Association between respiratory syncytial virus outbreaks and lower respiratory tract deaths of infants and young children

Current perspective in metal oxide based photocatalysts for virus disinfection: A review

Nanotechnology holds huge potential for the prevention of various viral outbreaks that have increased at a disquieting rate over the past decades. Metal oxide nanomaterials with oxidative capability are the effective materials that provide platforms as well as tools for the well understanding of the mechanism, its detection, and treatment of various viral diseases like measles, influenza, herpes, ebola, current COVID-19 etc. In this inclusive review, we survey various previous research articles on different notable photoactive transition metal oxides that possess enough potential to act as antiviral agents for the deactivation of harmful viruses. We investigated and highlighted the plausible photocatalytic oxidative mechanism of photoactive transition metal oxides in degrading viral coatings, genomic RNA using suitable free radical generation. The key finding of the present review article including the discovery of a vision on the suitable photocatalytic transition metal oxides that have been proven to be excellent against harmful viruses and consequently combatting deadly CoV-2 in the environment. This review intends to provide conclusive remarks and a realistic outlook on other advanced photocatalytic metal oxides as a potential solution in battling other similar upcoming pandemics.

Synthesis of 6-Aza-2-Hydroxyimino-5-Methylpyrimidine Nucleosides for Antiviral Evaluation

The syntheses of a series of novel 6-aza-2-hydroxyimino-5-methylpyrimidine and related nucleosides are described. A suitably protected 2-methylthiopyrimidine nucleoside was selected as the precursor for installing a hydroxyimino moiety at the C-2 position. The starting nucleobase 6-aza-5-methyl-2-thiouracil is prepared in two steps from thiosemicarbazone and ethyl pyruvate. This is subjected to coupling with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose under Vorbrüggen glycosylation conditions to provide the corresponding nucleoside in high yield. Activation of the nucleoside to the corresponding 2-methylthio derivative followed by treatment with hydroxylamine hydrochloride in pyridine provides the corresponding 2-hydroxyimino derivative in high yield. Finally, the synthesis of five free modified nucleoside analogs is described. The newly synthesized nucleosides have been evaluated against an RNA viral panel and moderate activity was observed against hepatitis C virus, Zika virus, and human respiratory syncytial virus. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Preparation of 6-aza-5-methyl-2-thiouracil Basic Protocol 2: Preparation of 6-aza-5-methyl-2-thiouridine and 6-aza-5-methyluridine Basic Protocol 3: Preparation of 6-aza-2-hydroxyimino-5-methyluridine Basic Protocol 4: Preparation of 6-aza-2-hydroxyimino-5-methyl-4-thiouridine and 6-aza-2-hydroxyimino-5-methylcytosine.

Respiratory Syncytial Virus Phosphoprotein Residue S156 Plays a Role in Regulating Genome Transcription and Replication

Respiratory syncytial virus (RSV) is a single-stranded, negative-sense RNA virus in the family Pneumoviridae and genus Orthopneumovirus that can cause severe disease in infants, immunocompromised adults, and the elderly. The RSV viral RNA-dependent RNA polymerase (vRdRp) complex is composed of the phosphoprotein (P) and the large polymerase protein (L). The P protein is constitutively phosphorylated by host kinases and has 41 serine (S) and threonine (T) residues as potential phosphorylation sites. To identify important phosphorylation residues in the P protein, we systematically and individually mutated all S and T residues to alanine (A) and analyzed their effects on genome transcription and replication by using a minigenome system. We found that the mutation of eight residues resulted in minigenome activity significantly lower than that of wild-type (WT) P. We then incorporated these mutations (T210A, S203A, T151A, S156A, T160A, S23A, T188A, and T105A) into full-length genome cDNA to rescue recombinant RSV. We were able to recover four recombinant viruses (with T151A, S156A, T160A, or S23A), suggesting that RSV-P residues T210, S203, T188, and T105 are essential for viral RNA replication. Among the four recombinant viruses rescued, rRSV-T160A caused a minor growth defect relative to its parental virus while rRSV-S156A had severely restricted replication due to decreased levels of genomic RNA. During infection, P-S156A phosphorylation was decreased, and when passaged, the S156A virus acquired a known compensatory mutation in L (L795I) that enhanced both WT-P and P-S156A minigenome activity and was able to partially rescue the S156A viral growth defect. This work demonstrates that residues T210, S203, T188, and T105 are critical for RSV replication and that S156 plays a critical role in viral RNA synthesis. IMPORTANCE RSV-P is a heavily phosphorylated protein that is required for RSV replication. In this study, we identified several residues, including P-S156, as phosphorylation sites that play critical roles in efficient viral growth and genome replication. Future studies to identify the specific kinase(s) that phosphorylates these residues can lead to kinase inhibitors and antiviral drugs for this important human pathogen.

Science-Based Strategies of Antiviral Coatings with Viricidal Properties for the COVID-19 Like Pandemics

The worldwide, extraordinary outbreak of coronavirus pandemic (i.e., COVID-19) and other emerging viral expansions have drawn particular interest to the design and development of novel antiviral, and viricidal, agents, with a broad-spectrum of antiviral activity. The current indispensable challenge lies in the development of universal virus repudiation systems that are reusable, and capable of inactivating pathogens, thus reducing risk of infection and transmission. In this review, science-based methods, mechanisms, and procedures, which are implemented in obtaining resultant antiviral coated substrates, used in the destruction of the strains of the different viruses, are reviewed. The constituent antiviral members are classified into a few broad groups, such as polymeric materials, metal ions/metal oxides, and functional nanomaterials, based on the type of materials used at the virus contamination sites. The action mode against enveloped viruses was depicted to vindicate the antiviral mechanism. We also disclose hypothesized strategies for development of a universal and reusable virus deactivation system against the emerging COVID-19. In the surge of the current, alarming scenario of SARS-CoV-2 infections, there is a great necessity for developing highly-innovative antiviral agents to work against the viruses. We hypothesize that some of the antiviral coatings discussed here could exert an inhibitive effect on COVID-19, indicated by the results that the coatings succeeded in obtaining against other enveloped viruses. Consequently, the coatings need to be tested and authenticated, to fabricate a wide range of coated antiviral products such as masks, gowns, surgical drapes, textiles, high-touch surfaces, and other personal protective equipment, aimed at extrication from the COVID-19 pandemic.

2-Hydroxyimino-6-aza-pyrimidine nucleosides: synthesis, DFT calculations, and antiviral evaluations

Synthesis, DFT calculations, and antiviral evaluation of a series of novel 2-hydroxyimino-6-aza-pyrimidine ribonucleosides is reported. The hydrogen bonding between the C²N–OH moiety and N³–H and/or N³ moieties shapes the pyrimidine nucleoside as purine.

Gradual replacement of all previously circulating respiratory syncytial virus A strain with the novel ON1 genotype in Lanzhou from 2010 to 2017

ON1 is a novel genotype of human respiratory syncytial virus (HRSV) subtype A, in children with acute respiratory tract infections (ARTIs). However, there is not much data on the prevalence and clinical and molecular characterization in China.Our study is based on the children who had respiratory infections positive for RSV-A admitted by Gansu Provincial Maternity and Child-care Hospital in Lanzhou (northwestern China) during the last 7 epidemic seasons from 2010 to 2017.In our study, different strains of the novel RSV-A genotype ON1, first identified in Canada in December 2010, were first detected in Gansu Provincial Maternity and Child-care Hospital in August 2012 and then followed by an abrupt expansion in the number of ON1 variants in the beginning of 2014 and eventually replaced all other RSV-A strains from 2015 to 2017. ON1 is characterized by a 72-nt duplication in the C-terminal region of the highly variable attachment glycoprotein (G), predicted to lengthen the polypeptide with 24 amino acids, including a 23-aa duplication, which likely changes antigenicity. New N-glycosylation sites occurred within the 23-aa duplication and 24-aa insertion of the ON1 viruses in our study. Notably, RSV infections occurred later, but peaked sooner from the 2014/2015 to 2016/2017 epidemic seasons, compared with the previous 4 seasons.Our study concluded that genotype ON1 has caused larger outbreaks and became the predominate genotype for HRSV subgroup A in Lanzhou from 2013 to 2017, and became the sole genotype of RSV-A in 2015/2016 and 2016/2017. Our data indicate that northwest of China and the world will eventually be dominated by the ON1 RSV-A genotype, including the possibility for vaccine development. Based on trends seen in RSV-B BA genotype, which predominated for decades, there is a possibility to develop a vaccine for children in the next 10 years.

Advances in respiratory virus therapeutics - A meeting report from the 6th isirv Antiviral Group conference

The International Society for Influenza and other Respiratory Virus Diseases held its 6th Antiviral Group (isirv-AVG) conference in Rockville, Maryland, November 13-15, 2018. The three-day program was focused on therapeutics towards seasonal and pandemic influenza, respiratory syncytial virus, coronaviruses including MERS-CoV and SARS-CoV, human rhinovirus, and other respiratory viruses. Updates were presented on several influenza antivirals including baloxavir, CC-42344, VIS410, immunoglobulin, immune plasma, MHAA4549A, pimodivir (JNJ-63623872), umifenovir, and HA minibinders; RSV antivirals including presatovir (GS-5806), ziresovir (AK0529), lumicitabine (ALS-008176), JNJ-53718678, JNJ-64417184, and EDP-938; broad spectrum antivirals such as favipiravir, VH244, remdesivir, and EIDD-1931/EIDD-2801; and host directed strategies including nitazoxanide, eritoran, and diltiazem. Other topics included considerations of novel endpoints such as ordinal scales and patient reported outcomes (PRO), and study design issues, and other regulatory considerations for antiviral drug development. The aim of this report is to provide a summary of the presentations given at this meeting.

Development of a reverse transcription recombinase polymerase amplification assay for rapid detection of human respiratory syncytial virus

Respiratory syncytial virus (RSV) is one of the most important causative agents that causing respiratory tract infection in children and associated with high morbidity and mortality. A diagnostic method would be a robust tool for identification of RSV infection, especially in the resource-limited settings. Recombinase polymerase amplification (RPA) is a novel isothermal amplification technique which has been widely employed to detect human/animal pathogens. In present study, a probe-based reverse transcription RPA (RT-RPA) assay was established for the detection of RSV. The primers and probe were designed based on the sequences of the conserved nucleocapsid (N) gene. The minimal detection limit of the RT-RPA assay for the detection of RSV B was 19 copies of RNA molecules at 95% probability, whereas the detection limit for RSV A was 10⁴ copies molecule. The assay was RSV-specific since it had no non-specific reactions with other common human pathogens. The clinical performance of the RT-RPA assay was validated using 188 nasopharyngeal aspirates (NPAs). The nucleic acid extraction of the samples was performed by use of the magnetic bead-based kit which didn't require the heavy and expensive centrifuge. The coincidence rates between RT-RPA and qRT-PCR for the clinical samples was 96%, indicating the RT-RPA assay had good diagnostic performance on clinical samples. The real-time RT-RPA assay combined with the manual genome extraction method make it potential to detect clinical samples in field, providing a possible solution for RSV diagnosis in remote rural areas in developing countries.

Development of an allosteric inhibitor class blocking RNA elongation by the respiratory syncytial virus polymerase complex

Respiratory syncytial virus (RSV) represents a significant health threat to infants and to elderly or immunocompromised individuals. There are currently no vaccines available to prevent RSV infections, and disease management is largely limited to supportive care, making the identification and development of effective antiviral therapeutics against RSV a priority. To identify effective chemical scaffolds for managing RSV disease, we conducted a high-throughput anti-RSV screen of a 57,000-compound library. We identified a hit compound that specifically blocked activity of the RSV RNA-dependent RNA polymerase (RdRp) complex, initially with moderate low-micromolar potency. Mechanistic characterization in an in vitro RSV RdRp assay indicated that representatives of this compound class block elongation of RSV RNA products after initial extension by up to three nucleotides. Synthetic hit-to-lead exploration yielded an informative 3D quantitative structure-activity relationship (3D-QSAR) model and resulted in analogs with more than 20-fold improved potency and selectivity indices (SIs) of >1,000. However, first-generation leads exhibited limited water solubility and poor metabolic stability. A second optimization strategy informed by the 3D-QSAR model combined with in silico pharmacokinetics (PK) predictions yielded an advanced lead, AVG-233, that demonstrated nanomolar activity against both laboratory-adapted RSV strains and clinical RSV isolates. This anti-RSV activity extended to infection of established cell lines and primary human airway cells. PK profiling in mice revealed 34% oral bioavailability of AVG-233 and sustained high drug levels in the circulation after a single oral dose of 20 mg/kg. This promising first-in-class lead warrants further development as an anti-RSV drug.

Orally Efficacious Broad-Spectrum Ribonucleoside Analog Inhibitor of Influenza and Respiratory Syncytial Viruses

Morbidity and mortality resulting from influenza-like disease are a threat, especially for older adults. To improve case management, next-generation broad-spectrum antiviral therapeutics that are efficacious against major drivers of influenza-like disease, including influenza viruses and respiratory syncytial virus (RSV), are urgently needed. Using a dual-pathogen high-throughput screening protocol for influenza A virus (IAV) and RSV inhibitors, we have identified N⁴-hydroxycytidine (NHC) as a potent inhibitor of RSV, influenza B viruses, and IAVs of human, avian, and swine origins. Biochemical in vitro polymerase assays and viral RNA sequencing revealed that the ribonucleotide analog is incorporated into nascent viral RNAs in place of cytidine, increasing the frequency of viral mutagenesis. Viral passaging in cell culture in the presence of an inhibitor did not induce robust resistance. Pharmacokinetic profiling demonstrated dose-dependent oral bioavailability of 36 to 56%, sustained levels of the active 5'-triphosphate anabolite in primary human airway cells and mouse lung tissue, and good tolerability after extended dosing at 800 mg/kg of body weight/day. The compound was orally efficacious against RSV and both seasonal and highly pathogenic avian IAVs in mouse models, reducing lung virus loads and alleviating disease biomarkers. Oral dosing reduced IAV burdens in a guinea pig transmission model and suppressed virus spread to uninfected contact animals through direct transmission. Based on its broad-spectrum efficacy and pharmacokinetic properties, NHC is a promising candidate for future clinical development as a treatment option for influenza-like diseases.

Genetic characterization respiratory syncytial virus in Kerala, the southern part of India

Respiratory syncytial virus (RSV) is an important cause of acute lower respiratory tract infection (ALRI) in infants and young children globally. RSV presents two antigenic groups RSV-A and -B. Genetic variability is also very high within each group. RSV circulation varies year to year and even varies among different regions. Data on circulatory pattern of RSV are available from other parts of India except Kerala. The aim of the study was to generate data about groups and genotypes of circulating RSV in Kerala. In this study, RSV positive samples received during January, 2012 to December, 2014 were used for genetic characterization. The samples were tested by using nucleocapsid (N) gene-based conventional multiplex reverse transcriptase polymerase chain reaction (RT-PCR) to identify the RSV group. Genotyping was done by nucleotide sequencing of the C-terminal region of the glycoprotein (G) gene. Out of the 130 patient samples tested, 49 samples were positive for RSV. Among the positive samples, 32 belong to the RSV-A and 17 belong to RSV-B virus. Phylogenetic analysis revealed that all RSV-A sequences (n = 22) belonged to NA1 genotype and five of the sequences showed the novel 72 nucleotide duplication and clustered into the newly designated ON1 genotype. All RSV-B sequences (n = 17) were clustered into the BA (BA9 and 10) genotype. From this study, we concluded both RSV-A and -B were co-circulated in Kerala and RSV-A was observed predominantly in 2012 and RSV-B in 2014. As per our best of knowledge, BA10 genotype is first observed in India.

Mortality due to Respiratory Syncytial Virus. Burden and Risk Factors

RATIONALE

Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization and an important cause of death in infants in the developing world. The relative contribution of social, biologic, and clinical risk factors to RSV mortality in low-income regions is unclear.

OBJECTIVES

To determine the burden and risk factors for mortality due to RSV in a low-income population of 84,840 infants.

METHODS

This was a prospective, population-based, cross-sectional, multicenter study conducted between 2011 and 2013. Hospitalizations and deaths due to severe lower respiratory tract illness (LRTI) were recorded during the RSV season. All-cause hospital deaths and community deaths were monitored. Risk factors for respiratory failure (RF) and mortality due to RSV were assessed using a hierarchical, logistic regression model.

MEASUREMENTS AND MAIN RESULTS

A total of 2,588 (65.5%) infants with severe LRTI were infected with RSV. A total of 157 infants (148 postneonatal) experienced RF or died with RSV. RSV LRTI accounted for 57% fatal LRTI tested for the virus. A diagnosis of sepsis (odds ratio [OR], 17.03; 95% confidence interval [CI], 13.14-21.16 for RF) (OR, 119.39; 95% CI, 50.98-273.34 for death) and pneumothorax (OR, 17.15; 95% CI, 13.07-21.01 for RF) (OR, 65.49; 95% CI, 28.90-139.17 for death) were the main determinants of poor outcomes.

CONCLUSIONS

RSV was the most frequent cause of mortality in low-income postneonatal infants. RF and death due to RSV LRTI, almost exclusively associated with prematurity and cardiopulmonary diseases in industrialized countries, primarily affect term infants in a developing world environment. Poor outcomes at hospitals are frequent and associated with the cooccurrence of bacterial sepsis and clinically significant pneumothoraxes.

CD4+ T cells support establishment of RSV-specific IgG and IgA antibody secreting cells in the upper and lower murine respiratory tract following RSV infection

The RSV vaccine field suffered a major set-back when children were vaccinated with a formalin-inactivated RSV vaccine (FI-RSV). Unexpectedly, the vaccinated children fared worse than unvaccinated children when they were naturally infected with RSV. Mouse models were then developed that implicated the CD4⁺ T helper cell population as a contributor to adverse events. Today, the T cell is viewed with much caution in the RSV field, and its induction by vaccination is sometimes discouraged. Here we re-emphasize the beneficial role of the CD4⁺ T cell. Experiments were performed with RSV-infected nude mice that received CD4⁺ T cells by adoptive transfer. Data demonstrated that CD4⁺ T cells were necessary for the induction of mucosal and systemic RSV-specific antibodies, for the establishment of RSV-specific IgG and IgA antibody secreting cells in the upper and lower respiratory tract, and for RSV clearance.

Identification of Non-Nucleoside Inhibitors of the Respiratory Syncytial Virus Polymerase Complex

Respiratory syncytial virus (RSV) represents a threat to infants, the elderly, and the immunocompromised. RSV entry blockers are in clinical trials, but escape mutations challenge their potential. In search of RSV inhibitors, we have integrated a signature resistance mutation into a recombinant RSV virus and applied the strain to high-throughput screening. Counterscreening of candidates returned 14 confirmed hits with activities in the nano- to low-micromolar range. All blocked RSV polymerase activity in minigenome assays. Compound 1a (GRP-74915) was selected for development based on activity (EC₅₀ = 0.21 μM, selectivity index (SI) 40) and scaffold. Resynthesis confirmed the potency of the compound, which suppressed viral RNA synthesis in infected cells. However, metabolic testing revealed a short half-life in the presence of mouse hepatocyte fractions. Metabolite tracking and chemical elaboration combined with 3D-quantitative structure-activity relationship modeling yielded analogues (i.e., 8n: EC₅₀ = 0.06 μM, SI 500) that establish a platform for the development of a therapeutic candidate.

Molecular evolution of respiratory syncytial virus subgroup A genotype NA1 and ON1 attachment glycoprotein (G) gene in central Vietnam

We performed molecular evolutionary analyses of the G gene C-terminal 3rd hypervariable region of RSV-A genotypes NA1 and ON1 strains from the paediatric acute respiratory infection patients in central Vietnam during the 2010-2012 study period. Time-scaled phylogenetic analyses were performed using Bayesian Markov Chain Monte Carlo (MCMC) method, and pairwise distances (p-distances) were calculated. Bayesian Skyline Plot (BSP) was constructed to analyze the time-trend relative genetic diversity of central Vietnam RSV-A strains. We also estimated the N-glycosylation sites within G gene hypervariable region. Amino acid substitutions under positive and negative selection pressure were examined using Conservative Single Likelihood Ancestor Counting (SLAC), Fixed Effects Likelihood (FEL), Internal Fixed Effects Likelihood (IFEL) and Mixed Effects Model for Episodic Diversifying Selection (MEME) models. The majority of central Vietnam ON1 strains detected in 2012 were classified into lineage 1 with few positively selected substitutions. As for the Vietnamese NA1 strains, four lineages were circulating during the study period with a few positive selection sites. Shifting patterns of the predominantly circulating NA1 lineage were observed in each year during the investigation period. Median p-distance of central Vietnam NA1 strains was wider (p-distance=0.028) than that of ON1 (p-distance=0.012). The molecular evolutionary rate of central Vietnam ON1 strains was estimated to be 2.55×10^-2 (substitutions/site/year) and was faster than NA1 (7.12×10^-3 (substitutions/site/year)). Interestingly, the evolutionary rates of both genotypes ON1 and NA1 strains from central Vietnam were faster than the global strains respectively. Furthermore, the shifts of N-glycosylation pattern within the G gene 3rd hypervariable region of Vietnamese NA1 strains were observed in each year. BSP analysis indicated the rapid growth of RSV-A effective population size in early 2012. These results suggested that the molecular evolution of RSV-A G gene detected in central Vietnam was fast with unique evolutionary dynamics.

A Cross-Study Biomarker Signature of Human Bronchial Epithelial Cells Infected with Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in children, elderly, and immunocompromised individuals. Despite of advances in diagnosis and treatment, biomarkers of RSV infection are still unclear. To understand the host response and propose signatures of RSV infection, previous studies evaluated the transcriptional profile of the human bronchial epithelial cell line—BEAS-2B—infected with different strains of this virus. However, the evolution of statistical methods and functional analysis together with the large amount of expression data provide opportunities to uncover novel biomarkers of inflammation and infections. In view of those facts publicly available microarray datasets from RSV-infected BEAS-2B cells were analyzed with linear model-based statistics and the platform for functional analysis InnateDB. The results from those analyses argue for the reevaluation of previously reported transcription patterns and biological pathways in BEAS-2B cell lines infected with RSV. Importantly, this study revealed a biosignature constituted by genes such as ABCC4, ARMC8, BCLAF1, EZH1, FAM118A, FAM208B, FUS, HSPH1, KAZN, MAP3K2, N6AMT1, PRMT2, S100PBP, SERPINA1, TLK2, ZNF322, and ZNF337 which should be considered in the development of new molecular diagnosis tools.

Structure-guided design of small-molecule therapeutics against RSV disease

INTRODUCTION

In the United States, respiratory syncytial virus (RSV) is responsible for the majority of infant hospitalizations resulting from viral infections, as well as a leading source of pneumonia and bronchiolitis in young children and the elderly. In the absence of vaccine prophylaxis or an effective antiviral for improved disease management, the development of novel anti-RSV therapeutics is critical. Several advanced drug development campaigns of the past decade have focused on blocking viral infection. These efforts have returned a chemically distinct panel of small-molecule RSV entry inhibitors, but binding sites and molecular mechanism of action appeared to share a common mechanism, resulting in comprehensive cross-resistance and calling for alternative druggable targets such as viral RNA-dependent RNA-polymerase complex. Areas Covered: In this review, the authors discuss the current status of the mechanism of action of RSV entry inhibitors. They also provide the recent structural insight into the organization of the polymerase complex that have revealed novel drug targets sites, and outline a path towards the discovery of next-generation RSV therapeutics. Expert opinion: Considering the tremendous progress experienced in our structural understanding of RSV biology in recent years and encouraging early results of a nucleoside analog inhibitor in clinical trials, there is high prospect that new generations of much needed effective anti-RSV therapeutics will become available for clinical use in the foreseeable future.

Recombinant measles AIK-C vaccine strain expressing heterologous virus antigens

Further attenuated measles vaccines were developed more than 50 years ago and have been used throughout the world. Recombinant measles vaccine candidates have been developed and express several heterologous virus protective antigens. Immunogenicity and protective actions were confirmed using experimental animals: transgenic mice, cotton rats, and primates. The recent development of measles vaccine-based vectored vaccine candidates has been reviewed and some information on recombinant measles vaccines expressing respiratory syncytial virus proteins has been shown and discussed.

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.

Blocking Respiratory Syncytial Virus Entry: A Story with Twists

Respiratory syncytial virus (RSV) is responsible for majority of infant hospitalizations due to viral infections. Despite its clinical importance, no vaccine against RSV or effective antiviral therapy is available. Several structural classes of small-molecule RSV entry inhibitor have been described and one compound has advanced to clinical testing. Mutations in either one of two resistance hot spots in the F protein mediate unusual pan-resistance to all of these inhibitor classes. Based on the biochemical characterization of resistant viruses and structural insight into the RSV F trimer, we propose a kinetic escape model as the origin of pan-resistance. Since a resistant RSV remained pathogenic in the mouse model, pan-resistance mutations could emerge rapidly in circulating RSV strains. We evaluate clinical implications and discuss consequences for the design of future RSV drug discovery campaigns.

Detection of influenza vaccine effectiveness among nursery school children: Lesson from a season with cocirculating respiratory syncytial virus

In the winter influenza epidemic season, patients with respiratory illnesses including respiratory syncytial virus (RSV) infections increase among young children. Therefore, we evaluated the effectiveness of influenza vaccine against influenza-like illness (ILI) using a technique to identify outbreaks of RSV infection and to distinguish those patients from ILI patients. The study subjects were 101 children aged 12 to 84 months attending nursery school. We classified the cases into 6 levels based on the definitions of ILI for outcomes. We established observation periods according to information obtained from regional surveillance and rapid diagnostic tests among children. Multivariate odds ratios (ORs) for each case classification were obtained using a logistic regression model for each observation period. For the entire observation period, ORs for cases with fever plus respiratory symptoms were reduced marginally significantly. For the local influenza epidemic period, only the OR for the most serious cases was significantly decreased (0.20 [95%CI: 0.04-0.94]). During the influenza outbreak among the nursery school children, multivariate ORs for fever plus respiratory symptoms decreased significantly (≥ 38.0°C plus ≥ one symptoms: 0.23 [0.06-0.91), ≥ 38.0°C plus ≥ 2 symptoms: 0.21 [0.05-0.85], ≥ 39.0°C plus ≥ one symptoms: 0.18 [0.04-0.93] and ≥ 39.0°C plus ≥ 2 symptoms: 0.16 [0.03-0.87]). These results suggest that confining observation to the peak influenza epidemic period and adoption of a strict case classification system can minimize outcome misclassification when evaluating the effectiveness of influenza vaccine against ILI, even if influenza and RSV cocirculate in the same season.

Sendai virus recombinant vaccine expressing a secreted, unconstrained respiratory syncytial virus fusion protein protects against RSV in cotton rats

The respiratory syncytial virus (RSV) is responsible for as many as 199000 annual deaths worldwide. Currently, there is no standard treatment for RSV disease and no vaccine. Sendai virus (SeV) is an attractive pediatric vaccine candidate because it elicits robust and long-lasting virus-specific B cell and T cell activities in systemic and mucosal tissues. The virus serves as a gene delivery system as well as a Jennerian vaccine against its close cousin, human parainfluenza virus type 1. Here we describe the testing of a recombinant SeV (SeVRSV-Fs) that expresses an unconstrained, secreted RSV-F protein as a vaccine against RSV in cotton rats. After a single intranasal immunization of cotton rats with SeVRSV-Fs, RSV-specific binding and neutralizing antibodies were generated. These antibodies exhibited cross-reactivity with both RSV A and B isolates. RSV-F-specific IFN-γ-producing T cells were also activated. The SeVRSV-Fs vaccine conferred protection against RSV challenge without enhanced immunopathology. In total, results showed that an SeV recombinant that expresses RSV F in an unconstrained, soluble form can induce humoral and cellular immunity that protects against infection with RSV.

Cross-resistance mechanism of respiratory syncytial virus against structurally diverse entry inhibitors

Respiratory syncytial virus (RSV) is a leading pediatric pathogen that is responsible for a majority of infant hospitalizations due to viral disease. Despite its clinical importance, no vaccine prophylaxis against RSV disease or effective antiviral therapeutic is available. In this study, we established a robust high-throughput drug screening protocol by using a recombinant RSV reporter virus to expand the pool of RSV inhibitor candidates. Mechanistic characterization revealed that a potent newly identified inhibitor class blocks viral entry through specific targeting of the RSV fusion (F) protein. Resistance against this class was induced and revealed overlapping hotspots with diverse, previously identified RSV entry blockers at different stages of preclinical and clinical development. A structural and biochemical assessment of the mechanism of unique, broad RSV cross-resistance against structurally distinct entry inhibitors demonstrated that individual escape hotspots are located in immediate physical proximity in the metastable conformation of RSV F and that the resistance mutations lower the barrier for prefusion F triggering, resulting in an accelerated RSV entry kinetics. One resistant RSV recombinant remained fully pathogenic in a mouse model of RSV infection. By identifying molecular determinants governing the RSV entry machinery, this study spotlights a molecular mechanism of broad RSV resistance against entry inhibition that may affect the impact of diverse viral entry inhibitors presently considered for clinical use and outlines a proactive design for future RSV drug discovery campaigns.

Recombinant measles viruses expressing respiratory syncytial virus proteins induced virus-specific CTL responses in cotton rats

Respiratory syncytial virus (RSV) is a common cause of serious lower respiratory tract illnesses in infants. Natural infections with RSV provide limited protection against reinfection because of inefficient immunological responses that do not induce long-term memory. RSV natural infection has been shown to induce unbalanced immune response. The effective clearance of RSV is known to require the induction of a balanced Th1/Th2 immune response, which involves the induction of cytotoxic T lymphocytes (CTL). In our previous study, recombinant AIK-C measles vaccine strains MVAIK/RSV/F and MVAIK/RSV/G were developed, which expressed the RSV fusion (F) protein or glycoprotein (G). These recombinant viruses elicited antibody responses against RSV in cotton rats, and no infectious virus was recovered, but small amounts of infiltration of inflammatory cells were observed in the lungs following RSV challenge. In the present study, recombinant AIK-C measles vaccine strains MVAIK/RSV/M2-1 and MVAIK/RSV/NP were developed, expressing RSV M2-1 or Nucleoprotein (NP), respectively. These viruses exhibited temperature-sensitivity (ts), which was derived from AIK-C, and expressed respective RSV antigens. The intramuscular inoculation of cotton rats with the recombinant measles virus led to the induction of CD8(+) IFN-γ(+) cells. No infectious virus was recovered from a lung homogenate following the challenge. A Histological examination of the lungs revealed a significant reduction in inflammatory reactions without alveolar damage. These results support the recombinant measles viruses being effective vaccine candidates against RSV that induce RSV-specific CTL responses with or without the development of an antibody response.

In search of a small-molecule inhibitor for respiratory syncytial virus

Respiratory syncytial virus has been an ongoing health problem for 50 years. Hospitalization rates due to virus-induced respiratory illness continue to be substantial for infants, small children, the elderly and the immunocompromised. The only currently available treatments are a broad-spectrum antiviral and two immunoprophylactic antibodies, all of which are reserved for high-risk patients. The combination of this limited therapeutic repertoire and the lack of a vaccine clearly demonstrates the need to continue the search for more efficacious and safe agents against respiratory syncytial virus. The following is a review on the current progress of that search.

The novel [4,5-e][1,3]diazepine-4,8-dione and acyclic carbamoyl imino-ureido derivatives of imidazole: synthesis, anti-viral and anti-tumor Activity evaluations

In the present paper, we report on the synthesis, and in vitro antiviral and cytostatic activities of a series of novel imidazole[4,5-e][1,3]diazepine-4,8-dione (compounds 9–11) and acyclic carbamoyl imino-ureido imidazole (compounds 12 and 13) derivatives. These new type of chemical entities showed no significant activity on the broad spectrum of DNA and RNA viruses. Results of antiproliferative assays performed on a panel of selected human tumor cell lines revealed that only compounds 1 and 5 showed moderate and selective cytostatic effect against HeLa cells (IC₅₀ = 24 and 32 µM) with no concomitant cytotoxic effects on human normal fibroblasts (BJ). Importantly, an imidazole derivative containing a pyrrolidine moiety linked via an ethylenic spacer (3) showed a selective cytostatic effect toward cervical carcinoma (HeLa) cells (IC₅₀ = 9.5 µM) with no apparent cytotoxicity on human normal fibroblasts (BJ). This compound can be therefore considered as a potential anti-tumor lead compound for further synthetic structure optimization.

Dual myxovirus screen identifies a small-molecule agonist of the host antiviral response

As we are confronted with an increasing number of emerging and reemerging viral pathogens, the identification of novel pathogen-specific and broad-spectrum antivirals has become a major developmental objective. Targeting of host factors required for virus replication presents a tangible approach toward obtaining novel hits with a broadened indication range. However, the identification of developable host-directed antiviral candidates remains challenging. We describe a novel screening protocol that interrogates the myxovirus host-pathogen interactome for broad-spectrum drug candidates and simultaneously probes for conventional, pathogen-directed hits. With resource efficiency and pan-myxovirus activity as the central developmental parameters, we explored coscreening against two distinct, independently traceable myxoviruses in a single-well setting. Having identified a pair of unrelated pathogenic myxoviruses (influenza A virus and measles virus) with comparable replication kinetics, we observed unimpaired coreplication of both viruses, generated suitable firefly and Renilla luciferase reporter constructs, respectively, and validated the protocol for up to a 384-well plate format. Combined with an independent counterscreen using a recombinant respiratory syncytial virus luciferase reporter, implementation of the protocol identified candidates with a broadened antimyxovirus profile, in addition to pathogen-specific hits. Mechanistic characterization revealed a newly discovered broad-spectrum lead that does not block viral entry but stimulates effector pathways of the innate cellular antiviral response. In summary, we provide proof of concept for the efficient discovery of broad-spectrum myxovirus inhibitors in parallel to para- and orthomyxovirus-specific hit candidates in a single screening campaign. The newly identified compound provides a basis for the development of a novel broad-spectrum small-molecule antiviral class.

Complete genome sequence of human respiratory syncytial virus genotype A with a 72-nucleotide duplication in the attachment protein G gene

The complete genome sequence of human respiratory syncytial virus genotype A (HRSV-A) with a 72-nucleotide duplication in the C-terminal part of the attachment protein G gene was determined and analyzed. The genome was 15,277 bp in length, and 0.46 to 6.03% variations were identified at the nucleotide level compared with the previously reported complete genome of HRSV-A. Characterization of the genome will improve understanding of the diversity of the HRSV-A major antigens and enable an in-depth analysis of its genetics.

Challenges to evaluating respiratory syncytial virus mortality in Bangladesh, 2004-2008

Background

Acute lower respiratory illness is the most common cause of death among children, globally. Data are not available to make accurate estimates on the global mortality from respiratory syncytial virus (RSV), specifically.

Methods

Respiratory samples collected from children under 5 years of age during 2004 to 2008 as part of population-based respiratory disease surveillance in an urban community in Dhaka, Bangladesh were tested for RSV, human metapneumovirus (HMPV), human parainfluenza virus (PIV) types 1, 2, and 3, influenza and adenovirus by RT-PCR. Verbal autopsy data were used to identify children who died from respiratory illness in a nearby rural community. Significance of the correlation between detections and community respiratory deaths was determined using Spearman's coefficient.

Results

RSV activity occurred during defined periods lasting approximately three months but with no clear seasonal pattern. There was no significant correlation between respiratory deaths and detection of any of the respiratory viruses studied.

Conclusion

Outbreaks of respiratory viruses may not be associated with deaths in children in the study site; however, the few respiratory deaths observed and community-to-community variation in the timing of outbreaks may have obscured an association. An accurate assessment of respiratory virus-associated deaths will require detections and death data to come from the same location and a larger study population.

Diversity and adaptation of human respiratory syncytial virus genotypes circulating in two distinct communities: public hospital and day care center

HRSV is one of the most important pathogens causing acute respiratory tract diseases as bronchiolitis and pneumonia among infants. HRSV was isolated from two distinct communities, a public day care center and a public hospital in São José do Rio Preto - SP, Brazil. We obtained partial sequences from G gene that were used on phylogenetic and selection pressure analysis. HRSV accounted for 29% of respiratory infections in hospitalized children and 7.7% in day care center children. On phylogenetic analysis of 60 HRSV strains, 48 (80%) clustered within or adjacent to the GA1 genotype; GA5, NA1, NA2, BA-IV and SAB1 were also observed. SJRP GA1 strains presented variations among deduced amino acids composition and lost the potential O-glycosilation site at amino acid position 295, nevertheless this resulted in an insertion of two potential O-glycosilation sites at positions 296 and 297. Furthermore, a potential O-glycosilation site insertion, at position 293, was only observed for hospital strains. Using SLAC and MEME methods, only amino acid 274 was identified to be under positive selection. This is the first report on HRSV circulation and genotypes classification derived from a day care center community in Brazil.

VIGOR extended to annotate genomes for additional 12 different viruses

A gene prediction program, VIGOR (Viral Genome ORF Reader), was developed at J. Craig Venter Institute in 2010 and has been successfully performing gene calling in coronavirus, influenza, rhinovirus and rotavirus for projects at the Genome Sequencing Center for Infectious Diseases. VIGOR uses sequence similarity search against custom protein databases to identify protein coding regions, start and stop codons and other gene features. Ribonucleicacid editing and other features are accurately identified based on sequence similarity and signature residues. VIGOR produces four output files: a gene prediction file, a complementary DNA file, an alignment file, and a gene feature table file. The gene feature table can be used to create GenBank submission. VIGOR takes a single input: viral genomic sequences in FASTA format. VIGOR has been extended to predict genes for 12 viruses: measles virus, mumps virus, rubella virus, respiratory syncytial virus, alphavirus and Venezuelan equine encephalitis virus, norovirus, metapneumovirus, yellow fever virus, Japanese encephalitis virus, parainfluenza virus and Sendai virus. VIGOR accurately detects the complex gene features like ribonucleicacid editing, stop codon leakage and ribosomal shunting. Precisely identifying the mat_peptide cleavage for some viruses is a built-in feature of VIGOR. The gene predictions for these viruses have been evaluated by testing from 27 to 240 genomes from GenBank.

Potent host-directed small-molecule inhibitors of myxovirus RNA-dependent RNA-polymerases

Therapeutic targeting of host cell factors required for virus replication rather than of pathogen components opens new perspectives to counteract virus infections. Anticipated advantages of this approach include a heightened barrier against the development of viral resistance and a broadened pathogen target spectrum. Myxoviruses are predominantly associated with acute disease and thus are particularly attractive for this approach since treatment time can be kept limited. To identify inhibitor candidates, we have analyzed hit compounds that emerged from a large-scale high-throughput screen for their ability to block replication of members of both the orthomyxovirus and paramyxovirus families. This has returned a compound class with broad anti-viral activity including potent inhibition of different influenza virus and paramyxovirus strains. After hit-to-lead chemistry, inhibitory concentrations are in the nanomolar range in the context of immortalized cell lines and human PBMCs. The compound shows high metabolic stability when exposed to human S-9 hepatocyte subcellular fractions. Antiviral activity is host-cell species specific and most pronounced in cells of higher mammalian origin, supporting a host-cell target. While the compound induces a temporary cell cycle arrest, host mRNA and protein biosynthesis are largely unaffected and treated cells maintain full metabolic activity. Viral replication is blocked at a post-entry step and resembles the inhibition profile of a known inhibitor of viral RNA-dependent RNA-polymerase (RdRp) activity. Direct assessment of RdRp activity in the presence of the reagent reveals strong inhibition both in the context of viral infection and in reporter-based minireplicon assays. In toto, we have identified a compound class with broad viral target range that blocks host factors required for viral RdRp activity. Viral adaptation attempts did not induce resistance after prolonged exposure, in contrast to rapid adaptation to a pathogen-directed inhibitor of RdRp activity.

The next ten stories on antiviral drug discovery (part E): advents, advances, and adventures

This review article presents the fifth part (part E) in the series of stories on antiviral drug discovery. The ten stories belonging to this fifth part are dealing with (i) aurintricarboxylic acid; (ii) alkenyldiarylmethanes; (iii) human immunodeficiency virus (HIV) integrase inhibitors; (iv) lens epithelium‐derived growth factor as a potential target for HIV proviral DNA integration; (v) the status presens of neuraminidase inhibitors NAIs in the control of influenza virus infections; (vi) the status presens on respiratory syncytial virus inhibitors; (vii) tricyclic (1,N‐2‐ethenoguanine)‐based acyclovir and ganciclovir derivatives; (viii) glycopeptide antibiotics as antivirals targeted at viral entry; (ix) the potential (off‐label) use of cidofovir in the treatment of polyoma (JC and BK) virus infections; and (x) finally, thymidine phosphorylase as a target for both antiviral and anticancer agents. © 2009 Wiley Periodicals, Inc. Med Res Rev, 31, No. 1, 118–160, 2010

AIK-C measles vaccine expressing fusion protein of respiratory syncytial virus induces protective antibodies in cotton rats

Respiratory syncytial virus (RSV) is the most common cause of respiratory infection in infants, and no vaccine is available. In this report, recombinant AIK-C measles vaccines, expressing the RSV G or F protein of subgroup A (MVAIK/RSV/G or F), were investigated as a RSV vaccine candidate. MVAIK/RSV/G or F had the original ts phenotype and expressed RSV/G or F protein. Cross-reactive neutralizing antibodies against RSV subgroups A and B were detected in cotton rats immunized intramuscularly with MVAIK/RSV/F but not MVAIK/RSV/G. In cotton rats infected with RSV, RSV was recovered and lung histopathological finding was compatible with interstitial pneumonia, demonstrating thickening of alveolar walls and infiltration of mononuclear cells. When cotton rats immunized with MVAIK/RSV/F were challenged with homologous RSV subgroup A, no infectious RSV was recovered and very mild inflammation was noted without RSV antigen expression. When they were challenged with subgroup B, protective efficacy decreased. When cotton rats immunized with MVAIK/RSV/G were challenged with RSV subgroup A, low levels of infectious virus were recovered from lung. When challenged with subgroup B, no protective effects was demonstrated, demonstrating large amounts of RSV antigen in bronchial-epithelial cells. MVAIK/RSV/F is promising candidate and protective effects should be confirmed in monkey model.

Correlation between inflammatory mediators in the nasopharyngeal secretion and in the serum of children with lower respiratory tract infection caused by respiratory syncytial virus and disease severity

OBJECTIVE

To determine whether the concentrations of inflammatory mediators (CCL5, soluble intercellular adhesion molecule type 1 [sICAM-1], TNF-alpha, IL-6 and IL-10) in the nasopharyngeal secretion and in the serum of children with lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) correlate with the clinical markers of disease severity.

METHODS

Between July of 2004 and December of 2005, 30 children less than three months of age, diagnosed with LRTI caused by RSV and admitted to a neonatal ICU, were included in this study.

RESULTS

The severity of disease at hospital admission, as determined with a modified clinical scoring system, presented a significant positive correlation with sICAM-1 and IL-10 concentrations in the nasopharyngeal secretion, as well as with IL-6 concentrations in the serum, of the patients. In addition, serum IL-6 concentrations presented a significant positive correlation with the duration of oxygen therapy and with the length of hospital stay.

CONCLUSIONS

At hospital admission, the concentrations of sICAM-1 and IL-10 in the nasopharyngeal secretion, as well as the concentration of IL-6 in the serum, could be used as markers of severity in patients with LRTI caused by RSV. The serum levels of IL-6 determined at admission could also be used to predict prolonged oxygen supplementation and hospital stay.

Human respiratory syncytial virus in children with acute respiratory tract infections in China

There are limited data on the prevalence and clinical and molecular characterization of human respiratory syncytial virus (HRSV) in children with acute respiratory tract infections (ARTIs) in China. From December 2006 to March 2009, 894 nasopharyngeal aspirates (NPAs) were collected from children under 14 years of age with ARTIs. Samples were screened for HRSV and genotyped by reverse transcription-PCR (RT-PCR) and sequencing. Demographic and clinical information was recorded. A total of 38.14% (341/894) of samples were positive for HRSV. Phylogenetic analysis revealed that 60.4% of the selected 227 RSV strains were GA2, 34.4% were BA, 4.8% were GB2, and 0.4% were GB3. A total of 40.47% of all of the RSV-positive samples were coinfected with other respiratory viruses, and adenovirus was the most common additional respiratory virus. No statistical differences were found in the frequency of diagnosis and symptoms between the coinfection group and monoinfection group. Additionally, no statistical differences were found in epidemiological characterizations or disease severity between genotype BA- and GA2-positive patients, except for a greater frequency of lower respiratory tract infections (LRTIs) (mostly bronchitis)with BA. HRSV is the most important viral pathogen in Chinese children with ARTIs. Four genotypes (i.e., GA2, BA, GB2, and GB3) circulate locally, and the predominant genotype may shift between seasons. Coinfection with other viruses does not affect disease severity. HRSV genotypes were not associated with different epidemiological characterizations or disease severity.

Fatality rates in published reports of RSV hospitalizations among high-risk and otherwise healthy children

OBJECTIVE

To review the fatalities among children hospitalized with respiratory syncytial virus (RSV) infection, and identify factors leading to a fatal outcome.

RESEARCH DESIGN AND METHODS

Review of literature identified from a structured search of PubMed (1966-2009) using the following Medical Subject Headings: respiratory syncytial virus infection; hospitalized; infants; and risk factors. Publications were restricted to: English language; full papers; inclusion of > or =10 subjects; children aged < or =18 years, hospitalization for RSV infection; and deaths reported. Case fatality rates were defined as number of deaths divided by number of children hospitalized for RSV and were calculated for each study.

RESULTS

Thirty-six studies met the inclusion and exclusion criteria. Case fatality rates among children hospitalized for RSV ranged from 0 to 33%. In general, studies showed that subgroups of high-risk children (chronic lung disease [CLD] 3.5-23%, congenital heart disease [CHD] 2-37%, and prematurity 0-6.1%) had higher fatality rates than older or otherwise healthy children (consistently <1%). Presence of severe underlying comorbidities such as neuromuscular disease, immunosuppression, and malignancies was associated with death among term and/or older (>1 year) children. Higher fatality rates were reported for infants receiving intensive unit care (1.1-8.6%), extracorporeal life support (33%) or for those who acquired nosocomial RSV infection (0-12.2%). The majority of studies did not report cause of death and clinical details of the fatal cases were often not provided. Other limitations of this review include our search limits, the possibility of inherent bias in our methodology that could result in an under or over estimation of case-fatality rates, and potential publication bias.

CONCLUSIONS

Children at high risk for RSV (CLD, CHD and prematurity), those with severe underlying comorbidities, or those with nosocomial RSV appear to be at increased risk for death after RSV hospitalization. More data are needed on cause of death and how much is directly attributable to RSV.

Molecular epidemiology and genetic variability of respiratory syncytial virus (RSV) in Stockholm, 2002-2003

The epidemiology and genetic variability of circulating respiratory syncytial virus (RSV) strains in Stockholm during the season 2002-2003 were studied in consecutive RSV isolates derived from respiratory samples and diagnosed in the laboratory. Two hundred thirty-four viruses were sequenced. The samples were mainly from children under 1 year old (79%). The phylogeny of the N-terminal part of the G gene was studied after amplification and sequencing. One hundred fifty-two viruses belonged to subgroup B and 82 to subgroup A. The subgroup A viruses could be further divided into genotypes GA2 (25) and GA5 (57) and the subgroup B viruses into GB3 (137) and SAB1 (15) strains. These strains clustered with subgroup A and subgroup B strains from Kenya from the same period, as well as with strains from Great Britain from 1995 to 1998. The dominance of subgroup B strains in Stockholm during 2002-2003 is in agreement with findings from other parts of the world during the same years. Only two genotypes of subgroup A, GA2 and GA5, were circulating during this time, and GA2 has been circulating in Sweden for more than 20 years. Consecutive strains from the same individual displayed no variability in the sequenced region, which was also true of strains that had been passaged in cell cultures.

Respiratory syncytial virus (RSV) fusion protein expressed by recombinant Sendai virus elicits B-cell and T-cell responses in cotton rats and confers protection against RSV subtypes A and B

The respiratory syncytial virus (RSV) is a serious pediatric pathogen for which there is currently no clinically approved vaccine. This report describes the design and testing of a new RSV vaccine construct (rSV-RSV-F), created by the recombination of an RSV F sequence with the murine parainfluenza virus-type 1 (Sendai virus, SV) genome. SV was selected as the vaccine backbone for this study, because it has previously been shown to elicit high-magnitude, durable immune activities in animal studies and has advanced to human safety trials as a xenogenic vaccine for human parainfluenza virus-type 1 (hPIV-1). Cells infected with the recombinant SV expressed RSV F protein, but F was not incorporated into progeny SV virions. When cotton rats were inoculated with the vaccine, high-titer RSV-binding and neutralizing antibodies as well as interferon-gamma-producing T-cells were induced. Most striking was the protection against intra-nasal RSV challenge conferred by the vaccine. The rSV-RSV-F construct was also tested as a mixture with a second SV construct expressing the RSV G protein, but no clear advantage was demonstrated by combining the two vaccines. As a final analysis, the efficacy of the rSV-RSV-F vaccine was tested against an array of RSV isolates. Results showed that neutralizing and protective responses were effective against RSV isolates of both A and B subtypes. Together, experimental results encourage promotion of this recombinant SV construct as a vaccine candidate for the prevention of RSV in humans.

A population-based study relevant to seasonal variations in causes of death in children undergoing surgery for congenital cardiac malformations

AIMS

Our objectives were, first, to study seasonal distribution of perioperative deaths within 30 days after surgery, and late death, in children undergoing surgery for congenitally malformed hearts, and second, to study the causes of late death.

METHODS

We analysed a retrospective cohort of 1,753 children with congenital cardiac malformations born and undergoing surgery in the period from 1990 through 2002 with a special focus on the causes of late death. The data was obtained from the registry of congenital cardiac malformations at Rikshospitalet, Oslo, and the Norwegian Medical Birth Registry. The mean follow-up from birth was 8.1 years, with a range from zero to 15.2 years.

RESULTS

During the period of follow-up, 204 (11.6%) of the children died having undergone previous surgery. Of these 124 (7.1%) died in the perioperative period, and 80 (4.5%) were late deaths. There were 56 late deaths during the 6 coldest months, compared with 24 during the 6 warmest months (p < 0.01). There was no significant seasonal variation in perioperative deaths. Respiratory infection was the most common cause of late death, and occurred in 25 children, of whom 24 died during the 6 coldest months. Of the 8 sudden late deaths, 7 occurred during the 6 coldest months. There was no seasonal variation for the other causes of death.

CONCLUSIONS

In children undergoing surgery for congenital cardiac malformations in Norway, there is a seasonal variation in late death, with a higher proportion occurring in the coldest months. Death related to respiratory infections predominantly occurs in the winter season, and is the overall most common cause of late death.

WITHDRAWN: Immunoglobulin for preventing respiratory syncytial virus infection

BACKGROUND

Respiratory Syncytial virus, the most important cause of lower respiratory tract infections in infants and young children in industrialized countries, is associated with increased morbidity in premature infants with or without bronchopulmonary dysplasia as well as those with congenital heart disease. Because of observations that lower rates of disease occur immediately after birth, presumably due to vertical transmission of maternal antibody, and animal studies where protection from pneumonia was observed through administration of immune globulin, the efficacy of passive prophylaxis in premature infants has been studied.

OBJECTIVES

This meta-analysis was performed to assess the effects of polyclonal respiratory syncytial virus hyperimmune globulin or monoclonal antibody in preventing RSV hospitalization, receipt of intensive care, mechanical ventilation, and mortality in those with underlying prematurity, bronchopulmonary dysplasia, or congenital heart disease.

SEARCH STRATEGY

We searched the Cochrane Acute Respiratory Infections trials register and MEDLINE in March, 1999. In addition, abstracts on these topics were sought from the Pediatric Academies Meetings and the Intersciences Conference on Antimicrobial Agents and Chemotherapy for the years 1994 to 1997, inclusive.

SELECTION CRITERIA

Randomized, controlled trials of prevention of RSV using immune globulin, respiratory syncytial virus immune globulin, or monoclonal RSV antibody in children with prematurity, bronchopulmonary dysplasia or congenital heart disease.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted data and assessed study quality. Only incidences could be pooled because data for durations was summarized in a manner that did not allow combining results across the studies.

MAIN RESULTS

Four studies with a total of 2598 subjects were included in the main analysis. All were randomized controlled trials. Two trials were not blinded. Three studies examined RSV hyperimmune globulin and one examined monoclonal RSV antibody. A study of a different monoclonal RSV antibody could not be included because it has not been presented or published. The pooled Peto Odds Ratios favoring prophylaxis were 0.48 (95% CI 0.37, 0.64), 0.47 (0.29, 0.77), and 0.99 (0.48, 2.07) for incidence of hospitalization, incidence of ICU admission, and incidence of mechanical ventilation, respectively. The numbers needed to prevent one hospitalization and one ICU admission are 17 and 50 respectively.

AUTHORS' CONCLUSIONS

RSVIG is effective in preventing RSV hospitalizations and admission to the intensive care unit, but not in preventing mechanical ventilation. There was a non-significant trend towards a higher mortality in children given RSVIG.

Morbidity profiles of patients consulting during influenza and respiratory syncytial virus active periods

We compared the burden of illness due to a spectrum of respiratory diagnostic categories among persons presenting in a sentinel general practice network in England and Wales during periods of influenza and of respiratory syncytial virus (RSV) activity. During all periods of viral activity, incidence rates of influenza-like illness, bronchitis and common cold were elevated compared to those in baseline periods. Excess rates per 100,000 of acute bronchitis were greater in children aged <1 year (median difference 2702, 95% CI 929-4867) and in children aged 1-4 years (994, 95% CI 338-1747) during RSV active periods rather than influenza; estimates for the two viruses were similar in other age groups. Excess rates of influenza-like illness in all age groups were clearly associated with influenza virus activity. For common cold the estimates of median excess rates were significantly higher in RSV active periods for the age groups <1 year (3728, 95% CI 632-5867) and 5-14 years (339, 95% CI 59-768); estimates were similar in other age groups for the two viruses. The clinical burden of disease associated with RSV is as great if not greater than influenza in patients of all ages presenting to general practitioners.

Respiratory syncytial virus infection and recurrent wheeze/asthma in children under five years: an epidemiological survey

AIM

To determine the rates of respiratory syncytial virus (RSV) infection in children under 5 years of age with recurrent wheeze or asthma and compare their clinical presentation, course and outcome with asthmatic children of the same age who did not have RSV.

METHODS

Children were recruited prospectively from the emergency department of the Royal Children's Hospital, Melbourne during peak RSV season in 1998. Information was collected regarding past and current asthma presentations, a nasopharyngeal asprirate was taken for viral isolation and all children were reviewed by telephone 1 week following presentation.

RESULTS

73 children were included with a median age of 28 months. RSV was isolated from 33 (45%) of children, one child had adenovirus and in the remainder no virus was isolated. Children less than 12 months were more likely to have RSV (70%). RSV-positive children had a longer duration of illness prior to hospital presentation than RSV-negative children but were not more likely to be admitted or to have a longer duration of ongoing symptoms.

CONCLUSION

A high rate of RSV infection was demonstrated in young children with recurrent wheeze or asthma during the RSV season. This information has important implications for the control of nosocomial infection with RSV (i.e. isolation of patients) and in targeting another group to be included for RSV vaccine development.

Seasonal Trends of Human Parainfluenza Viral Infections: United States, 1990–2004

BACKGROUND

Human parainfluenza viruses (HPIVs) are important causes of upper and lower respiratory tract illness among children and adults.

METHODS

We describe seasonal trends for individual HPIV serotypes and respiratory syncytial virus in the United States using data on the percentage of specimens with positive test results reported to the National Respiratory and Enteric Viruses Surveillance System during the period 1990-2004. Onset and conclusion dates for peaks in activity were determined with the Early Aberration Reporting System's cumulative sum method C2 by detecting periods when the number of positive HPIV test results was significantly greater than that observed for preceding weeks for each serotype.

RESULTS

During the study period, increases in the percentage of positive HPIV-3 and HPIV-2 test results occurred annually during April-June and October-November, respectively. Increases in the percentage of positive HPIV-1 test results occurred biennially during September-December during odd-numbered years. During years when HPIV-1 was not circulating, more HPIV-3 activity was reported, either as a longer spring season or as a second smaller period of increased activity noted in the fall. Seasonal peaks in respiratory syncytial virus activity occurred annually during November-April.

CONCLUSIONS

We provide a national perspective for HPIV activity during the 15-year study period and demonstrate distinct seasonal peaks in activity for HPIV-1, HPIV-2, and HPIV-3. In addition, our data suggest that there is an interaction between HPIV-3 and HPIV-1 activity, which may have implications in future prevention strategies.