Respiratory syncytial virus and parainfluenza virus

Autophagy, TGF-β, and SMAD-2/3 Signaling Regulates Interferon-β Response in Respiratory Syncytial Virus Infected Macrophages

Human respiratory syncytial virus (RSV) is a lung tropic virus causing severe airway diseases including bronchiolitis and pneumonia among infants, children, and immuno-compromised individuals. RSV triggers transforming growth factor-β (TGF-β) production from lung epithelial cells and TGF-β facilitates RSV infection of these cells. However, it is still unknown whether RSV infected myeloid cells like macrophages produce TGF-β and the role of TGF-β if any during RSV infection of these cells. Our study revealed that RSV infected macrophages produce TGF-β and as a consequence these cells activate TGF-β dependent SMAD-2/3 signaling pathway. Further mechanistic studies illustrated a role of autophagy in triggering TGF-β production from RSV infected macrophages. In an effort to elucidate the role of TGF-β and SMAD-2/3 signaling during RSV infection, we surprisingly unfolded the requirement of TGF-β—SMAD2/3 signaling in conferring optimal innate immune antiviral response during RSV infection of macrophages. Type-I interferon (e.g., interferon-β or IFN-β) is a critical host factor regulating innate immune antiviral response during RSV infection. Our study revealed that loss of TGF-β—SMAD2/3 signaling pathway in RSV infected macrophages led to diminished expression and production of IFN-β. Inhibiting autophagy in RSV infected macrophages also resulted in reduced production of IFN-β. Thus, our studies have unfolded the requirement of autophagy—TGF-β—SMAD2/3 signaling network for optimal innate immune antiviral response during RSV infection of macrophages.

Actin-Related Protein 2 (ARP2) and Virus-Induced Filopodia Facilitate Human Respiratory Syncytial Virus Spread

Human respiratory syncytial virus (RSV) is an enveloped RNA virus that is the most important viral cause of acute pediatric lower respiratory tract illness worldwide, and lacks a vaccine or effective antiviral drug. The involvement of host factors in the RSV replicative cycle remains poorly characterized. A genome-wide siRNA screen in human lung epithelial A549 cells identified actin-related protein 2 (ARP2) as a host factor involved in RSV infection. ARP2 knockdown did not reduce RSV entry, and did not markedly reduce gene expression during the first 24 hr of infection, but decreased viral gene expression thereafter, an effect that appeared to be due to inhibition of viral spread to neighboring cells. Consistent with reduced spread, there was a 10-fold reduction in the release of infectious progeny virions in ARP2-depleted cells at 72 hr post-infection. In addition, we found that RSV infection induced filopodia formation and increased cell motility in A549 cells and that this phenotype was ARP2 dependent. Filopodia appeared to shuttle RSV to nearby uninfected cells, facilitating virus spread. Expression of the RSV F protein alone from a plasmid or heterologous viral vector in A549 cells induced filopodia, indicating a new role for the RSV F protein, driving filopodia induction and virus spread. Thus, this study identified roles for ARP2 and filopodia in RSV-induced cell motility, RSV production, and RSV cell-to-cell spread.

Identification of Interferon-Stimulated Gene Proteins That Inhibit Human Parainfluenza Virus Type 3

A major arm of cellular innate immunity is type I interferon (IFN), represented by IFN-α and IFN-β. Type I IFN transcriptionally induces a large number of cellular genes, collectively known as IFN-stimulated gene (ISG) proteins, which act as antivirals. The IFIT (interferon-induced proteins with tetratricopeptide repeats) family proteins constitute a major subclass of ISG proteins and are characterized by multiple tetratricopeptide repeats (TPRs). In this study, we have interrogated IFIT proteins for the ability to inhibit the growth of human parainfluenza virus type 3 (PIV3), a nonsegmented negative-strand RNA virus of the Paramyxoviridae family and a major cause of respiratory disease in children. We found that IFIT1 significantly inhibited PIV3, whereas IFIT2, IFIT3, and IFIT5 were less effective or not at all. In further screening a set of ISG proteins we discovered that several other such proteins also inhibited PIV3, including IFITM1, IDO (indoleamine 2,3-dioxygenase), PKR (protein kinase, RNA activated), and viperin (virus inhibitory protein, endoplasmic reticulum associated, interferon inducible)/Cig5. The antiviral effect of IDO, the enzyme that catalyzes the first step of tryptophan degradation, could be counteracted by tryptophan. These results advance our knowledge of diverse ISG proteins functioning as antivirals and may provide novel approaches against PIV3.

IMPORTANCE

The innate immunity of the host, typified by interferon (IFN), is a major antiviral defense. IFN inhibits virus growth by inducing a large number of IFN-stimulated gene (ISG) proteins, several of which have been shown to have specific antiviral functions. Parainfluenza virus type 3 (PIV3) is major pathogen of children, and no reliable vaccine or specific antiviral against it currently exists. In this article, we report several ISG proteins that strongly inhibit PIV3 growth, the use of which may allow a better antiviral regimen targeting PIV3.

Community acquired respiratory virus infections in cancer patients-Guideline on diagnosis and management by the Infectious Diseases Working Party of the German Society for haematology and Medical Oncology

BACKGROUND

Community acquired viruses (CRVs) may cause severe disease in cancer patients. Thus, efforts should be made to diagnose CRV rapidly and manage CRV infections accordingly.

METHODS

A panel of 18 clinicians from the Infectious Diseases Working Party of the German Society for Haematology and Medical Oncology have convened to assess the available literature and provide recommendations on the management of CRV infections including influenza, respiratory syncytial virus, parainfluenza virus, human metapneumovirus and adenovirus.

RESULTS

CRV infections in cancer patients may lead to pneumonia in approximately 30% of the cases, with an associated mortality of around 25%. For diagnosis of a CRV infection, combined nasal/throat swabs or washes/aspirates give the best results and nucleic acid amplification based-techniques (NAT) should be used to detect the pathogen. Hand hygiene, contact isolation and face masks have been shown to be of benefit as general infection management. Causal treatment can be given for influenza, using a neuraminidase inhibitor, and respiratory syncytial virus, using ribavirin in addition to intravenous immunoglobulins. Ribavirin has also been used to treat parainfluenza virus and human metapneumovirus, but data are inconclusive in this setting. Cidofovir is used to treat adenovirus pneumonitis.

CONCLUSIONS

CRV infections may pose a vital threat to patients with underlying malignancy. This guideline provides information on diagnosis and treatment to improve the outcome.

Isolation & molecular characterization of human parainfluenza virus in Chennai, India

Background & objectives:

Human parainfluenza virus (HPIV) accounts for a significant proportion of lower respiratory tract infections in children as well as adults. This study was done to detect the presence of different subtypes of HPIV from patients having influenza like illness (ILI).

Methods:

Throat and nasal swabs from 232 patients with ILI who were negative for influenza viruses were tested by multiplex reverse transcription polymerase chain reaction(mRT-PCR) for the detection of human parainfluenza virus. All samples were inoculated in rhesus monkey kidney (LLC-MK2) cell line.

Results:

Of the 232 samples, 26(11.2%) were positive by mRT-PCR and nine (34.6%) showed cytopathic effect with syncytium formation for HPIV and all were HPIV-3 serotype, other serotypes like 1,2,4 were negative. The HPIV-3 strains (HN gene) were sequenced and analysed. Two novel mutations were identified at amino acid residues 295 and 297.

Interpretation & conclusions:

The mRT-PCR assay offers a rapid, sensitive and accurate diagnostic method for detection of HPIV which enables early detection and control. In our study there was a predominance of HPIV among 1-5 yr age group and the school going age group was less affected. Further studies need to be done to characterize HPIV isolated from different parts of the country.

Clinical potential of oligonucleotide-based therapeutics in the respiratory system

The discovery of an ever-expanding plethora of coding and non-coding RNAs with nodal and causal roles in the regulation of lung physiology and disease is reinvigorating interest in the clinical utility of the oligonucleotide therapeutic class. This is strongly supported through recent advances in nucleic acids chemistry, synthetic oligonucleotide delivery and viral gene therapy that have succeeded in bringing to market at least three nucleic acid-based drugs. As a consequence, multiple new candidates such as RNA interference modulators, antisense, and splice switching compounds are now progressing through clinical evaluation. Here, manipulation of RNA for the treatment of lung disease is explored, with emphasis on robust pharmacological evidence aligned to the five pillars of drug development: exposure to the appropriate tissue, binding to the desired molecular target, evidence of the expected mode of action, activity in the relevant patient population and commercially viable value proposition.

Potential Cost-Effectiveness of RSV Vaccination of Infants and Pregnant Women in Turkey: An Illustration Based on Bursa Data

Background

Worldwide, respiratory syncytial virus (RSV) is considered to be the most important viral cause of respiratory morbidity and mortality among infants and young children. Although no active vaccine is available on the market yet, there are several active vaccine development programs in various stages. To assess whether one of these vaccines might be a future asset for national immunization programs, modeling the costs and benefits of various vaccination strategies is needed.

Objectives

To evaluate the potential cost-effectiveness of RSV vaccination of infants and/or pregnant women in Turkey.

Methods

A multi-cohort static Markov model with cycles of one month was used to compare the cost-effectiveness of vaccinated cohorts versus non-vaccinated cohorts. The 2014 Turkish birth cohort was divided by twelve to construct twelve monthly birth cohorts of equal size (111,459 new-borns). Model input was based on clinical data from a multicenter prospective study from Bursa, Turkey, combined with figures from the (inter)national literature and publicly available data from the Turkish Statistical Institute (TÜÏK). Incremental cost-effectiveness ratios (ICERs) were expressed in Turkish Lira (TL) per quality-adjusted life year (QALY) gained.

Results

Vaccinating infants at 2 and 4 months of age would prevent 145,802 GP visits, 8,201 hospitalizations and 48 deaths during the first year of life, corresponding to a total gain of 1650 QALYs. The discounted ICER was estimated at 51,969 TL (26,220 US $ in 2013) per QALY gained. Vaccinating both pregnant women and infants would prevent more cases, but was less attractive from a pure economic point of view with a discounted ICER of 61,653 TL (31,106 US $ in 2013) per QALY. Vaccinating only during pregnancy would result in fewer cases prevented than infant vaccination and a less favorable ICER.

Conclusion

RSV vaccination of infants and/or pregnant women has the potential to be cost-effective in Turkey. Although using relatively conservative assumptions, all evaluated strategies remained slightly below the threshold of 3 times the GDP per capita.

Non-invasive Imaging of Sendai Virus Infection in Pharmacologically Immunocompromised Mice: NK and T Cells, but not Neutrophils, Promote Viral Clearance after Therapy with Cyclophosphamide and Dexamethasone

In immunocompromised patients, parainfluenza virus (PIV) infections have an increased potential to spread to the lower respiratory tract (LRT), resulting in increased morbidity and mortality. Understanding the immunologic defects that facilitate viral spread to the LRT will help in developing better management protocols. In this study, we immunosuppressed mice with dexamethasone and/or cyclophosphamide then monitored the spread of viral infection into the LRT by using a noninvasive bioluminescence imaging system and a reporter Sendai virus (murine PIV type 1). Our results show that immunosuppression led to delayed viral clearance and increased viral loads in the lungs. After cessation of cyclophosphamide treatment, viral clearance occurred before the generation of Sendai-specific antibody responses and coincided with rebounds in neutrophils, T lymphocytes, and natural killer (NK) cells. Neutrophil suppression using anti-Ly6G antibody had no effect on infection clearance, NK-cell suppression using anti-NK antibody delayed clearance, and T-cell suppression using anti-CD3 antibody resulted in no clearance (chronic infection). Therapeutic use of hematopoietic growth factors G-CSF and GM-CSF had no effect on clearance of infection. In contrast, treatment with Sendai virus-specific polysera or a monoclonal antibody limited viral spread into the lungs and accelerated clearance. Overall, noninvasive bioluminescence was shown to be a useful tool to study respiratory viral progression, revealing roles for NK and T cells, but not neutrophils, in Sendai virus clearance after treatment with dexamethasone and cyclophosphamide. Virus-specific antibodies appear to have therapeutic potential.

Parainfluenza Virus Infection

Human parainfluenza viruses (HPIVs) are single-stranded, enveloped RNA viruses of the Paramyoviridaie family. There are four serotypes which cause respiratory illnesses in children and adults. HPIVs bind and replicate in the ciliated epithelial cells of the upper and lower respiratory tract and the extent of the infection correlates with the location involved. Seasonal HPIV epidemics result in a significant burden of disease in children and account for 40% of pediatric hospitalizations for lower respiratory tract illnesses (LRTIs) and 75% of croup cases. Parainfluenza viruses are associated with a wide spectrum of illnesses which include otitis media, pharyngitis, conjunctivitis, croup, tracheobronchitis, and pneumonia. Uncommon respiratory manifestations include apnea, bradycardia, parotitis, and respiratory distress syndrome and rarely disseminated infection. Immunity resulting from disease in childhood is incomplete and reinfection with HPIV accounts for 15% of respiratory illnesses in adults. Severe disease and fatal pneumonia may occur in elderly and immunocompromised adults. HPIV pneumonia in recipients of hematopoietic stem cell transplant (HSCT) is associated with 50% acute mortality and 75% mortality at 6 months. Though sensitive molecular diagnostics are available to rapidly diagnose HPIV infection, effective antiviral therapies are not available. Currently, treatment for HPIV infection is supportive with the exception of croup where the use of corticosteroids has been found to be beneficial. Several novel drugs including DAS181 appear promising in efforts to treat severe disease in immunocompromised patients, and vaccines to decrease the burden of disease in young children are in development.

Association Between Updated Guideline-Based Palivizumab Administration and Hospitalizations for Respiratory Syncytial Virus Infections

BACKGROUND

Since its introduction, palivizumab has been used to prevent respiratory syncytial virus (RSV) infection in high-risk populations. Recommendations for palivizumab administration changed in 2014. We examined whether adherence to 2014 palivizumab guidelines affected RSV hospitalization rates.

METHODS

This was a retrospective sequential period analysis comparing the incidence of RSV hospitalization in patients younger than 2 years of age before and after implementation of 2014 palivizumab use criteria. Hospitalization data were prospectively collected through age-based surveillance for the post-2014 guideline period (November 1, 2014 to April 1, 2015 RSV season). Comparative data were collected retrospectively for hospitalizations during the pre-2014 guideline period of 2 previous RSV seasons (November 1, 2012 to April 1, 2013 and November 1, 2013 to April 1, 2014). The primary outcome was RSV hospitalization rate, and number of palivizumab doses administered was analyzed as a secondary outcome.

RESULTS

During the study period, 194 RSV hospitalizations occurred. The rate of RSV hospitalization was 5.37 per 1000 children <24 months in the pre-2014 guideline period versus 5.78 per 1000 children <24 months in the post-2014 guideline period (difference of +0.4, 95% confidence interval: -1.2 to +2, P = 0.622). During the pre-2014 guideline period, 21.7 doses per 1000 children <24 months of palivizumab were administered, which decreased to 10.3 doses per 1000 children <24 months in the post-2014 guideline period, yielding a reduction of 11.4 doses per 1000 children <24 months (95% confidence interval: 14.3-8.4, P < 0.001).

CONCLUSIONS

The implementation of 2014 palivizumab use criteria was not associated with an increased incidence of RSV hospitalization for children younger than 2 years of age but was associated with significantly less use of palivizumab.

Population-based Surveillance for Medically Attended Human Parainfluenza Viruses From the Influenza Incidence Surveillance Project, 2010-2014

BACKGROUND

Parainfluenza viruses (PIV) have been shown to contribute substantially to pediatric hospitalizations in the United States. However, to date, there has been no systematic surveillance to estimate the burden among pediatric outpatients.

METHODS

From August 2010 through July 2014, outpatient health care providers with enumerated patient populations in 13 states and jurisdictions participating in the Influenza Incidence Surveillance Project conducted surveillance of patients with influenza-like illness (ILI). Respiratory specimens were collected from the first 10 ILI patients each week with demographic and clinical data. Specimens were tested for multiple respiratory viruses, including PIV1-4, using reverse transcriptase-polymerase chain reaction assays. Cumulative incidence was calculated using provider patient population size as the denominator.

RESULTS

PIVs 1-3 were detected in 8.0% of 7716 ILI-related outpatient specimens: 30% were PIV1, 26% PIV2 and 44% PIV3. PIV circulation varied noticeably by year and type, with PIV3 predominating in 2010-2011 (incidence 110 per 100,000 children), PIV1 in 2011-2012 (89 per 100,000), dual predominance of PIV2 and PIV3 (88 and 131 per 100,000) in 2012-2013 and PIV3 (100 per 100,000) in 2013-2014. The highest incidence of PIV detections was among patients aged <5 years (259-1307 per 100,000). The median age at detection for PIV3 (3.4 years) was significantly lower than the median ages for PIV1 (4.5 years) and PIV2 (7.0 years; P < 0.05).

CONCLUSIONS

PIVs 1-3 comprise a substantial amount of medically attended pediatric ILI, particularly among children aged <5 years. Distinct seasonal circulation patterns as well as significant differences in rates by age were observed between PIV types.

The use of multiplex PCR for the diagnosis of viral severe acute respiratory infection in children: a high rate of co-detection during the winter season

Respiratory tract infection is a major cause of hospitalization in children. Although most such infections are viral in origin, it is difficult to differentiate bacterial and viral infections, as the clinical symptoms are similar. Multiplex polymerase chain reaction (PCR) methods allow testing for multiple pathogens simultaneously and are, therefore, gaining interest. This prospective case-control study was conducted from October 2013 to February 2014. Nasopharyngeal (NP) and oropharyngeal (throat) swabs were obtained from children admitted with severe acute respiratory infection (SARI) at a tertiary hospital. A control group of 40 asymptomatic children was included. Testing for 16 viruses was done by real-time multiplex PCR. Multiplex PCR detected a viral pathogen in 159/177 (89.9 %) patients admitted with SARI. There was a high rate of co-infection (46.9 %). Dual detections were observed in 64 (36.2 %), triple detections in 17 (9.6 %), and quadruple detections in 2 (1.1 %) of 177 samples. Seventy-eight patients required intensive care unit (ICU) admission, of whom 28 (35.8 %) had co-infection with multiple viruses. AdV, HBoV, HRV, HEV, and HCoV-OC43 were also detected among asymptomatic children. This study confirms the high rate of detection of viral nucleic acids by multiplex PCR among hospitalized children admitted with SARI, as well as the high rate of co-detection of multiple viruses. AdV, HBoV, HRV, HEV, and HCoV-OC43 were also detected in asymptomatic children, resulting in challenges in clinical interpretation. Studies are required to provide quantitative conclusions that will facilitate clinical interpretation and application of the results in the clinical setting.

Modelling estimates of the burden of respiratory syncytial virus infection in children in the UK

OBJECTIVE

The burden of respiratory syncytial virus (RSV) illness is not well characterised in primary care. We estimated the burden of disease attributable to RSV in children in the UK between 1995 and 2009.

DESIGN

Time-series regression modelling.

SETTING

A multiple linear regression model based on weekly viral surveillance (RSV and influenza, Public Health England), and controlled for non-specific seasonal drivers of disease, estimated the proportion of general practitioner (GP) episodes of care (counted as first visit in a series within 28 days; Clinical Practice Research Datalink, CPRD), hospitalisations (Hospital Episode Statistics, HES) and deaths (Office of National Statistics, ONS) attributable to RSV each season.

PARTICIPANTS

Children 0-17 years registered with a GP in CPRD, or with a respiratory disease outcome in the HES or ONS databases.

PRIMARY OUTCOME MEASURES

RSV-attributable burden of GP episodes, hospitalisations and deaths due to respiratory disease by age. RSV-attributable burden associated with selected antibiotic prescriptions.

RESULTS

RSV-attributable respiratory disease in the UK resulted in an estimated 450 158 GP episodes, 29 160 hospitalisations and 83 deaths per average season in children and adolescents, with the highest proportions in children <6 months of age (14 441/100 000 population, 4184/100 000 and 6/100 000, respectively). In an average season, there were an estimated 125 478 GP episodes for otitis media and 416 133 prescriptions for antibiotics attributable to RSV. More GP episodes, hospitalisations and deaths from respiratory disease were attributable to RSV than to influenza in children under 5 years.

CONCLUSIONS

The burden of RSV in children in the UK exceeds that of influenza. RSV in children and adolescents contributes substantially to GP office visits for a diverse range of illnesses, and was associated with an average 416 133 prescribed antibiotic courses per season. Effective antiviral treatments and preventive vaccines are urgently needed for the management of RSV infection in children.

TRIAL REGISTRATION NUMBER

NCT01706302.

Epithelial cell extrusion: Pathways and pathologies

To remove dying or unwanted cells from an epithelium while preserving the barrier function of the layer, epithelia use a unique process called cell extrusion. To extrude, the cell fated to die emits the lipid Sphingosine 1 Phosphate (S1P), which binds the G-protein-coupled receptor Sphingosine 1 Phosphate receptor 2 (S1P₂) in the neighboring cells that activates Rho-mediated contraction of an actomyosin ring circumferentially and basally. This contraction acts to squeeze the cell out apically while drawing together neighboring cells and preventing any gaps to the epithelial barrier. Epithelia can extrude out cells targeted to die by apoptotic stimuli to repair the barrier in the face of death or extrude live cells to promote cell death when epithelial cells become too crowded. Indeed, because epithelial cells naturally turn over by cell death and division at some of the highest rates in the body, epithelia depend on crowding-induced live cell extrusion to preserve constant cell numbers. If extrusion is defective, epithelial cells rapidly lose contact inhibition and form masses. Additionally, because epithelia act as the first line of defense in innate immunity, preservation of this barrier is critical for preventing pathogens from invading the body. Given its role in controlling constant cell numbers and maintaining barrier function, a number of different pathologies can result when extrusion is disrupted. Here, we review mechanisms and signaling pathways that control epithelial extrusion and discuss how defects in these mechanisms can lead to multiple diseases. We also discuss tactics pathogens have devised to hijack the extrusion process to infect and colonize epithelia.

Targeting human respiratory syncytial virus transcription anti-termination factor M2-1 to inhibit in vivo viral replication

Human respiratory syncytial virus (hRSV) is a leading cause of acute lower respiratory tract infection in infants, elderly and immunocompromised individuals. To date, no specific antiviral drug is available to treat or prevent this disease. Here, we report that the Smoothened receptor (Smo) antagonist cyclopamine acts as a potent and selective inhibitor of in vitro and in vivo hRSV replication. Cyclopamine inhibits hRSV through a novel, Smo-independent mechanism. It specifically impairs the function of the hRSV RNA-dependent RNA polymerase complex notably by reducing expression levels of the viral anti-termination factor M2-1. The relevance of these findings is corroborated by the demonstration that a single R151K mutation in M2-1 is sufficient to confer virus resistance to cyclopamine in vitro and that cyclopamine is able to reduce virus titers in a mouse model of hRSV infection. The results of our study open a novel avenue for the development of future therapies against hRSV infection.

A new real-time RT-qPCR assay for the detection, subtyping and quantification of human respiratory syncytial viruses positive- and negative-sense RNAs

Human respiratory syncytial virus (RSV) is a major health problem and the main cause of hospitalization due to bronchiolitis. RSV is divided into two antigenic subgroups, RSV-A and -B that co-circulate worldwide. Rapid and sensitive detection is desirable for proper patient handling while assessment of viral load may help to evaluate disease severity and progression. Finally RSV subtyping is needed to determine the prevalence and pathogenicity of each RSV subgroup, as well as their sensitivity to treatment. In this study, we took into account the most recent circulating RSV variants and designed two quantitative TaqMan one-step RT-PCR assays to detect and quantify both RSV subgroups separately. Standard dilutions of transcripts of positive and negative polarities were included in the assay validation to assess potential differences in sensitivity on negative-sense genomes and positive-sense RNAs. In addition, RSV detection in respiratory specimens of different types and sampled in different populations was compared to commercially available RSV diagnostic tools. Altogether, the RSV-A and -B assays revealed sensitive and quantitative over a wide range of viral loads, with a slight improved sensitivity of the RSV-B assay on positive sense transcripts, and allowed accurate RSV subtyping. We thus provide a useful tool for both RSV diagnostics and research.

Exploring the dynamics of respiratory syncytial virus (RSV) transmission in children

Respiratory syncytial virus (RSV) is the main cause of lower respiratory tract infections in children. Whilst highly seasonal, RSV dynamics can have either one-year (annual) or two-year (biennial) cycles. Furthermore, some countries show a 'delayed biennial' pattern, where the epidemic peak in low incidence years is delayed. We develop a compartmental model for RSV infection, driven by a seasonal forcing function, and conduct parameter space and bifurcation analyses to document parameter ranges that give rise to these different seasonal patterns. The model is sensitive to the birth rate, transmission rate, and seasonality parameters, and can replicate RSV dynamics observed in different countries. The seasonality parameter must exceed a threshold for the model to produce biennial cycles. Intermediate values of the birth rate produce the greatest delay in these biennial cycles, while the model reverts to annual cycles if the duration of immunity is too short. Finally, the existence of period doubling and period halving bifurcations suggests robust model dynamics, in agreement with the known regularity of RSV outbreaks. These findings help explain observed RSV data, such as regular biennial dynamics in Western Australia, and delayed biennial dynamics in Finland. From a public health perspective, our findings provide insight into the drivers of RSV transmission, and a foundation for exploring RSV interventions.

A dual drug regimen synergistically blocks human parainfluenza virus infection

Human parainfluenza type-3 virus (hPIV-3) is one of the principal aetiological agents of acute respiratory illness in infants worldwide and also shows high disease severity in the elderly and immunocompromised, but neither therapies nor vaccines are available to treat or prevent infection, respectively. Using a multidisciplinary approach we report herein that the approved drug suramin acts as a non-competitive in vitro inhibitor of the hPIV-3 haemagglutinin-neuraminidase (HN). Furthermore, the drug inhibits viral replication in mammalian epithelial cells with an IC₅₀ of 30 μM, when applied post-adsorption. Significantly, we show in cell-based drug-combination studies using virus infection blockade assays, that suramin acts synergistically with the anti-influenza virus drug zanamivir. Our data suggests that lower concentrations of both drugs can be used to yield high levels of inhibition. Finally, using NMR spectroscopy and in silico docking simulations we confirmed that suramin binds HN simultaneously with zanamivir. This binding event occurs most likely in the vicinity of the protein primary binding site, resulting in an enhancement of the inhibitory potential of the N-acetylneuraminic acid-based inhibitor. This study offers a potentially exciting avenue for the treatment of parainfluenza infection by a combinatorial repurposing approach of well-established approved drugs.

Trends in Respiratory Syncytial Virus and Bronchiolitis Hospitalization Rates in High-Risk Infants in a United States Nationally Representative Database, 1997-2012

BACKGROUND

Respiratory syncytial virus (RSV) causes significant pediatric morbidity and is the most common cause of bronchiolitis. Bronchiolitis hospitalizations declined among US infants from 2000‒2009; however, rates in infants at high risk for RSV have not been described. This study examined RSV and unspecified bronchiolitis (UB) hospitalization rates from 1997‒2012 among US high-risk infants.

METHODS

The Kids' Inpatient Database (KID) infant annual RSV (ICD-9 079.6, 466.11, 480.1) and UB (ICD-9 466.19, 466.1) hospitalization rates were estimated using weighted counts. Denominators were based on birth hospitalizations with conditions associated with high-risk for RSV: chronic perinatal respiratory disease (chronic lung disease [CLD]); congenital airway anomalies (CAA); congenital heart disease (CHD); Down syndrome (DS); and other genetic, metabolic, musculoskeletal, and immunodeficiency conditions. Preterm infants could not be identified. Hospitalizations were characterized by mechanical ventilation, inpatient mortality, length of stay, and total cost (2015$). Poisson and linear regression were used to test statistical significance of trends.

RESULTS

RSV and UB hospitalization rates were substantially elevated for infants with higher-risk CHD, CLD, CAA and DS without CHD compared with all infants. RSV rates declined by 47.0% in CLD and 49.7% in higher-risk CHD infants; no other declines in high-risk groups were observed. UB rates increased in all high-risk groups except for a 22.5% decrease among higher-risk CHD. Among high-risk infants, mechanical ventilation increased through 2012 to 20.4% and 13.5% of RSV and UB hospitalizations; geometric mean cost increased to $31,742 and $25,962, respectively, and RSV mortality declined to 0.9%.

CONCLUSIONS

Among high-risk infants between 1997 and 2012, RSV hospitalization rates declined among CLD and higher-risk CHD infants, coincident with widespread RSV immunoprophylaxis use in these populations. UB hospitalization rates increased in all high-risk groups except higher-risk CHD, suggesting improvement in the health status of higher-risk CHD infants, potentially due to enhanced surgical interventions. Mechanical ventilation use and RSV and UB hospitalization costs increased while RSV mortality declined.

Genetic diversity among human parainfluenza virus type 2 isolated in Croatia between 2011 and 2014

The dynamics and evolution of the human parainfluenza virus type 2 (HPIV2) in Croatia, and also globally, are largely unknown. Most HPIV2 infections are treated symptomatically outside the hospital setting. Thus, the diagnosis is missing making it difficult to follow the genetic variation and evolution of the HPIV2. This study explores hospitalized HPIV2 cases in Croatia during 4-year period (2011-2014). Most cases in this period were reported in October or November (68.75%) and most of patients were under 2 years of age (81.25%). For molecular analyses, we used the F and HN gene sequences and showed that although both regions are equally suitable for phylogenetic analyses it would be advantageous to use regions longer than 2 kb for HPIV2 analyses of isolates which are spatially and temporally closely related. We show here that the dominant cluster in this area was cluster G3 while only one strain isolated in this period was positioned in the distant cluster G1a. Further monitoring of the HPIV2 will determine whether cluster G3 will remain dominant or it will be overruled by cluster G1a. This will be important for the surveillance of virus circulation in population and significance of the viral infection. J. Med. Virol. 88:1733-1741, 2016. © 2016 Wiley Periodicals, Inc.

Best practice in the prevention and management of paediatric respiratory syncytial virus infection

Respiratory syncytial virus (RSV) infection is ubiquitous with almost all infants having been infected by 2 years of age and lifelong repeated infections common. It is the second largest cause of mortality, after malaria, in infants outside the neonatal period and causes up to 200,000 deaths per year worldwide. RSV results in clinical syndromes that include upper respiratory tract infections, otitis media, bronchiolitis (up to 80% of cases) and lower respiratory tract disease including pneumonia and exacerbations of asthma or viral-induced wheeze. For the purposes of this review we will focus on RSV bronchiolitis in infants in whom the greatest disease burden lies. For infants requiring hospital admission, the identification of the causative respiratory virus is used to direct cohorting or isolation and infection control procedures to minimize nosocomial transmission. Nosocomial RSV infections are associated with poorer clinical outcomes, including increased mortality, the need for mechanical ventilation and longer length of hospital stay. Numerous clinical guidelines for the management of infants with bronchiolitis have been published, although none are specific for RSV bronchiolitis. Ribavirin is the only licensed drug for the specific treatment of RSV infection but due to drug toxicity and minimal clinical benefit it has not been recommended for routine clinical use. There is currently no licensed vaccine to prevent RSV infection but passive immunoprophylaxis using a monoclonal antibody, palivizumab, reduces the risk of hospitalization due to RSV infection by 39-78% in various high-risk infants predisposed to developing severe RSV disease. The current management of RSV bronchiolitis is purely supportive, with feeding support and oxygen supplementation until the infant immune system mounts a response capable of controlling the disease. The development of a successful treatment or prophylactic agent has the potential to revolutionize the care and outcome for severe RSV infections in the world's most vulnerable infants.

Risk of nosocomial respiratory syncytial virus infection and effectiveness of control measures to prevent transmission events: a systematic review

Respiratory syncytial virus (RSV) causes a significant public health burden, and outbreaks among vulnerable patients in hospital settings are of particular concern. We reviewed published and unpublished literature from hospital settings to assess: (i) nosocomial RSV transmission risk (attack rate) during outbreaks, (ii) effectiveness of infection control measures. We searched the following databases: MEDLINE, EMBASE, CINAHL, Cochrane Library, together with key websites, journals and grey literature, to end of 2012. Risk of bias was assessed using the Cochrane risk of bias tool or Newcastle–Ottawa scale. A narrative synthesis was conducted. Forty studies were included (19 addressing research question one, 21 addressing question two). RSV transmission risk varied by hospital setting; 6–56% (median: 28·5%) in neonatal/paediatric settings (n = 14), 6–12% (median: 7%) in adult haematology and transplant units (n = 3), and 30–32% in other adult settings (n = 2). For question two, most studies (n = 13) employed multi‐component interventions (e.g. cohort nursing, personal protective equipment (PPE), isolation), and these were largely reported to be effective in reducing nosocomial transmission. Four studies examined staff PPE; eye protection appeared more effective than gowns and masks. One study reported on RSV prophylaxis for patients (RSV‐Ig/palivizumab); there was no statistical evidence of effectiveness although the sample size was small. Overall, risk of bias for included studies tended to be high. We conclude that RSV transmission risk varies widely during hospital outbreaks. Although multi‐component control strategies appear broadly successful, further research is required to disaggregate the effectiveness of individual components including the potential role of palivizumab prophylaxis.

Estimates of Parainfluenza Virus-Associated Hospitalizations and Cost Among Children Aged Less Than 5 Years in the United States, 1998-2010

BACKGROUND

Parainfluenza virus (PIV) is the second leading cause of hospitalization for respiratory illness in young children in the United States. Infection can result in a full range of respiratory illness, including bronchiolitis, croup, and pneumonia. The recognized human subtypes of PIV are numbered 1-4. This study calculates estimates of PIV-associated hospitalizations among U.S. children younger than 5 years using the latest available data.

METHODS

Data from the National Respiratory and Enteric Virus Surveillance System were used to characterize seasonal PIV trends from July 2004 through June 2010. To estimate the number of PIV-associated hospitalizations that occurred annually among U.S. children aged <5 years from 1998 through 2010, respiratory hospitalizations from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample were multiplied by the proportion of acute respiratory infection hospitalizations positive for PIV among young children enrolled in the New Vaccine Surveillance Network. Estimates of hospitalization charges attributable to PIV infection were also calculated.

RESULTS

Parainfluenza virus seasonality follows type-specific seasonal patterns, with PIV-1 circulating in odd-numbered years and PIV-2 and -3 circulating annually. The average annual estimates of PIV-associated bronchiolitis, croup, and pneumonia hospitalizations among children aged <5 years in the United States were 3888 (0.2 hospitalizations per 1000), 8481 per year (0.4 per 1000 children), and 10,186 (0.5 per 1000 children), respectively. Annual charges for PIV-associated bronchiolitis, croup, and pneumonia hospitalizations were approximately $43 million, $58 million, and $158 million, respectively.

CONCLUSIONS

The majority of PIV-associated hospitalizations in young children occur among those aged 0 to 2 years. When vaccines for PIV become available, immunization would be most effective if realized within the first year of life.

γδ T cells and the immune response to respiratory syncytial virus infection

γδ T cells are a subset of nonconventional T cells that play a critical role in bridging the innate and adaptive arms of the immune system. γδ T cells are particularly abundant in ruminant species and may constitute up to 60% of the circulating lymphocyte pool in young cattle. The frequency of circulating γδ T cells is highest in neonatal calves and declines as the animal ages, suggesting these cells may be particularly important in the immune system of the very young. Bovine respiratory syncytial virus (BRSV) is a significant cause of respiratory infection in calves, and is most severe in animals under one year of age. BRSV is also a significant factor in the development of bovine respiratory disease complex (BRDC), the leading cause of morbidity and mortality in feedlot cattle. Human respiratory syncytial virus (RSV) is closely related to BRSV and a leading cause of lower respiratory tract infection in infants and children worldwide. BRSV infection in calves shares striking similarities with RSV infection in human infants. To date, there have been few studies defining the role of γδ T cells in the immune response to BRSV or RSV infection in animals or humans, respectively. However, emerging evidence suggests that γδ T cells may play a critical role in the early recognition of infection and in shaping the development of the adaptive immune response through inflammatory chemokine and cytokine production. Further, while it is clear that γδ T cells accumulate in the lungs during BRSV and RSV infection, their role in protection vs. immunopathology remains unclear. This review will summarize what is currently known about the role of γδ T cells in the immune response to BRSV and BRDC in cattle, and where appropriate, draw parallels to the role of γδ T cells in the human response to RSV infection.

Prematurity and the burden of influenza and respiratory syncytial virus disease

BACKGROUND

Respiratory morbidity of former preterm infants and especially those with bronchopulmonary dysplasia (BPD) is high during infancy and early childhood.

DATA SOURCES

We performed a review based on a literature search including EMBASE, MEDLINE, and CINAHL databases to identify all relevant papers published in the English and German literature on influenza and respiratory syncytial virus infection associated with preterm infant, prematurity, and BPD between 1980 and 2014.

RESULTS

Recurrent respiratory symptoms remain common at preschool age, school age and even into young adulthood. Acute viral respiratory tract infections due to different pathogens cause significant morbidity and necessitate rehospitalizations during the first years of life. Influenza virus infection plays a minor role compared to respiratory syncytial virus (RSV) associated respiratory tract infection during infancy and early childhood. Nevertheless, particular morbidity to both viruses is high.

CONCLUSIONS

The particular burden of both viral diseases in preterm infants is dominated by RSV and its associated rehospitalizations during the first two years of life. Prophylactic measures include vaccination against influenza virus of family members and caregivers and active immunization starting at the age of 6 months, and monthly injections of palivizumab during the cold season to avoid severe RSV disease and its sequelae.

DAS181 Treatment of Severe Parainfluenza Virus 3 Pneumonia in Allogeneic Hematopoietic Stem Cell Transplant Recipients Requiring Mechanical Ventilation

Parainfluenza virus (PIV) may cause life-threatening pneumonia in allogeneic hematopoietic stem cell transplant (HSCT) recipients. Currently, there are no proven effective therapies. We report the use of inhaled DAS181, a novel sialidase fusion protein, for treatment of PIV type 3 pneumonia in two allogeneic hematopoietic SCT recipients with respiratory failure.

Respiratory Infections

The majority of respiratory tract infections (RTIs) are community acquired and are the single most common cause of physician office visits and among the most common causes of hospitalizations. The morbidity and mortality associated with RTIs are significant and the financial and social burden high due to lost time at work and school. The scope of clinical symptoms can significantly overlap among the respiratory pathogens, and the severity of disease can vary depending on patient age, underlying disease, and immune status, thereby leading to inaccurate presumptions about disease etiology. The rapid and accurate diagnosis of the causative agent of RTIs improves patient care, reduces morbidity and mortality, promotes effective hospital bed utilization and antibiotic stewardship, and reduces length of stay. This chapter focuses on the clinical utility, advantages, and disadvantages of viral and bacterial tests cleared by the Food and Drug Administration (FDA), and new promising technologies for the detection of bacterial agents of pneumonia currently in development or in US FDA clinical trials are briefly reviewed.

Viral infections in patients with acute respiratory infection in Northwest of Iran

Introduction

Acute respiratory infection (ARI) is one of the main causes of morbidity and mortality all around the world. The aim of this study was to determine the frequency, mortality and association with clinical entities of influenza virus type A, influenza virus type B, respiratory syncytial virus (RSV), coronavirus, and adenoviruses in patients with ARI.

Materials and Methods

During September 2014 till May 2015, 143 respiratory inpatients samples for viral testing collected from central Hospital in Northwest of Iran. A real-time reverse transcription-PCR (RT-PCR) assay was done to allow in one test the detection of influenza A and B viruses. Also, RSV and adenovirus were identified by Immunochromatography test.

Results

Twenty-four (46%) cases were positive for influenza A, which 11 (46%) of them were subtype H1N1 and 13 (54%) cases were subtype H3N2. Also, 21 (40%) cases were positive for influenza B, 5 (10%) cases were positive for RSV, and 2 (4%) cases were positive for adenovirus. One of the patients was positive for both influenza A and adenovirus. Two of the patients were positive for both influenza A and RSV. None of the patients were positive for coronavirus.

Conclusions

Our findings show the importance of influenza virus type A, influenza virus type B, RSV, and adenoviruses associated with ARI in hospitalized patient and the different epidemiological patterns of the viruses in Tabriz, Iran.

High burden of RSV hospitalization in very young children: a data linkage study

Linked administrative population data were used to estimate the burden of childhood respiratory syncytial virus (RSV) hospitalization in an Australian cohort aged <5 years. RSV-coded hospitalizations data were extracted for all children aged <5 years born in New South Wales (NSW), Australia between 2001 and 2010. Incidence was calculated as the total number of new episodes of RSV hospitalization divided by the child-years at risk. Mean cost per episode of RSV hospitalization was estimated using public hospital cost weights. The cohort comprised of 870 314 children. The population-based incidence/1000 child-years of RSV hospitalization for children aged <5 years was 4·9 with a rate of 25·6 in children aged <3 months. The incidence of RSV hospitalization (per 1000 child-years) was 11·0 for Indigenous children, 81·5 for children with bronchopulmonary dysplasia (BPD), 10·2 for preterm children with gestational age (GA) 32-36 weeks, 27·0 for children with GA 28-31 weeks, 39·0 for children with GA <28 weeks and 6·7 for term children with low birthweight. RSV hospitalization was associated with an average annual cost of more than AUD 9 million in NSW. RSV was associated with a substantial burden of childhood hospitalization specifically in children aged <3 months and in Indigenous children and children born preterm or with BPD.

A recombinant varicella vaccine harboring a respiratory syncytial virus gene induces humoral immunity

The varicella-zoster virus (VZV) Oka vaccine strain (vOka) is highly efficient and causes few adverse events; therefore, it is used worldwide. We previously constructed recombinant vOka (rvOka) harboring the mumps virus gene. Immunizing guinea pigs with rvOka induced the production of neutralizing antibodies against the mumps virus and VZV. Here, we constructed recombinant vOka viruses containing either the respiratory syncytial virus (RSV) subgroup A fusion glycoprotein (RSV A-F) gene or RSV subgroup B fusion glycoprotein (RSV B-F) gene (rvOka-RSV A-F or rvOka-RSV B-F). Indirect immunofluorescence and Western blot analyses confirmed the expression of each recombinant RSV protein in virus-infected cells. Immunizing guinea pigs with rvOka-RSV A-F or rvOka-RSV B-F led to the induction of antibodies against RSV proteins. These results suggest that the current varicella vaccine genome can be used to generate custom-made vaccine vectors to develop the next generation of live vaccines.

Cotton rat immune responses to virus-like particles containing the pre-fusion form of respiratory syncytial virus fusion protein

BACKGROUND

Virus-like particles (VLPs) based on Newcastle disease virus (NDV) core proteins, M and NP, and containing two chimera proteins, F/F and H/G, composed of the respiratory syncytial virus (RSV) fusion protein (F) and glycoprotein (G) ectodomains fused to the transmembrane and cytoplasmic domains of the NDV F and HN proteins, respectively, stimulate durable, protective anti-RSV neutralizing antibodies in mice. Furthermore, immunization of mice with a VLP containing a F/F chimera protein with modifications previously reported to stabilize the pre-fusion form of the RSV F protein resulted in significantly improved neutralizing antibody titers over VLPs containing the wild type F protein. The goal of this study was to determine if VLPs containing the pre-fusion form of the RSV F protein stimulated protective immune responses in cotton rats, a more RSV permissive animal model than mice.

METHODS

Cotton rats were immunized intramuscularly with VLPs containing stabilized pre-fusion F/F chimera protein as well as the H/G chimera protein. The anti-RSV F and RSV G antibody responses were determined by ELISA. Neutralizing antibody titers in sera of immunized animals were determined in plaque reduction assays. Protection of the animals from RSV challenge was assessed. The safety of the VLP vaccine was determined by monitoring lung pathology upon RSV challenge of immunized animals.

RESULTS

The Pre-F/F VLP induced neutralizing titers that were well above minimum levels previously proposed to be required for a successful vaccine and titers significantly higher than those stimulated by RSV infection. In addition, Pre-F/F VLP immunization stimulated higher IgG titers to the soluble pre-fusion F protein than RSV infection. Cotton rats immunized with Pre-F/F VLPs were protected from RSV challenge, and, importantly, the VLP immunization did not result in enhanced respiratory disease upon RSV challenge.

CONCLUSIONS

VLPs containing the pre-fusion RSV F protein have characteristics required for a safe, effective RSV vaccine.

Respiratory syncytial virus infection down-regulates antioxidant enzyme expression by triggering deacetylation-proteasomal degradation of Nrf2

Respiratory syncytial virus (RSV) is the most important cause of viral acute respiratory tract infections and hospitalizations in children, for which no vaccine or treatment is available. RSV infection in cells, mice, and children leads to rapid generation of reactive oxygen species, which are associated with oxidative stress and lung damage, due to a significant decrease in the expression of airway antioxidant enzymes (AOEs). Oxidative stress plays an important role in the pathogenesis of RSV-induced lung disease, as antioxidants ameliorate clinical disease and inflammation in vivo. The aim of this study is to investigate the unknown mechanism(s) of virus-induced inhibition of AOE expression. RSV infection is shown to induce a progressive reduction in nuclear and total cellular levels of the transcription factor NF-E2-related factor 2 (Nrf2), resulting in decreased binding to endogenous AOE gene promoters and decreased AOE expression. RSV induces Nrf2 deacetylation and degradation via the proteasome pathway in vitro and in vivo. Histone deacetylase and proteasome inhibitors block Nrf2 degradation and increase Nrf2 binding to AOE endogenous promoters, resulting in increased AOE expression. Known inducers of Nrf2 are able to increase Nrf2 activation and subsequent AOE expression during RSV infection in vitro and in vivo, with significant amelioration of oxidative stress. This is the first study to investigate the mechanism(s) of virus-induced inhibition of AOE expression. RSV-induced inhibition of Nrf2 activation, due to deacetylation and proteasomal degradation, could be targeted for therapeutic intervention aimed to increase airway antioxidant capacity during infection.

Cross-immunity between strains explains the dynamical pattern of paramyxoviruses

Viral respiratory tract diseases pose serious public health problems. Our ability to predict and thus, be able to prepare for outbreaks is strained by the complex factors driving the prevalence and severity of these diseases. The abundance of diseases and transmission dynamics of strains are not only affected by external factors, such as weather, but also driven by interactions among viruses mediated by human behavior and immunity. To untangle the complex out-of-phase annual and biennial pattern of three common paramyxoviruses, Respiratory Syncytial Virus (RSV), Human Parainfluenza Virus (HPIV), and Human Metapneumovirus (hMPV), we adopt a theoretical approach that integrates ecological and immunological mechanisms of disease interactions. By estimating parameters from multiyear time series of laboratory-confirmed cases from the intermountain west region of the United States and using statistical inference, we show that models of immune-mediated interactions better explain the data than those based on ecological competition by convalescence. The strength of cross-protective immunity among viruses is correlated with their genetic distance in the phylogenetic tree of the paramyxovirus family.

Replication-Competent Influenza Virus and Respiratory Syncytial Virus Luciferase Reporter Strains Engineered for Co-Infections Identify Antiviral Compounds in Combination Screens

Myxoviruses such as influenza A virus (IAV) and respiratory syncytial virus (RSV) are major human pathogens, mandating the development of novel therapeutics. To establish a high-throughput screening protocol for the simultaneous identification of pathogen- and host-targeted hit candidates against either pathogen or both, we have attempted co-infection of cells with IAV and RSV. However, viral replication kinetics were incompatible, RSV signal window was low, and an IAV-driven minireplicon reporter assay used in initial screens narrowed the host cell range and restricted the assay to single-cycle infections. To overcome these limitations, we developed an RSV strain carrying firefly luciferase fused to an innovative universal small-molecule assisted shut-off domain, which boosted assay signal window, and a hyperactive fusion protein that synchronized IAV and RSV reporter expression kinetics and suppressed the identification of RSV entry inhibitors sensitive to a recently reported RSV pan-resistance mechanism. Combined with a replication-competent recombinant IAV strain harboring nanoluciferase, the assay performed well on a human respiratory cell line and supports multicycle infections. Miniaturized to 384-well format, the protocol was validated through screening of a set of the National Institutes of Health Clinical Collection (NCC) in quadruplicate. These test screens demonstrated favorable assay parameters and reproducibility. Application to a LOPAC library of bioactive compounds in a proof-of-concept campaign detected licensed antimyxovirus therapeutics, ribavirin and the neuraminidase inhibitor zanamivir, and identified two unexpected RSV-specific hit candidates, Fenretinide and the opioid receptor antagonist BNTX-7. Hits were evaluated in direct and orthogonal dose-response counterscreens using a standard recRSV reporter strain expressing Renilla luciferase.

Assessing Uncertainty in A2 Respiratory Syncytial Virus Viral Dynamics

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis and pneumonia in children younger than 1 year of age in the United States. Moreover, RSV is being recognized more often as a significant cause of respiratory illness in older adults. Although RSV has been studied both clinically and in vitro, a quantitative understanding of the infection dynamics is still lacking. In this paper, we study the effect of uncertainty in the main parameters of a viral kinetics model of RSV. We first characterize the RSV replication cycle and extract parameter values by fitting the mathematical model to in vivo data from eight human subjects. We then use Monte Carlo numerical simulations to determine how uncertainty in the parameter values will affect model predictions. We find that uncertainty in the infection rate, eclipse phase duration, and infectious lifespan most affect the predicted dynamics of RSV. This study provides the first estimate of in vivo RSV infection parameters, helping to quantify RSV dynamics. Our assessment of the effect of uncertainty will help guide future experimental design to obtain more precise parameter values.

Biomarkers of respiratory syncytial virus (RSV) infection: specific neutrophil and cytokine levels provide increased accuracy in predicting disease severity

Despite fundamental advances in the research on respiratory syncytial virus (RSV) since its initial identification almost 60 years ago, recurring failures in developing vaccines and pharmacologic strategies effective in controlling the infection have allowed RSV to become a leading cause of global infant morbidity and mortality. Indeed, the burden of this infection on families and health care organizations worldwide continues to escalate and its financial costs are growing. Furthermore, strong epidemiologic evidence indicates that early-life lower respiratory tract infections caused by RSV lead to the development of recurrent wheezing and childhood asthma. While some progress has been made in the identification of reliable biomarkers for RSV bronchiolitis, a "one size fits all" biomarker capable of accurately and consistently predicting disease severity and post-acute outcomes has yet to be discovered. Therefore, it is of great importance on a global scale to identify useful biomarkers for this infection that will allow pediatricians to cost-effectively predict the clinical course of the disease, as well as monitor the efficacy of new therapeutic strategies.

Incidence, risk factors and hospital burden in children under five years of age hospitalised with respiratory syncytial virus infections

AIM

Respiratory syncytial virus (RSV) infections are among the most common lower respiratory tract infections in infants, but few studies have determined the age-specific incidence of hospitalisation in defined populations. This study gathered Swedish data on RSV in Gothenburg and its 10 surrounding municipalities from 2004 to 2011.

METHODS

Information was obtained from hospital databases of all patients up to five years of age who had a discharge diagnosis of an RSV infection and had a positive antigen detection or polymerase chain reaction test.

RESULTS

A total of 1764 children fulfilled the inclusion criteria and 238 of these were preterm. The incidence under one year of age was 17.4/1000/year, and in children aged one to four years it was 0.6/1000/year. RSV patients occupied a mean of 1141 hospital beds per year: 65 were treated in the intensive care unit, 27 needed ventilator support, 19 needed continuous positive airway pressure, 408 (23%) received antibiotics, 399 (23%) received steroids, and all but four patients received a bronchodilator. All children survived.

CONCLUSION

The incidence of RSV infections was high, medication use was high, and complications were low. Preterm infants had a higher risk, but most infants needing hospitalisation for RSV are full term and have no known risk factors.

Serious Adverse Events in the Canadian Registry of Children Receiving Palivizumab (CARESS) for Respiratory Syncytial Virus Prevention

OBJECTIVES

To evaluate the safety and tolerability of palivizumab for RSV prophylaxis in high-risk children in everyday practice.

METHODS

High-risk children prophylaxed against RSV infection were recruited into a prospective, observational, Canadian RSV Evaluation Study of Palivizumab (CARESS) registry with active, serious adverse event (SAE) monitoring from 2008 to 2013. SAE reports were systematically collected and assessed for severity and relationship to palivizumab. Data were analyzed by Chi-square or Fisher Exact Tests to examine group differences in proportions.

RESULTS

13025 infants received 57392 injections. Hospitalizations for respiratory-related illness (RIH) were reported in 915 patients, and SAEs other than RIH were reported in 52 patients. Of these, 6 (0.05%) patients had a total of 14 hypersensitivity reactions that were deemed possibly or probably related to palivizumab (incidence: 2.8 per 10,000 patient-months). The SAEs of 42 patients were assessed as not related to palivizumab. SAEs in the remaining 4 patients were not classifiable as their records were incomplete. There were no significant demographic predictors of SAE occurrence.

CONCLUSIONS

Under active surveillance, a small proportion of infants in the CARESS registry experienced SAEs that had a potential relationship with palivizumab and these appeared to be unpredictable in terms of onset. Palivizumab appears to be a safe and well-tolerated antibody for RSV prophylaxis in high-risk children in routine practice.

Respiratory Syncytial Virus in Hematopoietic Stem Cell Transplantation and Solid-Organ Transplantation

Respiratory syncytial virus (RSV), one of the most common causes of respiratory infections in immunocompetent individuals, can cause significant pulmonary morbidity and mortality in hematopoietic stem cell (HSCT) and less often in solid-organ transplant recipients. Early diagnosis and medical intervention prior to the progression from upper to lower respiratory tract viral involvement is essential to positively affect the clinical course. The greatest risk of disease progression from upper to lower respiratory tract disease is during the early posttransplant period for HSCT recipients, with lymphopenia being an important risk factor. Polymerase chain reaction has become the preferred method for rapidly diagnosing infection in this population because of higher sensitivity compared to traditional viral culture and direct viral antigen methods. Despite the lack of prospective randomized trials, retrospective pooled analyses have suggested that systemically delivered ribavirin (either aerosolized, oral, or IV; with or without immunomodulator therapy) can decrease the risk of progression of disease. Additionally, there are a number of clinical trials currently in process to evaluate several new agents that target RSV in the high-risk HSCT patient population.

Parainfluenza virus as a cause of acute respiratory infection in hospitalized children

Background

Human parainfluenza viruses account for a significant proportion of lower respiratory tract infections in children.

Objective

To assess the prevalence of Human parainfluenza viruses as a cause of acute respiratory infection and to compare clinical data for this infection against those of the human respiratory syncytial virus.

Methods

A prospective study in children younger than five years with acute respiratory infection was conducted. Detection of respiratory viruses in nasopharyngeal aspirate samples was performed using the indirect immunofluorescence reaction. Length of hospital stay, age, clinical history and physical exam, clinical diagnoses, and evolution (admission to Intensive Care Unit or general ward, discharge or death) were assessed. Past personal (premature birth and cardiopathy) as well as family (smoking and atopy) medical factors were also assessed.

Results

A total of 585 patients were included with a median age of 7.9 months and median hospital stay of six days. No difference between the HRSV+ and HPIV+ groups was found in terms of age, gender or length of hospital stay. The HRSV+ group had more fever and cough. Need for admission to the Intensive Care Unit was similar for both groups but more deaths were recorded in the HPIV+ group. The occurrence of parainfluenza peaked during the autumn in the first two years of the study.

Conclusion

Parainfluenza was responsible for significant morbidity, proving to be the second-most prevalent viral agent in this population after respiratory syncytial virus. No difference in clinical presentation was found between the two groups, but mortality was higher in the HPIV+ group.

Non-culturable bioaerosols in indoor settings: Impact on health and molecular approaches for detection

Despite their significant impact on respiratory health, bioaerosols in indoor settings remain understudied and misunderstood. Culture techniques, predominantly used for bioaerosol characterisation in the past, allow for the recovery of only a small fraction of the real airborne microbial burden in indoor settings, given the inability of several microorganisms to grow on agar plates. However, with the development of new tools to detect non-culturable environmental microorganisms, the study of bioaerosols has advanced significantly. Most importantly, these techniques have revealed a more complex bioaerosol burden that also includes non-culturable microorganisms, such as archaea and viruses. Nevertheless, air quality specialists and consultants remain reluctant to adopt these new research-developed techniques, given that there are relatively few studies found in the literature, making it difficult to find a point of comparison. Furthermore, it is unclear as to how this new non-culturable data can be used to assess the impact of bioaerosol exposure on human health. This article reviews the literature that describes the non-culturable fraction of bioaerosols, focussing on bacteria, archaea and viruses, and examines its impact on bioaerosol-related diseases. It also outlines available molecular tools for the detection and quantification of these microorganisms and states various research needs in this field.

Human parainfluenza virus type 3 (HPIV3) induces production of IFNγ and RANTES in human nasal epithelial cells (HNECs)

Background

Human parainfluenza virus type 3 (HPIV3), while infecting lower airway epithelial cells induces pneumonia and bronchiolitis in infants and children, and may lead to asthma exacerbations in children and adults. Respiratory viruses invading the airway epithelium activate innate immune response and induce inflammatory cytokine release contributing to the pathophysiology of upper and lower airway disorders. However, the effects of HPIV3 infection on nasal epithelial cells have not been well defined.

The aim of this study was to evaluate the effect of the HPIV3 infection on cultured human nasal epithelial cells (HNECs) and the release of interferon gamma and other cytokines.

Methods

RPMI 2650, a human nasal epithelial cell line was cultured into confluence and was infected with HPIV3 (MOI of 0.1, 0.01 and 0.001). The protein release into supernatants and mRNA expression of selected cytokines were assessed 24, 48 and 72 h after infection. Cytokine concentrations in supernatants were measured by ELISA and expression of cytokine mRNA in RPMI 2650 cells confirmed by real time RT-PCR analysis.

Results

HNECs infection with HPIV3 did not induce cytotoxicity for at least 48 hours, but significantly increased IFN-γ protein concentration in the cell supernatants at 24 h and 48 h post infection (by 387% and 485% respectively as compared to mock infected cells). At 24 h a significant increase in expression of mRNA for IFNγ was observed. RANTES protein concentration and mRNA expression were significantly increased at 72 h after infection (mean protein concentration: 3.5 ± 1.4 pg/mL for 0.001 MOI, 10.8 ± 4.6 pg/mL for 0.01 MOI and 61.5 ± 18.4 pg/mL for 0.1 MOI as compared to 2.4 ± 1.3 pg/mL for uninfected cells). No measurable concentrations of TNF-α, IL-10, TSLP, IL-8, GM-CSF or eotaxin, were detected in virus infected cells supernatants.

Conclusions

HPIV3 effectively infects upper airway epithelial cells and the infection is associated with induction of IFN-γ and generation of RANTES.

Respiratory syncytial virus (RSV) and its propensity for causing bronchiolitis

Infants and young children with acute onset of wheezing and reduced respiratory airflows are often diagnosed with obstruction and inflammation of the small bronchiolar airways, ie bronchiolitis. The most common aetological agents causing bronchiolitis in young children are the respiratory viruses, and of the commonly encountered respiratory viruses, respiratory syncytial virus (RSV) has a propensity for causing bronchiolitis. Indeed, RSV bronchiolitis remains the major reason why previously healthy infants are admitted to hospital. Why RSV infection is such a predominant cause of bronchiolitis is the subject of this review. By reviewing the available histopathology of RSV bronchiolitis, both in humans and relevant animal models, we identify hallmark features of RSV infection of the distal airways and focus attention on the consequences of columnar cell cytopathology occurring in the bronchioles, which directly impacts the development of bronchiolar obstruction, inflammation and disease. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The viral transcription group determines the HLA class I cellular immune response against human respiratory syncytial virus

The cytotoxic T-lymphocyte-mediated killing of virus-infected cells requires previous recognition of short viral antigenic peptides bound to human leukocyte antigen class I molecules that are exposed on the surface of infected cells. The cytotoxic T-lymphocyte response is critical for the clearance of human respiratory syncytial virus infection. In this study, naturally processed viral human leukocyte antigen class I ligands were identified with mass spectrometry analysis of complex human leukocyte antigen-bound peptide pools isolated from large amounts of human respiratory syncytial virus-infected cells. Acute antiviral T-cell response characterization showed that viral transcription determines both the immunoprevalence and immunodominance of the human leukocyte antigen class I response to human respiratory syncytial virus. These findings have clear implications for antiviral vaccine design.