How to use…respiratory viral studies

The Molecular Basis of Asthma Exacerbations Triggered by Viral Infections: The Role of Specific miRNAs

Viral respiratory infections are a significant clinical problem among the pediatric population and are one of the leading causes of hospitalization. Most often, upper respiratory tract infections are self-limiting. Still, those that involve the lower respiratory tract are usually associated with asthma exacerbations, leading to worsening or even the initiation of the disease. A key role in regulating the immune response and inflammation during viral infections and their impact on the progression of asthma has been demonstrated for miRNA molecules (microRNA). Their interaction with mRNA (messenger RNA) regulates gene expression in innate and acquired immune responses, making them valuable biomarkers for diagnostics, monitoring, and predicting asthma exacerbations. The following paper presents changes in the expression of miRNAs during the five most common viral infections causing asthma worsening, with particular emphasis on the pediatric population. In addition, we describe the molecular mechanisms by which miRNAs influence the pathogenesis of viral infection, immune responses, and asthma exacerbations. These molecules represent promising targets for future innovative therapeutic strategies, paving the way for developing personalized medicine for patients with viral-induced asthma exacerbations.

[Virological diagnosis of lower respiratory tract infections]

INTRODUCTION

The etiological diagnosis of bronchopulmonary infections cannot be assessed with clinical, radiological and epidemiological data alone. Viruses have been demonstrated to cause a large proportion of these infections, both in children and adults.

BACKGROUND

The diagnosis of viral bronchopulmonary infections is based on the analysis of secretions, collected from the lower respiratory tract when possible, by techniques that detect either influenza and respiratory syncytial viruses, or a large panel of viruses that can be responsible for respiratory disease. The latter, called multiplex PCR assays, allow a syndromic approach to respiratory infection. Their high cost for the laboratory raises the question of their place in the management of patients in terms of antibiotic economy and isolation. In the absence of clear recommendations, the strategy and equipment are very unevenly distributed in France.

OUTLOOK

Medico-economic analyses need to be performed in France to evaluate the place of these tests in the management of patients. The evaluation of the role of the different viruses often detected in co-infection, especially in children, also deserves the attention of virologists and clinicians.

CONCLUSIONS

The availability of new diagnostic technologies, the recent emergence of SARS-CoV-2, together with the availability of new antiviral drugs are likely to impact future recommendations for the management of viral bronchopulmonary infections.

Viral Etiology, Clinical Features and Antibiotic Use in Children <5 Years of Age in the Gambia Presenting With Influenza-like Illness

BACKGROUND

Knowledge regarding the prevalence, clinical features and etiology of pediatric influenza-like illness (ILI) remains limited in African settings. Furthermore, it is likely that many children presenting with ILI receive antibiotics unnecessarily. More data are required to develop antimicrobial stewardship practice and guide effective vaccine strategies. We undertook a 1-year prospective study of ILI in the Gambia.

METHODS

Children <5 years of age presenting with ILI from March 2018 to March 2019 were recruited. Clinical and antibiotic prescribing data were collected. Nasopharyngeal swabs were collected and analyzed for 12 respiratory viruses using a multiplex polymerase chain reaction.

RESULTS

From a total of 735 ILI episodes, 530 (72.1%) nasopharyngeal swabs were positive for ≥1 virus. Of these, 36.7% were positive for rhinovirus, 14.7% for respiratory syncytial virus, 8.4% for influenza and 7.2% for human metapneumovirus. Compared with children <6 months of age, influenza was more common in 6- to 23-month-old children [odd ratio (OR): 5.68; 95% confidence interval (CI): 1.72-18.76; P = 0.004]. Respiratory syncytial virus and human metapneumovirus were associated with low peripheral oxygen saturations (OR: 2.13; 95% CI: 1.23-3.69; P = 0.007; and OR: 2.44; 95% CI: 1.13-5.27; P = 0.023, respectively). Antibiotics were prescribed in 78.3% of all ILI cases.

CONCLUSIONS

A broad range of viruses are responsible for pediatric ILI in the Gambia. Refined treatment guidelines, improved diagnostic capacity and vaccines to prevent respiratory viruses will all play a role in reducing antimicrobial use for these cases.

Paediatric Virology and respiratory syncytial virus: An interview with Honorary Senior Lecturer in Paediatric Infectious Diseases Dr Simon B. Drysdale (St. George's, University of London, UK)

Dr Simon B. Drysdale, Consultant and Honorary Senior Lecturer in Paediatric Infectious Diseases at St. George's University Hospitals NHS Foundation Trust and St. George's, University of London, is one of the most talented early career academic specialists in Paediatric Infectious Diseases in the United Kingdom. His main research interest is respiratory syncytial virus (RSV); he is particularly interested in understanding the host susceptibility to RSV, the management of RSV infection and associated health economics and the development of treatments and immunisations/vaccines, which are currently lacking. According to Dr Drysdale, RSV is a significant cause of morbidity and mortality among young infants and older adults, particularly those with co-morbidities. While there is ample RSV epidemiological and healthcare cost data available for young infants and children, more data is required for older children and adults. There are currently several antiviral medications for the treatment of RSV infection in development; however, none have yet progressed beyond Phase 2 clinical trials. Multiple types of novel therapeutic molecules have been developed, including fusion and non-fusion inhibitors and polymerase inhibitors aimed at various RSV targets, such as the F protein and RNA polymerase. In recent years, great strides have been made with regards to an RSV vaccine or monoclonal antibody, with >40 candidates currently in development. A maternal RSV vaccine, which just completed a Phase 3 trial, was shown to have 44% efficacy against hospitalization for RSV lower respiratory tract infection in infants. A new long-acting monoclonal antibody against RSV infection, having shown excellent promise in a Phase 2 trial in infants, is about to be investigated in a Phase 3 clinical trial commencing shortly.

Respiratory illness and respiratory syncytial virus hospitalization in infants with a tracheostomy following prophylaxis with palivizumab

Data on respiratory-related illness and respiratory syncytial virus (RSV) infection in children with a tracheostomy are sparse. We determined respiratory illness hospitalization (RIH) and RSV-related hospitalization (RSVH) hazard ratios in children with a tracheostomy following prophylaxis compared with infants' prophylaxed for standard indications (prematurity ≤ 35 weeks' gestational age, bronchopulmonary dysplasia, and significant congenital heart disease) and children with complex medical disorders. Children who received ≥ 1 injection of palivizumab were prospectively enrolled across 32 Canadian sites during the RSV season. Respiratory illness event data were collected monthly. Data were analyzed using t tests, chi-square tests, and Cox proportional hazards adjusted for confounders. A total of 23,597 infants were enrolled; 220 tracheostomy, 19,402 standard indications, 3975 complex medical disorders. Of the 220 tracheostomy infants, 30 had bronchopulmonary dysplasia, 18 were premature, 12 had congenital heart disease, and 160 had other medical complexities. RIH and RSVH incidences (tracheostomy, standard indications, complex medical disorders) were 24.5%, 6.2%, and 9.8% and 2.0%, 1.5%, and 1.8% respectively. RIH hazard was significantly higher in tracheostomy infants compared with standard indications (HR = 1.8, 95% CI 1.1-3.0, p = 0.02) but was similar between the tracheostomy and complex medical disorders groups (HR = 1.3, 95% CI 0.7-2.2, p = 0.37). RSVH hazard was also similar in tracheostomy infants relative to standard indications and complex medical disorders (both p > 0.75). Children with tracheostomies who received palivizumab had an increased RIH hazard compared with the standard indications group. Similar RSVH hazard between tracheostomy, standard indications, and complex medical disorders groups suggests that children with tracheostomies may benefit from palivizumab by reducing RSVH during the RSV season.

Respiratory syncytial virus: diagnosis, prevention and management

Respiratory syncytial virus (RSV) is responsible for a large burden of disease globally and can present as a variety of clinical syndromes in children of all ages. Bronchiolitis in infants under 1 year of age is the most common clinical presentation hospitalizing 24.2 per 1000 infants each year in the United Kingdom. RSV has been shown to account for 22% of all episodes of acute lower respiratory tract infection in children globally. RSV hospitalization, that is, RSV severe disease, has also been associated with subsequent chronic respiratory morbidity. Routine viral testing in all children is not currently recommended by the United Kingdom National Institute for Health and Care Excellence (NICE) or the American Academy of Pediatrics (AAP) guidance and management is largely supportive. There is some evidence for the use of ribavirin in severely immunocompromised children. Emphasis is placed on prevention of RSV infection through infection control measures both in hospital and in the community, and the use of the RSV-specific monoclonal antibody, palivizumab, for certain high-risk groups of infants. New RSV antivirals and vaccines are currently in development. Ongoing work is needed to improve the prevention of RSV infection, not only because of the acute morbidity and mortality, but also to reduce the associated chronic respiratory morbidity after severe infection.