Human metapneumovirus and respiratory syncytial virus infections in older children with cystic fibrosis

Identification of potential immune/diagnosis related gene-immunocyte subtype networks in extracellular immune response to respiratory syncytial virus infection

INTRODUCTION

Respiratory syncytial virus (RSV) is one of the important pathogenic agents of pediatric respiratory tract infection. Weighted gene co-expression network analysis (WGCNA) is used to study autoimmune diseases, which can find potential hub genes. The diagnostic model based on hub genes and machine learning makes it possible to diagnose the extracellular immune response to RSV infection early.

OBJECTIVE

The aim of the present study was to identify potential immune, diagnose and treatment related genes expressed in RSV-infected cells.

METHODS

Firstly, gene expression data were downloaded from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs). Secondly, WGCNA was performed based on DEGs to obtain hub genes related to immunity score. Thirdly, protein-protein interaction (PPI) and the immune infiltration analysis of hub immune related genes were performed. Finally, diagnostic and immune related genes were identified by machine learning, followed by functional analysis.

RESULTS

Totally, 2063 DEGs were identified in the extracellular immune response to RSV infection. Among which, 10 key immune and diagnosis related genes were identified, including ITGA2B, GP9, ITGB3, SELP, PPBP, MPL, CXCL8, NFE2, PTGS1 and LY6G6F. Several immune/diagnosis related gene-immunocyte subtype networks were identified, such as CXCL8-Type 17 T helper cell, LY6G6F-CD56 bright natural killer cell, PPBP-activated CD4 T cell/T follicular helper cell, NFE2/PTGS1/SELP-activated dendritic cell, GP9/ITGA2B/MPL-activated CD8 T cell. ITGB3, MPL and PTGS1 could be considered as therapeutic targets. Some significantly enriched signaling pathways were identified, including hematopoietic cell lineage (involving GP9 and ITGA2B), cytokine-cytokine receptor interaction (involving MPL), chemokine signaling pathway (involving PPBP) and arachidonic acid metabolism (involving PTGS1).

CONCLUSIONS

The 10-immune related gene signature may be used as potential diagnostic markers for the extracellular immune response to RSV infection, which may provide a new field in searching for diagnostic and therapeutic molecules in the extracellular immune response to RSV infection.

A prospective surveillance study on the kinetics of the humoral immune response to the respiratory syncytial virus fusion protein in adults in Houston, Texas

Respiratory syncytial virus (RSV)-specific serum antibody has been correlated to protection of infection and reduction of severe disease, but reinfection is still frequent. In this study, we evaluated RSV-specific serum antibody activity following natural RSV re-infection to examine the longevity of the humoral immune response in adults. Nineteen healthy adult volunteers under sixty-five years of age were enrolled during the 2018-2019 RSV season in Houston, TX. Blood was collected at three study visits. The kinetics of RSV-neutralizing, RSV F site-specific competitive, and RSV-binding antibodies in serum samples were measured by microneutralization and enzyme-linked immunosorbent assays. Three distinct profiles of RSV-specific antibody kinetics were identified that were consistent with RSV infection status: uninfected, acutely infected, and recently infected. The uninfected group had stable antibody titers for the duration of the study period (185 days). The acutely infected group had lower antibody responses at the beginning of the study, supporting a correlate of infection, followed by a significant antibody response after infection that was maintained for at least 125 days. Unlike the acutely infected group, the recently infected group had a significant precipitous decrease in RSV antibody in only 60 days. This study is the first, to our knowledge, to describe this abrupt loss of RSV-specific antibody in detail. This rapid decline of antibody may present an obstacle for the development of vaccines with lasting protection against RSV, and perhaps other respiratory pathogens. Neutralizing antibody responses were greater to prototypic than contemporaneous RSV strains, regardless of infection status, indicating that original antigenic sin may impact the humoral immune response to new or emerging RSV strains.

A bird eye view on cystic fibrosis: An underestimated multifaceted chronic disorder

Cystic fibrosis (CF) is an autosomal recessive disease which involves the mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CF involves in the inflammatory processes and is considered as a multisystem disorder that is not confined to lungs, but it also affects other vital organs that leads to numerous co-morbidities. The respiratory disorder in the CF results in mortality and morbidity which is characterized by series of serious events involving mucus hypersecretion, microbial infections, airways obstruction, inflammation, destruction of epithelium, tissue remodeling and terminal lung diseases. Mucins are the high molecular weight glycoproteins important for the viscoelastic properties of the mucus, play a significant role in the disease mechanisms. Determining the functional association between the CFTR and mucins might help to identify the putative target for specific therapeutic approach. In fact, furin enzyme which helps in the entry of novel COVID-19 virus into the cell, is upregulated in CF and this can also serve as a potential target for CF treatment. Moreover, the use of nano-formulations for CF treatment is an area of research being widely studied as they have also demonstrated promising outcomes. The in-depth knowledge of non-coding RNAs like miRNAs and lncRNAs and their functional association with CFTR gene expression and mutation can provide a different range of opportunity to identify the promising therapeutic approaches for CF.

Past, Present and Future Approaches to the Prevention and Treatment of Respiratory Syncytial Virus Infection in Children

INTRODUCTION

The REGAL (RSV Evidence - A Geographical Archive of the Literature) series has provided a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This seventh and final publication covers the past, present and future approaches to the prevention and treatment of RSV infection among infants and children.

METHODS

A systematic review was undertaken of publications between January 1, 1995 and December 31, 2017 across PubMed, Embase and The Cochrane Library. Studies reporting data on the effectiveness and tolerability of prophylactic and therapeutic agents for RSV infection were included. Study quality and strength of evidence (SOE) were graded using recognized criteria. A further nonsystematic search of the published literature and Clinicaltrials.gov on antiviral therapies and RSV vaccines currently in development was also undertaken.

RESULTS

The systematic review identified 1441 studies of which 161 were included. Management of RSV remains centered around prophylaxis with the monoclonal antibody palivizumab, which has proven effective in reducing RSV hospitalization (RSVH) in preterm infants < 36 weeks' gestational age (72% reduction), children with bronchopulmonary dysplasia (65% reduction), and infants with hemodynamically significant congenital heart disease (53% reduction) (high SOE). Palivizumab has also shown to be effective in reducing recurrent wheezing following RSVH (high SOE). Treatment of RSV with ribavirin has conflicting success (moderate SOE). Antibodies with increased potency and extended half-life are currently entering phase 3 trials. There are approximately 15 RSV vaccines in clinical development targeting the infant directly or indirectly via the mother.

CONCLUSION

Palivizumab remains the only product licensed for RSV prophylaxis, and only available for high-risk infants. For the general population, there are several promising vaccines and monoclonal antibodies in various stages of clinical development, with the aim to significantly reduce the global healthcare impact of this common viral infection.

FUNDING

AbbVie.

Defining the Incidence and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Children with Chronic Diseases

INTRODUCTION

REGAL (RSV Evidence-a Geographical Archive of the Literature) has provided a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This review covers the risk and burden of RSV infection in children with underlying medical conditions or chronic diseases (excluding prematurity and congenital heart disease).

METHODS

A systematic review of publications between January 1, 1995 and December 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov was supplemented by papers identified by the authors through March 2017. Studies reporting data for hospital visits/admissions for RSV infection as well as studies reporting RSV-associated morbidity and mortality were included. Study quality and strength of evidence (SOE) were graded.

RESULTS

A total of 2703 studies were identified and 58 were included. Down syndrome, irrespective of prematurity and congenital heart disease (moderate SOE), immunocompromised children (low SOE), cystic fibrosis (low SOE), and neurologic conditions (low SOE) were associated with a significantly increased risk of RSV hospitalization. A number of other congenital malformations and chronic conditions were also associated with severe RSV disease (low SOE). In general, pre-existing disease was also a predisposing factor for RSV-related mortality (low SOE).

CONCLUSION

Severe RSV infection in infants and young children with underlying medical conditions or chronic diseases poses a significant health burden. Further studies are needed to fully quantify the epidemiology, burden and outcomes in these populations, in particular RSV-attributable mortality.

Viruses in cystic fibrosis patients' airways

Although bacteria have historically been considered to play a major role in cystic fibrosis (CF) airway damage, a strong impact of respiratory viral infections (RVI) is also now recognized. Emerging evidence confirms that respiratory viruses are associated with deterioration of pulmonary function and exacerbation and facilitation of bacterial colonization in CF patients. The aim of this review is to provide an overview of the current knowledge on respiratory viruses in CF airways, to discuss the resulting inflammation and RVI response, to determine how to detect the viruses, and to assess their clinical consequences, prevalence, and interactions with bacteria. The most predominant are Rhinoviruses (RVs), significantly associated with CF exacerbation. Molecular techniques, and especially multiplex PCR, help to diagnose viral infections, and the coming rise of metagenomics will extend knowledge of viral populations in the complex ecosystem of CF airways. Prophylaxis and vaccination are currently available only for Respiratory syncytial and Influenza virus (IV), but antiviral molecules are being tested to improve CF patients' care. All the points raised in this review highlight the importance of taking account of RVIs and their potential impact on the CF airway ecosystem.

The cost-effectiveness of palivizumab in infants with cystic fibrosis in the Canadian setting: A decision analysis model

BACKGROUND

Children with cystic fibrosis (CF) are at higher risk of severe respiratory syncytial virus (RSV) infection, which can lead to a decline in lung function. A monoclonal antibody, palivizumab (PMB), effectively prevents RSV hospitalizations; however, the high cost of PMB, approximately C$10,000 per patient per RSV season, limits its widespread use. We assess the cost-effectiveness of PMB prophylaxis in CF children less than 2 y of age from the Canadian healthcare payer's perspective.

METHODS

In 2014, a Markov cohort model of CF disease and infant RSV infections in the Canadian setting was developed based on literature data. Infants were treated with monthly PMB injections over the 5-month RSV season. Lifetime health outcomes, quality-adjusted life years (QALYs) and 2013 $CAD costs, discounted at 5%, were estimated. Findings are summarized as incremental cost-effectiveness ratios (ICERs) and budget impact. Deterministic sensitivity analysis was conducted to assess parameter uncertainty.

RESULTS

Implementation of a hypothetical Canadian RSV prophylaxis program resulted in ICERs of C$652,560 (all CF infants) and C$157,332 (high-risk CF infants) per QALY gained and an annual budget impact of C$1,400,000 (all CF infants) and C$285,000 (high-risk CF infants). The analysis was highly sensitive to the probability of severe RSV, the degree of lung deterioration following infection, and the cost of PMB.

CONCLUSIONS

Our results suggest PMB is not cost-effective in Canada by commonly used thresholds. However, given the rarity of CF and relatively small budget impact, consideration may be given for the selective use of PMB for immunoprophylaxis of RSV in high-risk CF infants on a case-by-case scenario basis.

Elucidation and clinical role of emerging viral respiratory tract infections in children

Acute respiratory viral infections (ARVI's) are the most common infectious disease in humans. With the appearance of molecular techniques the recovery of viruses has dramatically increased. Nowadays virologists can quickly discriminate virological families and related viruses from emerging viruses and consequently identify novel viruses. Many new respiratory viruses have been identified in children in the past 15 years. In this review we shortly discuss novel respiratory viruses and their pathogenic role in pediatric respiratory disease. Advantages and drawbacks of the technique and our current knowledge will be discussed. We will conclude this review with a general discussion on the future role of molecular diagnostic virology in the clinic.

Clinical and epidemiologic features of respiratory syncytial virus

Since its discovery in 1955, respiratory syncytial virus (RSV) has consistently been noted to be the single most important cause of lower respiratory tract illness in infants <1 year of age. RSV also causes repeat infections and significant disease throughout life. In addition to the young child, persons with compromised immune, pulmonary or cardiac systems, and the elderly have significant risk from infection. Though RSV causes the full spectrum of acute respiratory illnesses, it is most notably associated with signs and symptoms of increased airway resistance manifested as wheezing and, in the young child, diagnosed as bronchiolitis. In temperate climates, RSV occurs as yearly outbreaks usually between late fall and early spring lasting 3-4 months in a community. The timing of outbreaks varies between years and in the same year between regions and even between nearby communities. RSV can be a serious nosocomial pathogen in high risk individuals but nosocomial transmission that can often be prevented with meticulous attention to good infection control practices. High risk groups include the premature infants and persons of any age with compromised cardiac, pulmonary, or immune systems. Risk factors for infection include increased number of children in the household and day care center attendance. There are reasonable estimates of the sizable burden of RSV disease in infants and young children and the elderly but less data on disease in older children, the role of RSV in later reactive airway disease (see chapter by M.T. Lotz et al. , this volume), and RSV-associated mortality in developing countries. The available data on burden of disease suggests there are at least four potential target populations for a vaccine, the young infant, young children >4-6 months of age, pregnant women, and the elderly. A link between infection in the young infant and later reactive airway disease and mortality in developing countries is needed. Each target population has different vaccine safety and efficacy concerns and may warrant a different type of vaccine.

Palivizumab in preventing respiratory syncytial virus-related hospitalization in high-risk infants

Respiratory syncytial virus (RSV) causes seasonal epidemics (winter or wet-season) of serious lower respiratory tract infections in young infants with subsequent increased frequency of recurrent wheezing during early childhood. Palivizumab is a humanized monoclonal antibody that provides immunoprophylaxis against RSV when administered monthly over the RSV season. It significantly reduced hospitalizations in high-risk infants including preterm infants with and without bronchopulmonary dysplasia and infants with hemodynamically significant congenital heart disease. Since its license in 1998, approximately 36 methodologically different economic studies have been performed to prove cost-effectiveness of the product. The majority of cost-effectiveness analyses revealed costs of palivizumab exceeding anticipated savings from reduced RSV hospitalizations. A minority of studies performed cost-effectiveness analyses using incremental cost-effectiveness ratios as costs per quality-adjusted life-year gained. The wide variability in the results of economic studies with estimates ranging from cost savings to incremental costs of a high order of magnitude with its use is discussed, in the light of the continuing burden of RSV disease, the limited treatment modalities, and the continuing research for a vaccine.

Spectrum of viral infections in patients with cystic fibrosis

This review explores the extensive influence of viral infections leading to chronic deterioration of lung function in patients with cystic fibrosis (CF). The mechanisms how viral agents affect the pathogenesis as well as the inflammatory and immune response of CF are discussed. Viral infections of the upper and lower respiratory tract due to viruses in CF patients and methods for diagnosis of respiratory viruses are described in detail. The importance of respiratory and non-respiratory viral agents for the pathogenesis, especially for the exacerbation of bacterial lower respiratory tract infections and course of CF, is stressed, especially emphasizing respiratory syncytial virus, influenza virus, rhinovirus, and human herpes viruses. Possible harmful effects of further viruses like adenovirus, bocavirus, coronavirus, metapneumovirus, parainfluenzavirus on the lung function of CF patients are discussed. The potential use of adenovirus-based vectors for somatic gene therapy is mentioned.

Respiratory Syncytial Virus Prophylaxis in Special Populations: Is it Something Worth Considering in Cystic Fibrosis and Immunosuppression?

Respiratory syncytial virus (RSV) bronchiolitis is the leading cause of infant hospitalization in the United States. Prophylaxis with palivizumab is effective in reducing RSV hospitalizations in premature infants and in infants or children with chronic lung disease or congenital heart disease. Patients with CF or those who are immunocompromised may be at increased risk for RSV infection-related complications; hence, prophylaxis may prove beneficial to these populations. The extent of palivizumab use in the CF and immunocompromised populations is variable. Palivizumab appears to be safe and may be effective in infants and young children with CF and immunocompromise. However, well-designed, randomized, controlled trials published in peer-reviewed journals are lacking, and its routine use can therefore not be recommended at this time. If used in patients with CF or those who are immunocompromised, RSV prophylaxis should be restricted to peak outbreak months in order to optimize the cost benefit of palivizumab.

Role of neutralizing antibodies in adults with community-acquired pneumonia by respiratory syncytial virus

Background. Respiratory syncytial virus (RSV) has been implicated in the etiology of adult community-acquired pneumonia (CAP). We investigated RSV infection in Chilean adults with CAP using direct viral detection, real-time reverse-transcription polymerase chain reaction (rtRT-PCR), and serology (microneutralization assay).

Methods. RSV, other respiratory viruses, and bacteria were studied by conventional and molecular techniques in adults aged ≥18 years presenting with CAP to the healthcare facilities in Santiago, Chile from February 2005 through December 2007.

Results. All 356 adults with CAP enrolled had an acute blood sample collected at enrollment, and 184 had a convalescent blood sample. RSV was detected in 48 cases (13.4%). Immunofluorescence assay and viral isolation each detected only 1 infection (0.2%), whereas rtRT-PCR was positive in 32 (8.9%) cases and serology was positive in 20 (10.8%) cases. CAP clinical characteristics were similar in RSV-infected and non-RSV-infected cases. RSV-specific geometric mean serum-neutralizing antibody titer (GMST) was significantly lower at admission in the 48 RSV-infected cases compared with 308 non-RSV-infected adults (GMST in log₂: RSV/A 8.1 vs 8.9, and RSV/B 9.3 vs 10.4; P < .02).

Conclusions. RSV infection is frequent in Chilean adults with CAP. Microneutralization assay was as sensitive as rtRT-PCR in detecting RSV infection and is a good adjunct assay for diagnostic research. High RSV-specific serum-neutralizing antibody levels were associated with protection against common and severe infection. The development of a vaccine could prevent RSV-related CAP in adults.

Clinical significance of microbial infection and adaptation in cystic fibrosis

A select group of microorganisms inhabit the airways of individuals with cystic fibrosis. Once established within the pulmonary environment in these patients, many of these microbes adapt by altering aspects of their structure and physiology. Some of these microbes and adaptations are associated with more rapid deterioration in lung function and overall clinical status, whereas others appear to have little effect. Here we review current evidence supporting or refuting a role for the different microbes and their adaptations in contributing to poor clinical outcomes in cystic fibrosis.

The changing microbial epidemiology in cystic fibrosis

Infection of the airways remains the primary cause of morbidity and mortality in persons with cystic fibrosis (CF). This review describes salient features of the epidemiologies of microbial species that are involved in respiratory tract infection in CF. The apparently expanding spectrum of species causing infection in CF and recent changes in the incidences and prevalences of infection due to specific bacterial, fungal, and viral species are described. The challenges inherent in tracking and interpreting rates of infection in this patient population are discussed.

Respiratory syncytial virus engineered to express the cystic fibrosis transmembrane conductance regulator corrects the bioelectric phenotype of human cystic fibrosis airway epithelium in vitro

Cystic fibrosis (CF) is the most common lethal recessive genetic disease in the Caucasian population. It is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene that is normally expressed in ciliated airway epithelial cells and the submucosal glands of the lung. Since the CFTR gene was first characterized in 1989, a major goal has been to develop an effective gene therapy for CF lung disease, which has the potential to ameliorate morbidity and mortality. Respiratory syncytial virus (RSV) naturally infects the ciliated cells in the human airway epithelium. In addition, the immune response mounted against an RSV infection does not prevent subsequent infections, suggesting that an RSV-based vector might be effectively readministered. To test whether the large 4.5-kb CFTR gene could be expressed by a recombinant RSV and whether infectious virus could be used to deliver CFTR to ciliated airway epithelium derived from CF patients, we inserted the CFTR gene into four sites in a recombinant green fluorescent protein-expressing RSV (rgRSV) genome to generate virus expressing four different levels of CFTR protein. Two of these four rgRSV-CFTR vectors were capable of expressing CFTR with little effect on viral replication. rgRSV-CFTR infection of primary human airway epithelial cultures derived from CF patients resulted in expression of CFTR protein that was properly localized at the luminal surface and corrected the chloride ion channel defect in these cells.

The role of respiratory viruses in cystic fibrosis

Background

Previous studies have suggested a role played by respiratory viruses in the exacerbation of cystic fibrosis (CF). However, the impact of respiratory viruses could have been underestimated because of the low detection rate by conventional laboratory methods.

Methods

Children with CF had nasal swabs and sputum samples obtained on a routine basis and when they developed respiratory exacerbations. Nucleic Acid Sequence Based Amplification (NASBA) was used to detect respiratory viruses from nasal swabs. The definition of a respiratory exacerbation was when the symptom score totalled to 4 or more, or if the peak expiratory flow fell by more than 50 l/min from the child's usual best value, or if the parent subjectively felt that the child was developing a cold.

Results

71 patients had 165 reported episodes of respiratory exacerbations. 138 exacerbation samples were obtained of which 63 (46%) were positive for respiratory viruses. In contrast, 23 of 136 asymptomatic nasal swabs (16.9%) were positive for respiratory viruses. There was significantly more viruses being detected during respiratory exacerbations, in particular influenza A, influenza B and rhinovirus (p < 0.05).

Upper respiratory symptoms significantly correlated with positive respiratory viral detection (p < 0.05). This study also showed that viral respiratory exacerbations in CF could be independent from bacterial infections.

Conclusions

Respiratory viruses are associated with exacerbations in CF and upper respiratory symptoms are strong predictors for their presence. ‘Real-time’ NASBA has a rapid turn-around time and has the potential to aid clinical decision making, such as the use of anti-virals and administration of antibiotics.

The fusion protein of respiratory syncytial virus triggers p53-dependent apoptosis

Infection with respiratory syncytial virus (RSV) frequently causes inflammation and obstruction of the small airways, leading to severe pulmonary disease in infants. We show here that the RSV fusion (F) protein, an integral membrane protein of the viral envelope, is a strong elicitor of apoptosis. Inducible expression of F protein in polarized epithelial cells triggered caspase-dependent cell death, resulting in rigorous extrusion of apoptotic cells from the cell monolayer and transient loss of epithelial integrity. A monoclonal antibody directed against F protein inhibited apoptosis and was also effective if administered to A549 lung epithelial cells postinfection. F protein expression in epithelial cells caused phosphorylation of tumor suppressor p53 at serine 15, activation of p53 transcriptional activity, and conformational activation of proapoptotic Bax. Stable expression of dominant-negative p53 or p53 knockdown by RNA interference inhibited the apoptosis of RSV-infected A549 cells. HEp-2 tumor cells with low levels of p53 were not sensitive to RSV-triggered apoptosis. We propose a new model of RSV disease with the F protein as an initiator of epithelial cell shedding, airway obstruction, secondary necrosis, and consequent inflammation. This makes the RSV F protein a key target for the development of effective postinfection therapies.

Is there a role for influenza vaccination in cystic fibrosis?

BACKGROUND

Influenza vaccination is generally recommended to patients with Cystic Fibrosis (CF). Previous studies have shown that influenza infections cause worsening lung functions, disease progression and increase propensity of bacterial infections in CF. However, the clinical evidence in the effectiveness of influenza vaccination in CF is lacking.

AIMS

This study retrospectively reviewed the influenza vaccination status in the patients with CF and compared the influenza infection rates between the vaccinated and non-vaccinated groups. Finally the factors associated with non-adherence with vaccination were determined.

METHODS

Nasal swabs were obtained from 63 patients with CF between the age of 6 months to 18 years routinely and during respiratory exacerbations between October 2003 to April 2004. Influenza A and Influenza B were detected using Nucleic Acid Sequence Based Amplification (NASBA). The influenza vaccination status of these patients was retrospectively reviewed.

RESULTS

41 patients (65%) were vaccinated against influenza. For the 22 patients (35%) who were not vaccinated, 7 of them were scared of needles leading to non-adherence. Influenza virus was detected on 5 occasions; 3 were Influenza A (60%) and 2 were Influenza B (40%). 1 virus in the vaccinated group and 4 in the non-vaccinated were detected during the study period (p-value=0.046).

CONCLUSIONS

Although the current available evidence to support routine influenza vaccination is limited in CF, this study has shown that such practice may yet play a role in preventing its subsequent acquisition.