Respiratory Syncytial Virus: Infection, Detection, and New Options for Prevention and Treatment

Using Google Trends to Predict Pediatric Respiratory Syncytial Virus Encounters at a Major Health Care System

To assess whether Google search activity predicts lead-time for pediatric respiratory syncytial virus (RSV) encounters within a major health care system. Internet user search and health system encounter database analysis. Pediatric RSV encounter volumes across all clinics and hospitals in the Duke Health system were tabulated from 2005 to 2016. North Carolina Google user search activity for RSV were obtained over the same time period. Time series analysis was used to compare RSV encounters and search activity. Cross-correlation was used to determine the 'lag' time difference between Google user search interest for RSV and observed Pediatric RSV encounter volumes. Google search activity and Pediatric RSV encounter volumes demonstrated strong seasonality with predilection for winter months. Granger Causality testing revealed that North Carolina RSV Google search activity can predict pediatric RSV encounters at our health system (F = 5.72, p < 0.0001). Using cross-correlation, increases in Google search activity provided lead time of 0.21 weeks (1.47 days) prior to observed increases in Pediatric RSV encounter volumes at our health system. RSV is a common cause of upper airway obstruction in pediatric patients for which pediatric otolaryngologists are consulted. We demonstrate that Google search activity can predict RSV patient interactions with a major health system with a measurable lead-time. The ability to predict when illnesses in a population result in increased health care utilization would be an asset to health system providers, planners and administrators. Prediction of RSV would allow specific care pathways to be developed and resource needs to be anticipated before actual presentation.

Respiratory Virus Co-infection in Acute Respiratory Infections in Children

Purpose of Review

This investigation aims to understand the role and burden of viral co-infections for acute respiratory illnesses in children. Co-infection can be either viral-viral or viral-bacterial and with new technology there is more information on the role they play on the health of children.

Recent Findings

With the proliferation of multiplex PCR for rapid diagnosis of multiple viruses as well as innovations on identification of bacterial infections, research has been attempting to discover how these co-infections affect each other and the host. Studies are aiming to discern if the epidemiology of viruses seen at a population level is related to the interaction between different viruses on a host level. Studies are also attempting to discover the burden of morbidity and mortality of these viral-viral co-infections on the pediatric population. It is also becoming important to understand the interplay of certain viruses with specific bacteria and understanding the impact of viral-bacterial co-infections.

Summary

RSV continues to contribute to a large burden of disease for pediatric patients with acute respiratory illnesses. However, recent literature suggests that viral-viral co-infections do not add to this burden and might, in some cases, be protective of severe disease. Viral-bacterial co-infections, on the other hand, are most likely adding to the burden of morbidity in pediatric patients because of the synergistic way they can infect the nasopharyngeal space. Future research needs to focus on confirming these conclusions as it could affect hospital cohorting, role of molecular testing, and therapeutic interventions.

Integrating Duodenal Sampling in a Human Mass Balance Study to Quantify the Elimination Pathways of JNJ-53718678, a Respiratory Syncytial Virus Fusion Protein Inhibitor

INTRODUCTION

The study objective was to characterize the excretion and metabolic profile of the respiratory syncytial virus fusion protein inhibitor, JNJ-53718678. Prior animal and in vitro studies suggested three main elimination pathways: N-glucuronidation to M8; CYP(3A4) metabolism leading to circulating metabolites M5, M12, M19 and M37; and JNJ-53718678 biliary excretion. To gain insight into the relative contribution of JNJ-53718678 and M8 biliary excretion, duodenal fluid sampling was incorporated into this mass balance study.

METHODS

A single oral dose of 500 mg ¹⁴C-JNJ-53718678 was administered to six healthy male subjects. Four hours after study drug intake, gallbladder contraction was stimulated and duodenal fluid samples were collected. JNJ-53718678, its key circulating metabolites and total radioactivity (TR) were quantified in plasma, feces, urine and duodenal fluid. Safety was monitored throughout.

RESULTS

JNJ-53718678 and M12 represented 47.4% and 17.8%, respectively, of TR area under the curve (AUC)_∞ in plasma. M37 (9.6%), M19 (5.2%), M5 (4.3%) and M8 (1.4%) were minor metabolites; 70.6% of TR was recovered in feces and 19.9% in urine. Duodenal fluid concentrations (% of TR) were highest for JNJ-53718678 (11.6%) followed by M8 (10.4%), M5 (5.9%) and M12 (1.1%). In feces, 10-16% of TR was JNJ-53718678, 5-8% M5, < 1% M12 and < 1% M8. N-glucuronidation to M8 and direct biliary excretion of JNJ-53718678 represented 7% and 8% of drug clearance, respectively. JNJ-53718678 was safe and well tolerated.

CONCLUSIONS

JNJ-53718678 is primarily eliminated through CYP3A4-mediated metabolism. By integrating duodenal sampling, N-glucuronidation was confirmed as another metabolic pathway despite the low amount of M8 excreted in urine and feces.

TRIAL REGISTRATION

Eudract no. 2016-002664-14.

Linear and dendrimeric antiviral peptides: design, chemical synthesis and activity against human respiratory syncytial virus

Novel artificial peptides possess anti-RSV activity through a combination of two mechanisms: direct nonspecific destabilization of the viral envelope and competitive interaction with the RSV cellular receptor.

Neutrophil-endothelial interactions in respiratory syncytial virus bronchiolitis: An understudied aspect with a potential for prediction of severity of disease

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) causes significant morbidity and mortality among young infants worldwide. It is currently widely accepted that neutrophil influx into the airways is a hallmark of the pathophysiology. However, the exact mechanism of neutrophil migration from the vasculature into the alveolar space in RSV LRTI has received little attention. Data shows that endothelial cells become activated upon RSV infection, driving a 'pro-adhesive state' for circulating neutrophils with upregulation of endothelial intercellular adhesion molecule-1 (ICAM-1). During RSV LRTI different subsets of immature and mature neutrophils are present in the bloodstream, that upregulate integrins lymphocyte-function associated antigen (LFA)-1 and macrophage (Mac)-1, serving as ICAM-1 ligands. An alveolar gradient of interleukin-8 may serve as a potent chemoattractant for circulating neutrophils. Neutrophils from lung aspirates of RSV-infected infants show further signs of inflammatory and migratory activation, while soluble endothelial cell adhesion molecules (sCAMs), such as sICAM-1, have become measurable in the systemic circulation. Whether these mechanisms are solely responsible for neutrophil migration into the alveolar space remains under debate. However, data indicate that the currently postulated neutrophil influx into the lungs should rather be regarded as a neutrophil efflux from the vasculature, involving substantial neutrophil-endothelial interactions. Molecular patterns of these interactions may be clinically useful to predict outcomes of RSV LRTI and deserve further study.

Host Calcium Channels and Pumps in Viral Infections

Ca²⁺ is essential for virus entry, viral gene replication, virion maturation, and release. The alteration of host cells Ca²⁺ homeostasis is one of the strategies that viruses use to modulate host cells signal transduction mechanisms in their favor. Host calcium-permeable channels and pumps (including voltage-gated calcium channels, store-operated channels, receptor-operated channels, transient receptor potential ion channels, and Ca²⁺-ATPase) mediate Ca²⁺ across the plasma membrane or subcellular organelles, modulating intracellular free Ca²⁺. Therefore, these Ca²⁺ channels or pumps present important aspects of viral pathogenesis and virus–host interaction. It has been reported that viruses hijack host calcium channels or pumps, disturbing the cellular homeostatic balance of Ca²⁺. Such a disturbance benefits virus lifecycles while inducing host cells’ morbidity. Evidence has emerged that pharmacologically targeting the calcium channel or calcium release from the endoplasmic reticulum (ER) can obstruct virus lifecycles. Impeding virus-induced abnormal intracellular Ca²⁺ homeostasis is becoming a useful strategy in the development of potent antiviral drugs. In this present review, the recent identified cellular calcium channels and pumps as targets for virus attack are emphasized.

Respiratory syncytial virus A genotype classification based on systematic intergenotypic and intragenotypic sequence analysis

Respiratory syncytial virus (RSV), a leading cause of lower respiratory tract infections, is classified in two major groups (A and B) with multiple genotypes within them. Continuous changes in spatiotemporal distribution of RSV genotypes have been recorded since the identification of this virus. However, there are no established criteria for genotype definition, which affects the understanding of viral evolution, immunity, and development of vaccines. We conducted a phylogenetic analysis of 4,353 RSV-A G gene ectodomain sequences, and used 1,103 complete genome sequences to analyze the totallity of RSV-A genes. Intra- and intergenotype p-distance analysis and identification of molecular markers associated to specific genotypes were performed. Our results indicate that previously reported genotypes can be classified into nine distinct genotypes: GA1-GA7, SAA1, and NA1. We propose the analysis of the G gene ectodomain with a wide set of reference sequences of all genotypes for an accurate genotype identification.

A rapid and label-free platform for virus capture and identification from clinical samples

Viruses evolve rapidly and unpredictably, challenging the effectiveness of disease diagnostics. To help control outbreaks and understand their origins, the first step is often isolating viruses from infected samples for characterization. We demonstrate that multiple emerging virus strains can be simultaneously enriched and optically detected in only a few minutes without using any labels. A portable platform that captures viruses by their size, coupled to Raman spectroscopy, resulted in successful virus identification with 90% accuracy in real time directly from clinical samples. Furthermore, this viable enrichment process enables further culturing and characterization by electron microscopy and deep sequencing. This microplatform is an effective disease-monitoring system and broadens virus surveillance by enabling real-time virus identification.

Emerging and reemerging viruses are responsible for a number of recent epidemic outbreaks. A crucial step in predicting and controlling outbreaks is the timely and accurate characterization of emerging virus strains. We present a portable microfluidic platform containing carbon nanotube arrays with differential filtration porosity for the rapid enrichment and optical identification of viruses. Different emerging strains (or unknown viruses) can be enriched and identified in real time through a multivirus capture component in conjunction with surface-enhanced Raman spectroscopy. More importantly, after viral capture and detection on a chip, viruses remain viable and get purified in a microdevice that permits subsequent in-depth characterizations by various conventional methods. We validated this platform using different subtypes of avian influenza A viruses and human samples with respiratory infections. This technology successfully enriched rhinovirus, influenza virus, and parainfluenza viruses, and maintained the stoichiometric viral proportions when the samples contained more than one type of virus, thus emulating coinfection. Viral capture and detection took only a few minutes with a 70-fold enrichment enhancement; detection could be achieved with as little as 10² EID₅₀/mL (50% egg infective dose per microliter), with a virus specificity of 90%. After enrichment using the device, we demonstrated by sequencing that the abundance of viral-specific reads significantly increased from 4.1 to 31.8% for parainfluenza and from 0.08 to 0.44% for influenza virus. This enrichment method coupled to Raman virus identification constitutes an innovative system that could be used to quickly track and monitor viral outbreaks in real time.

The Burden of Respiratory Syncytial Virus Infection in Adults and Reproductive-Aged Women

Currently available data on respiratory syncytial virus (RSV) disease burden in adults and reproductive-aged women are limited. These data are critically needed to assist in the advancement of strategies related to maternal RSV vaccination for the passive protection of their newborn children.

Estimated Burden of Community-Onset Respiratory Syncytial Virus-Associated Hospitalizations Among Children Aged <2 Years in the United States, 2014-15

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of hospitalizations in young children. We estimated the burden of community-onset RSV-associated hospitalizations among US children aged <2 years by extrapolating rates of RSV-confirmed hospitalizations in 4 surveillance states and using probabilistic multipliers to adjust for ascertainment biases.

METHODS

From October 2014 through April 2015, clinician-ordered RSV tests identified laboratory-confirmed RSV hospitalizations among children aged <2 years at 4 influenza hospitalization surveillance network sites. Surveillance populations were used to estimate age-specific rates of RSV-associated hospitalization, after adjusting for detection probabilities. We extrapolated these rates using US census data.

RESULTS

We identified 1554 RSV-associated hospitalizations in children aged <2 years. Of these, 27% were admitted to an intensive care unit, 6% needed mechanical ventilation, and 5 died. Most cases (1047/1554; 67%) had no underlying condition. Adjusted age-specific RSV hospitalization rates per 100 000 population were 1970 (95% confidence interval [CI],1787 to 2177), 897 (95% CI, 761 to 1073), 531 (95% CI, 459 to 624), and 358 (95% CI, 317 to 405) for ages 0-2, 3-5, 6-11, and 12-23 months, respectively. Extrapolating to the US population, an estimated 49 509-59 867 community-onset RSV-associated hospitalizations among children aged <2 years occurred during the 2014-2015 season.

CONCLUSIONS

Our findings highlight the importance of RSV as a cause of hospitalization, especially among children aged <2 months. Our approach to estimating RSV-related hospitalizations could be used to provide a US baseline for assessing the impact of future interventions.

Respiratory Syncytial Virus Seasonality, Beijing, China, 2007-2015

During July 2007-June 2015, we enrolled 4,225 hospitalized children with pneumonia in a study to determine the seasonality of respiratory syncytial virus (RSV) infection in Beijing, China. We defined season as the period during which >10% of total PCRs performed each week were RSV positive. We identified 8 distinctive RSV seasons. On average, the season onset occurred at week 41 (mid-October) and lasted 33 weeks, through week 20 of the next year (mid-May); 97% of all RSV-positive cases occurred during the season. RSV seasons occurred 3-5 weeks earlier and lasted ≈6 weeks longer in RSV subgroup A-dominant years than in RSV subgroup B-dominant years. Our analysis indicates that monitoring such RSV subgroup shifts might provide better estimates for the onset of RSV transmission. PCR-based tests could be a flexible or complementary way of determining RSV seasonality in locations where RSV surveillance is less well-established, such as local hospitals throughout China.

Palivizumab Prophylaxis among Infants at Increased Risk of Hospitalization due to Respiratory Syncytial Virus Infection in UAE: A Hospital-Based Study

Background

Respiratory syncytial virus (RSV) represents a significant public health burden and the leading cause of lower respiratory tract infections globally, and it is the major cause of hospitalization during the winter. We aimed to evaluate the effectiveness of palivizumab prophylaxis to reduce the hospitalization in children at high risk of RSV infection.

Methods

We performed a retrospective observational single-arm hospital-based study including five RSV seasons (September to March) from 2012 to 2017. We retrospectively included premature infants born at less than 35 weeks of gestation with chronic lungs disease or hemodynamic significant congenital heart disease for palivizumab prophylaxis against RSV infection according to the criteria presented.

Results

A total of 925 children were enrolled in the study over the five RSV seasons. Of them, 410 (44.3%) infants born at <32 weeks of gestation and 515 (55.6%) infants born at 32-35 weeks of gestation with mean (±SD) birth weight of 1104.8 ± 402.85 and 1842.5 ± 377.5, respectively. The compliance with the course of palivizumab was reported in 841 (90.9%) children. Of them, about 75 (8.9%) hospitalized children were reported, and 17 (2.02%) RSV positive children were detected. Hospitalization due to RSV infection was decreased from 9.23% in the 2012-2013 season to 0.67% in the 2016-2017 season.

Conclusion

This study demonstrated that palivizumab prophylaxis in children at high risk of developing RSV infection was effective in reducing the risk of hospitalization with a high compliance rate over the five RSV seasons.

How Respiratory Syncytial Virus Genotypes Influence the Clinical Course in Infants Hospitalized for Bronchiolitis

Background

We aimed to study respiratory syncytial virus (RSV) genotype distribution, clinical presentation, and disease severity in infants with bronchiolitis from RSV subtypes and new RSV genotypes.

Methods

We prospectively enrolled previously healthy term infants less than 1 year old hospitalized for bronchiolitis in an Italian university hospital over 12 epidemic seasons. In 312 nasopharyngeal washings positive for RSV, we sequenced the viral genotype and analyzed this according to patient data. Strain-specific RSV loads were quantified for 273 specimens.

Results

From 2005-2006 to 2011-2012, the RSV-A genotype NA1 predominated, and was replaced in 2012 by the novel ON1. All infants infected with RSV subtype B were genotype BA. Stratifying data according to genotypes NA1, ON1, and BA showed that NA1-infected infants were the youngest and had the most severe clinical course. Conversely, BA-infected infants had less severe symptoms and more frequently had eosinophilia and a family history of asthma. Infants with the ON1 genotype had a milder clinical course than those with NA1 and more risk factors for asthma, despite having the highest viral loads.

Conclusion

The disease course in infants hospitalized for acute RSV bronchiolitis may depend on the RSV genotype.

[Respiratory syncytial virus]

Respiratory syncytial virus (RSV) is worldwide a very important virus leading to infection of the respiratory system. In particular preterm babies, infants and elderly adults are prone to developing severe diseases such as bronchiolitis or pneumonia, which require intensive care and cause increased mortality. Although RSV is rapidly detected, preventive and therapeutic measures are limited. New antivirals are already in clinical trials.

A DNA Vaccine in Which the RSV-F Ectodomain Is Covalently Linked to the Burkholderia pseudomallei Antigens TssM and Hcp1 Augments the Humoral and Cytotoxic Response in Mice

DNA vaccines have great potential to control infectious disease, particularly those caused by intracellular organisms. They are inexpensive to produce and can be quickly modified to combat emerging infectious threats, but often fail to generate a strong immunologic response limiting enthusiasm for their use in humans and animals. To improve the immunogenic response, we developed a DNA vaccine in which the F protein ectodomain of Respiratory Syncytial Virus (RSV-F) was covalently linked to specific antigens of interest. The presence of the RSV-F ectodomain allowed secretion of the translated fusion product out of the originally transfected cells followed by its active binding to adjacent cells. This allowed the targeting of a greater number of cells than those originally transfected, enhancing both humoral and cytotoxic immune responses against the expressed antigen(s). We developed an engrafted mouse model that used antigen-expressing tumor cells to assess the in vivo cytotoxic immune response to specific antigens. We then used this model to demonstrate that a DNA vaccine in which the RSV-F ectodomain is fused to two antigens expressed by Burkholderia pseudomallei, the intracellular gram-negative organism that causes melioidosis, generated a stronger cytotoxic response than a DNA vaccine that lacked the RSV-F sequence while still generating a robust humoral response.

Differential antiviral activities of respiratory syncytial virus (RSV) inhibitors in human airway epithelium

Objectives

We report the use of reconstituted 3D human airway epithelium cells (HuAECs) of bronchial origin in an air–liquid interface to study respiratory syncytial virus (RSV) infection and to assess the efficacy of RSV inhibitors in (pre-)clinical development.

Methods

HuAECs were infected with RSV-A Long strain (0.01 CCID₅₀/cell, where CCID₅₀ represents 50% cell culture infectious dose in HEp2 cells) on the apical compartment of the culture. At the time of infection or at 1 or 3 days post-infection, selected inhibitors were added and refreshed daily on the basal compartment of the culture. Viral shedding was followed up by apical washes collected daily and quantifying viral RNA by RT-qPCR.

Results

RSV-A replicates efficiently in HuAECs and viral RNA is shed for weeks after infection. RSV infection reduces the ciliary beat frequency of the ciliated cells as of 4 days post-infection, with complete ciliary dyskinesia observed by day 10. Treatment with RSV fusion inhibitors resulted in an antiviral effect only when added at the time of infection. In contrast, the use of replication inhibitors (both nucleoside and non-nucleoside) elicited a marked antiviral effect even when the start of treatment was delayed until 1 day or even 3 days after infection. Levels of the inflammation marker RANTES (mRNA) increased ∼200-fold in infected, untreated cultures (at 3 weeks post-infection), but levels were comparable to those of uninfected cultures in the presence of PC786, an RSV replication inhibitor, suggesting that an efficient antiviral treatment might inhibit virus-induced inflammation in this model.

Conclusions

Overall, HuAECs offer a robust and physiologically relevant model to study RSV replication and to assess the efficacy of antiviral compounds.

Respiratory syncytial virus infection in adults

Human respiratory syncytial virus (RSV) belongs to the recently defined Pneumoviridae family, Orthopneumovirus genus. It is a negative sense, single stranded RNA virus that results in epidemics of respiratory infections that typically peak in the winter in temperate climates and during the rainy season in tropical climates. Generally, one of the two genotypes (A and B) predominates in a single season, alternating annually, although regional variation occurs. RSV is a cause of disease and death in children, older people, and immunocompromised patients, and its clinical effect on adults admitted to hospital is clarified with expanded use of multiplex molecular assays. Among adults, RSV produces a wide range of clinical symptoms including upper respiratory tract infections, severe lower respiratory tract infections, and exacerbations of underlying disease. Here we discuss the latest evidence on the burden of RSV related disease in adults, especially in those with immunocompromise or other comorbidities. We review current therapeutic and prevention options, as well as those in development.

External validation and update of a prognostic model to predict mortality in hospitalized adults with RSV: A retrospective Dutch cohort study

Respiratory syncytial virus (RSV) causes significant mortality in hospitalized adults. Prediction of poor outcomes improves targeted management and clinical outcomes. We externally validated and updated existing models to predict poor outcome in hospitalized RSV-infected adults. In this single center, retrospective, observational cohort study, we included hospitalized adults with respiratory tract infections (RTIs) and a positive polymerase chain reaction for RSV (A/B) on respiratory tract samples (2005-2018). We validated existing prediction models and updated the best discriminating model by revision, recalibration, and incremental value testing. We included 192 RSV-infected patients (median age 60.7 years, 57% male, 65% immunocompromised, and 43% with lower RTI). Sixteen patients (8%) died within 30 days. During hospitalization, 16 (8%) died, 30 (16%) were admitted to intensive care unit, 21 (11%) needed invasive mechanical ventilation, and 5 (3%) noninvasive positive pressure ventilation. Existing models performed moderately at external validation, with C-statistics 0.6 to 0.7 and moderate calibration. Updating to a model including lower RTI, chronic pulmonary disease, temperature, confusion and urea, increased the C-statistic to 0.76 (95% confidence interval, 0.61-0.91) to predict in-hospital mortality. In conclusion, existing models to predict poor prognosis among hospitalized RSV-infected adults perform moderately at external validation. A prognostic model may help to identify and treat RSV-infected adults at high-risk of death.

Innate immune protection from pneumonia virus of mice induced by a novel immunomodulator is prolonged by dual treatment and mediated by macrophages

Respiratory syncytial virus (RSV) is responsible for a large proportion of acute lower respiratory tract infections, specifically in children. Pneumonia virus of mice (PVM) causes similar lung pathology and clinical disease in rodents, and is therefore an appropriate model of RSV infection. Previously, we demonstrated that a single intranasal dose of P-I-P, a novel immunomodulator composed of the toll-like receptor 3 agonist poly(I:C), an innate defense regulator peptide and a polyphosphazene, confers protection in Balb/c mice for up to 3 days from lethal PVM-15 infection. In the present study a dual intranasal treatment with P-I-P was shown to extend the duration of the protection conferred by P-I-P from PVM-15 challenge. Balb/c mice treated twice with P-I-P showed higher survival rates and milder clinical signs when compared to animals that received a single P-I-P dose. While the mice treated with two consecutive doses of P-I-P experienced some weight loss, they all recovered. The dual P-I-P treatment mediated infiltration of several innate immune cells into the BALF and lung, including alveolar macrophages, neutrophils, and γδ T cells. Partial depletion of alveolar macrophages decreased survival rates and exacerbated clinical signs of mice subjected to the P-I-P dual treatment regime followed by PVM-15 challenge. This suggests that the alveolar macrophage is at least partially responsible for the protection elicited by this novel prophylactic treatment strategy.

Immunoglobulin treatment for hospitalised infants and young children with respiratory syncytial virus infection

BACKGROUND

Millions of children are hospitalised due to respiratory syncytial virus (RSV) infection every year. Treatment is supportive, and current therapies (e.g. inhaled bronchodilators, epinephrine, nebulised hypertonic saline, and corticosteroids) are ineffective or have limited effect. Respiratory syncytial virus immunoglobulin is sometimes used prophylactically to prevent hospital admission from RSV-related illness. It may be considered for the treatment of established severe RSV infection or for treatment in an immunocompromised host, although it is not licenced for this purpose. It is unclear whether immunoglobulins improve outcomes when used as a treatment for established RSV infection in infants and young children admitted to hospital.  OBJECTIVES: To assess the effects of immunoglobulins for the treatment of RSV-proven lower respiratory tract infections in children aged up to three years, admitted to hospital.  SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, Ovid MEDLINE, Embase, CINAHL, and Web of Science (from inception to 6 November 2018) with no restrictions. We searched two trial registries for ongoing trials (to 30 March 2018) and checked the reference lists of reviews and included articles for additional studies.

SELECTION CRITERIA

Randomised controlled trials comparing immunoglobulins with placebo in hospitalised infants and children aged up to three years with laboratory-diagnosed RSV lower respiratory tract infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed risk of bias, and extracted data. We assessed evidence quality using GRADE.

MAIN RESULTS

We included seven trials involving 486 infants and children aged up to three years. The immunoglobulin preparations used in these trials included anti-RSV immunoglobulin and the monoclonal antibody preparations palivizumab and motavizumab. We assessed the primary outcomes of mortality, length of hospital stay, and adverse events as providing low- or very low-certainty evidence due to risk of bias and imprecision. All trials were conducted at sites in high-income countries (USA, Chile, New Zealand, Australia), with two studies including a site in a middle-income country (Panama). Five of the seven studies were "supported" or "sponsored" by the trial drug manufacturers. We found no evidence of a difference between immunoglobulins and placebo for mortality (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.14 to 5.27; 3 trials; 196 children; 4 deaths; 2 deaths amongst 98 children receiving immunoglobulins, and 2 deaths amongst 98 children receiving placebo. One additional death occurred in a fourth trial, however, the study group of the child was not known and the data were not included in the analysis; very low-certainty evidence), and length of hospitalisation (mean difference -0.70, 95% CI -1.83 to 0.42; 5 trials; 324 children; low-certainty evidence). There was no evidence of a difference between immunoglobulins and placebo in adverse events of any severity or seriousness (reported in five trials) or serious adverse events (four trials) (RR for any severity 1.18, 95% CI 0.78 to 1.78; 340 children; low-certainty evidence, and for serious adverse events 1.08, 95% CI 0.65 to 1.79; 238 children; low-certainty evidence).We found no evidence of a significant difference between immunoglobulins and placebo for any of our secondary outcomes. We identified one ongoing trial.

AUTHORS' CONCLUSIONS

We found insufficient evidence of a difference between immunoglobulins and placebo for any review outcomes. We assessed the evidence for the effects of immunoglobulins when used as a treatment for RSV lower respiratory tract infection in hospitalised infants and young children as of low or very low certainty due to risk of bias and imprecision. We are uncertain of the effects of immunoglobulins on these outcomes, and the true effect may be substantially different from the effects reported in this review. All trials were conducted in high-income countries, and data from populations in which the rate of death from RSV infection is higher are lacking.

Pharmacological effects of ginseng on infectious diseases

Ginseng has been traditionally used as an herbal nutritional supplement in Asian countries, including Korea, China, Japan, and Vietnam for several millennia. Most studies have focused on the role of ginseng on anti-oxidative stress, anti-inflammatory, and anti-cancer activities. Recently, modulator activities of ginseng on the immune responses during pathogenic bacterial and viral infections and beneficial effects of ginseng in infectious diseases have been elucidated. In vivo and in vitro studies revealed the potential of ginseng extracts and ginsenosides Rg1, Rg3, Rb1, Rb2, Rb3, compound K, Re, Rd, Rh2 for treatment of several infectious diseases. The molecular mechanisms of these effects mainly involve inflammatory cytokines (TNF-α, IL-6, IL-1β, IFN-γ, IL-10), apoptotic pathway (bcl-2, bcl-xL), PI3K/Akt pathway, MAPKs pathway, JAK2/STAT5, NF-κB pathway, and the inflammasome. In this review, we will summarize the current knowledge on the effects of ginseng in the immune responses during the infections and its bioactivities on the prevention of infectious diseases as well as its underlying mechanisms. Moreover, the therapeutic potential of ginseng as an anti-bacterial and anti-viral medication and vaccine adjuvant will be discussed as well.

Antiviral and Immunomodulatory Activity of Silver Nanoparticles in Experimental RSV Infection

Respiratory syncytial virus (RSV) is an important etiological agent of respiratory infection in children for which no specific treatment option is available. The RSV virion contains two surface glycoproteins (F and G) that are vital for the initial phases of infection, making them critical targets for RSV therapeutics. Recent studies have identified the broad-spectrum antiviral properties of silver nanoparticles (AgNPs) against respiratory pathogens, such as adenovirus, parainfluenza, and influenza. AgNPs achieve this by attaching to viral glycoproteins, blocking entry into the host cell. The objective of this study was to evaluate the antiviral and immunomodulatory effects of AgNPs in RSV infection. Herein we demonstrate AgNP-mediated reduction in RSV replication, both in epithelial cell lines and in experimentally infected BALB/c mice. Marked reduction in pro-inflammatory cytokines (i.e., IL-1α, IL-6, TNF-α) and pro-inflammatory chemokines (i.e., CCL2, CCL3, CCL5) was also observed. Conversely, CXCL1, G-CSF, and GM-CSF were increased in RSV-infected mice treated with AgNPs, consistent with an increase of neutrophil recruitment and activation in the lung tissue. Following experimental antibody-dependent depletion of neutrophils, the antiviral effect of AgNPs in mice treated was ablated. To our knowledge, this is the first in vivo report demonstrating antiviral activity of AgNPs during RSV infection.

Disease severity and clinical outcomes of community-acquired pneumonia caused by non-influenza respiratory viruses in adults: a multicentre prospective registry study from the CAP-China Network

Although broad knowledge of influenza viral pneumonia has been established, the significance of non-influenza respiratory viruses in community-acquired pneumonia (CAP) and their impact on clinical outcomes remains unclear, especially in the non-immunocompromised adult population.Hospitalised immunocompetent patients with CAP were prospectively recruited from 34 hospitals in mainland China. Respiratory viruses were detected by molecular methods. Comparisons were conducted between influenza and non-influenza viral infection groups.In total, 915 out of 2336 adult patients with viral infection were enrolled in the analysis, with influenza virus (28.4%) the most frequently detected virus, followed by respiratory syncytial virus (3.6%), adenovirus (3.3%), human coronavirus (3.0%), parainfluenza virus (2.2%), human rhinovirus (1.8%) and human metapneumovirus (1.5%). Non-influenza viral infections accounted for 27.4% of viral pneumonia. Consolidation was more frequently observed in patients with adenovirus infection. The occurrence of complications such as sepsis (40.1% versus 39.6%; p=0.890) and hypoxaemia (40.1% versus 37.2%; p=0.449) during hospitalisation in the influenza viral infection group did not differ from that of the non-influenza viral infection group. Compared with influenza virus infection, the multivariable adjusted odds ratios of CURB-65 (confusion, urea >7 mmol·L^-1, respiratory rate ≥30 breaths·min^-1, blood pressure <90 mmHg (systolic) or ≤60 mmHg (diastolic), age ≥65 years) ≥3, arterial oxygen tension/inspiratory oxygen fraction <200 mmHg, and occurrence of sepsis and hypoxaemia for non-influenza respiratory virus infection were 0.87 (95% CI 0.26-2.84), 0.72 (95% CI 0.26-1.98), 1.00 (95% CI 0.63-1.58) and 1.05 (95% CI 0.66-1.65), respectively. The hazard ratio of 90-day mortality was 0.51 (95% CI 0.13-1.91).The high incidence of complications in non-influenza viral pneumonia and similar impact of non-influenza respiratory viruses relative to influenza virus on disease severity and outcomes suggest more attention should be given to CAP caused by non-influenza respiratory viruses.

Recombinant live attenuated influenza vaccine viruses carrying CD8 T-cell epitopes of respiratory syncytial virus protect mice against both pathogens without inflammatory disease

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory disease in young children, elderly and immunocompromised adults. There is no licensed vaccine against RSV although development of an effective and safe RSV vaccine has been a high priority for several decades. Among the various vaccine platforms, the viral-vectored RSV vaccines based on licensed cold-adapted live attenuated influenza vaccine (LAIV) might offer an advantage of inducing adequate mucosal CD8 T cell immunity at the infection site of respiratory pathogens. We constructed two recombinant LAIV viruses expressing immunodominant T-cell epitopes of RSV M2-1 protein. The results in this study provide evidence that RSV CD8 T cell epitopes delivered by LAIV viral vector could confer protection against RSV infection without causing pulmonary eosinophilia and inflammatory RSV disease in mice. In addition, these chimeric LAIV-RSV vaccines retained their attenuated phenotype and ability to protect against virulent influenza virus, thus providing a unique approach to fight against two dangerous respiratory viral pathogens using a single vaccine preparation.

Alternative conformations of a major antigenic site on RSV F

The respiratory syncytial virus (RSV) fusion (F) glycoprotein is a major target of neutralizing antibodies arising from natural infection, and antibodies that specifically bind to the prefusion conformation of RSV F generally demonstrate the greatest neutralization potency. Prefusion-stabilized RSV F variants have been engineered as vaccine antigens, but crystal structures of these variants have revealed conformational differences in a key antigenic site located at the apex of the trimer, referred to as antigenic site Ø. Currently, it is unclear if flexibility in this region is an inherent property of prefusion RSV F or if it is related to inadequate stabilization of site Ø in the engineered variants. Therefore, we set out to investigate the conformational flexibility of antigenic site Ø, as well as the ability of the human immune system to recognize alternative conformations of this site, by determining crystal structures of prefusion RSV F bound to neutralizing human-derived antibodies AM22 and RSD5. Both antibodies bound with high affinity and were specific for the prefusion conformation of RSV F. Crystal structures of the complexes revealed that the antibodies recognized distinct conformations of antigenic site Ø, each diverging at a conserved proline residue located in the middle of an α-helix. These data suggest that antigenic site Ø exists as an ensemble of conformations, with individual antibodies recognizing discrete states. Collectively, these results have implications for the refolding of pneumovirus and paramyxovirus fusion proteins and should inform development of prefusion-stabilized RSV F vaccine candidates.

Spread and clinical severity of respiratory syncytial virus A genotype ON1 in Germany, 2011-2017

Background

The Respiratory Syncytial Virus (RSV) A genotype ON1, which was first detected in Ontario (Canada) in 2010/11, appeared in Germany in 2011/12. Preliminary observations suggested a higher clinical severity in children infected with this new genotype. We investigated spread and disease severity of RSV-A ON1 in pediatric in- and outpatient settings.

Methods

During 2010/11 to 2016/17, clinical characteristics and respiratory samples from children with acute respiratory tract infections (RTI) were obtained from ongoing surveillance studies in 33 pediatric practices (PP), one pediatric hospital ward (PW) and 23 pediatric intensive care units (PICU) in Germany. RSV was detected in the respiratory samples by PCR; genotypes were identified by sequencing. Within each setting, clinical severity markers were compared between RSV-A ON1 and RSV-A non-ON1 genotypes.

Results

A total of 603 children with RSV-RTI were included (132 children in PP, 288 in PW, and 183 in PICU). Of these children, 341 (56.6%) were infected with RSV-A, 235 (39.0%) with RSV-B, and one child (0.2%) with both RSV-A and RSV-B; in 26 (4.3%) children, the subtype could not be identified. In the 341 RSV-A positive samples, genotype ON1 was detected in 247 (72.4%), NA1 in 92 (26.9%), and GA5 in 2 children (0.6%). RSV-A ON1, rarely observed in 2011/12, was the predominant RSV-A genotype in all settings by 2012/13 and remained predominant until 2016/17. Children in PP or PW infected with RSV-A ON1 did not show a more severe clinical course of disease compared with RSV-A non-ON1 infections. In the PICU group, hospital stay was one day longer (median 8 days, inter-quartile range (IQR) 7–12 vs. 7 days, IQR 5–9; p = 0.02) and duration of oxygen treatment two days longer (median 6 days, IQR 4–9 vs. 4 days, IQR 2–6; p = 0.03) for children infected with RSV-A ON1.

Conclusions

In children, RSV-A ON1 largely replaced RSV-A non-ON1 genotypes within two seasons and remained the predominant RSV-A genotype in Germany during subsequent seasons. A higher clinical severity of RSV-A ON1 was observed within the group of children receiving PICU treatment, whereas in other settings clinical severity of RSV-A ON1 and non-ON1 genotypes was largely similar.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4266-y) contains supplementary material, which is available to authorized users.

Laboratory Evaluation of Rapid Antigen Detection Tests for More-Sensitive Detection of Respiratory Syncytial Virus Antigen

We evaluated two currently available rapid antigen detection tests (RADTs) for Respiratory syncytial virus (RSV), Sofia^® RSV FIA and BinaxNOW RSV Card (BinaxNOW). Between November 2017 and February 2018, 395 nasopharyngeal swabs were collected from children diagnosed with acute respiratory infections. The swabs were evaluated using the aforementioned RADTs, the reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR), and the direct immunofluorescence assay (DFA). The sensitivity of Sofia^® RSV FIA (80.82%) was significantly higher than that of BinaxNOW (53.42%) when RT-qPCR was used as the standard. This was confirmed with DFA. The sensitivities of Sofia^® RSV FIA (85.4% [41/48]) and BinaxNOW (58.3% [28/48]) were higher for RSV A than for RSV B (69.6% [16/23] and 43.5% [10/23], respectively). The optimal critical cycle threshold (Ct) values on RT-qPCR that correlated with Sofia^® RSV FIA and BinaxNOW were 24 and 22, respectively. The kappa value for Sofia^® RSV FIA and RT-qPCR was 0.962 in patients who were two years old or younger, but 0.648 in those who were more than two years old. Thus, Sofia^® RSV FIA is more sensitive than BinaxNOW; its results were affected by the RSV viral strain and load. Sofia^® RSV FIA is more effective in children who are ≤ 2 years old than in those who are > 2 years old.

Overview of Current Therapeutics and Novel Candidates Against Influenza, Respiratory Syncytial Virus, and Middle East Respiratory Syndrome Coronavirus Infections

Emergence and re-emergence of respiratory virus infections represent a significant threat to global public health, as they occur seasonally and less frequently (such as in the case of influenza virus) as pandemic infections. Some of these viruses have been in the human population for centuries and others had recently emerged as a public health problem. Influenza viruses have been affecting the human population for a long time now; however, their ability to rapidly evolve through antigenic drift and antigenic shift causes the emergence of new strains. A recent example of these events is the avian-origin H7N9 influenza virus outbreak currently undergoing in China. Human H7N9 influenza viruses are resistant to amantadines and some strains are also resistant to neuraminidase inhibitors greatly limiting the options for treatment. Respiratory syncytial virus (RSV) may cause a lower respiratory tract infection characterized by bronchiolitis and pneumonia mainly in children and the elderly. Infection with RSV can cause severe disease and even death, imposing a severe burden for pediatric and geriatric health systems worldwide. Treatment for RSV is mainly supportive since the only approved therapy, a monoclonal antibody, is recommended for prophylactic use in high-risk patients. The Middle East respiratory syndrome coronavirus (MERS-CoV) is a newly emerging respiratory virus. The virus was first recognized in 2012 and it is associated with a lower respiratory tract disease that is more severe in patients with comorbidities. No licensed vaccines or antivirals have been yet approved for the treatment of MERS-CoV in humans. It is clear that the discovery and development of novel antivirals that can be used alone or in combination with existing therapies to treat these important respiratory viral infections are critical. In this review, we will describe some of the novel therapeutics currently under development for the treatment of these infections.

Multiplex Platforms for the Identification of Respiratory Pathogens: Are They Useful in Pediatric Clinical Practice?

Respiratory tract infections (RTIs) are extremely common especially in the first year of life. Knowledge of the etiology of a RTI is essential to facilitate the appropriate management and the implementation of the most effective control measures. This perspective explains why laboratory methods that can identify pathogens in respiratory secretions have been developed over the course of many years. High-complexity multiplex panel assays that can simultaneously detect up to 20 viruses and up to four bacteria within a few hours have been marketed. However, are these platforms actually useful in pediatric clinical practice? In this manuscript, we showed that these platforms appear to be particularly important for epidemiological studies and clinical research. On the contrary, their routine use in pediatric clinical practice remains debatable. They can be used only in the hospital as they require specific equipment and laboratory technicians with considerable knowledge, training, and experience. Moreover, despite more sensitive and specific than other tests routinely used for respiratory pathogen identification, they do not offer significantly advantage for detection of the true etiology of a respiratory disease. Furthermore, knowledge of which virus is the cause of a respiratory disease is not useful from a therapeutic point of view unless influenza virus or respiratory syncytial virus are the infecting agents as effective drugs are available only for these pathogens. On the other hand, multiplex platforms can be justified in the presence of severe clinical manifestations, and in immunocompromised patients for whom specific treatment option can be available, particularly when they can be used simultaneously with platforms that allow identification of antimicrobial resistance to commonly used drugs. It is highly likely that these platforms, particularly those with high sensitivity and specificity and with low turnaround time, will become essential when new drugs effective and safe against most of the respiratory viruses will be available. Further studies on how to differentiate carriers from patients with true disease, as well as studies on the implications of coinfections and identification of antimicrobial resistance, are warranted.

Cytokines in the Respiratory Airway as Biomarkers of Severity and Prognosis for Respiratory Syncytial Virus Infection: An Update

The human respiratory syncytial virus (hRSV) is one of the most important causes of upper and lower respiratory tract infections in children and the main cause of bronchiolitis worldwide. Disease manifestations caused by hRSV may vary from mild to severe, occasionally requiring admission and hospitalization in intensive care units. Despite the high morbidity rates associated to bronchiolitis, treatment options against hRSV are limited and there are no current vaccination strategies to prevent infection. Importantly, the early identification of high-risk patients can help improve disease management and prevent complications associated with hRSV infection. Recently, the characterization of pro- and anti-inflammatory cytokine patterns produced during hRSV-related inflammatory processes has allowed the identification of potential prognosis biomarkers. A suitable biomarker should allow predicting the severity of the infection in a simple and opportune manner and should ideally be obtained from non-invasive samples. Among the cytokines associated with hRSV disease severity, IL-8, interferon-alpha (IFN-alpha), and IL-6, as well as the Th2-type cytokines thymic stromal lymphopoietin (TSLP), IL-3, and IL-33 have been highlighted as molecules with prognostic value in hRSV infections. In this review, we discuss current studies that describe molecules produced by patients during hRSV infection and their potential as biomarkers to anticipate the severity of the disease caused by this virus.

Respiratory Virus Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient

Respiratory virus infections in hematologic stem cell transplant recipients and patients with hematologic malignancies are increasingly recognized as a cause of significant morbidity and mortality. The often overlapping clinical presentation makes molecular diagnostic strategies imperative for rapid diagnosis and to inform understanding of the changing epidemiology of each of the respiratory viruses. Most respiratory virus infections are managed with supportive therapy, although there is effective antiviral therapy for influenza. The primary focus should remain on primary prevention infection control procedures and isolation precautions, avoidance of ill contacts, and vaccination for influenza.

Resveratrol‑loaded nanoparticles inhibit enterovirus 71 replication through the oxidative stress‑mediated ERS/autophagy pathway

A number of studies have demonstrated that resveratrol (RES) has a variety of biological functions, including cardiovascular protective effects, treatment of mutations, and anti‑inflammatory, anti‑tumor and antiviral effects. In the present study, RES‑loaded nanoparticles (RES‑NPs) were used to protect rhabdosarcoma (RD) cells from enterovirus 71 (EV71) infection, and the relevant mechanisms were also explored. An amphiphilic copolymer, monomethoxy poly (ethylene glycol)‑b‑poly (D,L‑lactide), was used as vehicle material, and RES‑NPs with necessitated drug‑loading content and suitable sizes were prepared under optimized conditions. RES‑NPs exhibited the ability to inhibit the increase of intracellular oxidative stress. The prospective mechanism for the function of RES‑NPs suggested was that RES‑NPs may inhibit the oxidative stress‑mediated PERK/eIF2α/ATF4 signaling pathway, downregulate the autophagy pathway and resist EV71‑induced RD cells injury. Furthermore, RES‑NPs treatment markedly inhibited the secretion of inflammatory factors, including interleukin (IL)‑6, IL‑8 and tumor necrosis factor‑α elicited by EV71 infection. Concomitantly, inhibitors of oxidative stress, endoplasmic reticulum stress (ERS) or autophagy were demonstrated to negate the anti‑inflammatory and antiviral effects of RES‑NPs on EV71‑infected RD cells. These results demonstrated that RES‑NPs attenuated EV71‑induced viral replication and inflammatory effects by inhibiting the oxidative stress‑mediated ERS/autophagy signaling pathway. In view of their safety and efficiency, these RES‑NPs have potential applications in protecting RD cells from EV71 injury.

Parainfluenza virus 5 (PIV5) amplifying virus-like particles expressing respiratory syncytial virus (RSV) antigens protect mice against RSV infection

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in children under one year of age. In addition to causing severe respiratory diseases in children, it is also a major cause of morbidity and mortality among the elderly and immunocompromised individuals. RSV is the most common cause of lower respiratory tract infections, yet there are currently no licensed vaccines. A parainfluenza virus 5 (PIV5)-based amplifying virus-like particle (AVLP), which enables the use of PIV5 RNA transcription/replication machinery to express gene of interest, has recently been developed. We evaluated the PIV5-based AVLP system as a vaccine platform for RSV by incorporating the fusion protein (F) gene and the transcription factor protein (M2-1) gene of RSV into the PIV5-AVLP backbone (AVLP-F and AVLP-M2-1, respectively). Mice immunized with a single dose of the AVLP-F or AVLP-M2-1 developed RSV-F or RSV-M2-1-specific immune responses, respectively. Both vaccine candidates elicited antigen-specific cell-mediated responses at levels comparable to or higher than an RSV infection. Most importantly, each vaccine was able to induce protection against RSV A2 challenge in the mouse model. These results indicate the potential of the PIV5-based AVLP system as a platform for vaccines against RSV infection.

Uncovering critical properties of the human respiratory syncytial virus by combining in vitro assays and in silico analyses

Many aspects of the respiratory syncytial virus (RSV) are still poorly understood. Yet these knowledge gaps have had and could continue to have adverse, unintended consequences for the efficacy and safety of antivirals and vaccines developed against RSV. Mathematical modelling was used to test and evaluate hypotheses about the rate of loss of RSV infectivity and the mechanisms and kinetics of RSV infection spread in SIAT cells in vitro. While the rate of loss of RSV integrity, as measured via qRT-PCR, is well-described by an exponential decay, the latter mechanism failed to describe the rate at which RSV A Long loses infectivity over time in vitro based on the data presented herein. This is unusual given that other viruses (HIV, HCV, influenza) have been shown to lose their infectivity exponentially in vitro, and indeed an exponential rate of loss of infectivity is always assumed in mathematical modelling and experimental analyses. The infectivity profile of RSV in HEp-2 and SIAT cells remained consistent over the course of an RSV infection, over time and a large range of infectivity. However, SIAT cells were found to be ∼ 100× less sensitive to RSV infection than HEp-2 cells. In particular, we found that RSV spreads inefficiently in SIAT cells, in a manner we show is consistent with the establishment of infection resistance in uninfected cells. SIAT cells are a good in vitro model in which to study RSV in vivo dissemination, yielding similar infection timescales. However, the higher sensitivity of HEp-2 cells to RSV together with its RSV infectivity profile being similar to that of SIAT cells, makes HEp-2 cells more suitable for quantifying RSV infectivity over the course of in vitro RSV infections in SIAT cells. Our findings highlight the importance and urgency of resolving the mechanisms at play in the dissemination of RSV infections in vitro, and the processes by which this infectivity is lost.

Epidemiology and outcomes of hospitalized adults with respiratory syncytial virus: A 6-year retrospective study

Objectives

Respiratory syncytial virus (RSV) is an important cause of morbidity and mortality in adults. Existing studies are limited by the number of seasons studied and most have focused on the immunocompromised.

Methods

A retrospective cohort study was conducted on all adults (≥18 years) with a positive RSV molecular test admitted from 2009 to 2015 to one hospital in Chicago, IL. Epidemiologic and outcomes data were collected after IRB approval.

Results

Of the 489 eligible patients, 227 had RSV A and 262 had RSV B. Patients had a median age of 61 years and comorbidity (eg, chronic lung disease [40.6%], obesity [37.8%], and cardiac disease [34.3%]). On presentation, most had cough (86.5%), fever (42.4%), and shortness of breath (38.2%). Severe disease was present in 27.6% of patients. Antibiotic was used in 76.3% inpatients and 45.8% at discharged despite few patients (4.7%) having documented bacterial infections. Supplemental oxygen and mechanical ventilation were utilized in 44.6% and 12.3%, respectively, while ICU level care was required in 26.9%. Most patients were discharged home (82.7%). Most deaths (68.4%, 13/19) were attributed to pneumonia or hypoxemia likely from RSV. Most fatal cases were seen in those with recent cancer treatment and older adults.

Conclusions

Respiratory syncytial virus in hospitalized adults is associated with significant morbidity and mortality with 26.9% requiring ICU level care. Antibiotics are commonly prescribed to patients with documented RSV, and antibiotics are frequently continued after diagnosis. Novel antiviral therapies are needed for RSV to improve outcomes and potentially improve antibiotic stewardship in patients without a bacterial infection.

Macrophage migration inhibitory factor (MIF) controls cytokine release during respiratory syncytial virus infection in macrophages

OBJECTIVE AND DESIGN

Respiratory syncytial virus (RSV) is the major cause of infection in children up to 2 years old and reinfection is very common among patients. Tissue damage in the lung caused by RSV leads to an immune response and infected cells activate multiple signaling pathways and massive production of inflammatory mediators like macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine. Therefore, we sought to investigate the role of MIF during RSV infection in macrophages.

METHODS

We evaluated MIF expression in BALB/c mice-derived macrophages stimulated with different concentrations of RSV by Western blot and real-time PCR. Additionally, different inhibitors of signaling pathways and ROS were used to evaluate their importance for MIF expression. Furthermore, we used a specific MIF inhibitor, ISO-1, to evaluate the role of MIF in viral clearance and in RSV-induced TNF-α, MCP-1 and IL-10 release from macrophages.

RESULTS

We showed that RSV induces MIF expression dependently of ROS, 5-LOX, COX and PI3K activation. Moreover, viral replication is necessary for RSV-triggered MIF expression. Differently, p38 MAPK in only partially needed for RSV-induced MIF expression. In addition, MIF is important for the release of TNF-α, MCP-1 and IL-10 triggered by RSV in macrophages.

CONCLUSIONS

In conclusion, we demonstrate that MIF is expressed during RSV infection and controls the release of pro-inflammatory cytokines from macrophages in an in vitro model.

Contribution of Cytokines to Tissue Damage During Human Respiratory Syncytial Virus Infection

The human respiratory syncytial virus (hRSV) remains one of the leading pathogens causing acute respiratory tract infections (ARTIs) in children younger than 2 years old, worldwide. Hospitalizations during the winter season due to hRSV-induced bronchiolitis and pneumonia increase every year. Despite this, there are no available vaccines to mitigate the health and economic burden caused by hRSV infection. The pathology caused by hRSV induces significant damage to the pulmonary epithelium, due to an excessive inflammatory response at the airways. Cytokines are considered essential players for the establishment and modulation of the immune and inflammatory responses, which can either be beneficial or harmful for the host. The deleterious effect observed upon hRSV infection is mainly due to tissue damage caused by immune cells recruited to the site of infection. This cellular recruitment takes place due to an altered profile of cytokines secreted by epithelial cells. As a result of inflammatory cell recruitment, the amounts of cytokines, such as IL-1, IL-6, IL-10, and CCL5 are further increased, while IL-10 and IFN-γ are decreased. However, additional studies are required to elicit the mediators directly associated with hRSV damage entirely. In addition to the detrimental induction of inflammatory mediators in the respiratory tract caused by hRSV, reports indicating alterations in the central nervous system (CNS) have been published. Indeed, elevated levels of IL-6, IL-8 (CXCL8), CCL2, and CCL4 have been reported in cerebrospinal fluid from patients with severe bronchiolitis and hRSV-associated encephalopathy. In this review article, we provide an in-depth analysis of the role of cytokines secreted upon hRSV infection and their potentially harmful contribution to tissue damage of the respiratory tract and the CNS.

Detection of ON1 and novel genotypes of human respiratory syncytial virus and emergence of palivizumab resistance in Lebanon

Respiratory syncytial virus (RSV) is a common cause of respiratory tract infections in children and immunocompromised individuals. A multi-center surveillance of the epidemiologic and molecular characteristics of RSV circulating in Lebanon was performed. The attachment (G) and fusion (F) glycoproteins were analyzed and compared to those reported regionally and globally. 16% (83/519) of the nasopharyngeal swabs collected during the 2016/17 season tested positive for RSV; 50% (27/54) were RSV-A and 50% (27/54) were RSV-B. Phylogenetic analysis of the G glycoprotein revealed predominance of the RSVA ON1 genotype, in addition to two novel Lebanese genotype variants, hereby named LBA1 and LBA2, which descended from the ON1 and NA2 RSV-A genotypes, respectively. RSV-B strains belonged to BA9 genotype except for one BA10. Deduced amino acid sequences depicted several unique substitutions, alteration of glycosylation patterns and the emergence of palivizumab resistance among the Lebanese viruses. The emergence of ON1 and other novel genotypes that are resistant to palivizumab highlights the importance of monitoring RSV globally.

Structure basis of neutralization by a novel site II/IV antibody against respiratory syncytial virus fusion protein

Globally, human respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections in newborns, young children, and the elderly for which there is no vaccine. The RSV fusion (F) glycoprotein is a major target for vaccine development. Here, we describe a novel monoclonal antibody (designated as R4.C6) that recognizes both pre-fusion and post-fusion RSV F, and binds with nanomole affinity to a unique neutralizing site comprised of antigenic sites II and IV on the globular head. A 3.9 Å-resolution structure of RSV F-R4.C6 Fab complex was obtained by single particle cryo-electron microscopy and 3D reconstruction. The structure unraveled detailed interactions of R4.C6 with antigenic site II on one protomer and site IV on a neighboring protomer of post-fusion RSV F protein. These findings significantly further our understanding of the antigenic complexity of the F protein and provide new insights into RSV vaccine design.

Phospholipid regulation of innate immunity and respiratory viral infection

Toll-like receptors (TLRs) coupled to intracellular signaling cascades function as central elements of innate immunity that control transcription of numerous pro-inflammatory genes. Two minor anionic phospholipids present in the pulmonary surfactant complex, palmitoyl-oleoyl-phosphatidylglycerol (POPG) and phosphatidylinositol (PI), antagonize the cognate ligand activation of TLRs 2 and 4. The lipids block recognition of activating ligands by the TLRs, either directly or via the TLR4 coreceptors CD14 and MD2. Antagonism of TLR activation results in inhibition of the initiating step of the pro-inflammatory signaling pathways. Evidence for this mechanism of action comes from direct binding studies between CD14 and MD2 with POPG and PI. Additional evidence for this mechanism of antagonism also comes from monitoring the reduction of protein phosphorylation events that characterize the intracellular signaling by activated TLRs. The pathogenesis of respiratory syncytial virus (RSV) and influenza A virus (IAV) have been linked to TLR4 activation, and we examined the action of POPG and PI as potential antagonists of the pathology of these viruses. Surprisingly, POPG and PI dramatically curtail infection, in addition to inhibiting inflammatory sequelae associated with RSV and IAV infections. The mechanism of action by the lipids is disruption of virus particle binding to host cell plasma membrane receptors, required for viral uptake. The antagonism of activation of TLRs and virus binding to the alveolar epithelium by resident constituents of the pulmonary surfactant system suggests that POPG and PI function in homeostasis, to prevent inflammatory processes that result in reductions in gas exchange within the alveolar compartment.

New therapies for acute RSV infections: where are we?

Respiratory syncytial virus (RSV) infection is one of the main causes of infant hospitalization and mortality. The single-stranded RNA virus codes for 11 proteins of which the F protein, a surface epitope responsible for RSV fusion, is the most targeted for developing antiviral medicines and vaccines. The peak of symptoms occurs around day 4 to 6 of illness and the airway obstruction is merely caused by the host immune inflammatory response. Risk factors for severe bronchiolitis are prematurity, comorbidity, and/or being immunocompromised. At present, there are no curative therapies available for RSV infections and treatment is supportive only. Development of new antiviral medicines is however promising. The aim of this review is to give a summary of the most important new antiviral therapies in clinical development for RSV infection and to explain their mode of action. We therefore performed a literature search on this topic.Conclusion: There are currently at least eight antivirals being investigated in clinical trials. They all use different approaches to either focus on preventing viral fusion with host cells or inhibiting virus replication. Some target RSV surface epitopes like the F protein to halt fusion, others aim for RNA chain termination, while small interfering RNAs downregulate viral protein production. What is known: • RSV bronchiolitis is a very important pediatric disease as it is one of the main causes of infant hospitalization and mortality. By the age of 2 years, 95% of all the infants worldwide will have been infected. • The only recommended therapy is supportive since there are no existing curative therapies yet. What this study adds: • This review gives an overview of the current progress in the research field of RSV antivirals with background information on their mode of action.

Key considerations for successful implementation of maternal immunization programs in low and middle income countries

The Maternal Neonatal Tetanus Elimination program is proof of concept for the feasibility and potential for maternal immunization to reduce neonatal mortality particularly in low and middle-income countries. Introduction of any additional vaccine into the antenatal space, such as Influenza and Pertussis, and potentially Respiratory Syncytial Virus and Group B Streptococcus vaccines in the future, requires strengthening of antenatal care and immunization services. Successful implementation also requires robust disease surveillance in pregnant women and neonates and active surveillance for adverse events following immunization to monitor the impact and ensure the safe use of the vaccine. This review outlines five key elements essential for successful implementation of a maternal immunization program focusing particularly on low and middle-income countries. These include; relevant considerations in supporting a decision to undertake a maternal immunization program including knowledge of local disease epidemiology, involvement of the consumer, healthcare provider recommendation, equitable access to maternal vaccination, and systems for disease surveillance, program evaluation and safety monitoring.

Utility of the Neonatal Calf Model for Testing Vaccines and Intervention Strategies for Use against Human RSV Infection

Respiratory syncytial virus (RSV) is a significant cause of pediatric respiratory tract infections. It is estimated that two-thirds of infants are infected with RSV during the first year of life and it is one of the leading causes of death in this age group worldwide. Similarly, bovine RSV is a primary viral pathogen in cases of pneumonia in young calves and plays a significant role in bovine respiratory disease complex. Importantly, naturally occurring infection of calves with bovine RSV shares many features in common with human RSV infection. Herein, we update our current understanding of RSV infection in cattle, with particular focus on similarities between the calf and human infection, and the recent reports in which the neonatal calf has been employed for the development and testing of vaccines and therapeutics which may be applied to hRSV infection in humans.

T Lymphocytes as Measurable Targets of Protection and Vaccination Against Viral Disorders

Continuous epidemiological surveillance of existing and emerging viruses and their associated disorders is gaining importance in light of their abilities to cause unpredictable outbreaks as a result of increased travel and vaccination choices by steadily growing and aging populations. Close surveillance of outbreaks and herd immunity are also at the forefront, even in industrialized countries, where previously eradicated viruses are now at risk of re-emergence due to instances of strain recombination, contractions in viral vector geographies, and from their potential use as agents of bioterrorism. There is a great need for the rational design of current and future vaccines targeting viruses, with a strong focus on vaccine targeting of adaptive immune effector memory T cells as the gold standard of immunity conferring long-lived protection against a wide variety of pathogens and malignancies. Here, we review viruses that have historically caused large outbreaks and severe lethal disorders, including respiratory, gastric, skin, hepatic, neurologic, and hemorrhagic fevers. To observe trends in vaccinology against these viral disorders, we describe viral genetic, replication, transmission, and tropism, host-immune evasion strategies, and the epidemiology and health risks of their associated syndromes. We focus on immunity generated against both natural infection and vaccination, where a steady shift in conferred vaccination immunogenicity is observed from quantifying activated and proliferating, long-lived effector memory T cell subsets, as the prominent biomarkers of long-term immunity against viruses and their associated disorders causing high morbidity and mortality rates.