CARD9 Deficiency Increases Hippocampal Injury Following Acute Neurotropic Picornavirus Infection but Does Not Affect Pathogen Elimination.

Neurotropic viruses target the brain and contribute to neurologic diseases. Caspase recruitment domain containing family member 9 (CARD9) controls protective immunity in a variety of infectious disorders. To investigate the effect of CARD9 in neurotropic virus infection, CARD9-/- and corresponding C57BL/6 wild-type control mice were infected with Theiler's murine encephalomyelitis virus (TMEV). Brain tissue was analyzed by histology, immunohistochemistry and molecular analyses, and spleens by flow cytometry. To determine the impact of CARD9 deficiency on T cell responses in vitro, antigen presentation assays were utilized. Genetic ablation of CARD9 enhanced early pro-inflammatory cytokine responses and accelerated infiltration of T and B cells in the brain, together with a transient increase in TMEV-infected cells in the hippocampus. CARD9-/- mice showed an increased loss of neuronal nuclear protein+ mature neurons and doublecortin+ neuronal precursor cells and an increase in ß-amyloid precursor protein+ damaged axons in the hippocampus. No effect of CARD9 deficiency was found on the initiation of CD8+ T cell responses by flow cytometry and co-culture experiments using virus-exposed dendritic cells or microglia-enriched glial cell mixtures, respectively. The present study indicates that CARD9 is dispensable for the initiation of early antiviral responses and TMEV elimination but may contribute to the modulation of neuroinflammation, thereby reducing hippocampal injury following neurotropic virus infection.

Respiratory pathogens and acute chest syndrome in children with sickle cell disease.

BACKGROUND: Acute chest syndromes (ACS) may be associated with upper respiratory tract infections, but the epidemiology of viral and intracellular respiratory pathogens in children with sickle cell disease (SCD) is not precisely known. The aim of this study was to describe the epidemiology of viral and intracellular respiratory pathogens in children with SCD presenting with fever and/or ACS. MATERIALS AND METHODS: An observational, prospective, single-centre cohort study with nested case-control analysis was conducted on children with SCD admitted from October 2016 to October 2017 for fever and/or ACS to the paediatric department of Robert Debré university hospital, Paris, France. They were screened for 20 respiratory pathogens by a multiplex PCR in the nasopharynx (FilmArray). RESULTS: We included 101 children. M/F sex ratio of 0.45. The median age was 3.2 years (IQR: 1.4-8.2). At least one pathogen was isolated in 67 patients (67%). The most frequent viruses were as follows: rhinovirus (n=33), adenovirus (n=14), respiratory syncytial virus (n=13) and parainfluenza viruses (n=11). Mycoplasma pneumoniae was detected in one case. Twenty-three (23%) presented with or developed ACS. A nested case-control analysis was performed, after pairing ACS with non-ACS children for age and inclusion period. There was no statistical association between any viral detection or multiple viral infection, and ACS (p=0.51) even though parainfluenza viruses were twice as common in ACS. CONCLUSIONS: Viral detection in febrile children with SCD is frequent, but its association with ACS was not demonstrated. In this study, M. pneumoniae was rare in young children with SCD experiencing ACS.

Human Rhinovirus Infections in Hematopoietic Cell Transplant Recipients: Risk Score for Progression to Lower Respiratory Tract Infection.

Human rhinovirus lower respiratory tract infection (LRTI) is associated with mortality after hematopoietic cell transplantation (HCT); however, risk factors for LRTI are not well characterized. We sought to develop a risk score for progression to LRTI from upper respiratory tract infection (URTI) in HCT recipients. Risk factors for LRTI within 90 days were analyzed using Cox regression among HCT recipients with rhinovirus URTI between January 2009 and March 2016. The final multivariable model included factors with a meaningful effect on the bootstrapped optimism corrected concordance statistic. Weighted score contributions based on hazard ratios were determined. Cumulative incidence curves estimated the probability of LRTI at various score cut-offs. Of 588 rhinovirus URTI events, 100 (17%) progressed to LRTI. In a final multivariable model allogeneic grafts, prior rhinovirus URTI, low lymphocyte count, low albumin, positive cytomegalovirus serostatus, recipient statin use, and steroid use ≥2 mg/kg/day were associated with progression to LRTI. A weighted risk score cut-off with the highest sensitivity and specificity was determined. Risk scores above this cut-off were associated with progression to LRTI (cumulative incidence 28% versus 11% below cut-off; P < .001). The weighted risk score for progression to rhinovirus LRTI can help identify and stratify patients for clinical management and for future clinical trials of therapeutics in HCT recipients.

Initial High Viral Load Is Associated with Prolonged Shedding of Human Rhinovirus in Allogeneic Hematopoietic Cell Transplant Recipients.

Recent data suggest human rhinovirus (HRV) is associated with lower respiratory tract infection and mortality in hematopoietic cell transplant (HCT) recipients. Examining risk factors for prolonged viral shedding may provide critical insight for the development of novel therapeutics and help inform infection prevention practices. Our objective was to identify risk factors for prolonged shedding of HRV post-HCT. We prospectively collected weekly nasal samples from allogeneic HCT recipients from day 0 to day 100 post-transplant, and performed real-time reverse transcriptase PCR (December 2005 to February 2010). Subjects with symptomatic HRV infection and a negative test within 2 weeks of the last positive were included. Duration of shedding was defined as time between the first positive and first negative samples. Cycle threshold (Ct) values were used as a proxy for viral load. HRV species were identified by sequencing the 5' noncoding region. Logistic regression analyses were performed to evaluate factors associated with prolonged shedding (≥21 days). We identified 38 HCT recipients with HRV infection fulfilling study criteria (32 adults, 6 children). Median duration of shedding was 9.5 days (range, 2 to 89 days); 18 patients had prolonged shedding. Among 26 samples sequenced, 69% were species A, and species B and C accounted for 15% each; the median shedding duration of HRV did not differ among species (P = .17). Bivariable logistic regression analyses suggest that initial high viral load (low Ct value) is associated with prolonged shedding. HCT recipients with initial high viral loads are at risk for prolonged HRV viral shedding.

Human rhinovirus detection in the lower respiratory tract of hematopoietic cell transplant recipients: association with mortality.

Human rhinoviruses are the most common respiratory viruses detected in patients after hematopoietic cell transplantation. Although rhinovirus appears to occasionally cause severe lower respiratory tract infection in immunocompromised patients, the clinical significance of rhinovirus detection in the lower respiratory tract remains unknown. We evaluated 697 recipients transplanted between 1993 and 2015 with rhinovirus in respiratory samples. As comparative cohorts, 273 recipients with lower respiratory tract infection caused by respiratory syncytial virus (N=117), parainfluenza virus (N=120), or influenza (N=36) were analyzed. Factors associated with mortality were analyzed using Cox proportional hazard models. Among 569 subjects with rhinovirus upper respiratory tract infection and 128 subjects with rhinovirus lower respiratory tract infection, probabilities of overall mortality at 90 days were 6% and 41%, respectively (P<0.001). The survival rate after lower respiratory tract infection was not affected by the presence of co-pathogens (55% in patients with co-pathogens, 64% in patients without, P=0.34). Low monocyte count (P=0.027), oxygen use (P=0.015), and steroid dose greater than 1 mg/kg/day (P=0.003) before diagnosis were significantly associated with mortality among patients with lower respiratory tract infection in multivariable analysis. Mortality after rhinovirus lower respiratory tract infection was similar to that after lower respiratory tract infection by respiratory syncytial virus, parainfluenza virus or influenza in an adjusted model. In summary, transplant recipients with rhinovirus detection in the lower respiratory tract had high mortality rates comparable to viral pneumonia associated with other well-established respiratory viruses. Our data suggest rhinovirus can contribute to severe pulmonary disease in immunocompromised hosts.

Human Parechovirus 1 Infection Occurs via αVß1 Integrin.

Human parechovirus 1 (HPeV-1) (family Picornaviridae) is a global cause of pediatric respiratory and CNS infections for which there is no treatment. Although biochemical and in vitro studies have suggested that HPeV-1 binds to αVß1, αVß3 and αVß6 integrin receptor(s), the actual cellular receptors required for infectious entry of HPeV-1 remain unknown. In this paper we analyzed the expression profiles of αVß1, αVß3, αVß6 and α5ß1 in susceptible cell lines (A549, HeLa and SW480) to identify which integrin receptors support HPeV-1 internalization and/or replication cycle. We demonstrate by antibody blocking assay, immunofluorescence microscopy and RT-qPCR that HPeV-1 internalizes and replicates in cell lines that express αVß1 integrin but not αVß3 or αVß6 integrins. To further study the role of ß1 integrin, we used a mouse cell line, GE11-KO, which is deficient in ß1 expression, and its derivate GE11-ß1 in which human integrin ß1 subunit is overexpressed. HPeV-1 (Harris strain) and three clinical HPeV-1 isolates did not internalize into GE11-KO whereas GE11-ß1 supported the internalization process. An integrin ß1-activating antibody, TS2/16, enhanced HPeV-1 infectivity, but infection occurred in the absence of visible receptor clustering. HPeV-1 also co-localized with ß1 integrin on the cell surface, and HPeV-1 and ß1 integrin co-endocytosed into the cells. In conclusion, our results demonstrate that in some cell lines the cellular entry of HPeV-1 is primarily mediated by the active form of αVß1 integrin without visible receptor clustering.

Frequency and Duration of Rhinovirus Infections in Children With Cystic Fibrosis and Healthy Controls: A Longitudinal Cohort Study.

BACKGROUND: Respiratory viral infections are an important cause of morbidity in patients with chronic respiratory diseases, such as cystic fibrosis (CF). We hypothesized that patients with CF are more susceptible to human rhinovirus (HRV) infections than healthy controls. METHODS: In a 6-month winter period, 20 young children with CF (0-7 years) and 18 age-matched healthy controls were sampled biweekly for HRV-polymerase chain reaction using nasopharyngeal swabs, irrespective of respiratory symptoms. Respiratory symptoms were scored twice a week. If any symptom was present, an additional sample was obtained. All HRV-positive samples were genotyped to distinguish HRV subtypes. RESULTS: We analyzed 645 samples, with comparable total numbers of samples in both groups. HRV was detected in 40.8% of all analyzed samples. Children with CF had significantly more HRV-positive samples compared with healthy controls, with a mean number (± standard deviation) of 8.1 ± 2.3 versus 5.7 ± 2.9 positive samples per individual (P < 0.01). Prolonged detection (>2 weeks) with the same HRV subtype occurred more frequently in the CF patients (P < 0.01). The genetic distribution and pattern of phylogenetic diversity of the different HRV subtypes were similar in both groups. CONCLUSIONS: This is the first in vivo longitudinal study showing that HRV is detected more frequently and persists for longer periods in CF patients compared with healthy controls. This might indicate increased viral replication and/or decreased antiviral defense in patients with CF.

Rhinovirus infection in children hospitalized with acute bronchiolitis and its impact on subsequent wheezing or asthma: a comparison of etiologies.

BACKGROUD: Children who suffer a viral lower respiratory infection early in life are prone to subsequent wheezing and asthma: RSV and rhinovirus are thought to be the primary causative pathogens. Epidemiologic and long-term data on these pathogens in Thailand are limited. OBJECTIVES: To detect the causative pathogens in children hospitalized with a first episode of acute wheezing and to compare the respective impact on the recurrence of wheezing and development of asthma. METHOD: We conducted a 5-year cohort study of children under 2 hospitalized with acute bronchiolitis at two tertiary hospitals. Nasopharyngeal secretions were collected at admission to determine the causative pathogens by RT-PCR. RESULTS: 145/170 samples (85%) were positive for pathogens. RSV, rhinovirus, influenza, bacteria and hMPV was found in 64.7%, 18.2%, 17.6%, 12.9% and 3.5% of children respectively. The majority (94/152; 62%) of participants reported having recurrent wheezing within the first year of follow-up (mean duration 5.5 ± 7.2 months). Only 16% still had wheezing episodes after 5 years. Asthma was diagnosed in 41 children (45%), most of whom were treated with inhaled corticosteroid. There were no statistically significant differences among the various etiologies. CONCLUSION: Rhinovirus ranked second after RSV as the cause of hospitalizations of children with acute bronchiolitis. More than half of these children had recurrent wheezing which mostly disappeared before the age of 6. Nearly half were subsequently diagnosed with asthma at the 5th year of follow-up. The specific pathogens did not account for a statistically significant difference in subsequent wheezing or asthma development.