Project description:Rationale: Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections and hospitalizations in infants worldwide. Known risk factors, however, incompletely explain the variability of RSV disease severity among children. We postulate that severity of RSV infection is influenced in part by modulation of the host immune response by the local microbial ecosystem at the time of infection. Objectives: To define whether different nasopharyngeal microbiota profiles are associated with distinct host transcriptome profiles and severity in children with RSV infection. Methods: We analyzed the nasopharyngeal microbiota profiles of young children with mild and severe RSV disease and healthy matched controls by 16S-rRNA sequencing. In parallel, we analyzed whole blood gene expression profiles to study the relationship between microbial community composition, the RSV-induced host transcriptional response and clinical disease severity. Measurements and Main results: We identified five nasopharyngeal microbiota profiles characterized by enrichment of H. influenzae, Streptococcus, Corynebacterium, Moraxella or S. aureus. RSV infection and RSV hospitalization were positively associated with H. influenzae and Streptococcus, and negatively associated with S. aureus abundance, independent of age. The host response to RSV was defined by overexpression of interferon-related genes, and this was independent of the microbiota composition. On the other hand, transcriptome profiles of RSV infected children with H. influenzae and Streptococcus-dominated microbiota were characterized by greater overexpression of genes linked to toll-like receptor-signaling and neutrophil activation and were more frequently hospitalized Conclusions: Our data suggest an immunomodulatory role for the resident nasopharyngeal microbial community early in RSV infection, potentially affecting RSV disease severity.
Project description:Analysis of transcriptional profiles in whole blood and nasopharyngeal swaps from children hospitalized with lower respiratory tract infections at their admission and their discharge, and diagnosed with either RSV or rhinovirus infections. The hypothesis is that this information will contribute to better understand the viral specific immunity and host responses to RSV infection and may suggest leads for the develoment of vaccines and specific treatment.
Project description:Analysis of transcriptional profiles in whole blood and nasopharyngeal swaps from children hospitalized with lower respiratory tract infections at their admission and their discharge, and diagnosed with either RSV or rhinovirus infections. The hypothesis is that this information will contribute to better understand the viral specific immunity and host responses to RSV infection and may suggest leads for the develoment of vaccines and specific treatment.
Project description:The objective of this study was to identify gene expression markers of disease severity in a cohort of RSV infected children Respiratory syncytial virus (RSV) is the number one pathogen causing lower respiratory tract infection that leads to hospitalization in young children. Despite growing insights in the disease pathogenesis, the clinical presentation in these children is highly variable and heterogeneous, and reliable markers predictive of disease progression are lacking. We characterized the host response to acute RSV infection to identify biomarkers associated with RSV disease and disease severity. Whole genome transcriptome was analysed early on the disease course in blood samples from otherwise healthy children <2 years of age, who were either hospitalized (n = 110) or evaluated as outpatients (n = 37) due to RSV infection. Age-matched non-RSV-infected healthy children (n = 51) were analysed in parallel. A clustering approach on the transcriptome data revealed biologically meaningful biomarkers associated with progression to severe RSV disease. Overall, the whole blood transcriptome pointed to alterations in frequency of specific immune cell types (neutrophils, T- and B-lymphocytes, NK cells, monocytes) in RSV-infected children. In addition, a cluster enriched for neutrophil degranulation genes, was highly correlated with clinical disease severity. The driver genes of this cluster (OLFM4, ELANE, MMP8, BPI, CEACAM8, LCN2, LTF and MPO) were selected and validated in independent existing transcriptomics datasets. We identified a set of genes involved in neutrophil degranulation as markers for RSV disease severity. Additional prospective studies using these markers are required to further confirm their value as predictive tool in routine clinical care.
Project description:To study the transcriptional profile of patients with acute RSV or Influenza infection,children of median age 2.4 months (range 1.5-8.6) hospitalized with acute RSV and influenza virus infection were offered study enrollment after microbiologic confirmation of the diagnosis. Blood samples were collected from them within 42-72 hours of hospitalization. We excluded children with suspected or proven polymicrobial infections, with underlying chronic medical conditions (i.e congenital heart disease, renal insufficiency), with immunodeficiency, or those who received systemic steroids or other immunomodulatory therapies. The RSV cohort consisted of 51 patients with median age of 2 months (range 1.5-3.9) and the influenza cohort had 28 patients with median age of 5.5 months (range 1.4-21). Control samples were obtained from healthy children undergoing elective surgical procedures or at outpatient clinic visits. To exclude viral co-infections we performed nasopharyngeal viral cultures of all subjects. We recruited 10 control patients for the RSV cohort with median age of 6.7 months (range 5-10), and 12 control patients for the influenza cohort with median age of18.5 months (range 10.5-26). We used microarrays to obtain the transcriptional profile of PBMCs from patients with acute RSV or Influenza infection and compared these signatures with the transcriptional profile of primary airway epithelial cells infected with RSV or Influenza.
Project description:In order to understand the immunopathogenesis of severe influenza H1N1/09, we compared the whole blood RNA transcriptome of children hospitalised with H1N1/09 infection with that of children hospitalised with RSV or bacterial infection Blood was collected into PAX gene tubes (PreAnalytiX). Total RNA integrity was assessed using an Agilent 2100 Bioanalyzer (Agilent, Palo Alto, CA). Labeled cRNA was hybridized to Illumina Human HT-12 v3 Beadchips. Observational, prospective study. Patients were recruited at or after presentation to hospital. Main inclusion criteria were presence of illness of sufficient severity to warrant blood tests for clinical reasons, in child aged <17 years. Patient numbers recruited were as follows: H1N1/09 infection (n=25) RSV (n=34) (n=21), and healthy paediatric controls (n=33). After exclusion of children with co-infections, numbers of arrays analysed in were as follows: H1N1/09 n=19; RSV n=22; bacterial infection n=18; controls n=33
Project description:Respiratory viral infections follow an unpredictable clinical course in young children ranging from a common cold to respiratory failure. The transition from mild to severe disease occurs rapidly and is difficult to predict. The pathophysiology underlying disease severity has remained elusive. There is an urgent need to better understand the immune response in this disease to come up with biomarkers that may aid clinical decision making. In a prospective study, flow cytometric and genome-wide gene expression analyses were performed on blood samples of 26 children with a diagnosis of severe, moderate or mild Respiratory Syncytial Virus (RSV) infection. Differentially expressed genes were validated using Q-PCR in a second cohort of 80 children during three consecutive winter seasons. FACS analyses were also performed in the second cohort and on recovery samples of severe cases in the first cohort. Severe RSV infection was associated with a transient but marked decrease in CD4+ T, CD8+ T, and NK cells in peripheral blood. Gene expression analyses in both cohorts identified Olfactomedin4 (OLFM4) as a fully discriminative marker between children with mild and severe RSV infection, giving a PAM cross-validation error of 0%. Patients with an OLFM4 gene expression level above -7.5 were 6 times more likely to develop severe disease, after correction for age at hospitalization and gestational age. In conclusion, by combining genome-wide expression profiling of blood cell subsets with clinically well-annotated samples, OLFM4 was identified as a biomarker for severity of pediatric RSV infection. Samples were taken of 26 patients with acute RSV infections, divided into mild (n=9), moderate (n=9) and severe (n=8) disease. From moderate and severe diseased patients recovery samples were obtained as well.
Project description:Background: There is limited data on how different RSV genotypes and associated viral loads influence disease phenotypes. We characterized the genetic variability of RSV strains during five non-consecutive respiratory seasons, and evaluated the role of RSV subtypes, genotypes and viral loads on clinical disease severity. Methods: Healthy infants hospitalized with RSV bronchiolitis were prospectively enrolled and nasopharyngeal samples obtained within 24h of hospitalization for RSV load quantitation by PCR, typing and genotyping. Parameters of disease severity were assessed, and multivariate models constructed to identify virologic and clinical factors predictive of clinical outcomes. Results: From March 2004 to April 2011, we enrolled 253 patients (56.5 % males; median age 2.1 (1.1-4.0) months). RSV A infections predominated over RSV B (69% vs. 31%; p<0.001) and showed greater genotype variability. The most common genotypes were RSV A/GA2, A/GA5 and RSV B/BA. Infants infected with RSV GA5 had higher viral loads compared with GA2 or BA infection (p<0.01), independent of duration of symptoms. After adjusting for other covariates, RSV A/GA5 infections were associated with longer hospital stay. Conclusions: RSV A infections were more frequent than RSV B infections and displayed greater genetic variability. Infections with GA5 were independently associated with clinical disease severity.
Project description:To study the transcriptional profile of patients with acute RSV or Influenza infection,children of median age 2.4 months (range 1.5-8.6) hospitalized with acute RSV and influenza virus infection were offered study enrollment after microbiologic confirmation of the diagnosis. Blood samples were collected from them within 42-72 hours of hospitalization. We excluded children with suspected or proven polymicrobial infections, with underlying chronic medical conditions (i.e congenital heart disease, renal insufficiency), with immunodeficiency, or those who received systemic steroids or other immunomodulatory therapies. The RSV cohort consisted of 51 patients with median age of 2 months (range 1.5-3.9) and the influenza cohort had 28 patients with median age of 5.5 months (range 1.4-21). Control samples were obtained from healthy children undergoing elective surgical procedures or at outpatient clinic visits. To exclude viral co-infections we performed nasopharyngeal viral cultures of all subjects. We recruited 10 control patients for the RSV cohort with median age of 6.7 months (range 5-10), and 12 control patients for the influenza cohort with median age of18.5 months (range 10.5-26).
Project description:Respiratory viral infections follow an unpredictable clinical course in young children ranging from a common cold to respiratory failure. The transition from mild to severe disease occurs rapidly and is difficult to predict. The pathophysiology underlying disease severity has remained elusive. There is an urgent need to better understand the immune response in this disease to come up with biomarkers that may aid clinical decision making. In a prospective study, flow cytometric and genome-wide gene expression analyses were performed on blood samples of 26 children with a diagnosis of severe, moderate or mild Respiratory Syncytial Virus (RSV) infection. Differentially expressed genes were validated using Q-PCR in a second cohort of 80 children during three consecutive winter seasons. FACS analyses were also performed in the second cohort and on recovery samples of severe cases in the first cohort. Severe RSV infection was associated with a transient but marked decrease in CD4+ T, CD8+ T, and NK cells in peripheral blood. Gene expression analyses in both cohorts identified Olfactomedin4 (OLFM4) as a fully discriminative marker between children with mild and severe RSV infection, giving a PAM cross-validation error of 0%. Patients with an OLFM4 gene expression level above -7.5 were 6 times more likely to develop severe disease, after correction for age at hospitalization and gestational age. In conclusion, by combining genome-wide expression profiling of blood cell subsets with clinically well-annotated samples, OLFM4 was identified as a biomarker for severity of pediatric RSV infection.