Respiratory syncytial virus subtype circulation and associated disease severity at an Australian paediatric referral hospital, 2014-2018

Evaluating the Impact of N-Glycan Sequon Removal in the p27 Peptide on RSV F Protein Immunogenicity and Functionality

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in young children, elderly and immunocompromised patients worldwide. The RSV fusion (F) protein, which has 5-6 N-glycosylation sites depending on the strain, is a major target for vaccine development. Two to three of these sites are located in the p27 peptide, which is considered absent in virions. Prior research from our group showed that removing the N-glycan at position 116 (N116) in p27 led to higher neutralizing antibody responses and better protection against RSV. In this study, the effect of single, double and triple N-glycan deletion mutations in F p27 was evaluated. Surprisingly, all mutants exhibited similar expressions and functionality to the wild-type F protein. All F p27 glycomutants induced neutralizing antibodies and lowered lung viral loads after an RSV challenge in a mouse model. Although N-glycans in p27 influence immune responses, their exact role in RSV biology remains unclear. Possibly, these glycans, which are mostly conserved, play a role in other aspects of virus replication and biology.

Differences Between RSV A and RSV B Subgroups and Implications for Pharmaceutical Preventive Measures

INTRODUCTION

Understanding the differences between respiratory syncytial virus (RSV) subgroups A and B provides insights for the development of prevention strategies and public health interventions. We aimed to describe the structural differences of RSV subgroups, their epidemiology, and genomic diversity. The associated immune response and differences in clinical severity were also investigated.

METHODS

A literature review from PubMed and Google Scholar (1985-2023) was performed and extended using snowballing from references in captured publications.

RESULTS

RSV has two major antigenic subgroups, A and B, defined by the G glycoprotein. The RSV F fusion glycoprotein in the prefusion conformation is a major target of virus neutralizing antibodies and differs in surface exposed regions between RSV A and RSV B. The subgroups co-circulate annually, but there is considerable debate as to whether clinical severity is impacted by the subgroup of the infecting RSV strain. Large variations between the studies reporting RSV subgroup impact on clinical severity were observed. A tendency for higher disease severity may be attributed to RSV A but no consensus could be reached as to whether infection by one of the subgroup caused more severe outcomes. RSV genotype diversity decreased over the last two decades, and ON and BA have become the sole lineages detected for RSV A and RSV B, since 2014. No studies with data obtained after 2014 reported a difference in disease severity between the two subgroups. RSV F is relatively well conserved and highly similar between RSV A and B, but changes in the amino acid sequence have been observed. Some of these changes led to differences in F antigenic sites compared to reference F sequences (e.g., RSV/A Long strain), which are more pronounced in antigenic sites of the prefusion conformation of RSV B. Initial results from the second season after vaccination suggest specific RSV B efficacy wanes more rapidly than RSV A for RSV PreF-based monovalent vaccines.

CONCLUSIONS

RSV A and RSV B both contribute substantially to the global RSV burden. Both RSV subgroups cause severe disease and none of the available evidence to date suggests any differences in clinical severity between the subgroups. Therefore, it is important to implement measures effective at preventing disease due to both RSV A and RSV B to ensure impactful public health interventions. Monitoring overtime will be needed to assess the impact of waning antibody levels on subgroup-specific efficacy.

Seasonality, Clinical Characteristics, and Outcomes of Respiratory Syncytial Virus Disease by Subtype Among Children Aged <5 Years: New Vaccine Surveillance Network, United States, 2016-2020

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of acute respiratory illnesses in children. RSV can be broadly categorized into 2 major subtypes: A and B. RSV subtypes have been known to cocirculate with variability in different regions of the world. Clinical associations with viral subtype have been studied among children with conflicting findings such that no conclusive relationships between RSV subtype and severity have been established.

METHODS

During 2016-2020, children aged <5 years were enrolled in prospective surveillance in the emergency department or inpatient settings at 7 US pediatric medical centers. Surveillance data collection included parent/guardian interviews, chart reviews, and collection of midturbinate nasal plus/minus throat swabs for RSV (RSV-A, RSV-B, and untyped) using reverse transcription polymerase chain reaction.

RESULTS

Among 6398 RSV-positive children aged <5 years, 3424 (54%) had subtype RSV-A infections, 2602 (41%) had subtype RSV-B infections, and 272 (5%) were not typed, inconclusive, or mixed infections. In both adjusted and unadjusted analyses, RSV-A-positive children were more likely to be hospitalized, as well as when restricted to <1 year. By season, RSV-A and RSV-B cocirculated in varying levels, with 1 subtype dominating proportionally.

CONCLUSIONS

Findings indicate that RSV-A and RSV-B may only be marginally clinically distinguishable, but both subtypes are associated with medically attended illness in children aged <5 years. Furthermore, circulation of RSV subtypes varies substantially each year, seasonally and geographically. With introduction of new RSV prevention products, this highlights the importance of continued monitoring of RSV-A and RSV-B subtypes.

No association between disease severity and respiratory syncytial virus subtypes RSV-A and RSV-B in hospitalized young children in Norway

OBJECTIVE

There is conflicting evidence whether subtypes of Respiratory syncytial virus have different seasonality or are differentially associated with clinical severity. We aimed to explore the associations between disease severity and RSV subtypes RSV-A and RSV-B and to describe the circulation of RSV subtypes pattern by season and age.

METHODS

Active prospective hospital surveillance for RSV-A and RSV-B in children <59 months of age was conducted during 2015-2018. All febrile children 12-59 months of age were enrolled, whereas children <12 months were eligible if presenting with fever or respiratory symptoms. Risk factors and upper and lower respiratory tract infection was identified by linkage to national registry data and analyzed using penalized maximum likelihood logistic regression.

RESULTS

Both RSV-A and B were found to co-circulate throughout all three study seasons, and no clear seasonal pattern was identified. Likewise, we found no association between sex or measures of severity with RSV-A or RSV-B. There was significantly more RSV-A than RSV-B among children with comorbidities.

CONCLUSIONS

No association was found between disease severity or sex and RSV subtypes RSV-A and RSV-B in hospitalized young children in Norway.

Characterisation of RSV infections in children without chronic diseases aged 0-36 months during the post-COVID-19 winter season 2022/2023

Background

Respiratory syncytial virus (RSV) is one of the leading causes of hospitalisation, morbidity, and mortality due to respiratory infection in the first years of life. This longitudinal prospective study outlines the 2022/23 season's viral patterns in Austria after the epidemiological changes determined by public health measures. We aimed to highlight differences within the RSV subtypes and genotypes in 0-36-month-old children without chronic diseases in the outpatient setting.

Methods

From November 2022 to March 2023 children younger than 36 months admitted to Vienna's largest paediatric primary healthcare centre with an acute respiratory infection were enrolled in this study. Nasal swabs and multiplex PCR panels detected 20 viruses including RSV subtypes and genotypes. Clinical presentation, features, and treatment of the participants were documented and analysed using the Modified Tal Score (MTS). Patients were scheduled for a telemedical follow-up one week after the initial appointment. Analysis was done using descriptive statistics, including Cramér V and binominal logarithmic regression.

Results

Among the 345 samples from 329 children, RSV was the most common virus (31.9%), followed by influenza (17.5%) and rhinovirus infections (20.58%). Of the RSV positive samples, only 13 cases were RSV subtype A (11.8%), whereas 97 were of subtype B (87.3%); ON1 and BA9 were the only detectable RSV genotypes (ON1: BA9 = 1:9.25). RSV was the main predictor of hospitalisation (OR: 7.5, 95% CI: (1.46-38.40), and age had a significant but smaller effect (OR: 0.89, 95% CI: (0.81-0.99). Almost all patients' clinical status improved within the first days.

Conclusion

RSV cases showed a rapid onset in late November 2022, and subtype B was predominant throughout the season. RSV infection was associated with higher hospitalisation rates, even after excluding high-risk patients (preterm and severe chronic diseases population).Further testing in the upcoming winter seasons will improve our knowledge of the dominant subtype and its association with disease severity, especially with the development of novel RSV vaccine candidates.

Genetic diversity and its impact on disease severity in respiratory syncytial virus subtype-A and -B bronchiolitis before and after pandemic restrictions in Rome

OBJECTIVES

To scrutinize whether the high circulation of respiratory syncytial virus (RSV) observed in 2021-2022 and 2022-2023 was due to viral diversity, we characterized RSV-A and -B strains causing bronchiolitis in Rome, before and after the COVID-19 pandemic.

METHODS

RSV-positive samples, prospectively collected from infants hospitalized for bronchiolitis from 2017-2018 to 2022-2023, were sequenced in the G gene; phylogenetic results and amino acid substitutions were analyzed. Subtype-specific data were compared among seasons.

RESULTS

Predominance of RSV-A and -B alternated in the pre-pandemic seasons; RSV-A dominated in 2021-2022 whereas RSV-B was predominant in 2022-2023. RSV-A sequences were ON1 genotype but quite distant from the ancestor; two divergent clades included sequences from pre- and post-pandemic seasons. Nearly all RSV-B were BA10 genotype; a divergent clade included only strains from 2021-2022 to 2022-2023. RSV-A cases had lower need of O2 therapy and of intensive care during 2021-2022 with respect to all other seasons. RSV-B infected infants were more frequently admitted to intensive care units and needed O2 in 2022-2023.

CONCLUSIONS

The intense RSV peak in 2021-2022, driven by RSV-A phylogenetically related to pre-pandemic strains is attributable to the immune debt created by pandemic restrictions. The RSV-B genetic divergence observed in post-pandemic strains may have increased the RSV-B specific immune debt, being a possible contributor to bronchiolitis severity in 2022-2023.

Association between PM2.5-bound metals and pediatric respiratory health in Guangzhou: An ecological study investigating source, health risk, and effect

Background

The adverse effects of 2.5-μm particulate matter (PM2.5) exposure on public health have become an increasing concern worldwide. However, epidemiological findings on the effects of PM2.5-bound metals on children's respiratory health are limited and inconsistent because PM2.5 is a complicated mixture.

Objectives

Given the vulnerability of children's respiratory system, aim to pediatric respiratory health, this study evaluated the potential sources, health risks, and acute health effects of ambient PM2.5-bound metals among children in Guangzhou, China from January 2017 to December 2019.

Methods

Potential sources of PM2.5-bound metals were detected using positive matrix factorization (PMF). A health risk assessment was conducted to investigate the inhalation risk of PM2.5-bound metals in children. The associations between PM2.5-bound metals and pediatric respiratory outpatient visits were examined with a quasi-Poisson generalized additive model (GAM).

Results

During 2017–2019, the daily mean concentrations of PM2.5 was 53.39 μg/m3, and the daily mean concentrations of PM2.5-bound metals range 0.03 ng/m3 [thorium (Th) and beryllium (Be)] from to 396.40 ng/m3 [iron (Fe)]. PM2.5-bound metals were mainly contributed by motor vehicles and street dust. PM2.5-bound arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr)(VI), nickel (Ni), and lead (Pb) were found to pose a carcinogenic risk (CR). A quasi-Poisson GAM was constructed that showed there were significant associations between PM2.5 concentrations and pediatric outpatient visits for respiratory diseases. PM2.5 was significantly associated with pediatric outpatient visits for respiratory diseases. Moreover, with a 10 μg/m3 increase in Ni, Cr(VI), Ni, and As concentrations, the corresponding pediatric outpatient visits for respiratory diseases increased by 2.89% (95% CI: 2.28–3.50%), acute upper respiratory infections (AURIs) increased by 2.74% (2.13–3.35%), influenza and pneumonia (FLU&amp;PN) increased by 23.36% (20.09–26.72%), and acute lower respiratory infections (ALRIs) increased by 16.86% (15.16–18.60%), respectively.

Conclusions

Our findings showed that PM2.5 and PM2.5-bound As, Cd, Co, Cr(VI), Ni, and Pb had adverse effects on pediatric respiratory health during the study period. New strategies are required to decrease the production of PM2.5 and PM2.5-bound metals by motor vehicles and to reduce levels of street dust to reduce children's exposure to these pollutants and thereby increase child health.

Analysis of circulating respiratory syncytial virus A strains in Shanghai, China identified a new and increasingly prevalent lineage within the dominant ON1 genotype

Respiratory syncytial virus A (RSV-A) is one of the commonest pathogens causing acute respiratory tract infections in infants and children globally. The currently dominant circulating genotype of RSV-A, ON1, was first detected in Shanghai, China in 2011, but little data are available regarding its subsequent circulation and clinical impact here. In this work, we analyzed RSV-A infection in a cohort of patients hospitalized for acute respiratory infections in Shanghai Children’s Hospital, and RSV-A was detected in ~10% of these cases. RSV-A G gene sequencing revealed that all successfully sequenced strains belonged to ON1 genotype, but in phylogenetic analysis, the majority of these sequences formed a clade separate from the four previously established lineages within ON1. The new lineage, denoted ON1-5, was supported by phylogenetic analyses using additional G gene sequences from RSV-A strains isolated in Shanghai and elsewhere. ON1-5 first appeared in 2015 in China and the Netherlands, and has since spread to multiple continents and gained dominance in Asia. In our cohort, ON1-5 was not associated with markedly different clinical presentations compared to other ON1 lineages. ON1-5 strains are characterized by four amino acid variations in the two mucin-like regions of G protein, and one variation (N178G) within the highly conserved CCD domain that is involved in receptor binding. These data highlight the continuous evolution of RSV-A, and suggest the possibility of the virus acquiring variations in domains traditionally considered to be conserved for fitness gain.

Management of Hospitalized Respiratory Syncytial Virus Bronchiolitis in the Pediatric Ward in Spain: Assessing the Impact of a New Clinical Practice Protocol

BACKGROUND

Bronchiolitis caused by the respiratory syncytial virus (RSV) is the main reason for hospitalization in infants. Supportive care is the mainstay of treatment, and tests are restricted to a few indications. During 2015, our hospital bronchiolitis protocol (2015 HBP) was updated according to the latest practice guidelines.

OBJECTIVE

The objective of this study was to assess implementation of the 2015 HBP and the clinical outcome of children aged ≤ 24 months with RSV bronchiolitis admitted to a pediatric ward.

METHODS

We compared the use of treatments and tests, hospital length of stay (LOS), and oxygen requirements before implementation of the 2015 HBP (2014-2015 and 2015-2016 seasons) and after implementation (2016-2017 and 2017-2018 seasons).

RESULTS

The study population comprised 251 children (44.90%) in the first period and 308 (55.10%) in the second (median age 99 days, interquartile range 44-233). After implementation of the 2015 HBP, a statistically significant reduction was found in the percentage of patients undergoing the following treatments or diagnostic tests: salbutamol, from 57.77 to 31.17% (p < 0.001); epinephrine, from 61.75 to 1.30% (p < 0.001); 3% hypertonic saline, from 70.12 to 6.82% (p < 0.001); antibiotics, from 33.07 to 23.05% (p = 0.008); and chest X-ray, from 43.82 to 31.17% (p = 0.001). No statistically significant reductions were observed in the use of corticosteroids and blood tests. Hospital LOS and oxygen requirements were similar in each period.

CONCLUSIONS

Appropriate implementation of the 2015 HBP in the pediatric ward improves the use of medication and chest X-ray without modifying clinical outcomes. However, further efforts are needed to reduce the use of salbutamol, corticosteroids, and blood tests.