Rhinovirus infection associated with serious lower respiratory illness in patients with bronchopulmonary dysplasia

Early-life hyperoxia-induced Flt3L drives neonatal lung dendritic cell expansion and proinflammatory responses

Premature infants with chronic lung disease, bronchopulmonary dysplasia (BPD), develop recurrent cough and wheezing following respiratory viral infections. The mechanisms driving the chronic respiratory symptoms are ill-defined. We have shown that hyperoxic exposure of neonatal mice (a model of BPD) increases the activated lung CD103+ dendritic cells (DCs) and these DCs are required for exaggerated proinflammatory responses to rhinovirus (RV) infection. Since CD103+ DC are essential for specific antiviral responses and their development depends on the growth factor Flt3L, we hypothesized that early-life hyperoxia stimulates Flt3L expression leading to expansion and activation of lung CD103+ DCs and this mediates inflammation. We found that hyperoxia numerically increased and induced proinflammatory transcriptional signatures in neonatal lung CD103+ DCs, as well as CD11bhi DCs. Hyperoxia also increased Flt3L expression. Anti-Flt3L antibody blocked CD103+ DC development in normoxic and hyperoxic conditions, and while it did not affect the baseline number of CD11bhi DCs, it neutralized the effect of hyperoxia on these cells. Anti-Flt3L also inhibited hyperoxia-induced proinflammatory responses to RV. In tracheal aspirates from preterm infants mechanically-ventilated for respiratory distress in the first week of life levels of FLT3L, IL-12p40, IL-12p70 and IFN-γ were higher in infants who went on to develop BPD and FLT3L levels positively correlated with proinflammatory cytokines levels. This work highlights the priming effect of early-life hyperoxia on lung DC development and function and the contribution of Flt3L in driving these effects.

Gelsolin Attenuates Neonatal Hyperoxia-Induced Inflammatory Responses to Rhinovirus Infection and Preserves Alveolarization

Prematurity and bronchopulmonary dysplasia (BPD) increase the risk of asthma later in life. Supplemental oxygen therapy is a risk factor for chronic respiratory symptoms in infants with BPD. Hyperoxia induces cell injury and release of damage-associated molecular patterns (DAMPs). Cytoskeletal filamentous actin (F-actin) is a DAMP which binds Clec9a, a C-type lectin selectively expressed on CD103+ dendritic cells (DCs). Co-stimulation of Clec9a and TLR3 induces maximal proinflammatory responses. We have shown that neonatal hyperoxia (a model of BPD) increases lung IL-12+Clec9a+CD103+ DCs, pro-inflammatory responses and airway hyperreactivity following rhinovirus (RV) infection. CD103+ DCs and Clec9a are required for these responses. Hyperoxia increases F-actin levels in bronchoalveolar lavage fluid (BALF). We hypothesized that the F-actin severing protein gelsolin attenuates neonatal hyperoxia-induced Clec9a+CD103+ DC-dependent pro-inflammatory responses to RV and preserves alveolarization. We exposed neonatal mice to hyperoxia and treated them with gelsolin intranasally. Subsequently we inoculated the mice with RV intranasally. Alternatively, we inoculated normoxic neonatal mice with BALF from hyperoxia-exposed mice (hyperoxic BALF), RV and gelsolin. We analyzed lung gene expression two days after RV infection. For in vitro studies, lung CD11c+ cells were isolated from C57BL/6J or Clec9a^gfp-/- mice and incubated with hyperoxic BALF and RV. Cells were analyzed by flow cytometry. In neonatal mice, gelsolin blocked hyperoxia-induced Il12p40, TNF-α and IFN-γ mRNA and protein expression in response to RV infection. Similar effects were observed when gelsolin was co-administered with hyperoxic BALF and RV. Gelsolin decreased F-actin levels in hyperoxic BALF in vitro and inhibited hyperoxia-induced D103lo DC expansion and inflammation in vivo. Gelsolin also attenuated hyperoxia-induced hypoalveolarization. Further, incubation of lung CD11c+ cells from WT and Clec9a^gfp-/- mice with hyperoxic BALF and RV, showed Clec9a is required for maximal hyperoxic BALF and RV induced IL-12 expression in CD103+ DCs. Finally, in tracheal aspirates from mechanically ventilated human preterm infants the F-actin to gelsolin ratio positively correlates with FiO2, and gelsolin levels decrease during the first two weeks of mechanical ventilation. Collectively, our findings demonstrate a promising role for gelsolin, administered by inhalation into the airway to treat RV-induced exacerbations of BPD and prevent chronic lung disease.

The critical role of collagen VI in lung development and chronic lung disease

Type VI collagen (collagen VI) is an obligate extracellular matrix component found mainly in the basement membrane region of many mammalian tissues and organs, including skeletal muscle and throughout the respiratory system. Collagen VI is probably most recognized in medicine as the genetic cause of a spectrum of muscular dystrophies, including Ullrich Congenital Myopathy and Bethlem Myopathy. Collagen VI is thought to contribute to myopathy, at least in part, by mediating muscle fiber integrity by anchoring myoblasts to the muscle basement membrane. Interestingly, collagen VI myopathies present with restrictive respiratory insufficiency, thought to be due primarily to thoracic muscular weakening. Although it was recently recognized as one of the (if not the) most abundant collagens in the mammalian lung, there is a substantive knowledge gap concerning its role in respiratory system development and function. A few studies have suggested that collagen VI insufficiency is associated with airway epithelial cell survival and altered lung function. Our recent work suggested collagen VI may be a genomic risk factor for chronic lung disease in premature infants. Using this as motivation, we thoroughly assessed the role of collagen VI in lung development and in lung epithelial cell biology. Here, we describe the state-of-the-art for collagen VI cell and developmental biology within the respiratory system, and reveal its essential roles in normal developmental processes and airway epithelial cell phenotype and intracellular signaling.

Lung CD103+dendritic cells and Clec9a signaling are required for neonatal hyperoxia-induced inflammatory responses to rhinovirus infection

Premature infants, especially those with bronchopulmonary dysplasia (BPD), develop recurrent severe respiratory viral illnesses. We have shown that hyperoxic exposure of immature mice, a model of BPD, increases lung IL-12-producing Clec9a+ CD103+ dendritic cells (DCs), pro-inflammatory responses, and airway hyperreactivity following rhinovirus (RV) infection. However, the requirement for CD103+ DCs and Clec9a, a DAMP receptor that binds necrotic cell cytoskeletal filamentous actin (F-actin), for RV-induced inflammatory responses has not been demonstrated. To test this, 2-day-old C57BL/6J, CD103+ DC-deficient Batf3-/- or Clec9agfp-/- mice were exposed to normoxia or hyperoxia for 14 days. Also, selected mice were treated with neutralizing antibody against CD103. Immediately after hyperoxia, the mice were inoculated with RV intranasally. We found that compared with wild-type mice, hyperoxia-exposed Batf3-/- mice showed reduced levels of IL-12p40, IFN-γ, and TNF-α, fewer IFN-γ-producing CD4+ T cells, and decreased airway responsiveness following RV infection. Similar effects were observed in anti-CD103-treated and Clec9agfp-/- mice. Furthermore, hyperoxia increased airway dead cell number and extracellular F-actin levels. Finally, studies in preterm infants with respiratory distress syndrome showed that tracheal aspirate CLEC9A expression positively correlated with IL12B expression, consistent with the notion that CLEC9A+ cells are responsible for IL-12 production in humans as well as mice. We conclude that CD103+ DCs and Clec9a are required for hyperoxia-induced pro-inflammatory responses to RV infection. In premature infants, Clec9a-mediated activation of CD103+ DCs may promote pro-inflammatory responses to viral infection, thereby driving respiratory morbidity.

Time to Say Goodbye to Bronchiolitis, Viral Wheeze, Reactive Airways Disease, Wheeze Bronchitis and All That

The diagnosis and management of infants and children with a significant viral lower respiratory tract illness remains the subject of much debate and little progress. Over the decades various terms for such illnesses have been in and fallen out of fashion or have evolved to mean different things to different clinicians. Terms such as "bronchiolitis," "reactive airways disease," "viral wheeze," and many more are used to describe the same condition and the same term is frequently used to describe illnesses caused by completely different dominant pathologies. This lack of clarity is due, in large part, to a failure to understand the basic underlying inflammatory and associated processes and, in part, due to the lack of a simple test to identify a condition such as asthma. Moreover, there is a lack of insight into the fact that the same pathology can produce different clinical signs at different ages. The consequence is that terminology and fashions in treatment have tended to go around in circles. As was noted almost 60 years ago, amongst pre-school children with a viral LRTI and airways obstruction there are those with a "viral bronchitis" and those with asthma. In the former group, a neutrophil dominated inflammation response is responsible for the airways' obstruction whilst amongst asthmatics much of the obstruction is attributable to bronchoconstriction. The airways obstruction in the former group is predominantly caused by airways secretions and to some extent mucosal oedema (a "snotty lung"). These patients benefit from good supportive care including supplemental oxygen if required (though those with a pre-existing bacterial bronchitis will also benefit from antibiotics). For those with a viral exacerbation of asthma, characterized by bronchoconstriction combined with impaired b-agonist responsiveness, standard management of an exacerbation of asthma (including the use of steroids to re-establish bronchodilator responsiveness) represents optimal treatment. The difficulty is identifying which group a particular patient falls into. A proposed simplified approach to the nomenclature used to categorize virus associated LRTIs is presented based on an understanding of the underlying pathological processes and how these contribute to the physical signs.

Status asthmaticus requiring extracorporeal membrane oxygenation associated with rhinovirus infection

Objective: Evolving research links human rhinovirus (HRV) with status asthmaticus (SA) as well as severe respiratory illness in patients with atopy and asthma. This case series reviews five episodes of HRV-associated SA that required extracorporeal membrane oxygenation (ECMO). Methods: Charts of four patients, five total episodes of ECMO, with SA secondary to HRV were reviewed in this IRB-approved case series. Outcomes included demographic information, past medical history, clinical parameters and spirometry. Results: Patients (three male, one female), mean age 9 years (range 7-12 years) at the time of admission, were African American, on Medicaid, carried a diagnosis of persistent asthma, and had documented non-adherence to prescribed, daily controller medications. One patient had passive smoke exposure. All patients had a mean IgE of 734 (range 12-2497) with seasonal allergic rhinitis was diagnosed in three patients. Cases occurred in spring (3/5) and fall (2/5). Venous/venous ECMO (4/5) or venous/arterial ECMO (1/5) was continued for a mean duration of 4.2 days (range 3-7 days). Spirometry after hospitalization had a mean FEV₁ of 1.59 L (81% predicted, range 69%-91%), and an FEF_25%-75% 1.13 L (47.5% predicted, range 41%-65%) at an average of 16.7 weeks post ECMO. Conclusions: This case series highlights the association between persistent, poorly controlled asthma and severe SA with HRV infection resulting in ECMO. Despite life-threatening illness, these patients did not demonstrate significant large-airway obstruction following infection. However, patients showed persistently abnormal small airway function, which could be a risk factor or early evidence of vulnerability to infection.

PrEP-001 prophylactic effect against rhinovirus and influenza virus - RESULTS of 2 randomized trials

BACKGROUND

PrEP-001 Nasal Powder, a proprietary formulation of polyriboinosinic and polyribocytidylic acid effectively elicits a cellular innate immune response in nasal epithelium. The aim of these 2 studies was to investigate the safety and efficacy of PrEP-001 prophylaxis against rhinovirus (HRV-A16) and influenza-A (H3N2-IAV).

METHODS

Healthy subjects randomly received 2 doses of PrEP-001 or placebo, 48 and 24 h pre-challenge with 10 TCID₅₀ of HRV-A16 (Study 1) or H3N2-IAV (Study 2).

RESULTS

In Study 1, PrEP-001 reduced median total symptom score from 38.5 to 4.5 (p = 0.004), median symptom duration from 6.0 to 1.7 days and median mucus production from 15 g to 3 g. The percentage of subjects classified as ill was reduced 3-fold (placebo 73%, PrEP-001 23%, p = 0.002). In Study 2, PrEP-001 reduced median total symptom score from 8.0 to 4.1 (p = 0.021), median symptom duration from 4.6 to 3.7 days and median mucus production from 3.6 g to 1.5 g. The percentage of subjects classified as ill was reduced 2-fold (placebo 48%, PrEP-001 24%, p = 0.064). PrEP-001 reduced peak viral shedding in both studies, as assessed by qRT-PCR of nasal lavage. Seroconversion rates were comparable between placebo and PrEP-001 (Study 1: 77% [both arms]; Study 2: placebo 73%, PrEP-001 80%). PrEP-001 was well-tolerated, with no clinically significant adverse events.

CONCLUSIONS

PrEP-001 reduced the number of individuals with clinical illness and attenuated severity and duration of HRV-A16 and H3N2-IAV infections without compromising seroconversion, and was well-tolerated. This supports further evaluation of PrEP-001 as a potential pan-viral prophylaxis for upper respiratory tract infections.

CLINICAL TRIAL REGISTRATION

Study 1, HRV-A16 study: EudraCT Number 2012-005579-14 (study conducted before ClinicalTrials.gov registration required). Study 2, H3N2-IAV study: EudraCT Number 2015-002895-26 and ClinicalTrials.gov: NCT03220048.

Respiratory viral infections in infancy and school age respiratory outcomes and healthcare costs

OBJECTIVES

To determine the impact of viral lower respiratory tract infections (LRTIs) in infancy including rhinovirus (RV) and infancy respiratory syncytial virus (RSV), on school age pulmonary function and healthcare utilization in prematurely born children.

WORKING HYPOTHESIS

School age respiratory outcomes would be worse and healthcare utilization greater in children who had viral LRTIs in infancy.

STUDY DESIGN

Prospective study.

SUBJECT SELECTION

A cohort of prematurely born children who had symptomatic LRTIs during infancy documented, was recalled.

METHODS

Pulmonary function was assessed at 5 to 7 years of age and health related costs of care from aged one to follow-up determined.

RESULTS

Fifty-one children, median gestational age 33⁺⁶ weeks, were assessed at a median (IQR) age 7.03 (6.37-7.26) years. Twenty-one children had no LRTI, 14 RV LRTI, 10 RSV LRTI, and 6 another viral LRTI (other LRTI). Compared to the no LRTI group, the RV group had a lower FEV₁ (P = 0.033) and the other LRTI group a lower FVC (P = 0.006). Non-respiratory medication costs were higher in the RV (P = 0.018) and RSV (P = 0.013) groups. Overall respiratory healthcare costs in the RV (£153/year) and RSV (£27/year) groups did not differ significantly from the no LRTI group (£56/year); the other LRTI group (£431/year) had higher respiratory healthcare costs (P = 0.042).

CONCLUSIONS

In moderately prematurely born children, RV and RSV LRTIs in infancy were not associated with higher respiratory healthcare costs after infancy. Children who experienced LRTIs caused by other respiratory viruses (including RV) had higher respiratory healthcare costs and greater pulmonary function impairment.

Paediatric Virology and its interaction between basic science and clinical practice (Review)

The 3rd Workshop on Paediatric Virology, which took place on October 7th, 2017 in Athens, Greece, highlighted the role of breast feeding in the prevention of viral infections during the first years of life. Moreover, it focused on the long-term outcomes of respiratory syncytial virus and rhinovirus infections in prematurely born infants and emphasised the necessity for the development of relevant preventative strategies. Other topics that were covered included the vaccination policy in relation to the migration crisis, mother‑to‑child transmission of hepatitis B and C viruses, vaccination against human papilloma viruses in boys and advances on intranasal live‑attenuated vaccination against influenza. Emphasis was also given to the role of probiotics in the management of viral infections in childhood, the potential association between viral infections and the pathogenesis of asthma, fetal and neonatal brain imaging and the paediatric intensive care of children with central nervous system viral infections. Moreover, an interesting overview of the viral causes of perinatal mortality in ancient Greece was given, where recent archaeological findings from the Athenian Agora's bone well were presented. Finally, different continuing medical educational options in Paediatric Virology were analysed and evaluated. The present review provides an update of the key topics discussed during the workshop.

Refining anti-inflammatory therapy strategies for bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a severe lung disease of preterm infants, which is characterized by fewer, enlarged alveoli and increased inflammation. BPD has grave consequences for affected infants, but no effective and safe therapy exists. We previously showed that prophylactic treatment with interleukin-1 receptor antagonist (IL-1Ra) prevents murine BPD induced by perinatal inflammation and hyperoxia. Here, we used the same BPD model to assess whether an alternative anti-inflammatory agent, protein C (PC), is as effective as IL-1Ra against BPD. We also tested whether delayed administration or a higher dose of IL-1Ra affects its ability to ameliorate BPD and investigated aspects of drug safety. Pups were reared in room air (21% O2 ) or hyperoxia (65% or 85% O2 ) and received daily injections with vehicle, 1200 IU/kg PC, 10 mg/kg IL-1Ra (early or late onset) or 100 mg/kg IL-1Ra. After 3 or 28 days, lung and brain histology were assessed and pulmonary cytokines were analysed using ELISA and cytokine arrays. We found that PC only moderately reduced the severe impact of BPD on lung structure (e.g. 18% increased alveolar number by PC versus 34% by IL-1Ra); however, PC significantly reduced IL-1β, IL-1Ra, IL-6 and macrophage inflammatory protein (MIP)-2 by up to 89%. IL-1Ra at 10 mg/kg prevented BPD more effectively than 100 mg/kg IL-1Ra, but only if treatment commenced at day 1 of life. We conclude that prophylactic low-dose IL-1Ra and PC ameliorate BPD and have potential as the first remedy for one of the most devastating diseases preterm babies face.

Functional and genetic predisposition to rhinovirus lower respiratory tract infections in prematurely born infants

Term born infants are predisposed to human rhinovirus (HRV) lower respiratory tract infections (LRTI) by reduced neonatal lung function and genetic susceptibility. Our aim was to investigate whether prematurely born infants were similarly predisposed to HRV LRTIs or any other viral LRTIs. Infants born less than 36 weeks of gestational age were recruited. Prior to neonatal/maternity unit discharge, lung function (functional residual capacity by helium gas dilution and multiple breath washout, lung clearance index and compliance (C_rs), and resistance (R_rs) of the respiratory system) was assessed and DNA samples assessed for eight single nucleotide polymorphisms (SNPs) in seven genes: ADAM33, IL10, MMP16 NFκB1A,SFTPC, VDR, and NOS2A. Infants were prospectively followed until 1 year corrected age. Nasopharyngeal aspirates (NPAs) were sent whenever an infant developed a LRTI and tested for 13 viruses. One hundred and thirty-nine infants were included in the analysis. Infants who developed HRV LRTIs had reduced C_rs (1.6 versus 1.2 mL/cmH₂O/kg, p = 0.044) at 36 weeks postmenstrual age. A SNP in the gene coding for the vitamin D receptor was associated with the development of HRV LRTIs and any viral LRTIs (p = 0.02).

CONCLUSION

Prematurely born infants may have both a functional and genetic predisposition to HRV LRTIs. What is Known: • Term born infants are predisposed to rhinovirus lower respiratory tract (HRV LRTIs) infection by reduced neonatal lung function. • Term born infants requiring hospitalisation due to HRV bronchiolitis were more likely to have single nucleotide polymorphism (SNP) in the IL-10 gene. What is New: • Prematurely born infants who developed a HRV LRTI had lower C _rs before maternity unit discharge. • A SNP in the gene coding for the vitamin D receptor was associated with the development of HRV LRTIs and overall respiratory viral LRTIs in prematurely born infants.

The genetic predisposition to bronchopulmonary dysplasia

PURPOSE OF REVIEW

Bronchopulmonary dysplasia (BPD) is a prevalent chronic lung disease in premature infants. Twin studies have shown strong heritability underlying this disease; however, the genetic architecture of BPD remains unclear.

RECENT FINDINGS

A number of studies employed different approaches to characterize the genetic aberrations associated with BPD, including candidate gene studies, genome-wide association studies, exome sequencing, integrative omics analysis, and pathway analysis. Candidate gene studies identified a number of genes potentially involved with the development of BPD, but the etiological contribution from each gene is not substantial. Copy number variation studies and three independent genome-wide association studies did not identify genetic variations significantly and consistently associated with BPD. A recent exome-sequencing study pointed to rare variants implicated in the disease. In this review, we summarize these studies' methodology and findings, and suggest future research directions to better understand the genetic underpinnings of this potentially life-long lung disease.

SUMMARY

Genetic factors play a significant role in the development of BPD. Recent studies suggested that rare variants in genes participating in lung development pathways could contribute to BPD susceptibility.

Rhinovirus-induced airway cytokines and respiratory morbidity in severely premature children

BACKGROUND

Rhinovirus (RV) has been linked to the pathogenesis of asthma. Prematurity is a risk factor for severe RV infection in early life, but is unknown if RV elicits enhanced pro-asthmatic airway cytokine responses in premature infants. This study investigated whether young children born severely premature (<32 wks gestation) exhibit airway secretion of Th2 and Th17 cytokines during natural RV infections and whether RV-induced Th2-Th17 responses are linked to more respiratory morbidity in premature children during the first 2 yrs of life.

METHODS

We measured Th2 and Th17 nasal airway cytokines in a retrospective cohort of young children aged 0-2 yrs with PCR-confirmed RV infection or non-detectable virus. Protein levels of IL-4, IL-13, TSLP, and IL-17 were determined with multiplex immunoassays. Demographic and clinical variables were obtained by electronic medical record (EMR) review.

RESULTS

The study comprised 214 children born full term (n = 108), preterm (n = 44) or severely premature (n = 62). Natural RV infection in severely premature children was associated with elevated airway secretion of Th2 (IL-4 and IL-13) and Th17 (IL-17) cytokines, particularly in subjects with history of bronchopulmonary dysplasia. Severely premature children with high RV-induced airway IL-4 had recurrent respiratory hospitalizations (median 3.65 hosp/yr; IQR 2.8-4.8) and were more likely to have at least one pediatric intensive care unit admission during the first 2 yrs of life (OR 8.72; 95% CI 1.3-58.7; p = 0.02).

CONCLUSIONS

Severely premature children have increased airway secretion of Th2 and Th17 cytokines during RV infections, which is associated with more respiratory morbidity in the first 2 yrs of life.

Echinacea reduces the risk of recurrent respiratory tract infections and complications: a meta-analysis of randomized controlled trials

INTRODUCTION

Respiratory tract infections are common, and these infections occur frequently in children, susceptible adults, and older persons. The risk for recurrences and complications relates not only to the presence of viruses but also to immune function. Therefore, modulation of the immune system and antiviral interventions such as echinacea might reduce the risk of recurrences and possibly the development of complications.

METHODS

MEDLINE, EMBASE, CAplus, BIOSIS, CABA, AGRICOLA, TOXCENTER, SCISEARCH, NAHL, and NAPRALERT were searched for clinical trials that studied recurrent respiratory infections and complications on treatment with echinacea extracts in a generally healthy population. Two independent reviewers selected randomized, placebo-controlled studies of high methodological quality and a Jadad score of ≥4. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated according to a fixed effect model.

RESULTS

Six clinical studies with a total of 2458 participants were included in the meta-analysis. Use of echinacea extracts was associated with reduced risk of recurrent respiratory infections (RR 0.649, 95% CI 0.545-0.774; P < 0.0001). Ethanolic extracts from echinacea appeared to provide superior effects over pressed juices, and increased dosing during acute episodes further enhanced these effects. Three independent studies found that in individuals with higher susceptibility, stress or a state of immunological weakness, echinacea halved the risk of recurrent respiratory infections (RR 0.501, 95% CI 0.380-0.661; P < 0.0001). Similar preventive effects were observed with virologically confirmed recurrent infections (RR 0.420, 95% CI 0.222-0.796; P = 0.005). Complications including pneumonia, otitis media/externa, and tonsillitis/pharyngitis were also less frequent with echinacea treatment (RR 0.503, 95% CI 0.384-0.658; P < 0.0001).

CONCLUSION

Evidence indicates that echinacea potently lowers the risk of recurrent respiratory infections and complications thereof. Immune modulatory, antiviral, and anti-inflammatory effects might contribute to the observed clinical benefits, which appear strongest in susceptible individuals.

Utility of animal and in vivo experimental infection of humans with rhinoviruses in the development of therapeutic agents for viral exacerbations of asthma and chronic obstructive pulmonary disease

There is an association with acute viral infection of the respiratory tract and exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Although these exacerbations are associated with several types of viruses, human rhinoviruses (HRVs) are associated with the vast majority of disease exacerbations. Due to the lack of an animal species that is naturally permissive for HRVs to use as a facile model system, and the limitations associated with animal models of asthma and COPD, studies of controlled experimental infection of humans with HRVs have been used and conducted safely for decades. This review discusses how these experimental infection studies with HRVs have provided a means of understanding the pathophysiology underlying virus-induced exacerbations of asthma and COPD with the goal of developing agents for their prevention and treatment.

The impact of human rhinovirus infection in pediatric patients undergoing heart surgery

Human rhinovirus (HRV), the most common cause of upper respiratory infection in children, can present as bronchiolitis, pneumonia, or asthma exacerbations. The impact of HRV in infants and toddlers with congenital heart disease is poorly defined. A case-control study was performed to compare the clinical course for 19 young children with respiratory symptoms who tested positive for rhinovirus after heart surgery with that of 56 matched control subjects. The control subjects were matched by surgical repair, age, weight, and time of the year. Patients with known HRVs before surgery and control subjects with respiratory symptoms or positive test results for viruses were excluded from the study. Human rhinovirus infection was associated with more than a tenfold increase in the odds of noninvasive ventilation after extubation (odds ratio [OR] 11.45; 95 % confidence interval [CI] 3.97-38.67), a 12-fold increase in the probability of extubation failure (OR 12.84; 95 % CI 2.93-56.29), and increased use of pulmonary medications including bronchodilator and nitric oxide (p < 0.001). As a result, the hospital length of stay (HLOS) was two times longer than for the control subjects (p < 0.001), and the cardiac intensive care unit (CICU) length of stay (CICU LOS) was three times longer (p < 0.0001). The intubation time was significantly longer (p < 0.001), and the CICU respiratory charges were significantly greater (p = 0.001) for the infected patients. Human rhinovirus increases resource use and prolongs postoperative recovery after pediatric heart surgery. Surgery timing should be delayed for patients with rhinovirus if possible.

Respiratory outcome of prematurely born infants following human rhinovirus A and C infections

Human rhinoviruses (HRVs) are a common cause of lower respiratory tract infections (LRTIs) and are associated with chronic respiratory morbidity. Our aim was to determine whether HRV species A or C were associated with chronic respiratory morbidity and increased health care utilisation in prematurely born infants. A number of 153 infants with a median gestational age of 34 (range 23-35) weeks were prospectively followed. Nasopharyngeal aspirates were collected whenever the infants had LRTIs regardless of hospitalisation status. Parents completed a respiratory diary card and health questionnaire about their infant when they were 11 and 12 months corrected age, respectively. The health-related cost of care during infancy was calculated from the medical records using the National Health Service (NHS) reference costing scheme and the British National Formulary for children. There were 32 infants that developed 40 HRV LRTIs; samples were available from 23 of the 32 infants for subtyping. Nine infants had HRV-A LRTIs, 13 HRV-C LRTIs, and one infant had a HRV-B LRTI. Exclusion of infants who also had RSV LRTIs revealed that the infants who had a HRV-C LRTI were more likely to wheeze (p < 0.0005) and use respiratory medications (p < 0.0005) and had more days of wheeze (p = 0.01) and used an inhaler (p = 0.02) than the no LRTI group. In addition, the respiratory cost of care was greater for the HRV-C LRTI than the no LRTI group (p < 0.0005).

CONCLUSION

Our results suggest HRV-C is associated with chronic respiratory morbidity during infancy in prematurely born infants.

[Adult respiratory sequelae of premature birth]

INTRODUCTION

Between 5 and 7% of babies are born prematurely. In the paediatric age group, the respiratory morbidity of these patients is well known, particularly in cases of bronchopulmonary dysplasia (BPD). On the other hand, very few data are available concerning their adult respiratory status.

BACKGROUND

There are currently three different groups of ex-premature babies: (1) those with no BPD who are usually not considered as respiratory high-risk adults but have not been well studied; (2) ex-premature babies with BPD who have an increased risk of asthma, respiratory infections, bronchial obstruction aggravated by smoking, and non-atopic bronchial hyperreactivity; this group has been well studied but not beyond 30 years of age; (3) the babies born very prematurely and affected with a new form of BPD due to neonatal intensive care at a very immature stage of pulmonary development, and for whom the future in adult life is unknown but worrying because of reduced lung volumes since birth.

VIEWPOINTS AND CONCLUSIONS

The respiratory physician must be aware of these groups of adults who he may encounter and who may develop, sooner or later, a certain type of chronic obstructive pulmonary disease.

Rate and influence of respiratory virus co-infection on pandemic (H1N1) influenza disease

OBJECTIVES

Many patients with influenza have more than one viral agent with co-infection frequencies reported as high as 20%. The impact of respiratory virus copathogens on influenza disease is unclear. We sought to determine if respiratory virus co-infection with pandemic H1N1 altered clinical disease.

METHODS

Respiratory samples from 229 and 267 patients identified with and without H1N1 influenza respectively were screened for the presence of 13 seasonal respiratory viruses by multiplex RT-PCR. Disease severity between coinfected and monoinfected H1N1 patients were quantified using a standardized clinical severity scale. Influenza viral load was calculated by quantitative RT-PCR.

RESULTS

Thirty (13.1%) influenza samples screened positive for the presence of 31 viral copathogens. The most prominent copathogens included rhinovirus (61.3%), and coronaviruses (16.1%). Median clinical severity of both monoinfected and coinfected groups were 1. Patients coinfected with rhinovirus tended to have lower clinical severity (median 0), whereas non-rhinovirus co-infections had substantially higher clinical severity (median 2). No difference in H1N1 viral load was observed between coinfected and monoinfected groups.

CONCLUSIONS

Respiratory viruses co-infect patients with influenza disease. Patients coinfected with rhinovirus had less severe disease while non-rhinovirus co-infections were associated with substantially higher severity without changes in influenza viral titer.

The Transition from Bronchopulmonary Dysplasia to Childhood Chronic Lung Disease

The impact of a preterm birth on lung function in later life is not always predictable and the variability of lung phenotype in these children can be striking even among children of the same gestational age. Although many children with a history of bronchopulmonary dysplasia (BPD) improve with age, others continue to manifest significant pulmonary abnormalities. Several different lung phenotypes have been described in older children with a history of BPD. These descriptions have been based in part on chronic respiratory symptoms, pulmonary function abnormalities, and response to respiratory illnesses. These lung phenotypes include large and/or small airway dysfunction, impaired alveolar growth characterized by decreased pulmonary reserve, and pulmonary hypertension found primarily in children with severe chronic lung disease. Children with a history of BPD can manifest 1 or more of these lung phenotypes with varying degrees of severity. Currently, treatment of respiratory symptoms is primarily supportive and symptom based. Although many children improve with age, others continue to have chronic respiratory symptoms into adult life. The development of standardized guidelines for the care of children after discharge from the neonatal intensive care unit may help direct appropriate therapy, limit lung injury, and maximize lung growth potential in this vulnerable group of children.

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.

Rhinoviruses are a major cause of wheezing and hospitalization in children less than 2 years of age

BACKGROUND

Human rhinoviruses (HRV) are now considered major respiratory pathogens. We sought to determine whether HRV are a cause of wheezing and/or hospitalization in children <2 years old.

METHODS

A polymerase chain reaction assay was used to screen for HRV infection in 4 categories of children <2 years old: (1) with symptoms of respiratory tract disease without wheezing; (2) with wheezing with or without other symptoms; (3) who were asymptomatic and; (4) who had a respiratory specimen submitted to a diagnostic laboratory. All specimens were collected between January and December 2004. Phylogenetic analyses were performed on most HRV isolates.

RESULTS

Twenty-eight (17%) of 165 children with symptoms of respiratory infection without wheezing; 21 (26.3%) of 80 children with wheezing; 3 (3%) of 93 asymptomatic children; and 47 (23.3%) of 202 children with specimens submitted to the diagnostic laboratory tested positive for HRV. The difference between the rates of infection in the asymptomatic group and in each of the 3 other categories was statistically significant (P </= 0.01). Among HRV-positive children with samples submitted to the diagnostic laboratory, 55% were hospitalized, which was similar to that observed for respiratory syncytial virus (52.7%) among children of a similar age group and time period (P = 0.85). Diverse groups of HRV were circulating during the 1-year study period.

CONCLUSIONS

HRV are important pathogens among children <2 years old and are responsible for a significant proportion of wheezing this age group. The hospitalization rates of HRV-positive children seem to be similar to that of respiratory syncytial virus.

Antiviral therapy for respiratory tract infections

Viruses are important pathogens causing respiratory tract infections both in the community and health-care facility settings. They are extremely common causes of morbidity in the competent hosts and some are associated with significant mortality in the compromised individuals. With wider application of molecular techniques, novel viruses are being described and old viruses are found to have new significance in different epidemiological and clinical settings. Some of these emerging pathogens may have the potential to cause pandemics or global spread of a severe disease, as exemplified by severe acute respiratory syndrome and avian influenza. Antiviral therapy of viral respiratory infections is often unnecessary in the competent hosts because most of them are selflimiting and effective agents are not always available. In the immunocompromised individuals or for infections caused by highly pathogenic viruses, such as avian influenza viruses (AIV), antiviral treatment is highly desirable, despite the fact that many of the agents may not have undergone stringent clinical trials. In immunocompetent hosts, antiviral therapy can be stopped early because adaptive immune response can usually be mounted within 5-14 days. However, the duration of antiviral therapy in immunosuppressed hosts depends on clinical and radiological resolution, the degree and duration of immunosuppression, and therefore maintenance therapy is sometimes needed after the initial response. Immunotherapy and immunoprophylaxis appear to be promising directions for future research. Appropriate and targeted immunomodulation may play an important adjunctive role in some of these infections by limiting the extent of end-organ damage and multi-organ failure in some fulminant infections.

Rhinovirus infection in hospitalized children in Hong Kong: a prospective study

OBJECTIVES

To analyze the clinical features and estimate the hospitalization disease burden of rhinovirus infection in children in Hong Kong.

METHODS

In this prospective study, nasopharyngeal aspirates were taken from children aged <18 years with symptoms of acute respiratory infection admitted to Queen Mary Hospital on one fixed day of the week during August 2001-July 2002 for detection of common respiratory viruses by immunofluorescence, viral culture, and for rhinovirus, human metapneumovirus, and coronaviruses by reverse transcription polymerase chain reaction. The clinical features of rhinovirus infections were analyzed and hospitalization disease burden was estimated.

RESULTS

Altogether 239 of the 426 nasopharyngeal aspirates (56.1%) were positive for respiratory viruses, including 151 patients with rhinovirus (35.4%). The median age was 2.34 years. Upper respiratory infection, asthma exacerbation, pneumonia, and acute bronchiolitis were diagnosed in 44.4%, 19.9%, 11.3%, and 7.9%, respectively. The most common symptoms were cough (81.5%), runny nose (76.8%), and fever (68.9%). Shortness of breath, wheezes, and crepitation were present in 25.8%, 29.1%, and 18.5%, respectively. Fifty-five of 99 patients (55.6%) had chest radiographic abnormalities, most commonly perihilar streakiness. Children with chronic diseases were more likely to have lower respiratory tract infection and these children required longer hospitalization (mean 0.6 days longer). Coinfection with other respiratory pathogens was common (33.1%).

CONCLUSION

Rhinovirus is frequently associated with asthmatic exacerbations and lower respiratory tract infection, especially in children with chronic diseases and is potentially an important contributor to hospitalization in children in Hong Kong.

Rapid multiplex nested PCR for detection of respiratory viruses

Respiratory tract infections can be caused by a heterogeneous group of viruses and bacteria that produce similar clinical presentations. Specific diagnosis therefore relies on laboratory investigation. This study developed and evaluated five groups of multiplex nested PCR assays that could simultaneously detect 21 different respiratory pathogens: influenza A virus (H1N1, H3N2, and H5N1); influenza B virus; parainfluenza virus types 1, 2, 3, 4a, and 4b; respiratory syncytial virus A and B; human rhinoviruses; human enteroviruses; human coronaviruses OC43 and 229E; severe acute respiratory syndrome coronavirus; human metapneumoviruses; Mycoplasma pneumoniae; Chlamydophila pneumoniae; Legionella pneumophila; and adenoviruses (A to F). These multiplex nested PCRs adopted fast PCR technology. The high speed of fast PCR (within 35 min) greatly improved the efficiency of these assays. The results show that these multiplex nested PCR assays are specific and more sensitive (100- to 1,000-fold) than conventional methods. Among the 303 clinical specimens tested, the multiplex nested PCR achieved an overall positive rate of 48.5% (95% confidence interval [CI], 42.9 to 54.1%), which was significantly higher than that of virus isolation (20.1% [95% CI, 15.6 to 24.6%]) and that of direct detection by immunofluorescence assay (13.5% [95% CI, 9.7 to 17.4%]). The improved sensitivity was partly due to the higher sensitivity of multiplex nested PCR than that of conventional methods in detecting cultivatable viruses. Moreover, the ability of the multiplex nested PCR to detect noncultivatable viruses, particularly rhinoviruses, coronavirus OC43, and metapneumoviruses, contributed a major gain (15.6%) in the overall positive rate. In conclusion, rapid multiplex nested PCR assays can improve the diagnostic yield for respiratory infections to allow prompt interventive actions to be taken.

The effect of oral pleconaril on hepatic cytochrome P450 3A activity in healthy adults using intravenous midazolam as a probe

Pleconaril is a viral capsid inhibitor under evaluation for treatment of infections caused by rhinoviruses and enteroviruses. This study evaluated the effect of pleconaril on hepatic cytochrome P450 (CYP) 3A activity as assessed by intravenous (IV) midazolam. Healthy adults received oral pleconaril 400 mg 3 times daily for 16 doses. Single-dose, IV midazolam 0.025 mg/kg was administered before and during pleconaril administration. Midazolam and pleconaril plasma concentrations were assayed by LC/MS/MS. Bioequivalence was assessed by least squares geometric mean ratios (LS-GMR) with 90% confidence intervals (90% CIs) for the measured midazolam pharmacokinetic parameters. Sixteen subjects were enrolled, and 14 subjects completed the study. Pleconaril decreased midazolam AUC(0-infinity) 28% and increased systemic clearance 39%. LS-GMR (90% CI) were 0.718 (0.674-0.765) and 1.392 (1.307-1.483), respectively. Plasma pleconaril concentrations steadily increased over time. Observed changes in midazolam AUC(0-infinity) and systemic clearance suggest that oral pleconaril increased hepatic CYP3A activity in healthy adults.

DURATION OF PLECONARIL EFFECT ON CYTOCHROME P450 3A ACTIVITY IN HEALTHY ADULTS USING THE ORAL BIOMARKER MIDAZOLAM

The objective of this study was to evaluate the duration of oral pleconaril (a picornavirus inhibitor) effect on intestinal and hepatic cytochrome P450 (P450) 3A activity as assessed by oral midazolam. Healthy adults received oral midazolam (0.075 mg/kg) on days 1 (baseline), 7, 9, 13, 20, 27, and 34. Oral pleconaril (400 mg) three times daily for 15 doses was administered on days 2 through 7. Blood samples were collected during each day of midazolam dosing to determine plasma midazolam concentrations. On days 5, 6, and 7, blood samples were collected to determine plasma pleconaril concentrations. Midazolam pharmacokinetics were determined by noncompartmental analyses, with bioequivalence assessed by least-squares geometric mean ratios (LS-GMR) and 90% confidence intervals (90% CI). Eighteen subjects completed the study. Midazolam C(max) (LS-GMR; 90% CI) decreased 24% on day 7 (0.76; 0.66-0.87). Midazolam oral clearance increased 53% on day 7 (1.53; 1.38-1.69). Midazolam oral clearance remained different on days 9 (1.38; 1.25-1.52) and 13 (1.19; 1.07-1.31) versus day 1. Midazolam volume of distribution (1.82; 1.57-2.11) and elimination half-life (1.19; 1.03-1.38) were also different on day 7 in comparison with day 1. Oral pleconaril increased intestinal and hepatic CYP3A activity. The duration of increased CYP3A activity by pleconaril was at least 6 days (but no longer than 13 days) after pleconaril discontinuation.

Bronchopulmonary dysplasia in preterm infants: pathophysiology and management strategies

Bronchopulmonary dysplasia (BPD) has classically been described as including inflammation, architectural disruption, fibrosis, and disordered/delayed development of the infant lung. As infants born at progressively earlier gestations have begun to survive the neonatal period, a 'new' BPD, consisting primarily of disordered/delayed development, has emerged. BPD causes not only significant complications in the newborn period, but is associated with continuing mortality, cardiopulmonary dysfunction, re-hospitalization, growth failure, and poor neurodevelopmental outcome after hospital discharge. Four major risk factors for BPD include premature birth, respiratory failure, oxygen supplementation, and mechanical ventilation, although it is unclear whether any of these factors is absolutely necessary for development of the condition. Genetic susceptibility, infection, and patent ductus arteriosus have also been implicated in the pathogenesis of the disease. The strategies with the strongest evidence for effectiveness in preventing or lessening the severity of BPD include prevention of prematurity and closure of a clinically significant patent ductus arteriosus. Some evidence of effectiveness also exists for single-course therapy with antenatal glucocorticoids in women at risk for delivering premature infants, surfactant replacement therapy in intubated infants with respiratory distress syndrome, retinol (vitamin A) therapy, and modes of respiratory support designed to minimize 'volutrauma' and oxygen toxicity. The most effective treatments for ameliorating symptoms or preventing exacerbation in established BPD include oxygen therapy, inhaled glucocorticoid therapy, and vaccination against respiratory pathogens.Many other strategies for the prevention or treatment of BPD have been proposed, but have weaker or conflicting evidence of effectiveness. In addition, many therapies have significant side effects, including the possibility of worsening the disease despite symptom improvement. For instance, supraphysiologic systemic doses of glucocorticoids lessen the incidence of BPD in infants at risk for the disease, and promote weaning of oxygen and mechanical ventilation in infants with established BPD. However, the side effects of systemic glucocorticoid therapy, most notably the recently recognized adverse effects on neurodevelopment, preclude their routine use for the prevention or treatment of BPD. Future research in BPD will most probably focus on continued incremental improvements in outcome, which are likely to be achieved through the combined effects of many therapeutic modalities.

Practical implementation of a multiplex PCR for acute respiratory tract infections in children

Molecular testing for acute respiratory infections (ARIs) has documented value but limited implementation due to questions that typically slow the acceptance of new tests. This study sought to address these questions and achieve implementation. Rhinovirus was added to a nested multiplex PCR (M-PCR), increasing its diagnostic yield. Over one winter, three hospital pediatric departments used the M-PCR to complement their direct fluorescent-antibody assay (DFA) for respiratory syncytial virus (RSV). Clinicians recorded "pretest probability estimates" (using continuous scales for various pathogen groups) for comparison with test results; treatments and test turnaround times were also recorded. Transnasal and throat swabs, with or without nasopharyngeal aspirate (NPA), were M-PCR tested. NPA-containing sample sets found to be RSV positive by DFA were not further tested. Single PCR for human metapneumovirus (hMPV) was performed retrospectively. Of 178 ARI episodes representing 172 patients, NPA was included in 97 sample sets; 54 (56%) were determined to be RSV positive. The other NPA-containing sample sets (n = 43) yielded 27 findings (63%), and the swab-only sets (n = 81) yielded 47 findings (58%); rhinovirus was found most often. Testing for hMPV yielded seven positive results. M-PCR median turnaround times were 4 days in swab-only samples and 5 days with NPA. Antibiotics were prescribed in 50 episodes, at rates similar for RSV and rhinovirus. Pretest probability estimates of a viral cause were lower in episodes caused by rhinovirus than in episodes caused by RSV. The hospitals continued to use M-PCR for NPA-containing samples found to be RSV negative by DFA. Test implementation is more likely with higher diagnostic yield and a protocol that reflects day-to-day clinical and laboratory operations.

Etiology of community-acquired pneumonia in hospitalized school-age children: evidence for high prevalence of viral infections

BACKGROUND

Community-acquired pneumonia (CAP) in young children is most commonly associated with viral infections; however, the role of viruses in CAP of school-age children is still inconclusive.

METHODS

Seventy-five school-age children hospitalized with CAP were prospectively evaluated for the presence of viral and bacterial pathogens. Nasopharyngeal washes were examined by polymerase chain reaction for viruses and atypical bacteria. Antibody assays to detect bacterial pathogens in acute-phase and convalescent-phase serum samples were also performed.

RESULTS

A viral infection was identified in 65% of cases. Rhinovirus RNA was detected in 45% of patients; infection with another virus occurred in 31%. The most common bacterial pathogen was Mycoplasma pneumoniae, which was diagnosed in 35% of cases. Chlamydia pneumoniae DNA was not detected in any patient; results of serological tests were positive in only 2 patients (3%). Mixed infections were documented in 35% of patients, and the majority were a viral-bacterial combination.

CONCLUSIONS

The high prevalence of viral and mixed viral-bacterial infections supports the notion that the presence of a virus, acting either as a direct or an indirect pathogen, may be the rule rather than the exception in the development of CAP in school-age children requiring hospitalization.

Do rhinoviruses cause pneumonia in children?

Rhinoviruses are the most common precipitants of the common cold and have been associated with different infections of the respiratory tract, such as otitis media and sinusitis. They have also been implicated in the induction of acute asthma exacerbations, most of which are preceded by a common cold. Although in several occasions, mainly in immunocompromised hosts, severe lower respiratory tract infections have been attributed to rhinovirus infections, it is still unclear whether and to what extent these viruses contribute as pathogens in community-acquired pneumonia. Current mechanistic data suggest that rhinoviruses could be the cause of pneumonia in immunocompetent subjects. This notion is supported by epidemiological evidence, however, more clinical studies are needed to assess the actual burden.

Rhinovirus and the lower respiratory tract

Human rhinoviruses (HRVs) are well‐recognised causes of common colds and associated upper respiratory tract complications such as sinusitis and otitis media. This article reviews information linking HRV infection to illness in the lower respiratory tract. HRVs are capable of efficient replication in vitro at temperatures present in the tracheobronchial tree and have been shown to cause productive infection, elaboration of cytokines and chemokines, and up‐regulation of cell surface markers in human bronchial epithelial cells. In situ hybridisation studies have proven that HRV infection occurs in the tracheobronchial tree following experimental infection. Clinical studies report that HRV infection is the second most frequently recognised agent associated with pneumonia and bronchiolitis in infants and young children and commonly causes exacerbations of pre‐existing airways disease in those with asthma, chronic obstructive pulmonary disease or cystic fibrosis. HRV infection is associated with one‐third to one‐half of asthma exacerbations depending on age and is linked to asthma hospitalisations in both adults and children. Limited information implicates HRV infection as a cause of severe lower respiratory tract illness in older adults and in highly immunocompromised hosts, particularly bone marrow transplant recipients. More information is needed about the pathogenesis of HRV infection with regard to lower respiratory tract complications in these diverse patient groups. Given the large unmet medical need associated with HRV infections, safe and effective antiviral agents are needed for both prevention and treatment of these infections. Copyright © 2004 John Wiley & Sons, Ltd.

Discharge and aftercare in chronic lung disease of the newborn

This article deals with the discharge planning and continuing care of babies with chronic lung disease of the newborn (CLD), especially those with a continuing oxygen requirement, with some reference to longer term outcome. The pattern of CLD has changed since early descriptions, and the most useful definition for persisting morbidity in a baby with lung disease is a continuing oxygen requirement beyond 36 weeks post-menstrual age. Long-term oxygen therapy to maintain oxygen saturation at a mean of 95% or more and prevent levels below 90% is the cornerstone of management, and with adequate oxygen therapy the excess mortality previously reported in CLD can largely be avoided. Care must be given to the method of assessing oxygen saturation: overnight monitoring using appropriate recording devices is recommended. Exposure to respiratory viruses should be minimized where possible. Metabolic requirements are increased, but if efforts are made to maintain adequate energy input the long-term outlook for catch-up growth in height is good. Respiratory morbidity is increased in early life, but this improves in later childhood, along with lung function and exercise tolerance. Although respiratory symptoms should be treated as they arise, there is no evidence for long-term benefit from any pharmacological intervention in CLD.

Pleconaril, a novel antipicornaviral agent

Despite the availability of therapy for selected symptoms, no specific antiviral agents are available to treat or prevent infections due to the viruses of the Picornaviridae family--rhinoviruses and enteroviruses. Characterization of the three-dimensional structure of picornaviruses in the 1980s allowed development of compounds targeted at the virus itself. Pleconaril is a novel, orally available, systemically acting molecule whose pharmacokinetics are characterized by a two-compartment open model with first-order absorption and with a safety profile similar to that of placebo. It shows promising results in treatment of picornaviral respiratory tract infections, meningitis, and other life-threatening infections.

Coronavirus-related nosocomial viral respiratory infections in a neonatal and paediatric intensive care unit: a prospective study

The incidence of nosocomial viral respiratory infections (NVRI) in neonates and children hospitalized in paediatric and neonatal intensive care units (PNICU) is unknown. Human coronaviruses (HCoV) have been implicated in NVRI in hospitalized preterm neonates. The objectives of this study were to determine the incidence of HCoV-related NVRI in neonates and children hospitalized in a PNICU and the prevalence of viral respiratory tract infections in staff. All neonates (age< or =28 days) and children (age>28 days) hospitalized between November 1997 and April 1998 were included. Nasal samples were obtained by cytological brush at admission and weekly thereafter. Nasal samples were taken monthly from staff. Virological studies were performed, using indirect immunofluorescence, for HCoV strains 229E and OC43, respiratory syncytial virus (RSV), influenza virus types A and B, paramyxoviruses types 1, 2 and 3 and adenovirus. A total of 120 patients were enrolled (64 neonates and 56 children). Twenty-two samples from 20 patients were positive (incidence 16.7%). In neonates, seven positive samples, all for HCoV, were detected (incidence 11%). Risk factors for NVRI in neonates were: duration of hospitalization, antibiotic treatment and duration of parenteral nutrition (P<0.01). Monthly prevalence of viral infections in staff was between 0% and 10.5%, mainly with HCoV. In children, 15 samples were positive in 13 children at admission (seven RSV, five influenza and three adenovirus) but no NVRI were observed. In spite of a high rate of community-acquired infection in hospitalized children, the incidence of NVRI with common respiratory viruses appears low in neonates, HCoV being the most important pathogen of NRVI in neonates during this study period. Further research is needed to evaluate the long-term impact on pulmonary function.

Association of rhinovirus infection with increased disease severity in acute bronchiolitis

Respiratory syncytial virus (RSV) is the major pathogen responsible for acute bronchiolitis in infancy. However, evaluation of the relative importance of rhinovirus or multiple viral infections has been hampered by the lack of sensitive diagnostic methodologies. Therefore, in this study we used the reverse transcription-polymerase chain reaction for 11 respiratory pathogens to assess the etiology in infants with acute bronchiolitis and correlate it with clinical characteristics of the disease. Viruses were detected in 73.7% of patients. RSV was identified in 72.4% of virologically confirmed cases, rhinovirus in 29%, whereas multiple infections represented 19.5% of cases, most of which (69%) were combinations of rhinovirus with RSV. In a logistic regression model controlling for age, sex, birth weight, presence of fever, and day of disease on admission, the presence of rhinovirus was found to increase by approximately five-fold, the risk for severe disease. Multiple pathogens had a similar trend in the univariate analysis, which was eliminated in the multivariate model. Multiple virus cases were admitted to the hospital later in the course of their disease than unique pathogen cases, suggesting successive infections. In conclusion, rhinovirus is second only to RSV as a causative agent of bronchiolitis and is associated with more severe disease. The presence of more than one pathogen may influence the natural history of acute bronchiolitis.

Pneumonia due to viral and atypical organisms and their sequelae

Most children presenting with pneumonia in the industrialised world will have a viral or 'atypical' organism. The clinical features of these 'atypical' pneumonias may be indistinguishable from bacterial pneumonia. New diagnostic techniques such as the polymerase chain reaction may help in diagnosis and choice of treatment, where appropriate. The pathological and clinical features of infection with each agent are discussed, together with their sequelae.

Respiratory illness caused by picornavirus infection: a review of clinical outcomes

BACKGROUND

Respiratory infections result from invasion of the respiratory tract, mainly by viruses, and are the leading cause of acute morbidity in individuals of all ages worldwide. During peak season, picornaviruses cause 82% of all episodes of acute nasopharyngitis (the common cold), the most frequent manifestation of acute respiratory infection, and produce more restriction of activity and physician consultations annually than any other viral or bacterial source of respiratory illness.

OBJECTIVE

This article reviews the clinical impact and outcomes of picornavirus-induced respiratory infections in specific populations at risk for complications. It also discusses the potential economic impact of the morbidity associated with picornavirus-induced respiratory infection.

METHODS

Relevant literature was identified through searches of MEDLINE, OVID, International Pharmaceutical Abstracts, and Lexis-Nexis. The search terms used were picornavirus, rhinovirus, enterovirus, viral respiratory infection, upper respiratory infection, disease burden, economic, cost, complications, asthma, COPD, immunocompromised, elderly otitis media, and sinusitis. Additional publications were identified from the reference lists of the retrieved articles.

CONCLUSIONS

Based on the clinical literature, picornavirus infections are associated with severe morbidity as well as considerable economic and societal costs. Future research should focus on identifying patterns of illness and the costs associated with management of these infections. New treatments should be assessed not only in terms of their ability to produce the desired clinical outcome, but also in terms of their ability to reduce the burden of disease, decrease health care costs, and improve productivity.

Seasonal pattern of early mortality and infectious complications in liver transplant recipients

Seasonal variation has been documented in the frequency and attributable mortality of a number of medical illnesses and infections in the nontransplantation setting. Whether similar trends exist in transplant recipients is not known. Seasonal rates of overall and early mortality and contributory variables stratified by season were assessed in 190 consecutive liver transplant recipients who underwent transplantation over a 10-year period. The frequency of infectious complications and rejection was also assessed and stratified by season of transplantation. Early (deaths occurring in the first year posttransplantation), but not overall, mortality correlated significantly with seasonality. Of patients with early mortality, 43% (13 of 30 patients) died in winter; 23% (7 of 30 patients), in spring; 13% (4 of 30 patients), in summer; and 20% (6 of 30 patients), in fall. The frequency of deaths in winter was significantly greater than for all other seasons (P = .022). The high wintertime mortality could not be explained by previously recognized risk factors portending a poor outcome, e.g., United Network for Organ Sharing status, Child-Pugh score, surgical time, blood loss, pretransplantation and posttransplantation dialysis, infections, rejection, or increased immunosuppression. Strong trends toward a higher rate of cytomegalovirus disease in patients who underwent transplantation in fall (P = .09) and bacterial infections in those who underwent transplantation in winter were documented (P = .09). There was no correlation between seasonality and rejection. Early mortality in winter in liver transplant recipients was significantly greater than if the deaths were totally random. Whether the seasonal clustering of deaths and infections is triggered by respiratory viruses, yet unrecognized viruses, or unknown exogenous factors remains to be determined.

Pleconaril: a novel antipicornaviral drug

Pleconaril (VP-63843) 3-[3,5-dimethyl-4[[3-(3-methyl-5-isoxazolyl)propyl] oly]phenyl]-5-(trifluoromethyl)-1,2,4-oxadiazole is a novel, broad spectrum antipicornaviral agent. Pleconaril binds to a hydrophobic pocket in the viral capsid inducing conformational changes, which lead to altered receptor binding and viral uncoating. Pleconaril is orally bioavailable and achieves serum concentrations in excess of those required to inhibit 90% of clinical rhino- and enteroviral isolates in vitro. It possesses the additional advantage of achieving several fold higher concentrations within the central nervous system and nasal secretions than in serum, a characteristic that is highly desirable for an antiviral targeted towards viruses known to cause central nervous system and upper respiratory tract infections. Approximately 80% of an orally administered dose is excreted in the faeces within 48 h. Urine excretion accounts for the remainder of the drug. Pleconaril has demonstrated an excellent safety profile in dose escalation and clinical studies. Clinical studies have reported a reduction in the duration and intensity of symptoms in children and adults with enteroviral meningitis and in adults with rhinoviral respiratory tract infections treated with pleconaril. Lastly, pleconaril has demonstrated efficacy in the treatment of severe life-threatening enteroviral infections of the newborn and in immunosuppressed individuals. Pleconaril appears to be a promising drug for the treatment of enteroviral and rhinoviral infections.

Activity of pleconaril against enteroviruses

The activity of pleconaril in cell culture against prototypic enterovirus strains and 215 clinical isolates of the most commonly isolated enterovirus serotypes was examined. The latter viruses were isolated by the Centers for Disease Control and Prevention during the 1970s and 1980s from clinically ill subjects. Pleconaril at a concentration of Collapse

Key Words Collapse

MESH Headings

• Animals
• Animals, Newborn
• Animals, Suckling
• Antiviral Agents/pharmacokinetics
• Antiviral Agents/pharmacology
• Antiviral Agents/therapeutic use
• Cells, Cultured
• Coxsackievirus Infections/drug therapy
• Coxsackievirus Infections/virology
• Enterovirus/classification
• Enterovirus/drug effects
• Enterovirus/isolation & purification
• Female
• Humans
• Male
• Mice
• Mice, Inbred BALB C
• Mice, Inbred ICR
• Oxadiazoles/pharmacokinetics
• Oxadiazoles/pharmacology
• Oxadiazoles/therapeutic use
• Oxazoles
• Serotyping
• Virus Replication/drug effects

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Grants Collapse

Affiliation(s)

D C Pevear ViroPharma Incorporated, Exton, Pennsylvania 19341, USA.
T M Tull
M E Seipel
J M Groarke

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Rhinoviruses: important respiratory pathogens

The most frequent viruses associated with respiratory infections are human rhinoviruses (HRVs). Although the majority of HRV infections are mild and self-limited, HRV is an important cause of respiratory disease across all age groups. Recent studies using reverse transcriptase polymerase chain reaction to detect HRV genomes have established the importance of HRVs in predisposing to or causing otitis media, sinusitis and exacerbations of asthma, as well as other lower respiratory tract disorders. Among elderly people, infants and immunocompromised hosts HRV infections are often associated with lower respiratory tract morbidity and rarely mortality. How often active viral replication occurs in the middle ear, sinuses or the lower respiratory tract remains to be determined. However, the high incidence of HRV infections and their frequent association with upper and lower respiratory tract complications highlight the need for more effective means of prevention and treatment.

Serious respiratory illness associated with rhinovirus infection in a pediatric population

BACKGROUND

Rhinoviruses have long been associated with mild upper respiratory illness in both adults and children. However, the role of rhinoviruses as lower respiratory tract pathogens has not been fully characterized. Previous data suggests that rhinoviruses may cause severe lower respiratory illness in young children or infants.

OBJECTIVES

The present study describes the clinical presentations, severity of illness and outcomes for a large cohort of pediatric patients with documented rhinovirus infections.

SUBJECTS AND METHODS

A retrospective chart review was done on 93 pediatric patients from whom 101 nasopharyngeal or endotracheal specimens were positive by viral culture for a rhinovirus. All patients were hospitalized or seen in the pediatric emergency department at The Children's Hospital of Philadelphia between 1 January, 1990 and 31 May, 1996.

RESULTS

Of the 93 patients, 52 were male and 41 female. The age range was 0 days to 18 years with 25 (27%) less than 3 months, 42 (45%) between 3 and 12 months and 26 (28%) over the age of 12 months. Clinical presentations on evaluation in the emergency department or admission included 78 (84%) patients with acute respiratory illness, 13 (17%) with fever and suspected sepsis and 11 (12%) with other complaints. Reported physical findings on examination included one or more lower respiratory symptoms or signs of acute distress and fever greater than or equal to 38.1 degrees C. A total of 64 (69%) children were noted to have significant past medical histories, including 28 (44%) with prematurity or complicated neonatal courses, 11 (17%) with prior reactive airways, 8 (12%) with congenital cardiac disease and 7 (11%) with neurologic disorders. Of the patients, 29 (31%) were considered to be otherwise healthy children with no underlying dysfunctions. The mean duration of hospitalization for 69 patients admitted with respiratory illness who did not develop subsequent unrelated complications was 3.7 days. No significant bacterial or fungal pathogens were identified in 91% of the cases.

CONCLUSIONS

This study shows that rhinoviruses were associated with severe lower respiratory illness and hospitalization in a large pediatric population and that rhinovirus infection was a complicating factor in those patients with underlying or predisposing conditions.