Determinants of immunoglobulin G responses to respiratory syncytial virus and rhinovirus in children and adults

Introduction

Exposure to respiratory viruses is a significant cause of morbidity and affects virus-specific antibody levels. Little is known about determinants associated with immune response to these viruses. We aimed to investigate the determinants of respiratory syncytial virus (RSV)- and rhinovirus (RV)- specific IgG responses in both children and adults.

Methods

The study is based on the EGEA cohort, composed of 530 samples of children in EGEA1 (1991-95) and 1241 samples of adults in EGEA2 (2003-07). Cumulative RV-specific IgG levels (species A, B and C) and IgG levels to RSV-G protein were measured by using micro-array technoloy. Multiple linear mixed models (random effect to account for familial dependence) were performed to assess associations between age, sex, body mass index (BMI), tobacco smoke exposure and season of blood sampling with RSV-and RV-specific IgG levels.

Results

In children (11.1 ± 2.8 years old, 57% boys), higher RV-specific IgG levels were associated with older age (only for RV-B), female sex and lower BMI, while only older age was associated with higher RSV-specific IgG levels. In adults (43.5 ± 16.7 years old, 48% men), younger age, female sex, lower BMI, active smoking and all seasons except summer were associated with higher RV-specific IgG levels. Older age, active smoking and all seasons except summer were associated with higher RSV-specific IgG levels.

Conclusion

Personal and seasonal determinants of RSV- and RV-specific IgG levels seem to vary according to the respiratory virus type and between children and adults, suggesting different patterns of responses along the life course.

Changes in Viral Dynamics Following the Legal Relaxation of COVID-19 Mitigation Measures in Japan From Children to Adults: A Single Center Study, 2020-2023

INTRODUCTION

Respiratory infections are an ongoing global health challenge. The COVID-19 pandemic triggered global nonpharmacological measures that reshaped public health. In Japan, the shift from legal to individual discretion in pandemic management started on May 8, 2023. However, it still unknown how the relaxation of measures affects respiratory pathogens across age groups.

METHODS

We collected 16,946 samples from 13,526 patients between February 2020 and September 2023, analyzing the circulating respiratory pathogen dynamics using FilmArray respiratory panel.

RESULTS

Our analysis revealed significant increases in the positivity rates of respiratory pathogens across multiple age groups after relaxation. The pathogens including adenovirus, Bordetella pertussis, parainfluenza 2 and parainfluenza 4 showed increased positivity predominantly in children aged under 10 years. Conversely, some pathogens including human metapneumovirus, rhinovirus/enterovirus, and respiratory virus (RSV) increased in broad range of age groups. SARS-CoV-2 positivity rates decreased in children under 10 years but increased in those aged over 60 years.

DISCUSSION

Age-stratified analysis reveals a dynamic pattern of circulating pathogen in each age group after relaxation measures. This study provides essential epidemiologic data that can guide strategies to protect different age groups and effectively respond to respiratory infections in post-COVID-19 era.

Bronchiolitis hospital admission in infancy is associated with later preschool ventilation inhomogeneity

BACKGROUND

Rhinovirus (RV) positive bronchiolitis episodes in infancy confer a higher risk to develop asthma in later childhood with associated lung function impairments. We aimed to investigate the association between the type of virus causing a bronchiolitis hospitalization episode and lung ventilation inhomogeneities at preschool age.

METHODS

Infants hospitalized with a clinical diagnosis of moderate (ward admission) or severe (pediatric intensive care ward admission) bronchiolitis were prospectively followed-up at preschool age to assess nitrogen (N2 ) multiple breath washout (MBW). Lung clearance index (LCI), functional residual capacity (FRC), and concentration normalized phase III slope analysis (SnIII ) indices were reported from ≥2 technically acceptable trials. Differences between groups were calculated using logistic and linear regression and adjusted for confounders (sex, age at bronchiolitis admission, height at visit, maternal asthma, and doctor-diagnosed asthma, including interaction terms between the latter three). An interaction term was included in a regression model to test for an interaction between RV bronchiolitis severity and MBW parameters at preschool age.

RESULTS

One hundred and thirty-nine subjects attended preschool follow-up, of which 84 out of 103 (82%) performing MBW had technically acceptable data. Children with a history of RV positive bronchiolitis (n = 39) had increased LCI (adjusted β-coefficient [aβ] = 0.33, 95% confidence interval [CI] 0.02-0.65, p = 0.040) and conductive airways ventilation inhomogeneity [Scond ] (aβ = 0.016, CI 0.004-0.028, p = 0.011) when compared with those with a RV negative bronchiolitis history (n = 45). In addition, we found a statistical interaction between RV bronchiolitis and bronchiolitis severity strengthening the association with LCI (aβ = 0.93, CI 0.20-1.58, p = 0.006).

CONCLUSION

Children with a history of hospital admission for RV positive bronchiolitis in infancy might be at a higher risk of lung ventilation inhomogeneities at preschool age, arising from the peripheral conducting airways.

Sphingosine Prevents Rhinoviral Infections

Rhinoviral infections cause approximately 50% of upper respiratory tract infections and novel treatment options are urgently required. We tested the effects of 10 μM to 20 μM sphingosine on the infection of cultured and freshly isolated human cells with minor and major group rhinovirus in vitro. We also performed in vivo studies on mice that were treated with an intranasal application of 10 μL of either a 10 μM or a 100 μM sphingosine prior and after infection with rhinovirus strains 1 and 2 and determined the infection of nasal epithelial cells in the presence or absence of sphingosine. Finally, we determined and characterized a direct binding of sphingosine to rhinovirus. Our data show that treating freshly isolated human nasal epithelial cells with sphingosine prevents infections with rhinovirus strains 2 (minor group) and 14 (major group). Nasal infection of mice with rhinovirus 1b and 2 is prevented by the intranasal application of sphingosine before or as long as 8 h after infection with rhinovirus. Nasal application of the same doses of sphingosine exerts no adverse effects on epithelial cells as determined by hemalaun and TUNEL stainings. The solvent, octylglucopyranoside, was without any effect in vitro and in vivo. Mechanistically, we demonstrate that the positively charged lipid sphingosine binds to negatively charged molecules in the virus, which seems to prevent the infection of epithelial cells. These findings indicate that exogenous sphingosine prevents infections with rhinoviruses, a finding that could be therapeutically exploited. In addition, we demonstrated that sphingosine has no obvious adverse effects on the nasal mucosa. Sphingosine prevents rhinoviral infections by a biophysical mode of action, suggesting that sphingosine could serve to prevent many viral infections of airways and epithelial cells in general. Future studies need to determine the molecular mechanisms of how sphingosine prevents rhinoviral infections and whether sphingosine also prevents infections with other viruses inducing respiratory tract infections. Furthermore, our studies do not provide detailed pharmacokinetics that are definitely required before the further development of sphingosine.

CA, Harmon B, Espinola JA, Reck Cechinel L, Batabyal R, Freishtat RJ, Hahn A. Bacterial small RNAs may mediate immune response differences seen in respiratory syncytial virus versus rhinovirus bronchiolitis

Bronchiolitis, a viral lower respiratory infection, is the leading cause of infant hospitalization, which is associated with an increased risk for developing asthma later in life. Bronchiolitis can be caused by several respiratory viruses, such as respiratory syncytial virus (RSV), rhinovirus (RV), and others. It can also be caused by a solo infection (e.g., RSV- or RV-only bronchiolitis) or co-infection with two or more viruses. Studies have shown viral etiology-related differences between RSV- and RV-only bronchiolitis in the immune response, human microRNA (miRNA) profiles, and dominance of certain airway microbiome constituents. Here, we identified bacterial small RNAs (sRNAs), the prokaryotic equivalent to eukaryotic miRNAs, that differ between infants of the 35th Multicenter Airway Research Collaboration (MARC-35) cohort with RSV- versus RV-only bronchiolitis. We first derived reference sRNA datasets from cultures of four bacteria known to be associated with bronchiolitis (i.e., Haemophilus influenzae, Moraxella catarrhalis, Moraxella nonliquefaciens, and Streptococcus pneumoniae). Using these reference sRNA datasets, we found several sRNAs associated with RSV- and RV-only bronchiolitis in our human nasal RNA-Seq MARC-35 data. We also determined potential human transcript targets of the bacterial sRNAs and compared expression of the sRNAs between RSV- and RV-only cases. sRNAs are known to downregulate their mRNA target, we found that, compared to those associated with RV-only bronchiolitis, sRNAs associated with RSV-only bronchiolitis may relatively activate the IL-6 and IL-8 pathways and relatively inhibit the IL-17A pathway. These data support that bacteria may be contributing to inflammation differences seen in RSV- and RV-only bronchiolitis, and for the first time indicate that the potential mechanism in doing so may be through bacterial sRNAs.

Seasonality and Genotype Diversity of Human Rhinoviruses during an Eight-Year Period in Slovenia

Due to the high socioeconomic burden of rhinoviruses, the development of prevention and treatment strategies is of high importance. Understanding the epidemiological and clinical features of rhinoviruses is essential in order to address these issues. Our study aimed to define the seasonality and molecular epidemiology of rhinoviruses in Slovenia. Over a period of eight years, a total of 20,425 patients from sentinel primary healthcare settings and sentinel hospitals were examined for a panel of respiratory viruses in the national programme for the surveillance of influenza-like illnesses and acute respiratory infections. The patients were from all age groups and had respiratory infections of various severity. Infection with a rhinovirus was confirmed using an RT-rPCR in 1834 patients, and 1480 rhinoviruses were genotyped. The molecular analysis was linked to demographical and meteorological data. We confirmed the year-round circulation of rhinoviruses with clear seasonal cycles, resulting in two seasonal waves with peaks in spring and autumn. High levels of genotype variability and co-circulation were confirmed between and within seasons and were analysed in terms of patient age, the patient source reflecting disease severity, and meteorological factors. Our study provides missing scientific information on the genotype diversity of rhinoviruses in Slovenia. As most previous investigations focused on exclusive segments of the population, such as children or hospitalised patients, and for shorter study periods, our study, with its design, size and length, contributes complementary aspects and new evidence-based knowledge to the regional and global understanding of rhinovirus seasonality and molecular epidemiology.

Single-Molecule Analysis of Genome Uncoating from Individual Human Rhinovirus Particles, and Modulation by Antiviral Drugs

Infection of humans by many viruses is typically initiated by the internalization of a single virion in each of a few susceptible cells. Thus, the outcome of the infection process may depend on stochastic single-molecule events. A crucial process for viral infection, and thus a target for developing antiviral drugs, is the uncoating of the viral genome. Here a force spectroscopy procedure using an atomic force microscope is implemented to study uncoating for individual human rhinovirus particles. Application of an increasing mechanical force on a virion led to a high force-induced structural transition that facilitated extrusion of the viral RNA molecule without loss of capsid integrity. Application of force to virions that h ad previously extruded the RNA, or to RNA-free capsids, led to a lower force-induced event associated with capsid disruption. The kinetic parameters are determined for each reaction. The high-force event is a stochastic process governed by a moderate free energy barrier (≈20 kcal mol-1 ), which results in a heterogeneous population of structurally weakened virions in which different fractions of the RNA molecule are externalized. The effects of antiviral compounds or capsid mutation on the kinetics of this reaction reveal a correlation between the reaction rate and virus infectivity.

Membrane lipid composition of bronchial epithelial cells influences antiviral responses during rhinovirus infection

Lipids and their mediators have important regulatory functions in many cellular processes, including the innate antiviral response. The aim of this study was to compare the lipid membrane composition of in vitro differentiated primary bronchial epithelial cells (PBECs) with ex vivo bronchial brushings and to establish whether any changes in the lipid membrane composition affect antiviral defense of cells from donors without and with severe asthma. Using mass spectrometry, we showed that the lipid membrane of in vitro differentiated PBECs was deprived of polyunsaturated fatty acids (PUFAs) compared to ex vivo bronchial brushings. Supplementation of the culture medium with arachidonic acid (AA) increased the PUFA-content to more closely match the ex vivo membrane profile. Rhinovirus (RV16) infection of AA-supplemented cultures from healthy donors resulted in significantly reduced viral replication while release of inflammatory mediators and prostaglandin E2 (PGE2) was significantly increased. Indomethacin, an inhibitor of prostaglandin-endoperoxide synthases, suppressed RV16-induced PGE2 release and significantly reduced CXCL-8/IL-8 release from AA-supplemented cultures indicating a link between PGE2 and CXCL8/IL-8 release. In contrast, in AA-supplemented cultures from severe asthmatic donors, viral replication was enhanced whereas PTGS2 expression and PGE2 release were unchanged and CXCL8/IL-8 was significantly reduced in response to RV16 infection. While the PTGS2/COX-2 pathway is initially pro-inflammatory, its downstream products can promote symptom resolution. Thus, reduced PGE2 release during an RV-induced severe asthma exacerbation may lead to prolonged symptoms and slower recovery. Our data highlight the importance of reflecting the in vivo lipid profile in in vitro cell cultures for mechanistic studies.

Rhinovirus protease cleavage of nucleoporins: perspective on implications for airway remodeling

Human Rhinoviruses (RV) are a major cause of common colds and infections in early childhood and can lead to subsequent development of asthma via an as yet unknown mechanism. Asthma is a chronic inflammatory pulmonary disease characterized by significant airway remodeling. A key component of airway remodeling is the transdifferentiation of airway epithelial and fibroblast cells into cells with a more contractile phenotype. Interestingly, transforming growth factor-beta (TGF-β), a well characterized inducer of transdifferentiation, is significantly higher in airways of asthmatics compared to non-asthmatics. RV infection induces TGF-β signaling, at the same time nucleoporins (Nups), including Nup153, are cleaved by RV proteases disrupting nucleocytoplasmic transport. As Nup153 regulates nuclear export of SMAD2, a key intermediate in the TGF-β transdifferentiation pathway, its loss of function would result in nuclear retention of SMAD2 and dysregulated TGF-β signaling. We hypothesize that RV infection leads to increased nuclear SMAD2, resulting in sustained TGF-β induced gene expression, priming the airway for subsequent development of asthma. Our hypothesis brings together disparate studies on RV, asthma and Nup153 with the aim to prompt new research into the role of RV infection in development of asthma.

Comparative analysis of mortality in patients admitted with an infection with influenza A/B virus, respiratory syncytial virus, rhinovirus, metapneumovirus or SARS-CoV-2

Background

While influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are recognised as a cause of severe illness and mortality, clinical interest for respiratory syncytial virus (RSV), rhinovirus and human metapneumovirus (hMPV) infections is still limited.

Methods

We conducted a retrospective database study comparing baseline characteristics and 30-day mortality in a large cohort of adult patients admitted for an overnight stay or longer with an influenza virus (A/B), rhinovirus, hMPV, RSV or SARS-CoV-2 infection. For non-SARS-CoV-2 viruses, data were included for the period July 2017-February 2020. For SARS-CoV-2, data between March 2020 and March 2022 were included.

Results

Covariate-adjusted 30-day mortality following RSV, hMPV or rhinovirus infections was substantial (crude mortality 8-10%) and comparable with mortality following hospitalisation with an influenza A virus infection. Mortality following a SARS-CoV-2 infection was consistently higher than for any other respiratory virus, at any point in time (crude mortality 14-25%). Odds of mortality for SARS-CoV-2 compared with influenza A declined from 4.9 to 1.7 over the course of the pandemic. Patients with SARS-CoV-2 infection had less comorbidity than patients with other respiratory virus infections and were more often male. In this cohort, age was related to mortality following hospitalisation, while an association with comorbidity was not apparent.

Conclusions

With the exception of SARS-CoV-2 infections, we find the clinical outcome of common respiratory virus infections requiring hospitalisation more similar than often assumed. The observed mortality from SARS-CoV-2 was significantly higher, but the difference with other respiratory viruses became less distinct over time.

Respiratory Viruses in Wastewater Compared with Clinical Samples, Leuven, Belgium

In a 2-year study in Leuven, Belgium, we investigated the use of wastewater sampling to assess community spread of respiratory viruses. Comparison with the number of positive clinical samples demonstrated that wastewater data reflected circulation levels of typical seasonal respiratory viruses, such as influenza, respiratory syncytial virus, and enterovirus D68.

Are lung ultrasound features more severe in infants with bronchiolitis and coinfections?

Background

The lung ultrasound (LUS) score can be a useful tool to predict the need for respiratory support and the length of hospital stay in infants with bronchiolitis.

Objective

To compare lung ultrasound features in neonates and infants up to three months of age with bronchiolitis to determine whether LUS scores (range 0-36) differ in infants with coinfections or not.

Methods

Neonates and infants younger than three months admitted to neonatal units from October 2022 to March 2023, who underwent lung ultrasound evaluation on admission, were included in this retrospective study.

Results

We included 60 patients who underwent LUS evaluation at admission. Forty-two infants (70.0%) had a single viral infection. Eighteen infants (30.0%) had a coinfection: fifteen infants (25.0%) had more than one virus at PCR; one infant (1.7%) had both a viral coinfection and a viral-bacteria coinfection; two infants (3.3%) had viral-bacteria coinfection. Infants with a single viral infection and those with coinfections had similar LUS scores globally and in different lung zones. An LUS score higher than 8 was identified to significantly predict the need for any respiratory support (p = 0.0035), whereas an LUS score higher than 13 was identified to significantly predict the need for mechanical ventilation (p = 0.024).

Conclusion

In our small cohort of neonates and infants younger than three months hospitalized with bronchiolitis, we found no statistically significant differences in the LUS score on admission between patients with a single viral infection and those with multiple infections.

Antibiotic Utilization in Hospitalized Children with Bronchiolitis: A Prospective Study Investigating Clinical and Epidemiological Characteristics at a Secondary Hospital in Madrid (2004-2022)

Bronchiolitis is a viral respiratory infection, with respiratory syncytial virus (RSV) being the most frequent agent, requiring hospitalization in 1% of affected children. However, there continues to be a noteworthy incidence of antibiotic prescription in this setting, further exacerbating the global issue of antibiotic resistance. This study, conducted at Severo Ochoa Hospital in Madrid, Spain, focused on antibiotic usage in children under 2 years of age who were hospitalized for bronchiolitis between 2004 and 2022. In that time, 5438 children were admitted with acute respiratory infection, and 1715 infants (31.5%) with acute bronchiolitis were included. In total, 1470 (87%) had a positive viral identification (66% RSV, 32% HRV). Initially, antibiotics were prescribed to 13.4% of infants, but this percentage decreased to 7% during the COVID-19 pandemic thanks to adherence to guidelines and the implementation of rapid and precise viral diagnostic methods in the hospital. HBoV- and HAdV-infected children and those with viral coinfections were more likely to receive antibiotics in the univariate analysis. A multivariate logistic regression analysis revealed a statistically independent association between antibiotic prescription and fever > 38 °C (p < 0.001), abnormal chest-X ray (p < 0.001), ICU admission (p = 0.015), and serum CRP (p < 0.001). In conclusion, following guidelines and the availability of rapid and reliable viral diagnostic methods dramatically reduces the unnecessary use of antibiotics in infants with severe bronchiolitis.

Poly I:C Pre-Treatment Induced the Anti-Viral Interferon Response in Airway Epithelial Cells

Type I and III interferons are among the most important antiviral mediators. Increased susceptibility to infections has been described as being associated with impaired interferon response in asthmatic patients. In this work, we focused on the modulation of interferon dysfunction after the rhinovirus infection of airway epithelial cells. Therefore, we tested polyinosinic:polycytidylic acid (poly I:C), a TLR3 agonist, as a possible preventive pre-treatment to improve this anti-viral response. In our human study on asthma, we found a deficiency in interferon levels in the nasal epithelial cells (NEC) from asthmatics at homeostatic level and after RV infection, which might contribute to frequent airway infection seen in asthmatic patients compared to healthy controls. Finally, pre-treatment with the immunomodulatory substance poly I:C before RV infection restored IFN responses in airway epithelial cells. Altogether, we consider poly I:C pre-treatment as a promising strategy for the induction of interferon response prior to viral infections. These results might help to improve current therapeutic strategies for allergic asthma exacerbations.

Positive and negative viral associations in patients with acute respiratory tract infections in primary care: the ECOVIR study

Introduction

Acute respiratory infections (ARIs) are the most common viral infections encountered in primary care settings. The identification of causal viruses is still not available in routine practice. Although new strategies of prevention are being identified, knowledge of the relationships between respiratory viruses remains limited.

Materials and methods

ECOVIR was a multicentric prospective study in primary care, which took place during two pre-pandemic seasons (2018-2019 and 2019-2020). Patients presenting to their General practitioner (GP) with ARIs were included, without selecting for age or clinical conditions. Viruses were detected on nasal swab samples using a multiplex Polymerase Chain Reaction test focused on 17 viruses [Respiratory Syncytial Virus-A (RSV-A), RSV-B, Rhinovirus/Enterovirus (HRV), human Metapneumovirus (hMPV), Adenovirus (ADV), Coronaviruses (CoV) HKU1, NL63, 229E, OC43, Influenza virus (H1 and H3 subtypes), Influenza virus B, Para-Influenza viruses (PIVs) 1-4, and Bocavirus (BoV)].

Results

Among the 668 analyzed samples, 66% were positive for at least one virus, of which 7.9% were viral codetections. The viral detection was negatively associated with the age of patients. BoV, ADV, and HRV occurred more significantly in younger patients than the other viruses (p < 0.05). Codetections were significantly associated with RSV, HRV, BoV, hMPV, and ADV and not associated with influenza viruses, CoV, and PIVs. HRV and influenza viruses were negatively associated with all the viruses. Conversely, a positive association was found between ADV and BoV and between PIVs and BoV.

Conclusion

Our study provides additional information on the relationships between respiratory viruses, which remains limited in primary care.

Full genome sequence of a human rhinovirus A1B, obtained in Kazakhstan

Here, we report the full nucleotide sequence of the RvA1B/KZ/2021/87 rhinovirus, identified through metagenomic sequencing of nasopharyngeal swabs collected from patients exhibiting respiratory symptoms in Kazakhstan during 2021.

Human bocavirus 1 coinfection is associated with decreased cytokine expression in the rhinovirus-induced first wheezing episode in children

BACKGROUND

Rhinovirus (RV)-induced first wheezing episodes in children are associated with a markedly increased risk of asthma. Previous studies have suggested that human bocavirus 1 (HBoV1) may modify RV-induced immune responses in young children. We investigated cytokine profiles of sole RV- and dual RV-HBoV1-induced first wheezing episodes, and their association with severity and prognosis.

METHODS

Fifty-two children infected with only RV and nine children infected with dual RV-HBoV1, aged 3-23 months, with severe first wheezing episodes were recruited. At acute illness and 2 weeks later, peripheral blood mononuclear cells were isolated, and stimulated with anti-CD3/anti-CD28 in vitro. Multiplex ELISA was used to quantitatively identify 56 different cytokines at both study points. Patients were prospectively followed for 4 years.

RESULTS

The mean age of the children was 14.3 months, and 30% were sensitized. During the acute illness, the adjusted analyses revealed a decrease in the expression of IL-1b, MIP-1b, Regulated upon activation, normal T cell expressed and presumably secreted (CCL5), TNF-a, TARC, and ENA-78 in the RV-HBoV1 group compared with the RV group. In the convalescence phase, the RV-HBoV1 group was characterized by decreased expression of Fractalkine, MCP-3, and IL-8 compared to the RV group. Furthermore, the hospitalization time was associated with the virus group and cytokine response (interaction p < 0.05), signifying that increased levels of epidermal growth factor and MIP-1b were related with a shorter duration of hospitalization in the RV-HBoV1 coinfection group but not in the RV group.

CONCLUSIONS

Different cytokine response profiles were detected between the RV and the RV-HBoV1 groups. Our results show the idea that RV-induced immune responses may be suppressed by HBoV1.

Respiratory virus infections after allogeneic stem cell transplantation: Current understanding, knowledge gaps, and recent advances

Before the COVID-19 pandemic, common community-acquired seasonal respiratory viruses (CARVs) were a significant threat to the health and well-being of allogeneic hematopoietic cell transplant (allo-HCT) recipients, often resulting in severe illness and even death. The pandemic has further highlighted the significant risk that immunosuppressed patients, including allo-HCT recipients, face when infected with SARS-CoV-2. As preventive transmission measures are relaxed and CARVs circulate again among the community, including in allo-HSCT recipients, it is crucial to understand the current state of knowledge, gaps, and recent advances regarding CARV infection in allo-HCT recipients. Urgent research is needed to identify seasonal respiratory viruses as potential drivers for future pandemics.

Trend in respiratory viruses' activity in the COVID-19 area

OBJECTIVES

SARS-CoV-2 has impacted the detection of seasonal respiratory viruses. We retrospectively assessed the trend in the detection of 10 viruses in the COVID-19 area in 2 hospitals located in the Paris area.

METHODS

All patients positive for a respiratory virus in two hospitals from September 2016 to August 2021 were retrospectively included. The rate of RT-PCR positive for each virus was calculated for the 2020-2021 season and the 2019-2020 season in comparison to a baseline of 3 seasons, i.e. 2016-2017, 2017-2018, and 2018-2019.

RESULTS

Overall, 7,835 patients were tested positive from September 2016 to August 2021. The detection of respiratory virus dramatically falls on week-11 of 2020, as the number of RT-PCR performed. Then, 3 trends were identified: a) almost a disappearance for influenza; b) a 10-weeks delay in the seasonal outbreak for RSV; c) a persistence of circulation with variable activity for other viruses. In comparison to a baseline of three seasons (2016-2019), the rate of positive patients was lower during the 2020-2021 season for coronavirus (4.51% vs. 1.26%, P < 0.0001), adenovirus (1.93% vs. 1.34%, P = 0.14), bocavirus (0.58% vs. 0.11%, P = 0.08), and enterovirus (0.28% vs. 0.0%, P = 0.12). In contrast, the rate of hMPV-positive (1.92% vs. 2.83%, P = 0.03) and hPIV-positive (2.17% vs. 2.99%, P = 0.06) patients increased.

CONCLUSIONS

The fall in the number of respiratory viruses detected might be related to the lower number of tests performed and the implementation of non pharmaceutical intervention (NPI). Then, all viruses except influenza are detected, probably as a consequence of high adherence to influenza vaccines. Despite, a lower number of tests being performed, the rate of hMPV-positive and hPIV-positive patients increased suggesting an active circulation of these viruses. Altogether, these findings suggest a persistent circulation of common respiratory viruses all over the COVID-19 era.

The Picornaviridae Family: Knowledge Gaps, Animal Models, Countermeasures, and Prototype Pathogens

Picornaviruses are nonenveloped particles with a single-stranded RNA genome of positive polarity. This virus family includes poliovirus, hepatitis A virus, rhinoviruses, and Coxsackieviruses. Picornaviruses are common human pathogens, and infection can result in a spectrum of serious illnesses, including acute flaccid myelitis, severe respiratory complications, and hand-foot-mouth disease. Despite research on poliovirus establishing many fundamental principles of RNA virus biology and the first transgenic animal model of disease for infection by a human virus, picornaviruses are understudied. Existing knowledge gaps include, identification of molecules required for virus entry, understanding cellular and humoral immune responses elicited during virus infection, and establishment of immune-competent animal models of virus pathogenesis. Such knowledge is necessary for development of pan-picornavirus countermeasures. Defining enterovirus A71 and D68, human rhinovirus C, and echoviruses 29 as prototype pathogens of this virus family may provide insight into picornavirus biology needed to establish public health strategies necessary for pandemic preparedness.

Interactive effects between CDHR3 genotype and rhinovirus species for diagnosis and severity of respiratory tract infections in hospitalized children

Rhinovirus (RV) is the leading pathogen causing childhood wheezing, with rhinovirus C (RV-C) species reported to cause asthma exacerbation. Allele A of single-nucleotide polymorphism (SNP) CDHR3_rs6967330 upregulates epithelial expression of RV-C receptors which results in more severe asthma exacerbations in children. Nevertheless, there are limited data on interactions between CDHR3 variants and their impact on severity of RV-related pediatric respiratory tract infections (RTIs). Medical records of RV-related RTIs in children aged below 18 years who were hospitalized in two public hospitals in 2015-2016 were independently reviewed by two paediatricians. Archived nasopharyngeal aspirates were retrieved for RV detection and sequencing as well as CDHR3 genotyping. HaploView v.5.0 and generalized multifactor dimensionality reduction (GMDR) analysis were employed for haplotypic assignment and gene-environment interaction analyses. Among 1019 studied cases, our results confirmed the relationship between RV-C species and more severe RTIs. Besides the top risk variant rs6967330-A, we identified rs140154310-T to be associated with RV-C susceptibility under the additive model [odds ratio (OR) 2.53, 95% CI 1.15-5.56; P = 0.021]. Rs140154310 was associated with wheezing illness (OR 2.38, 95% CI 1.12-5.04; P = 0.024), with such association being stronger in subjects who wheezed due to RV-C infections (OR 2.71, 95% CI 1.32-5.58; P = 0.007). Haplotype GAG constructed from rs4730125, rs6967330, and rs73195665 was associated with increased risk of RV-C infection (OR 1.71, 95% CI 1.11-2.65; P = 0.016) and oxygen supplementation (OR 1.93, 95% CI 1.13-3.30; P = 0.016). GMDR analyses revealed epistatic interaction between rs140154310 and rs6967330 of CDHR3 for RV-C infection (P = 0.001), RV-C-associated lower RTI (P = 0.004), and RV-C-associated wheeze (P = 0.007). There was synergistic gene-environmental interaction between rs3887998 and RV-C for more severe clinical outcomes (P < 0.001). To conclude, rs140154310-T is another risk variant for RV-C susceptibility and more severe RTIs. Synergistic epistatic interaction is found between CDHR3 SNPs and RV-C for RTI severity, which is likely mediated by susceptibility to RV-C. Haplotypic analysis and GMDR should be included in identifying prediction models of CDHR3 for childhood asthma and RTIs. IMPORTANCE This case-control study investigated the interaction between CDHR3 genotypes and rhinovirus (RV) species on disease severity in Hong Kong children hospitalized for respiratory tract infection (RTI). There were synergistic effects between RV-C and CDHR3 SNPs for RTI severity, which was mainly driven by RV-C. Specifically, rs6967330 and rs140154310 alone and their epistatic interaction were associated with RV-C-related and severe RTIs in our subjects. Therefore, genotyping of CDHR3 SNPs may help physicians formulate prediction models for severity of RV-associated RTIs.

Adsorption of Respiratory Syncytial Virus, Rhinovirus, SARS-CoV-2, and F+ Bacteriophage MS2 RNA onto Wastewater Solids from Raw Wastewater

Despite the widespread adoption of wastewater surveillance, more research is needed to understand the fate and transport of viral genetic markers in wastewater. This information is essential for optimizing monitoring strategies and interpreting wastewater surveillance data. In this study, we examined the solid-liquid partitioning behavior of four viruses in wastewater: SARS-CoV-2, respiratory syncytial virus (RSV), rhinovirus (RV), and F+ coliphage/MS2. We used two approaches: (1) laboratory partitioning experiments using lab-grown viruses and (2) distribution experiments using endogenous viruses in raw wastewater. Partition experiments were conducted at 4 and 22 °C. Wastewater samples were spiked with varying concentrations of each virus, solids and liquids were separated via centrifugation, and viral RNA concentrations were quantified using reverse-transcription-digital droplet PCR (RT-ddPCR). For the distribution experiments, wastewater samples were collected from six wastewater treatment plants and processed without spiking exogenous viruses; viral RNA concentrations were measured in wastewater solids and liquids. In both experiments, RNA concentrations were higher in the solid fraction than the liquid fraction by approximately 3-4 orders of magnitude. Partition coefficients (KF) ranged from 2000-270,000 mL·g-1 across viruses and temperature conditions. Distribution coefficients (Kd) were consistent with results from partitioning experiments. Further research is needed to understand how virus and wastewater characteristics might influence the partitioning of viral genetic markers in wastewater.

Navigating paediatric virology through the COVID‑19 era (Review)

The present review article presents the key messages of the 8th Workshop on Paediatric Virology organised virtually by the Institute of Paediatric Virology based on the island of Euboea in Greece. The major topics covered during the workshop were the following: i) New advances in antiviral agents and vaccines against cytomegalovirus; ii) hantavirus nephropathy in children; iii) human rhinovirus infections in children requiring paediatric intensive care; iv) complications and management of human adenovirus infections; v) challenges of post‑coronavirus disease 2019 (COVID‑19) syndrome in children and adolescents; and vi) foetal magnetic resonance imaging in viral infections involving the central nervous system. The COVID‑19 era requires a more intensive, strategic, global scientific effort in the clinic and in the laboratory, focusing on the diagnosis, management and prevention of viral infections in neonates and children.

Evaluation of sequence hybridization for respiratory viruses using the Twist Bioscience Respiratory Virus Research panel and the OneCodex Respiratory Virus sequence analysis workflow

Respiratory viral infections are a major global clinical problem, and rapid, cheap, scalable and agnostic diagnostic tests that capture genome-level information on viral variation are urgently needed. Metagenomic approaches would be ideal, but remain currently limited in that much of the genetic content in respiratory samples is human, and amplifying and sequencing the viral/pathogen component in an unbiased manner is challenging. PCR-based tests, including those which detect multiple pathogens, are already widely used, but do not capture information on strain-level variation; tests with larger viral repertoires are also expensive on a per-test basis. One intermediate approach is the use of large panels of viral probes or 'baits', which target or 'capture' sequences representing complete genomes amongst several different common viral pathogens; these are then amplified, sequenced and analysed with a sequence analysis workflow. Here we evaluate one such commercial bait capture method (the Twist Bioscience Respiratory Virus Research Panel) and sequence analysis workflow (OneCodex), using control (simulated) and patient samples head-to-head with a validated multiplex PCR clinical diagnostic test (BioFire FilmArray). We highlight the limited sensitivity and specificity of the joint Twist Bioscience/OneCodex approach, which are further reduced by shortening workflow times and increasing sample throughput to reduce per-sample costs. These issues with performance may be driven by aspects of both the laboratory (e.g. capacity to enrich for viruses present in low numbers), bioinformatics methods used (e.g. a limited viral reference database) and thresholds adopted for calling a virus as present or absent. As a result, this workflow would require further optimization prior to any implementation for respiratory virus characterization in a routine diagnostic healthcare setting.

Histamine-releasing factor in severe asthma and rhinovirus-associated asthma exacerbation

BACKGROUND

Histamine-releasing factor (HRF) is implicated in allergic diseases. We previously showed its pathogenic role in murine models of asthma.

OBJECTIVE

We aim to present data analysis from 3 separate human samples (sera samples from asthmatic patients, nasal washings from rhinovirus [RV]-infected individuals, and sera samples from patients with RV-induced asthma exacerbation) and 1 mouse sample to investigate correlates of HRF function in asthma and virus-induced asthma exacerbations.

METHODS

Total IgE and HRF-reactive IgE/IgG as well as HRF in sera from patients with mild/moderate asthma or severe asthma (SA) and healthy controls (HCs) were quantified by ELISA. HRF secretion in culture media from RV-infected adenovirus-12 SV40 hybrid virus transformed human bronchial epithelial cells and in nasal washings from experimentally RV-infected subjects was analyzed by Western blotting. HRF-reactive IgE/IgG levels in longitudinal serum samples from patients with asthma exacerbations were also quantified.

RESULTS

HRF-reactive IgE and total IgE levels were higher in patients with SA than in HCs, whereas HRF-reactive IgG (and IgG1) level was lower in asthmatic patients versus HCs. In comparison with HRF-reactive IgElow asthmatic patients, HRF-reactive IgEhigh asthmatic patients had a tendency to release more tryptase and prostaglandin D2 on anti-IgE stimulation of bronchoalveolar lavage cells. RV infection induced HRF secretion from adenovirus-12 SV40 hybrid virus transformed bronchial epithelial cells, and intranasal RV infection of human subjects induced increased HRF secretion in nasal washes. Asthmatic patients had higher levels of HRF-reactive IgE at the time of asthma exacerbations associated with RV infection, compared with those after the resolution. This phenomenon was not seen in asthma exacerbations without viral infections.

CONCLUSIONS

HRF-reactive IgE is higher in patients with SA. RV infection induces HRF secretion from respiratory epithelial cells both in vitro and in vivo. These results suggest the role of HRF in asthma severity and RV-induced asthma exacerbation.