the inflammatory response that plays a critical role in their pathogenesis. The inflammatory response induced by respiratory viruses can be a double-edged sword since it can be initially induced to be antiviral and protective/reparative from virus-induced injuries. Still, it can also be detrimental to host cells and tissues. However, the mechanisms that differentiate the complex crosstalk between favorable host inflammatory responses and harmful inflammatory responses are poorly understood. This review explores the complex interplay between viral pathogens and the host immune response, mainly focusing on the role of inflammation in the pathogenesis of VRIs. We discuss how inflammation can both contain and exacerbate the progression of viral infections, highlighting potential therapeutic targets and emerging drugs for modulating the aberrant inflammatory responses during VRIs.

Dynamic features of virus protein 1 and substitutions in the 3-phenyl ring determine the potency and broad-spectrum activity of capsid-binding pyrazolo[3,4-d]pyrimidines against rhinoviruses

Pyrazolo[3,4-d]pyrimidines represent one potent class of well tolerated and highly active rhinovirus (RV) inhibitors that act as capsid binders. The lead compound OBR-5-340 inhibits a broad-spectrum of RVs. Aiming to improve lead activity, we evaluated the impact of structural modifications in the 3-phenyl ring of OBR-5-340 on its potency and spectrum of anti-RV activity vitro. Our results demonstrate the crucial role of substitution at position 4 for strong, broad-spectrum anti-RV activity. The 4-methyl (RCB23137) and 4-chloro (RCB23138) derivatives outperformed OBR-5-340 in terms of potency and anti-RV activity spectrum. Based on these findings, the compounds were selected for computational binding studies. Molecular dynamic simulations with six RVs differing in OBR-5-340, RCB23137, and RCB23138 sensitivity proved the impact of dynamic features of two VP1 loops enveloping these inhibitors on antiviral potency.

Combating Emerging Respiratory Viruses: Lessons and Future Antiviral Strategies

Emerging viral diseases, including seasonal illnesses and pandemics, pose significant global public health risks. Respiratory viruses, particularly coronaviruses and influenza viruses, are associated with high morbidity and mortality, imposing substantial socioeconomic burdens. This review focuses on the current landscape of respiratory viruses, particularly influenza and SARS-CoV-2, and their antiviral treatments. It also discusses the potential for pandemics and the development of new antiviral vaccines and therapies, drawing lessons from past outbreaks to inform future strategies for managing viral threats.

Outcomes of corticosteroid therapy in patients with viral community-acquired pneumonia

AIM

The objective of this study was to assess the therapeutic effects of corticosteroids in adult patients hospitalized with viral community-acquired pneumonia.

METHODS

This is a retrospective analysis of data collected prospectively from November 1996 to June 2024. All adult patients with viral community-acquired pneumonia were enrolled. The primary outcome was 30-day mortality. Secondary outcomes included all-cause in-hospital mortality, ICU admission, length of ICU and hospital stay, mechanical ventilation, and 1-year mortality. Propensity score matching (PSM) was used to obtain balance among the baseline variables in the two groups.

RESULTS

Of the 524 patients with viral pneumonia, 30 (6%) received corticosteroids and 494 (94%) did not. Patients were primarily male (n = 299, 57%), with a median [Q1-Q3] age of 66.9 [55-81] years. The 3:1 propensity matching procedure identified 90 patients not treated with corticosteroid (CS-) as controls. After PSM, no difference in 30-day mortality was found [7% (95%CI 1 to 22%) vs. 4% (95%CI 1 to 11%), p = 0.639]. The risk of death at 30 days did not differ significantly in unmatched and matched cohorts [Hazard Ratio (HR) 1.33 (0.32-5.63), p = 0.695 vs. HR 1.51 (0.28-8.27), p = 0.632, respectively]. Nor were differences found in hospital length of stay, ICU admission and length of stay, or mechanical ventilation requirement and duration between matched and unmatched CS + and CS-.

CONCLUSIONS

There were no significant differences in the primary and secondary outcomes regarding the use of corticosteroids in patients with viral pneumonia.

Surveillance of respiratory viruses by aerosol screening in indoor air as an early warning system for epidemics

The development of effective methods for the surveillance of seasonal respiratory viruses is required for the timely management of outbreaks. We aimed to survey Influenza-A, Influenza-B, RSV-A, Rhinovirus and SARS-CoV-2 surveillance in a tertiary hospital and a campus over 5 months. The effectiveness of air screening as an early warning system for respiratory viruses was evaluated in correlation with respiratory tract panel test results. The overall viral positivity was higher on the campus than in the hospital (55.0% vs. 38.0%). Influenza A was the most prevalent pathogen in both locations. There were two influenza peaks (42nd and 49th weeks) in the hospital air, and a delayed peak was detected on campus in the 1st-week of January. Panel tests indicated a high rate of Influenza A in late December. RSV-A-positivity was higher on the campus than the hospital (21.6% vs. 7.4%). Moreover, we detected two RSV-A peaks in the campus air (48th and 51st weeks) but only one peak in the hospital and panel tests (week 49). Although rhinovirus was the most common pathogen in panel tests, rhinovirus positivity was low in air samples. The air screening for Influenza-B and SARS-Cov-2 revealed comparable positivity rates with panel tests. Air screening can be integrated into surveillance programs to support infection control programs for potential epidemics of respiratory virus infections except for rhinoviruses.

Antiviral Properties of Moringa oleifera Leaf Extracts against Respiratory Viruses

Moringa oleifera (M. oleifera) is a plant widely used for its beneficial properties both in medical and non-medical fields. Because they produce bioactive metabolites, plants are a major resource for drug discovery. In this study, two different cultivars of leaves of M. oleifera (Salento and Barletta) were obtained by maceration or microwave-assisted extraction (MAE). We demonstrated that extracts obtained by MAE exhibited a lower cytotoxic profile compared to those obtained by maceration at concentrations ranged from 25 to 400 µg/mL, on both Vero CCL-81 and Vero/SLAM cells. We examined their antiviral properties against two viruses, i.e., the human coronavirus 229E (HCoV-229E) and measles virus (MeV), which are both responsible for respiratory infections. The extracts were able to inhibit the infection of both viruses and strongly prevented their attack and entry into the cells in a range of concentrations from 50 to 12 µg/mL. Particularly active was the variety of Salento that registered a 50% inhibitory concentration (IC50) at 21 µg/mL for HCoV-229E and at 6 µg/mL for MeV. We identified the presence of several compounds through high performance liquid chromatography (HPLC); in particular, chlorogenic and neochlorogenic acids, quercetin 3-O-β-d-glucopyranoside (QGP), and glucomoringin (GM) were mainly observed. In the end, M. oleifera can be considered a promising candidate for combating viral infections with a very strong action in the early stages of viral life cycle, probably by destructuring the viral particles blocking the virus-cell fusion.

A T-Cell-Derived 3-Gene Signature Distinguishes SARS-CoV-2 from Common Respiratory Viruses

Research on the host responses to respiratory viruses could help develop effective interventions and therapies against the current and future pandemics from the host perspective. To explore the pathogenesis that distinguishes SARS-CoV-2 infections from other respiratory viruses, we performed a multi-cohort analysis with integrated bioinformatics and machine learning. We collected 3730 blood samples from both asymptomatic and symptomatic individuals infected with SARS-CoV-2, seasonal human coronavirus (sHCoVs), influenza virus (IFV), respiratory syncytial virus (RSV), or human rhinovirus (HRV) across 15 cohorts. First, we identified an enhanced cellular immune response but limited interferon activities in SARS-CoV-2 infection, especially in asymptomatic cases. Second, we identified a SARS-CoV-2-specific 3-gene signature (CLSPN, RBBP6, CCDC91) that was predominantly expressed by T cells, could distinguish SARS-CoV-2 infection, including Omicron, from other common respiratory viruses regardless of symptoms, and was predictive of SARS-CoV-2 infection before detectable viral RNA on RT-PCR testing in a longitude follow-up study. Thereafter, a user-friendly online tool, based on datasets collected here, was developed for querying a gene of interest across multiple viral infections. Our results not only identify a unique host response to the viral pathogenesis in SARS-CoV-2 but also provide insights into developing effective tools against viral pandemics from the host perspective.

At-home testing for respiratory viruses: a minireview of the current landscape

The landscape of at-home testing using over-the-counter (OTC) tests has been evolving over the last decade. The United States Food and Drug Administration Emergency Use Authorization rule has been in effect since the early 2000s, and it was widely employed during the severe acute respiratory syndrome coronavirus 2 pandemic to authorize antigen and nucleic acid detection tests for use in central laboratories as well as OTC. During the pandemic, the first at-home tests for respiratory viruses became available for consumer use, which opened the door for additional respiratory virus OTC tests. Concerns may exist regarding the public's ability to properly collect samples, perform testing, interpret results, and report results to public health authorities. However, favorable comparison studies between OTC testing and centralized laboratory test results suggest that OTC testing may have a place in healthcare, and it is likely here to stay. This mini-review of OTC tests for viral respiratory diseases will briefly cover the regulatory and reimbursement environment, current OTC test availability, as well as the advantages and limitations of OTC tests.

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

Molecular mechanism of rhinovirus escape from the Pyrazolo[3,4-d]pyrimidine capsid-binding inhibitor OBR-5-340 via mutations distant from the binding pocket: Derivatives that brake resistance

Rhinoviruses (RVs) cause the common cold. Attempts at discovering small molecule inhibitors have mainly concentrated on compounds supplanting the medium chain fatty acids residing in the sixty icosahedral symmetry-related hydrophobic pockets of the viral capsid of the Rhinovirus-A and -B species. High-affinity binding to these pockets stabilizes the capsid against structural changes necessary for the release of the ss(+) RNA genome into the cytosol of the host cell. However, single-point mutations may abolish this binding. RV-B5 is one of several RVs that are naturally resistant against the well-established antiviral agent pleconaril. However, RV-B5 is strongly inhibited by the pyrazolopyrimidine OBR-5-340. Here, we report on isolation and characterization of RV-B5 mutants escaping OBR-5-340 inhibition and show that substitution of amino acid residues not only within the binding pocket but also remote from the binding pocket hamper inhibition. Molecular dynamics network analysis revealed that strong inhibition occurs when an ensemble of several sequence stretches of the capsid proteins enveloping OBR-5-340 move together with OBR-5-340. Mutations abrogating this dynamic, regardless of whether being localized within the binding pocket or distant from it result in escape from inhibition. Pyrazolo [3,4-d]pyrimidine derivatives overcoming OBR-5-340 escape of various RV-B5 mutants were identified. Our work contributes to the understanding of the properties of capsid-binding inhibitors necessary for potent and broad-spectrum inhibition of RVs.

Correlation of bioactive marker compounds of an orally applied Morus alba root bark extract with toxicity and efficacy in BALB/c mice

Introduction: In traditional Chinese medicine, the root bark of Morus alba L. is used to treat respiratory infections. Recently, anti-inflammatory and multiple anti-infective activities (against influenza viruses, corona virus 2, S. aureus, and S. pneumoniae) were shown in vitro for a standardized root bark extract from M. alba (MA60). Sanggenons C and D were identified as major active constituents of MA60. The aim of the present preclinical study was to evaluate, whether these findings are transferable to an in vivo setting. Methods: MA60 was orally administered to female BALB/c mice to determine 1) the maximum tolerated dose (MTD) in an acute toxicity study and 2) its anti-influenza virus and anti-inflammatory effects in an efficacy study. A further aim was to evaluate whether there is a correlation between the obtained results and the amount of sanggenons C and D in serum and tissues. For the quantitation of the marker compounds sanggenons C and D in serum and tissue samples an UPLC-ESI-MS method was developed and validated. Results: In our study setting, the MTD was reached at 100 mg/kg. In the efficacy study, the treatment effects were moderate. Dose-dependent quantities of sanggenon C in serum and sanggenon D in liver samples were detected. Only very low concentrations of sanggenons C and D were determined in lung samples and none of these compounds was found in spleen samples. There was no compound accumulation when MA60 was administered repeatedly. Discussion: The herein determined low serum concentration after oral application once daily encourages the use of an alternative application route like intravenous, inhalation or intranasal administration and/or multiple dosing in further trials. The established method for the quantitation of the marker sanggenon compounds in tissue samples serves as a basis to determine pharmacokinetic parameters such as their bioavailability in future studies.

25 Years Responding to Respiratory and Other Viruses with Mass Spectrometry

This review article presents the development and application of mass spectrometry (MS) approaches, developed in the author's laboratory over the past 25 years, to detect; characterise, type and subtype; and distinguish major variants and subvariants of respiratory viruses such as influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). All features make use of matrix-assisted laser desorption ionisation (MALDI) mass maps, recorded for individual viral proteins or whole virus digests. A MALDI-based immunoassay in which antibody-peptide complexes were preserved on conventional MALDI targets without their immobilisation led to an approach that enabled their indirect detection. The site of binding, and thus the molecular antigenicity of viruses, could be determined. The same approach was employed to study antivirals bound to their target viral protein, the nature of the binding residues, and relative binding affinities. The benefits of high-resolution MS were exploited to detect sequence-conserved signature peptides of unique mass within whole virus and single protein digests. These enabled viruses to be typed, subtyped, their lineage determined, and variants and subvariants to be distinguished. Their detection using selected ion monitoring improved analytical sensitivity limits to aid the identification of viruses in clinical specimens. The same high-resolution mass map data, for a wide range of viral strains, were input into a purpose-built algorithm (MassTree) in order to both chart and interrogate viral evolution. Without the need for gene or protein sequences, or any sequence alignment, this phylonumerics approach also determines and displays single-point mutations associated with viral protein evolution in a single-tree building step.

Clinical Characterization of Respiratory Syncytial Virus Infection in Adults: A Neglected Disease?

Lower respiratory tract infections (LRIs) are a significant cause of disability-adjusted life-years (DALYs) across all age groups, especially in children under 9 years of age, and adults over 75. The main causative agents are viruses, such as influenza and respiratory syncytial virus (RSV). Viral LRIs in adults have historically received less attention. This study investigated the incidence of RSV and influenza in adult patients admitted to a referral hospital, as well as the clinical profile of these infections. Molecular testing was conducted on nasopharyngeal samples taken from a respiratory surveillance cohort comprising adult (15-59 years) and elderly (60+ years) hospitalized patients who tested negative for SARS-CoV-2, to determine the prevalence for influenza and RSV. Influenza was found to be less frequent among the elderly. The main symptoms of RSV infections were cough, fever, dyspnea, malaise, and respiratory distress, while headache, nasal congestion, a sore throat, and myalgia were most frequent in influenza. Elderly patients with RSV were not found to have more severe illness than adults under age 60, underscoring the importance of providing the same care to adults with this viral infection.

Differential roles of regulatory T cells in acute respiratory infections

Acute respiratory infections trigger an inflammatory immune response with the goal of pathogen clearance; however, overexuberant inflammation causes tissue damage and impairs pulmonary function. CD4+FOXP3+ regulatory T cells (Tregs) interact with cells of both the innate and the adaptive immune system to limit acute pulmonary inflammation and promote its resolution. Tregs also provide tissue protection and coordinate lung tissue repair, facilitating a return to homeostatic pulmonary function. Here, we review Treg-mediated modulation of the host response to respiratory pathogens, focusing on mechanisms underlying how Tregs promote resolution of inflammation and repair of acute lung injury. We also discuss potential strategies to harness and optimize Tregs as a cellular therapy for patients with severe acute respiratory infection and discuss open questions in the field.

Editorial

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Clinical performance evaluation of the Fluorecare® SARS-CoV-2 & Influenza A/B & RSV rapid antigen combo test in symptomatic individuals

BACKGROUND

A SARS-CoV-2+Flu A/B+RSV Combo Rapid test may be more relevant than Rapid Antigen Diagnostic (RAD) tests targeting only SARS-CoV-2 since we are facing a concurrent circulation of these viruses during the winter season.

OBJECTIVES

To assess the clinical performance of a SARS-CoV-2+Flu A/B+RSV Combo test in comparison to a multiplex RT-qPCR.

STUDY DESIGN

Residual nasopharyngeal swabs issued from 178 patients were included. All patients, adults and children, were symptomatic and presented at the emergency department with flu-like symptoms. Characterization of the infectious viral agent was done by RT-qPCR. The viral load was expressed as cycle threshold (Ct). Samples were then tested using the multiplex RAD test Fluorecare^®ฏ SARS-CoV-2 & Influenza A/B & RSV Antigen Combo Test. Data analysis was carried out using descriptive statistics.

RESULTS

The sensitivity of the test varies according to the virus, with the highest sensitivity observed for Influenza A (80.8.% [95%CI: 67.2 - 94.4]) and the lowest sensitivity observed for RSV (41.5% [95%CI: 26.2 - 56.8]). Higher sensitivities were observed for samples with high viral loads (Ct < 20) and decrease with low viral loads. The specificity for SARS-CoV-2, RSV and Influenza A and B was >95%.

CONCLUSIONS

The Fluorecare® combo antigenic presents satisfying performance in real-life clinical setting for Influenza A and B in samples with high viral load. This could be useful to allow a rapid (self-)isolation as the transmissibility of these viruses increase with the viral load. According to our results, its use to rule-out SARS-CoV-2 and RSV infection is not sufficient.

Quinones as Promising Compounds against Respiratory Viruses: A Review

Respiratory viruses represent a world public health problem, giving rise to annual seasonal epidemics and several pandemics caused by some of these viruses, including the COVID-19 pandemic caused by the novel SARS-CoV-2, which continues to date. Some antiviral drugs have been licensed for the treatment of influenza, but they cause side effects and lead to resistant viral strains. Likewise, aerosolized ribavirin is the only drug approved for the therapy of infections by the respiratory syncytial virus, but it possesses various limitations. On the other hand, no specific drugs are licensed to treat other viral respiratory diseases. In this sense, natural products and their derivatives have appeared as promising alternatives in searching for new compounds with antiviral activity. Besides their chemical properties, quinones have demonstrated interesting biological activities, including activity against respiratory viruses. This review summarizes the activity against respiratory viruses and their molecular targets by the different types of quinones (both natural and synthetic). Thus, the present work offers a general overview of the importance of quinones as an option for the future pharmacological treatment of viral respiratory infections, subject to additional studies that support their effectiveness and safety.

Respiratory infections

Respiratory infections, whether acute or chronic, are extremely frequent in both adults and children, representing an increased economic burden on healthcare systems, morbidity and mortality. These infections can be either community- or hospital-acquired. Both non-immunosuppressed and immunosuppressed patients can develop such health issues, although prevalence is higher in the latter group. In terms of microbial aetiology, the causative pathogen can be viral, bacterial, fungal or parasitic. In this European Respiratory Review (ERR) series, the authors review some key issues relating to the aforementioned topics.

A new European Respiratory Review series explores respiratory infectionshttps://bit.ly/3A5eN3A