Review of new and newly discovered respiratory tract viruses in children

The small nonstructural protein NP1 of human bocavirus 1 directly interacts with Ku70 and RPA70 and facilitates viral DNA replication

Human bocavirus 1 (HBoV1), a member of the genus Bocaparvovirus of the family Parvoviridae, causes acute respiratory tract infections in young children. Well-differentiated pseudostratified human airway epithelium cultured at an air-liquid interface (HAE-ALI) is an ideal in vitro culture model to study HBoV1 infection. Unique to other parvoviruses, bocaparvoviruses express a small nonstructured protein NP1 of ~25 kDa from an open reading frame (ORF) in the center of the viral genome. NP1 plays an important role in viral DNA replication and pre-mRNA processing. In this study, we performed an affinity purification assay to identify HBoV1 NP1-inteacting proteins. We identified that Ku70 and RPA70 directly interact with the NP1 at a high binding affinity, characterized with an equilibrium dissociation constant (KD) of 95 nM and 122 nM, respectively. Furthermore, we mapped the key NP1-interacting domains of Ku70 at aa266-439 and of RPA70 at aa181-422. Following a dominant negative strategy, we revealed that the interactions of Ku70 and RPA70 with NP1 play a significant role in HBoV1 DNA replication not only in an in vitro viral DNA replication assay but also in HBoV1-infected HAE-ALI cultures. Collectively, our study revealed a novel mechanism by which HBoV1 NP1 enhances viral DNA replication through its direct interactions with Ku70 and RPA70.

The large nonstructural protein (NS1) of the human bocavirus 1 (HBoV1) directly interacts with Ku70, which plays an important role in virus replication in human airway epithelia

Human bocavirus 1 (HBoV1), an autonomous human parvovirus, causes acute respiratory tract infections in young children. HBoV1 infects well-differentiated (polarized) human airway epithelium cultured at an air-liquid interface (HAE-ALI). HBoV1 expresses a large nonstructural protein, NS1, that is essential for viral DNA replication. HBoV1 infection of polarized human airway epithelial cells induces a DNA damage response (DDR) that is critical to viral DNA replication involving DNA repair with error-free Y-family DNA polymerases. HBoV1 NS1 or the isoform NS1-70 per se induces a DDR. In this study, using the second-generation proximity-dependent biotin identification (BioID2) approach, we identified that Ku70 is associated with the NS1-BioID2 pulldown complex through a direct interaction with NS1. Biolayer interferometry (BLI) assay determined a high binding affinity of NS1 with Ku70, which has an equilibrium dissociation constant (K_D) value of 0.16 μM and processes the strongest interaction at the C-terminal domain. The association of Ku70 with NS1 was also revealed during HBoV1 infection of HAE-ALI. Knockdown of Ku70 and overexpression of the C-terminal domain of Ku70 significantly decreased HBoV1 replication in HAE-ALI. Thus, our study provides, for the first time, a direct interaction of parvovirus large nonstructural protein NS1 with Ku70.

IMPORTANCE Parvovirus infection induces a DNA damage response (DDR) that plays a pivotal role in viral DNA replication. The DDR includes activation of ATM (ataxia telangiectasia mutated), ATR (ATM- and RAD3-related), and DNA-PKcs (DNA-dependent protein kinase catalytic subunit). The large nonstructural protein (NS1) often plays a role in the induction of DDR; however, how the DDR is induced during parvovirus infection or simply by the NS1 is not well studied. Activation of DNA-PKcs has been shown as one of the key DDR pathways in DNA replication of HBoV1. We identified that HBoV1 NS1 directly interacts with Ku70, but not Ku80, of the Ku70/Ku80 heterodimer at high affinity. This interaction is also important for HBoV1 replication in HAE-ALI. We propose that the interaction of NS1 with Ku70 recruits the Ku70/Ku80 complex to the viral DNA replication center, which activates DNA-PKcs and facilitates viral DNA replication.

Hairpin transfer-independent Parvovirus DNA Replication Produces Infectious Virus

Parvoviruses package a linear single-stranded DNA genome with hairpin structures at both ends. It has been thought that terminal hairpin sequences are indispensable for viral DNA replication. Here, we provide evidence that the hairpin-deleted duplex genomes of human bocavirus 1 (HBoV1) replicate in human embryonic kidney (HEK) 293 cells. We propose an alternative model for HBoV1 DNA replication in which the leading strand can initiate strand-displacement without "hairpin-transfer." The transfection of the HBoV1 duplex genomes that retain a minimal replication origin at the right-end (OriR), but with extensive deletions in the right-end hairpin (REH), generated viruses in HEK293 cells at a level 10-20 times lower than the wild-type (WT) duplex genome. Importantly, these viruses that have a genome with various deletions after the OriR, but not the one retaining only the OriR, replicated in polarized human airway epithelia. We discovered that the 18-nt sequence (nt 5,403-5,420) beyond the OriR was sufficient to confer virus replication in polarized human airway epithelia, although its progeny virus production was ∼5 times lower than that of the WT virus. Thus, our study demonstrates that hairpin transfer-independent productive parvovirus DNA replication can occur. Importance Hairpin transfer-independent parvovirus replication was modeled with human bocavirus 1 (HBoV1) duplex genomes whose 5' hairpin structure was ablated by various deletions. In HEK293 cells, these duplex viral genomes with ablated 5'/hairpin sequence replicated efficiently and generated viruses that productively infected polarized human airway epithelium. Thus, for the first time, we reveal a previously unknown phenomenon that the productive parvovirus DNA replication does not depend on the hairpin sequence at REH to initiate "rolling hairpin" DNA replication. Notably, the intermediates of viral DNA replication, as revealed two-dimensional electrophoresis, from transfections of hairpin sequence-deleted duplex genome and full-length genome in HEK293 cells, as well as from virus infection of polarized human airway epithelia are similar. Thus, the establishment of the hairpin transfer-independent parvoviral DNA replication deepens our understanding in viral DNA replication and may have implications in development of parvovirus-based viral vectors with alternative properties.

A Prospective Study of Etiological Agents Among Febrile Patients in Sierra Leone

Introduction

Sierra Leone has one of the highest burdens of febrile illnesses in the world. As the incidence of malaria diminishes, a better understanding of the spectrum of etiological agents was important for accurate diagnosis and empirical treatment of febrile illness.

Methods

Blood, nasopharyngeal, and fecal specimens were collected from febrile patients for serological, molecular detection, and microbiologic culture to identify potential pathogens.

Results

For this prospective study, 142 febrile patients were enrolled. The prevalence of malaria was higher in children aged 5–15 years old (P = 0.185) and adults (P = 0.018). Acute respiratory infection (ARI) presented more commonly in the under 5 years old group (P = 0.009). For diarrhea, all children groups (P = 0.024) were predominant. A total of 22.5% of the febrile patients had malaria infection, 19.7% had typhoid infection, and 2.8% were coinfected with malaria and typhoid. ARI was the most common causes of fever, accounting for 31.7% of patients, influenza A virus, Mycoplasma pneumoniae, and five other respiratory pathogens were found. Diarrhea accounted for 16.2%, and seven kinds of diarrhea bacteria were isolated. Hepatitis B accounted for 8.5%, including five cases of spontaneous bacterial peritonitis, and ascites smear staining were both Gram-negative bacteria. Tuberculous encephalitis, parasitic diseases (ascaris and filariasis), and skin infection caused by Staphylococcus aureus accounted for 0.7%, 2.1%, and 0.7%, respectively.

Conclusions

Evidence of a wide spectrum of febrile etiological agents other than malaria was identified. The spread of malaria rapid diagnostic tests (RDTs) out of hospital and establishment of a national standard for Widal test will reduce the misdiagnosis of febrile diseases. Antibiotics against Gram-negative bacteria are helpful for empirical treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00474-y.

Sierra Leone has one of the highest burdens of febrile illnesses in the world. Evidence of a wide spectrum of febrile pathogens other than malaria has been proven in this study. We considered that the etiology of febrile patients was closely related to local geography, heredity, immune features, economic industry, living habits, air pollution, medical and health conditions, and this was fully analyzed and discussed. The screening process used in this study can further simplify and identify the etiological agents of fever in more than 70% of the study population. This laid the foundation for the establishment of a more simplified and efficient diagnosis and treatment process in the local area. We also found the characteristics of age distribution of different febrile diseases. Children were an important susceptible population to fever. This study indicated the importance of reliable diagnostic tests for febrile pathogens and provided the necessary information for RDT requirements. The spread of malaria RDTs out of hospital and establishment of a national standard for Widal test will reduce the misdiagnosis of febrile diseases. For empirical treatment, antimalarial treatment was still targeted at falciparum malaria in Sierra Leone. Antibiotics against Gram-negative bacteria contributed to the empirical treatment of febrile diseases. For patients with acute respiratory tract infection, Gram-positive coccal antibiotics could be candidates for treatment. In addition, systematic and professional treatment of liver diseases should be promoted to reduce infection complications.

Systematic review and meta-analysis of the prevalence of common respiratory viruses in children < 2 years with bronchiolitis in the pre-COVID-19 pandemic era

Introduction

The advent of genome amplification assays has allowed description of new respiratory viruses and to reconsider the role played by certain respiratory viruses in bronchiolitis. This systematic review and meta-analysis was initiated to clarify the prevalence of respiratory viruses in children with bronchiolitis in the pre-COVID-19 pandemic era.

Methods

We performed an electronic search through Pubmed and Global Index Medicus databases. We included observational studies reporting the detection rate of common respiratory viruses in children with bronchiolitis using molecular assays. Data was extracted and the quality of the included articles was assessed. We conducted sensitivity, subgroups, publication bias, and heterogeneity analyses using a random effect model.

Results

The final meta-analysis included 51 studies. Human respiratory syncytial virus (HRSV) was largely the most commonly detected virus 59.2%; 95% CI [54.7; 63.6]). The second predominant virus was Rhinovirus (RV) 19.3%; 95% CI [16.7; 22.0]) followed by Human bocavirus (HBoV) 8.2%; 95% CI [5.7; 11.2]). Other reported viruses included Human Adenovirus (HAdV) 6.1%; 95% CI [4.4; 8.0]), Human Metapneumovirus (HMPV) 5.4%; 95% CI [4.4; 6.4]), Human Parainfluenzavirus (HPIV) 5.4%; 95% CI [3.8; 7.3]), Influenza 3.2%; 95% CI [2.2; 4.3], Human Coronavirus (HCoV) 2.9%; 95% CI [2.0; 4.0]), and Enterovirus (EV) 2.9%; 95% CI [1.6; 4.5]). HRSV was the predominant virus involved in multiple detection and most codetections were HRSV + RV 7.1%, 95% CI [4.6; 9.9]) and HRSV + HBoV 4.5%, 95% CI [2.4; 7.3]).

Conclusions

The present study has shown that HRSV is the main cause of bronchiolitis in children, we also have Rhinovirus, and Bocavirus which also play a significant role. Data on the role played by SARS-CoV-2 in children with acute bronchiolitis is needed.

Review registration

PROSPERO, CRD42018116067.

Neonatal vaccine effectiveness and the role of adjuvants

Introduction: Neonates are less responsive to vaccines than adults, making it harder to protect newborns against infection. Neonatal differences in antigen-presenting cell, B and T cell function, all likely contribute. A key question is whether novel adjuvants might be able to make neonatal vaccines more effective. Areas covered: This review addresses the issues of how to improve neonatal vaccines, which we have defined as vaccines given in the first 4 weeks of life in a human infant or the first week of life in a mouse. A search was performed using keywords including 'neonatal immunity', 'neonatal immunisation', 'vaccine' and 'adjuvant' of PubMed articles published between 1960 and 2018. Expert opinion: Sugar-like structures have recently been shown to prime the infant adaptive immune system to respond to vaccines, being potentially more effective than traditional adjuvants. Sugar-based compounds with beneficial adjuvant effects in neonatal vaccine models include delta inulin (Advax), curdlan, and trehalose 6,6'-dibehenate. Such compounds make interesting neonatal adjuvant candidates, either used alone or in combination with traditional innate immune adjuvants.

DNA Damage Signaling Is Required for Replication of Human Bocavirus 1 DNA in Dividing HEK293 Cells

Human bocavirus 1 (HBoV1), an emerging human-pathogenic respiratory virus, is a member of the genus Bocaparvovirus of the Parvoviridae family. In human airway epithelium air-liquid interface (HAE-ALI) cultures, HBoV1 infection initiates a DNA damage response (DDR), activating all three phosphatidylinositol 3-kinase-related kinases (PI3KKs): ATM, ATR, and DNA-PKcs. In this context, activation of PI3KKs is a requirement for amplification of the HBoV1 genome (X. Deng, Z. Yan, F. Cheng, J. F. Engelhardt, and J. Qiu, PLoS Pathog, 12:e1005399, 2016, https://doi.org/10.1371/journal.ppat.1005399), and HBoV1 replicates only in terminally differentiated, nondividing cells. This report builds on the previous discovery that the replication of HBoV1 DNA can also occur in dividing HEK293 cells, demonstrating that such replication is likewise dependent on a DDR. Transfection of HEK293 cells with the duplex DNA genome of HBoV1 induces hallmarks of DDR, including phosphorylation of H2AX and RPA32, as well as activation of all three PI3KKs. The large viral nonstructural protein NS1 is sufficient to induce the DDR and the activation of the three PI3KKs. Pharmacological inhibition or knockdown of any one of the PI3KKs significantly decreases both the replication of HBoV1 DNA and the downstream production of progeny virions. The DDR induced by the HBoV1 NS1 protein does not cause obvious damage to cellular DNA or arrest of the cell cycle. Notably, key DNA replication factors and major DNA repair DNA polymerases (polymerase η [Pol η] and polymerase κ [Pol κ]) are recruited to the viral DNA replication centers and facilitate HBoV1 DNA replication. Our study provides the first evidence of the DDR-dependent parvovirus DNA replication that occurs in dividing cells and is independent of cell cycle arrest.

IMPORTANCE

The parvovirus human bocavirus 1 (HBoV1) is an emerging respiratory virus that causes lower respiratory tract infections in young children worldwide. HEK293 cells are the only dividing cells tested that fully support the replication of the duplex genome of this virus and allow the production of progeny virions. In this study, we demonstrate that HBoV1 induces a DDR that plays significant roles in the replication of the viral DNA and the production of progeny virions in HEK293 cells. We also show that both cellular DNA replication factors and DNA repair DNA polymerases colocalize within centers of viral DNA replication and that Pol η and Pol κ play an important role in HBoV1 DNA replication. Whereas the DDR that leads to the replication of the DNA of other parvoviruses is facilitated by the cell cycle, the DDR triggered by HBoV1 DNA replication or NS1 is not. HBoV1 is the first parvovirus whose NS1 has been shown to be able to activate all three PI3KKs (ATM, ATR, and DNA-PKcs).

The role of the NxTAG® respiratory pathogen panel assay and other multiplex platforms in clinical practice

INTRODUCTION

The advent of nucleic acid amplification tests has significantly improved the aetiologic diagnosis of respiratory infections. However, multiplex real-time polymerase chain reaction (PCR) can be technologically challenging. Areas covered: This paper reports the results of the main published studies on the NxTAG Respiratory Pathogen Panel (RPP) and discusses the advantages and disadvantages of extensive use of multiplex assays in clinical practice. Expert commentary: Currently available data seem to indicate that routine use of multiplex assays, including NxTAG RPP Assay, should be recommended only when epidemiological data concerning circulation of viruses and bacteria have to be collected. Their use in clinical practice seems debatable. They have limited sensitivity and specificity at least in the identification of some infectious agents or, as in the case of NxTAG RPP, they have not been evaluated in a sufficient number of patients to allow definitive conclusions. In the future, the clinical relevance of multiplex assays, including NxTAG RPP, could significantly increase, mainly because a number of new antiviral agents effective against several respiratory viruses for which no drug is presently available will be marketed. In addition, it is highly likely that the efficiency of multiplex assays will be significantly improved.

Influenza-Like Illness Diagnosis and Management in the Acute Care Setting

During influenza season, acute respiratory illness due to influenza is difficult to distinguish from other influenza-like illnesses, but testing should be reserved for situations when timely results will influence management or infection control measures. Immunization status and timing of disease onset notwithstanding, a neuraminidase inhibitor should be offered immediately for certain high-risk children; neuraminidase inhibitor treatment should be considered if shorter illness is warranted or an at-risk sibling may be protected. Antipyretics and cough control may be useful. Immunization with an age-appropriate dose of an inactivated influenza vaccine is the cornerstone of prevention for health care personnel and our patients.

Analysis of cis and trans Requirements for DNA Replication at the Right-End Hairpin of the Human Bocavirus 1 Genome

Parvoviruses are single-stranded DNA viruses that use the palindromic structures at the ends of the viral genome for their replication. The mechanism of parvovirus replication has been studied mostly in the dependoparvovirus adeno-associated virus 2 (AAV2) and the protoparvovirus minute virus of mice (MVM). Here, we used human bocavirus 1 (HBoV1) to understand the replication mechanism of bocaparvovirus. HBoV1 is pathogenic to humans, causing acute respiratory tract infections, especially in young children under 2 years old. By using the duplex replicative form of the HBoV1 genome in human embryonic kidney 293 (HEK293) cells, we identified the HBoV1 minimal replication origin at the right-end hairpin (OriR). Mutagenesis analyses confirmed the putative NS1 binding and nicking sites within the OriR. Of note, unlike the large nonstructural protein (Rep78/68 or NS1) of other parvoviruses, HBoV1 NS1 did not specifically bind OriR in vitro, indicating that other viral and cellular components or the oligomerization of NS1 is required for NS1 binding to the OriR. In vivo studies demonstrated that residues responsible for NS1 binding and nicking are within the origin-binding domain. Further analysis identified that the small nonstructural protein NP1 is required for HBoV1 DNA replication at OriR. NP1 and other viral nonstructural proteins (NS1 to NS4) colocalized within the viral DNA replication centers in both OriR-transfected cells and virus-infected cells, highlighting a direct involvement of NP1 in viral DNA replication at OriR. Overall, our study revealed the characteristics of HBoV1 DNA replication at OriR, suggesting novel characteristics of autonomous parvovirus DNA replication.

IMPORTANCE

Human bocavirus 1 (HBoV1) causes acute respiratory tract infections in young children. The duplex HBoV1 genome replicates in HEK293 cells and produces progeny virions that are infectious in well-differentiated airway epithelial cells. A recombinant AAV2 vector pseudotyped with an HBoV1 capsid has been developed to efficiently deliver the cystic fibrosis transmembrane conductance regulator gene to human airway epithelia. Here, we identified both cis-acting elements and trans-acting proteins that are required for HBoV1 DNA replication at the right-end hairpin in HEK293 cells. We localized the minimal replication origin, which contains both NS1 nicking and binding sites, to a 46-nucleotide sequence in the right-end hairpin. The identification of these essential elements of HBoV1 DNA replication acting both in cis and in trans will provide guidance to develop antiviral strategies targeting viral DNA replication at the right-end hairpin and to design next-generation recombinant HBoV1 vectors, a promising tool for gene therapy of lung diseases.

Hospital admission due to respiratory viral infections in moderate preterm, late preterm and term infants during their first year of life

Background

Respiratory viral infections are a major cause of hospitalisation in infants <1 year and might cause severe symptoms in preterm infants. Our aim was to analyse admissions due to respiratory infections in moderate, late and term infants, and to identify risk factors for hospitalisation in preterm versus term.

Methods

Prospective study in a cohort of moderate and late preterm, and term infants born between October/2011 and December/2012. Admissions due to respiratory infections during the first year of life were analysed and compared among moderate (32–33), late (34–36) and term infants. Sixteen respiratory viruses were detected by RT-PCR. Clinical data were collected.

Results

30 (20.9%) out of 143 preterm infants required admission for respiratory infection, versus 129 (6.9%) of 1858 term infants born in the same period (p < 0.0001, OR: 3.6 CI 2.0 to 5.0). Hospitalised children had a higher prevalence of hyaline membrane disease (HMD) at birth (p < 0.001, OR: 7.7 CI: 2.121 to 27.954) and needed more mechanical ventilation (p < 0.001, OR: 5.7 CI: 1.813 to 18.396). Virus was identified in 25/30 (83%) preterm babies, and in 110/129 (85%) term infants. The most frequent viruses in preterm infants were RSV (76%) rhinovirus (20%). Clinical and epidemiological characteristics among term and preterm infants were similar.

Conclusions

The risk of respiratory admissions during the first year of life is up to 3.6 times higher in moderate and late preterm. Once admitted, clinical features of respiratory episodes requiring hospitalisation are similar among term and preterm infants. Hyaline membrane disease and mechanical ventilation were also risk factors for respiratory admissions.

PCR testing for paediatric acute respiratory tract infections

Acute respiratory tract infection (ARI) is a frequently occurring disease in children. It is a clinical diagnosis for which no internationally accepted diagnostic test is available. The majority of ARI is viral in origin, though diagnostic tests for viruses were rarely performed in the past. In the past 2 decades, new molecular techniques have been introduced in many hospitals. They are capable of generating a high yield of viral and bacterial diagnoses, but their impact upon clinical practices is still questionable. In this paper, we discuss the difficulties of diagnosing ARI in children, the indications for conventional and new diagnostics and their implications.

Beyond malaria--causes of fever in outpatient Tanzanian children

BACKGROUND

As the incidence of malaria diminishes, a better understanding of nonmalarial fever is important for effective management of illness in children. In this study, we explored the spectrum of causes of fever in African children.

METHODS

We recruited children younger than 10 years of age with a temperature of 38°C or higher at two outpatient clinics--one rural and one urban--in Tanzania. Medical histories were obtained and clinical examinations conducted by means of systematic procedures. Blood and nasopharyngeal specimens were collected to perform rapid diagnostic tests, serologic tests, culture, and molecular tests for potential pathogens causing acute fever. Final diagnoses were determined with the use of algorithms and a set of prespecified criteria.

RESULTS

Analyses of data derived from clinical presentation and from 25,743 laboratory investigations yielded 1232 diagnoses. Of 1005 children (22.6% of whom had multiple diagnoses), 62.2% had an acute respiratory infection; 5.0% of these infections were radiologically confirmed pneumonia. A systemic bacterial, viral, or parasitic infection other than malaria or typhoid fever was found in 13.3% of children, nasopharyngeal viral infection (without respiratory symptoms or signs) in 11.9%, malaria in 10.5%, gastroenteritis in 10.3%, urinary tract infection in 5.9%, typhoid fever in 3.7%, skin or mucosal infection in 1.5%, and meningitis in 0.2%. The cause of fever was undetermined in 3.2% of the children. A total of 70.5% of the children had viral disease, 22.0% had bacterial disease, and 10.9% had parasitic disease.

CONCLUSIONS

These results provide a description of the numerous causes of fever in African children in two representative settings. Evidence of a viral process was found more commonly than evidence of a bacterial or parasitic process. (Funded by the Swiss National Science Foundation and others.).

Human bocavirus 1 infects commercially available primary human airway epithelium cultures productively

Human bocavirus 1 (HBoV1), a human parvovirus, belongs to the genus Bocavirus of the Parvoviridae family. It causes wheezing in young children with acute respiratory tract infections. HBoV1 has been shown to infect polarized human airway epithelium (HAE) made in house, and induces airway epithelial damage. In this study, two commercially available HAE cultures, EpiAirway and MucilAir HAE, were examined for HBoV1 infection. Both HAE cultures support fully productive HBoV1 infection. Infected EpiAirway and MucilAir HAE cultures showed loss of cilia, disruption of the tight junction barrier, and a significant decrease in transepithelial electrical resistance. Notably, HBoV1 persistent infection was demonstrated by maintaining HBoV1-infected EpiAirway HAE for as long as 50 days. After 2 days post-infection, progeny virus was produced consistently daily at a level of over 2×10(8) viral genome copies per culture (0.6 cm(2)). This study is the first to use commercial sources of HAE cultures for HBoV1 infection. The availability of these cultures will enable a wide range of laboratories to study HBoV1 infection.

Virus-induced exacerbations in asthma and COPD

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation and/or airflow limitation due to pulmonary emphysema. Chronic bronchitis, pulmonary emphysema, and bronchial asthma may all be associated with airflow limitation; therefore, exacerbation of asthma may be associated with the pathophysiology of COPD. Furthermore, recent studies have suggested that the exacerbation of asthma, namely virus-induced asthma, may be associated with a wide variety of respiratory viruses. COPD and asthma have different underlying pathophysiological processes and thus require individual therapies. Exacerbation of both COPD and asthma, which are basically defined and diagnosed by clinical symptoms, is associated with a rapid decline in lung function and increased mortality. Similar pathogens, including human rhinovirus, respiratory syncytial virus, influenza virus, parainfluenza virus, and coronavirus, are also frequently detected during exacerbation of asthma and/or COPD. Immune response to respiratory viral infections, which may be related to the severity of exacerbation in each disease, varies in patients with both COPD and asthma. In this regard, it is crucial to recognize and understand both the similarities and differences of clinical features in patients with COPD and/or asthma associated with respiratory viral infections, especially in the exacerbative stage. In relation to definition, epidemiology, and pathophysiology, this review aims to summarize current knowledge concerning exacerbation of both COPD and asthma by focusing on the clinical significance of associated respiratory virus infections.

Virus-induced exacerbations in asthma and COPD

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation and/or airflow limitation due to pulmonary emphysema. Chronic bronchitis, pulmonary emphysema, and bronchial asthma may all be associated with airflow limitation; therefore, exacerbation of asthma may be associated with the pathophysiology of COPD. Furthermore, recent studies have suggested that the exacerbation of asthma, namely virus-induced asthma, may be associated with a wide variety of respiratory viruses. COPD and asthma have different underlying pathophysiological processes and thus require individual therapies. Exacerbation of both COPD and asthma, which are basically defined and diagnosed by clinical symptoms, is associated with a rapid decline in lung function and increased mortality. Similar pathogens, including human rhinovirus, respiratory syncytial virus, influenza virus, parainfluenza virus, and coronavirus, are also frequently detected during exacerbation of asthma and/or COPD. Immune response to respiratory viral infections, which may be related to the severity of exacerbation in each disease, varies in patients with both COPD and asthma. In this regard, it is crucial to recognize and understand both the similarities and differences of clinical features in patients with COPD and/or asthma associated with respiratory viral infections, especially in the exacerbative stage. In relation to definition, epidemiology, and pathophysiology, this review aims to summarize current knowledge concerning exacerbation of both COPD and asthma by focusing on the clinical significance of associated respiratory virus infections.

A single dose of azithromycin does not improve clinical outcomes of children hospitalised with bronchiolitis: a randomised, placebo-controlled trial

Objective

Bronchiolitis, one of the most common reasons for hospitalisation in young children, is particularly problematic in Indigenous children. Macrolides may be beneficial in settings where children have high rates of nasopharyngeal bacterial carriage and frequent prolonged illness. The aim of our double-blind placebo-controlled randomised trial was to determine if a large single dose of azithromycin (compared to placebo) reduced length of stay (LOS), duration of oxygen (O₂) and respiratory readmissions within 6 months of children hospitalised with bronchiolitis. We also determined the effect of azithromycin on nasopharyngeal microbiology.

Methods

Children aged ≤18 months were randomised to receive a single large dose (30 mg/kg) of either azithromycin or placebo within 24 hrs of hospitalisation. Nasopharyngeal swabs were collected at baseline and 48hrs later. Primary endpoints (LOS, O₂) were monitored every 12 hrs. Hospitalised respiratory readmissions 6-months post discharge was collected.

Results

97 children were randomised (n = 50 azithromycin, n = 47 placebo). Median LOS was similar in both groups; azithromycin = 54 hours, placebo = 58 hours (difference between groups of 4 hours 95%CI -8, 13, p = 0.6). O₂ requirement was not significantly different between groups; Azithromycin = 35 hrs; placebo = 42 hrs (difference 7 hours, 95%CI -9, 13, p = 0.7). Number of children re-hospitalised was similar 10 per group (OR = 0.9, 95%CI 0.3, 2, p = 0.8). At least one virus was detected in 74% of children. The azithromycin group had reduced nasopharyngeal bacterial carriage (p = 0.01) but no difference in viral detection at 48 hours.

Conclusion

Although a single dose of azithromycin reduces carriage of bacteria, it is unlikely to be beneficial in reducing LOS, duration of O₂ requirement or readmissions in children hospitalised with bronchiolitis. It remains uncertain if an earlier and/or longer duration of azithromycin improves clinical and microbiological outcomes for children. The trial was registered with the Australian and New Zealand Clinical Trials Register. Clinical trials number: ACTRN12608000150347. http://www.anzctr.org.au/TrialSearch.aspx.

Pediatric chronic lower respiratory disorders: microbiological and immunological phenotype

The role of infectious agents in children with recurrent/chronic lower respiratory disorders (R/CLRDs) is not clear, whereas it has been largely studied in acute respiratory diseases. The purpose of the study was to evaluate the frequency of infections, in particular viral infections, in children with R/CLRDs correlating their presence with clinical/biohumoral parameters. Eighty children affected by R/CLRDs underwent bronchoscopy and analysis of bronchoalveolar lavage (BAL) for cells, mediators (eosinophil cationic protein-ECP, interleukin-IL-8, tumor necrosis factor-TNFα) and pathogens (viruses and bacteria). Viral genomes were detected in 50/80 (62.5%) children. Rhinovirus, the principal detected virus (26/50, 52%), occurred more frequently in male children. Higher percentages of BAL neutrophils and IL-8 values were detected in virus positive than negative children. ECP values resulted significantly higher in the children with rhinovirus than in those with other viruses. No other statistically significant correlation between viral findings and clinical/biohumoral data were found. Respiratory viruses, especially rhinovirus, seem to play an important role in children with R/CLRDs. They are associated with changes in BAL cellularity and inflammatory cytokines. Further studies are needed to confirm the persistence of viruses in these patients and to identify eventual therapeutic strategies.

Breaking in: human metapneumovirus fusion and entry

Human metapneumovirus (HMPV) is a leading cause of respiratory infection that causes upper airway and severe lower respiratory tract infections. HMPV infection is initiated by viral surface glycoproteins that attach to cellular receptors and mediate virus membrane fusion with cellular membranes. Most paramyxoviruses use two viral glycoproteins to facilitate virus entry—an attachment protein and a fusion (F) protein. However, membrane fusion for the human paramyxoviruses in the Pneumovirus subfamily, HMPV and respiratory syncytial virus (hRSV), is unique in that the F protein drives fusion in the absence of a separate viral attachment protein. Thus, pneumovirus F proteins can perform the necessary functions for virus entry, i.e., attachment and fusion. In this review, we discuss recent advances in the understanding of how HMPV F mediates both attachment and fusion. We review the requirements for HMPV viral surface glycoproteins during entry and infection, and review the identification of cellular receptors for HMPV F. We also review our current understanding of how HMPV F mediates fusion, concentrating on structural regions of the protein that appear to be critical for membrane fusion activity. Finally, we illuminate key unanswered questions and suggest how further studies can elucidate how this clinically important paramyxovirus fusion protein may have evolved to initiate infection by a unique mechanism.

Elucidation and clinical role of emerging viral respiratory tract infections in children

Acute respiratory viral infections (ARVI's) are the most common infectious disease in humans. With the appearance of molecular techniques the recovery of viruses has dramatically increased. Nowadays virologists can quickly discriminate virological families and related viruses from emerging viruses and consequently identify novel viruses. Many new respiratory viruses have been identified in children in the past 15 years. In this review we shortly discuss novel respiratory viruses and their pathogenic role in pediatric respiratory disease. Advantages and drawbacks of the technique and our current knowledge will be discussed. We will conclude this review with a general discussion on the future role of molecular diagnostic virology in the clinic.

Temperature, nitrogen dioxide, circulating respiratory viruses and acute upper respiratory infections among children in Taipei, Taiwan: a population-based study

OBJECTIVE

This study investigated whether outpatient visits of acute upper respiratory infections for children aged less than 15 years are associated with temperature, air pollutants and circulating respiratory viruses in Taipei, Taiwan, from 2003 to 2007.

METHODS

Outpatient records for acute upper respiratory infections (ICD9 CM codes: 460, 462, 463,464, 465.9 and 487) in a randomly selected sample (n=39,766 children in 2005) was used to estimate the cumulative relative risks (RR) associated with average temperature lasting for 8 days (lag 0-7 days), air pollutants (NO2, O3 and PM(2.5)) lasting for 6 days (lag 0-5 days), and virus-specific positive isolation rate lasting for 11 days (lag 0-10 days) using distributed lag non-linear models after controlling for relative humidity, wind speed, day of week, holiday effects and long-term trend.

RESULTS

Average temperature of 33 °C was associated with the lowest risk for outpatient visits of acute upper respiratory infections. Relative to 33 °C, cumulative 8-day RR was highest at 15 °C of ambient average temperature [RR=1.94; 95% confidence interval (CI): 1.78, 2.11]. With the first quartile as reference, cumulative 6-day RRs were 1.25 (95% CI: 1.21, 1.29) for NO2, 1.04 (95% CI: 1.01, 1.06) for O3, and 1.00 (95% CI: 0.98, 1.03) for PM(2.5) at the 95th percentile. Per-standard deviation (SD) increase of virus-specific isolation rate for influenza type A (SD=13.2%), type B (SD=8.76%), and adenoviruses (SD=5.25%) revealed statistical significance for overall 11-day RRs of 1.02 (95% CI: 1.01, 1.03), 1.05 (95% CI: 1.03, 1.06) and 1.04 (95% CI: 1.03, 1.05), respectively.

CONCLUSIONS

Current study suggested a positive association between outpatient visits for acute upper respiratory infections and ambient environment factors, including average temperature, air pollutants, and circulating respiratory viruses.

Formation of a stable mimic of ambient particulate matter containing viable infectious respiratory syncytial virus and its dry-deposition directly onto cell cultures

Epidemiological associations of worse respiratory outcomes from combined exposure to ambient particulate matter (PM) and respiratory viral infection suggest possible interactions between PM and viruses. To characterize outcomes of such exposures, we developed an in vitro mimic of the in vivo event of exposure to PM contaminated with respiratory syncytial virus (RSV). Concentration of infectious RSV stocks and a particle levitation apparatus were the foundations of the methodology developed to generate specific numbers of PM mimics (PM(Mimics)) of known composition for dry, direct deposition onto airway epithelial cell cultures. Three types of PM(Mimics) were generated for this study: (i) carbon alone (P(C)), (ii) carbon and infectious RSV (P(C+RSV)), and (iii) aerosols consisting of RSV (A(RSV)). P(C+RSV) were stable in solution and harbored infectious RSV for up to 6 months. Unlike A(RSV) infection, P(C+RSV) infection was found to be dynamin dependent and to cause lysosomal rupture. Cells dosed with PM(Mimics) comprised of RSV (A(RSV)), carbon (P(C)), or RSV and carbon (P(C+RSV)) responded differentially as exemplified by the secretion patterns of IL-6 and IL-8. Upon infection, and prior to lung cell death due to viral infection, regression analysis of these two mediators in response to incubation with A(RSV), P(C), or P(C+RSV) yielded higher concentrations upon infection with the latter and at earlier time points than the other PM(Mimics). In conclusion, this experimental platform provides an approach to study the combined effects of PM-viral interactions and airway epithelial exposures in the pathogenesis of respiratory diseases involving inhalation of environmental agents.

Specific viruses detected in nigerian children in association with acute respiratory disease

Occurrence of different viruses in acute respiratory tract infections of Nigerian children was examined. Respiratory swabs were collected from 246 children referred to hospital clinics because of acute respiratory symptoms from February through May 2009. Validated real-time RT-PCR techniques revealed nucleic acids of at least one virus group in 189 specimens (77%). Human rhinoviruses and parainfluenza viruses were present each in one third of the children. Adenoviruses, enteroviruses, human metapneumovirus, human bocavirus, and influenza C virus were also relatively common. Possibly due to their seasonal occurrence, influenza A and B virus, and respiratory syncytial virus were detected rarely. We conclude that all major groups of respiratory tract viruses are causing illness in Nigerian children.

Comparative evaluation of the Seegene Seeplex RV15 and real-time PCR for respiratory virus detection

Respiratory virus infections contribute substantially both to hospitalizations of young children, and to morbidity in immunocompromised patients such as those with hematological malignancies. Their rapid and accurate diagnosis is essential to patient management. To evaluate the prospective utility of Seeplex® DPO technology in respiratory virus diagnosis, a panel of 99 respiratory samples positive by real‐time RT‐PCR for one or more viruses was assayed by the Seegene Seeplex® RV12 system. As well as being able to detect all 10 viruses in the real‐time RT‐PCR system with the exception of enteroviruses, RV12 can also distinguish between the two subgroups of RSV and detect two subgroups of coronaviruses. Seven of the nine viruses in common with the RT‐PCR were detected reliably by RV12. Eleven samples RT‐PCR‐positive for Metapneumovirus and five samples positive for influenza B were not detected by RV12. Seegene developed a second‐generation system, RV15, which not only allowed detection of three additional viruses, but also addressed the potential problems with RV12 specificity. To address these concerns, 84 respiratory samples positive for a range of viruses by real‐time PCR were assayed with RV15. The results of this evaluation improved significantly upon those seen with RV12. The high throughput capabilities and potential lower technical requirements afforded by the Seeplex® system may offer an alternative to real‐time RT‐PCR systems. J. Med. Virol. 83:1469–1475, 2011. © 2011 Wiley‐Liss, Inc.

Timely diagnosis of respiratory tract infections: evaluation of the performance of the Respifinder assay compared to the xTAG respiratory viral panel assay

Background

Respiratory tract infections are the most common cause of hospitalization in infants and young children and are typically caused by viral or, less commonly, bacterial pathogens.

Existing non-molecular diagnostic methods have several drawbacks such as limited sensitivity, long turn-a-round time and limited number of pathogens that can be detected.

Objectives

Nucleic acid amplification methods can increase sensitivity and enable the initiation of appropriate interventions without delay.

Broad-spectrum detection and identification circumvent the use of individual diagnostic DNA or RNA based assays. At present, several commercial assays are available for broad-spectrum detection.

Study design

We compared the performance of the xTAG Respiratory Viral Panel (RVP) (Luminex Molecular Diagnostics, Toronto, Canada) with that of the Respifinder (Pathofinder, Maastricht, Netherlands) for 9 external quality assurance (EQA) panels (QCMD, Scotland) consisting of a total of 106 EQA samples.

Results

Both the RVP and the Respifinder assay have an excellent specificity. Sensitivity was 33% and 78% for the RVP and the Respifinder assay, respectively. For both assays, sensitivity was low for weak positive samples.

Discussion

The results of our study seem to indicate a better sensitivity for the Respifinder. Analysis of patient samples is necessary to evaluate the clinical performance.

Non-invasive sample collection for respiratory virus testing by multiplex PCR

Background

Identifying respiratory pathogens within populations is difficult because invasive sample collection, such as with nasopharyngeal aspirate (NPA), is generally required. PCR technology could allow for non-invasive sampling methods.

Objective

Evaluate the utility of non-invasive sample collection using anterior nare swabs and facial tissues for respiratory virus detection by multiplex PCR.

Study design

Children aged 1 month–17 years evaluated in a pediatric emergency department for respiratory symptoms had a swab, facial tissue, and NPA sample collected. All samples were tested for respiratory viruses by multiplex PCR. Viral detection rates were calculated for each collection method. Sensitivity and specificity of swabs and facial tissues were calculated using NPA as the gold standard.

Results

285 samples from 95 children were evaluated (92 swab-NPA pairs, 91 facial tissue-NPA pairs). 91% of NPA, 82% of swab, and 77% of tissue samples were positive for ≥ 1 virus. Respiratory syncytial virus (RSV) and human rhinovirus (HRV) were most common. Overall, swabs were positive for 74% of virus infections, and facial tissues were positive for 58%. Sensitivity ranged from 17 to 94% for swabs and 33 to 84% for tissues. Sensitivity was highest for RSV (94% swabs and 84% tissues). Specificity was ≥95% for all viruses except HRV for both collection methods.

Conclusions

Sensitivity of anterior nare swabs and facial tissues in the detection of respiratory viruses by multiplex PCR varied by virus type. Given its simplicity and specificity, non-invasive sampling for PCR testing may be useful for conducting epidemiologic or surveillance studies in settings where invasive testing is impractical or not feasible.

Human bocavirus as an important cause of respiratory tract infection in Taiwanese children

BACKGROUND

Human bocavirus (HBoV), first described in September 2005, was considered a causative agent of previously unexplained respiratory tract diseases. However, only few reports provide the evidence for an association between HBoV and respiratory tract diseases. We conducted a prospective clinical and molecular study of HBoV in Taiwan.

METHODS

We enrolled 705 children who visited our outpatient pediatric clinics in a medical center because of symptoms and signs of respiratory tract infections from November 2008 to October 2009. Throat swab was performed and HBoV polymerase chain reaction and viral culture were done simultaneously.

RESULTS

Positive viral results were confirmed in 159 (22.6%) of the 705 children. HBoV was found in 35 samples and it was supposed to be as a single virus in 32 samples because viral isolation of these 32 samples did not identify other virus. The other three patients had coinfection with another virus. One child got HBoV reinfection 6 months after the first infection. Seventy-one percentage of these HBoV infections occurred between November and March. Of the 34 children with positive HBoV, 26 (76%) patients were younger than 5 years; their common symptoms were cough, rhinorrhea, and fever; the most common diagnoses were bronchitis (34%, 12/35) and sinusitis (31%, 11/35) followed by pharyngitis (29%, 10/35) and asthma exacerbation (26%, 9/35). Three of the 34 patients needed hospitalization.

CONCLUSION

HBoV is an emerging human parvovirus that may cause respiratory tract infection in young children. Diseases associated with HBoV may range from pharyngitis, sinusitis, acute otitis media to bronchitis, asthma, and even pneumonia.

Health Care–Associated Infection in the Pediatric Intensive Care Unit

•Handwashing is the most important means of preventing nosocomial infection. Each pediatric intensive care unit should develop programs to increase compliance with hand hygiene. •Nonessential invasive devices should be removed. Establish routines that require individual patient evaluation of device use daily. •Antimicrobial stewardship aims to minimize overexposure and unnecessary use of broad-spectrum antibiotics. Antibiotic-resistant bacteria are an increasing concern as a cause of hospital-acquired infection, requiring a multipronged approach to control that includes adherence to isolation procedures, appropriate use of antibiotics, educational interventions, prescribing guidelines, and restriction of the use of some antibiotics. •A comprehensive infection prevention and control program allied with organizational quality and patient safety programs is an essential strategy for minimizing hospital-acquired infections. Critical care teams should establish strong collaborative partnerships with the infection prevention and control service. •Parents and visitors should be made partners of the infection control team to help prevent infection in their children.