Chronic Rhinoviral Infection in Lung Transplant Recipients

Detection of human rhinoviruses in the lower respiratory tract of lung transplant recipients

The occurrence of human rhinoviruses (HRV) and its relationship to clinical and histopathological findings were investigated in 127 bronchoalveolar lavage specimens from 36 lung transplant recipients by real-time RT-PCR. In addition, 286 samples from 235 other immunocompromised and immunocompetent patients were also studied. HRV was detected in 41.7% of lung transplant recipients vs 14.5% of other patients (p < 0.0001), and no differences in viral load were observed. Acute respiratory insufficiency was found in 15 cases, three of which were HRV positive (viral load, 6.3 x 10(6) RNA copies/ml in one patient with chronic graft dysfunction). A diagnosis of pneumonia was made in 10 out of 127 cases, two of which were HRV positive (viral load, 10(3)-10(4) in cases of co-infection). Acute rejection was diagnosed in 12 cases, three of which were HRV positive (viral load, 10(3) in two cases of co-infection and 10(5) in a single infection). HRV infection may involve the lower respiratory tract, particularly in the presence of an impaired pulmonary background, such as a transplanted lung. Clinical evaluation should take into account the viral load, with a load of >10(5) possibly being associated with clinical symptoms, although lower loads can be detected in both symptomatic and asymptomatic patients.

The human rhinovirus: human-pathological impact, mechanisms of antirhinoviral agents, and strategies for their discovery

As the major etiological agent of the common cold, human rhinoviruses (HRV) cause millions of lost working and school days annually. Moreover, clinical studies proved an association between harmless upper respiratory tract infections and more severe diseases e.g. sinusitis, asthma, and chronic obstructive pulmonary disease. Both the medicinal and socio-economic impact of HRV infections and the lack of antiviral drugs substantiate the need for intensive antiviral research. A common structural feature of the approximately 100 HRV serotypes is the icosahedrally shaped capsid formed by 60 identical copies of viral capsid proteins VP1-4. The capsid protects the single-stranded, positive sense RNA genome of about 7,400 bases in length. Both structural as well as nonstructural proteins produced during the viral life cycle have been identified as potential targets for blocking viral replication at the step of attachment, entry, uncoating, RNA and protein synthesis by synthetic or natural compounds. Moreover, interferon and phytoceuticals were shown to protect host cells. Most of the known inhibitors of HRV replication were discovered as a result of empirical or semi-empirical screening in cell culture. Structure-activity relationship studies are used for hit optimization and lead structure discovery. The increasing structural insight and molecular understanding of viral proteins on the one hand and the advent of innovative computer-assisted technologies on the other hand have facilitated a rationalized access for the discovery of small chemical entities with antirhinoviral (anti-HRV) activity. This review will (i) summarize existing structural knowledge about HRV, (ii) focus on mechanisms of anti-HRV agents from synthetic and natural origin, and (iii) demonstrate strategies for efficient lead structure discovery.

[Children with cancer and respiratory viral infection: epidemiology, diagnosis and treatment options]

Community-adquired respiratory viral infection is the most common cause of febrile infection in children, and an important cause of infection to consider in children with cancer. Nevertheless, there are few well-designed, controlled studies in this population, which makes it difficult to understand the importance, behaviour and management of these viruses in immunocompromised children. New diagnostic techniques in PCR-based microbiology, could provide many opportunities for early diagnosis, preventing the spread of the virus and to implement the correct therapy. It is important to design appropriate prospective studies to assess these types of infections in children with cancer. In this review we analyse the main studies published in the literature, evaluating the epidemiology, diagnosis and management of children with cancer and respiratory viral infection.

Allergic sensitization is associated with rhinovirus-, but not other virus-, induced wheezing in children

BACKGROUND

Data on the link between atopy and viral wheeze are limited.

AIM

To evaluate the association between IgE sensitization and viral infection in wheezing children.

METHODS

This is an observational study in hospitalized wheezing children (n = 247; median age 1.6 ; interquartile range 1.1, 2.9). Eighteen respiratory viral infections were studied using all available methods. A specific immunoglobulin E (IgE) sensitization for common food and aeroallergens and other atopy-related variables including total IgE, blood and nasal eosinophils, exhaled nitric oxide, eczema and atopic eczema, parental allergy and asthma, number of wheezing episodes, positive asthma predictive index or asthma and use of inhaled corticosteroid were correlated with specific viral etiology.

RESULTS

Atopy was closely associated with sole rhinovirus etiology (n = 58) but not with sole respiratory syncytial virus, sole enterovirus, sole human bocavirus, sole other virus, mixed viral, or virus negative etiology. The number of sensitizations was particularly associated with sole rhinovirus etiology (odds ratio 4.59; 95% confidence interval 1.78, 11.8; adjusted to age and sex), followed by aeroallergen sensitization (respectively; 4.18; 2.00, 8.72), total IgE level (2.06; 1.32, 3.21), food allergen sensitization (2.02; 1.08, 3.78), and nasal eosinophil count (1.52; 1.08, 2.13).

CONCLUSIONS

According to our data, allergic sensitization is positively linked to rhinovirus-, but not other virus-, associated wheezing and calls attention for studies to test rhinovirus-associated wheezing as a part of asthma risk indices.

Human rhinovirus C: a newly discovered human rhinovirus species

Although often ignored, human rhinoviruses (HRVs) are the most frequent causes of respiratory tract infections (RTIs). A group of closely related novel rhinoviruses have recently been discovered. Based on their unique phylogenetic position and distinct genomic features, they are classified as a separate species, HRV-C. After their discovery, HRV-C viruses have been detected in patients worldwide, with a reported prevalence of 1.4-30.9% among tested specimens. This suggests that the species contribute to a significant proportion of RTIs that were unrecognized in the past. HRV-C is also the predominant HRV species, often with a higher detection rate than that of the two previously known species, HRV-A and HRV-B. HRV-C infections appear to peak in fall or winter in most temperate or subtropical countries, but may predominate in the rainy season in the tropics. In children, HRV-C is often associated with upper RTIs, with asthma exacerbation and wheezing episodes being common complications. The virus has also been detected in children with bronchitis, bronchiolitis, pneumonia, otitis media, sinusitis and systemic infections complicated by pericarditis. As for adults, HRV-C has been associated with more severe disease such as pneumonia and exacerbation of chronic obstructive pulmonary disease. However, larger clinical studies with asymptomatic controls are required to better define the significance of HRV-C infection in the adult population. On the basis of VP4 sequence analysis, a potential distinct subgroup within HRV-C has also been identified, although more complete genome sequences are needed to better define the genetic diversity of HRV-C.

Viral respiratory tract infections and asthma: the course ahead

Inquiries into the relationships between viral respiratory tract illnesses and the inception and exacerbation of asthma are being facilitated by recent advances in research approaches and technology. In this article we identify important knowledge gaps and future research questions, and we discuss how new investigational tools, including improved respiratory tract virus detection techniques, will permit current and future researchers to define these relationships and the host, virus, developmental, and environmental mechanisms that regulate them. A better understanding of these processes should facilitate the development of improved strategies for the prevention and treatment of virus-induced wheezing illnesses and asthma exacerbations and, possibly, the ultimate goal of discovering effective approaches for the primary prevention of asthma.

Newly identified human rhinoviruses: molecular methods heat up the cold viruses

Human rhinovirus (HRV) infections cause at least 70% of virus‐related wheezing exacerbations and cold and flu‐like illnesses. They are associated with otitis media, sinusitis and pneumonia. Annually, the economic impact of HRV infections costs billions in healthcare and lost productivity. Since 1987, 100 officially recognised HRV serotypes reside in two genetically distinct species; HRV A and HRV B, within the genus Enterovirus, family Picornaviridae. Sequencing of their ∼7kb genomes was finalised in 2009. Since 1999, many globally circulating, molecularly‐defined ‘strains’, perhaps equivalent to novel serotypes, have been discovered but remain uncharacterised. Many of these currently unculturable strains have been assigned to a proposed new species, HRV C although confusion exists over the membership of the species. There has not been sufficient sampling to ensure the identification of all strains and no consensus criteria exist to define whether clinical HRV detections are best described as a distinct strain or a closely related variant of a previously identified strain (or serotype). We cannot yet robustly identify patterns in the circulation of newly identified HRVs (niHRVs) or the full range of associated illnesses and more data are required. Many questions arise from this new found diversity: what drives the development of so many distinct viruses compared to other species of RNA viruses? What role does recombination play in generating this diversity? Are there species‐ or strain‐specific circulation patterns and clinical outcomes? Are divergent strains sensitive to existing capsid‐binding antivirals? This update reviews the findings that trigger these and other questions arising during the current cycle of intense rhinovirus discovery. Copyright © 2010 John Wiley & Sons, Ltd.

Rhinovirus infection of allergen-sensitized and -challenged mice induces eotaxin release from functionally polarized macrophages

Human rhinovirus is responsible for the majority of virus-induced asthma exacerbations. To determine the immunologic mechanisms underlying rhinovirus (RV)-induced asthma exacerbations, we combined mouse models of allergic airways disease and human rhinovirus infection. We inoculated OVA-sensitized and challenged BALB/c mice with rhinovirus serotype 1B, a minor group strain capable of infecting mouse cells. Compared with sham-infected, OVA-treated mice, virus-infected mice showed increased lung infiltration with neutrophils, eosinophils and macrophages, airway cholinergic hyperresponsiveness, and increased lung expression of cytokines including eotaxin-1/CCL11, IL-4, IL-13, and IFN-gamma. Administration of anti-eotaxin-1 attenuated rhinovirus-induced airway eosinophilia and responsiveness. Immunohistochemical analysis showed eotaxin-1 in the lung macrophages of virus-infected, OVA-treated mice, and confocal fluorescence microscopy revealed colocalization of rhinovirus, eotaxin-1, and IL-4 in CD68-positive cells. RV inoculation of lung macrophages from OVA-treated, but not PBS-treated, mice induced expression of eotaxin-1, IL-4, and IL-13 ex vivo. Macrophages from OVA-treated mice showed increased expression of arginase-1, Ym-1, Mgl-2, and IL-10, indicating a shift in macrophage activation status. Depletion of macrophages from OVA-sensitized and -challenged mice reduced eosinophilic inflammation and airways responsiveness following RV infection. We conclude that augmented airway eosinophilic inflammation and hyperresponsiveness in RV-infected mice with allergic airways disease is directed in part by eotaxin-1. Airway macrophages from mice with allergic airways disease demonstrate a change in activation state characterized in part by altered eotaxin and IL-4 production in response to RV infection. These data provide a new paradigm to explain RV-induced asthma exacerbations.

Proposals for the classification of human rhinovirus species C into genotypically assigned types

Human rhinoviruses (HRVs) are common respiratory pathogens associated with mild upper respiratory tract infections, but also increasingly recognized in the aetiology of severe lower respiratory tract disease. Wider use of molecular diagnostics has led to a recent reappraisal of HRV genetic diversity, including the discovery of HRV species C (HRV-C), which is refractory to traditional virus isolation procedures. Although it is heterogeneous genetically, there has to date been no attempt to classify HRV-C into types analogous to the multiple serotypes identified for HRV-A and -B and among human enteroviruses. Direct investigation of cross-neutralization properties of HRV-C is precluded by the lack of methods for in vitro culture, but sequences from the capsid genes (VP1 and partial VP4/VP2) show evidence for marked phylogenetic clustering, suggesting the possibility of a genetically based system comparable to that used for the assignment of new enterovirus types. We propose a threshold of 13% divergence for VP1 nucleotide sequences for type assignment, a level that classifies the current dataset of 86 HRV-C VP1 sequences into a total of 33 types. We recognize, however, that most HRV-C sequence data have been collected in the VP4/VP2 region (currently 701 sequences between positions 615 and 1043). We propose a subsidiary classification of variants showing > 10% divergence in VP4/VP2, but lacking VP1 sequences, to 28 provisionally assigned types (subject to confirmation once VP1 sequences are determined). These proposals will assist in future epidemiological and clinical studies of HRV-C conducted by different groups worldwide, and provide the foundation for future exploration of type-associated differences in clinical presentations and biological properties.

Recurrent and persistent respiratory tract viral infections in patients with primary hypogammaglobulinemia

Background

The occurrence of respiratory tract viral infections in patients with primary hypogammaglobulinemia has not been studied.

Objective

We conducted a prospective 12-month follow-up study of respiratory tract infections in 12 adult patients with primary hypogammaglobulinemia.

Methods

Nasal swab samples and induced sputum samples were taken at the onset of acute respiratory tract infection and every 3 months thereafter. Samples were tested for bacteria and viruses. PCR tests were performed for 15 respiratory tract viruses. In case the results for rhinovirus were positive, follow-up nasal swab samples were taken every 2 weeks until rhinoviral PCR results became negative. Patients completed symptom diaries, which were collected every month. The spouses of the patients served as healthy control subjects.

Results

During the 12-month period, the 12 patients had 65 episodes of acute respiratory tract infections, and the 11 spouses had 12 acute episodes (P < .001). Respiratory tract viruses were found in sputum in 54% of the infections. Rhinovirus was the most common virus. In more than half of our patients, rhinoviral PCR results stayed positive for more than 2 months. The most long-acting persistence with the same rhinovirus was 4 months.

Conclusions

Despite adequate immunoglobulin replacement therapy, patients with primary hypogammaglobulinemia have increased susceptibility to respiratory tract viral infections. Rhinoviral infections are frequent and prolonged.

Human monocytic cells direct the robust release of CXCL10 by bronchial epithelial cells during rhinovirus infection

BACKGROUND

Human rhinovirus (HRV) infections are a major cause of exacerbations in chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease, but HRV-induced immune responses of the lower airway are poorly understood. Earlier work examining cytokine release following HRV infection has focused on epithelial cells because they serve as the principal site of viral replication, and internalization and replication of viral RNA appear necessary for epithelial cell mediator release. However, during HRV infection, only a small proportion of epithelial cells become infected. As HRV-induced cytokine levels in vivo are markedly elevated, this observation suggests that other mechanisms independent of direct viral infection may induce epithelial cell cytokine release.

OBJECTIVE

Our aim was to test for the importance of interactions between human bronchial epithelial cells (HBECs) and monocytic cells in the control of mediator release during HRV exposure.

METHODS

In vitro models of HRV serotype-16 (HRV16) infection of primary HBECs and human monocytic cells, in mono or co-culture, were used. We assessed HRV16-induced CXCL10 and CCL2 protein release via ELISA.

RESULTS

Co-culture of human monocytic and bronchial epithelial cells promoted a synergistic augmentation of CXCL10 and CCL2 protein release following HRV16 challenge. Transfer of conditioned media from HRV16-treated monocytic cells to epithelial cultures induced a robust release of CXCL10 by the epithelial cells. This effect was greatly attenuated by type I IFN receptor blocking antibodies, and could be recapitulated by IFN-alpha addition.

CONCLUSIONS

Our data indicate that epithelial CXCL10 release during HRV infection is augmented by a monocytic cell-dependent mechanism involving type I IFN(s). Our findings support a key role for monocytic cells in the amplification of epithelial cell chemokine production during HRV infection, and help to explain how an inflammatory milieu is created in the lower airways even in the absence of extensive viral replication and epithelial infection.

Rhinovirus genome evolution during experimental human infection

Human rhinoviruses (HRVs) evolve rapidly due in part to their error-prone RNA polymerase. Knowledge of the diversity of HRV populations emerging during the course of a natural infection is essential and represents a basis for the design of future potential vaccines and antiviral drugs. To evaluate HRV evolution in humans, nasal wash samples were collected daily for five days from 15 immunocompetent volunteers experimentally infected with a reference stock of HRV-39. In parallel, HeLa-OH cells were inoculated to compare HRV evolution in vitro. Nasal wash in vivo assessed by real-time PCR showed a viral load that peaked at 48–72 h. Ultra-deep sequencing was used to compare the low-frequency mutation populations present in the HRV-39 inoculum in two human subjects and one HeLa-OH supernatant collected 5 days post-infection. The analysis revealed hypervariable mutation locations in VP2, VP3, VP1, 2C and 3C genes and conserved regions in VP4, 2A, 2B, 3A, 3B and 3D genes. These results were confirmed by classical sequencing of additional samples, both from inoculated volunteers and independent cell infections, and suggest that HRV inter-host transmission is not associated with a strong bottleneck effect. A specific analysis of the VP1 capsid gene of 15 human cases confirmed the high mutation incidence in this capsid region, but not in the antiviral drug-binding pocket. We could also estimate a mutation frequency in vivo of 3.4×10⁻⁴ mutations/nucleotides and 3.1×10⁻⁴ over the entire ORF and VP1 gene, respectively. In vivo, HRV generate new variants rapidly during the course of an acute infection due to mutations that accumulate in hot spot regions located at the capsid level, as well as in 2C and 3C genes.

Human rhinovirus and coronavirus detection among allogeneic hematopoietic stem cell transplantation recipients

Little is known about clinical and virologic manifestations of rhinovirus (HRV) and coronavirus (HCoV) infections after hematopoietic cell transplantation (HCT). We performed surveillance for 1 year and describe the natural history of these infections during the first 100 days after allogeneic HCT, when symptom surveys and upper respiratory samples were collected weekly. Samples were tested using RT-PCR for HRVs and HCoVs (OC43, 229E, HKU1, and NL63). Among 215 patients, 64 (30%) patients had 67 infections. Day 100 cumulative incidence estimate was 22.3% for HRV and 11.1% for HCoV. Median duration of viral shedding was 3 weeks; prolonged shedding of at least 3 months occurred in 6 of 45 patients with HRV and 3 of 22 with HCoV. Six patients with HRV and 9 with HCoV were asymptomatic. HRV infection was associated with rhinorrhea, congestion, postnasal drip, sputum, and cough; HCoV infection was not associated with respiratory symptoms or hepatic dysfunction. Lower respiratory infection developed in 2 patients with HRV before day 100, and 1 each with HRV and HCoV after day 100. HRV and HCoV infections are common in the first 100 days after HCT, viral shedding lasts more than 3 weeks in half, and lower respiratory infection is rare.

Clinical and molecular epidemiology of human rhinovirus C in children and adults in Hong Kong reveals a possible distinct human rhinovirus C subgroup

BackgroundA novel human rhinovirus (HRV) species, HRV-C, was recently discovered, but its clinical features and epidemiology, compared with HRV-A and HRV-B, remains poorly understood, especially in adults

MethodsOne thousand two hundred nasopharyngeal aspirate samples obtained from hospitalized children and adults during a 1-year period were subject to reverse-transcriptase polymerase chain reaction to detect HRV. The clinical and molecular epidemiology of the 3 HRV species was analyzed

ResultsHRVs were detected in 178 (29.7%) of 600 nasopharyngeal aspirate samples from children and 42 (7%) of 600 nasopharyngeal aspirate samples from adults. HRV-A was most prevalent (n=111), followed by HRV-C (n=91) and HRV-B (n=18). Although upper respiratory tract infection was the most common presentation in children, 8 (62%) of the 13 adults with HRV-C infection had pneumonia, compared with 6 (27%) of the 22 adults with HRV-A infection (P<.05). Wheezing episodes were also more common among individuals with HRV-C (37%) and HRV-A (20%) infection than among those with HRV-B (0%) infection (P<.05). Clinical and molecular data analysis revealed HRV-C as a frequent cause of community and institutionalized outbreaks. A diverse set of HRV-C genotypes was circulating throughout the year, among which a potential distinct subgroup of strains was observed

ConclusionHRV-C is associated with pneumonia in adults and outbreaks of respiratory infections requiring hospitalization. A potential novel HRV-C subgroup was identified

Correlation of rhinovirus load in the respiratory tract and clinical symptoms in hospitalized immunocompetent and immunocompromised patients

While human rhinoviruses (HRVs) are well accepted as a major cause of common cold syndromes (rhinitis), their role in the etiology of lower respiratory tract infections is still controversial, and their detection in asymptomatic patients is relatively common. The HRV pathogenic role in four groups of hospitalized patients (pediatric immunocompetent and immunocompromised patients, and adult immunocompetent and immunocompromised patients) was investigated by quantifying HRV load in nasopharyngeal aspirates or bronchoalveolar lavage samples by real-time reverse transcription PCR (RT-PCR). Real-time RT-PCR was performed in duplicate on all respiratory samples resulting positive by qualitative RT-PCR. In addition, molecular typing allowed detection of all known HRV species (A, B, and C). In immunocompetent pediatric patients HRVs were mostly associated with lower respiratory tract infections (in the absence of other viral agents) and wheezing, when viral load was > or =10(6) RNA copies/ml. In young immunocompromised patients (stem cell transplantation recipients), an inverse correlation between HRV persistence over time and time at which the infection occurred after transplantation was observed, whereas in adult immunocompromised patients (lung transplant recipients) HRVs could be detected at a medium-low level (<10(5) RNA copies/ml) in bronchoalveolar lavage samples taken routinely from asymptomatic patients. In conclusion, when detected at high viral load, HRVs may cause severe upper and lower respiratory tract infections, whereas when detected at a medium-low viral load, an event more frequent in immunocompromised subjects, they may represent only bystander viruses.

Is intrinsic asthma synonymous with infection?

Rackemann described the 'intrinsic asthma' population over 50 years ago as a unique subgroup that was characterized by onset of progressive loss of lung function beginning later in life, possibly after a respiratory infection. It has also been associated with a female predominance, aspirin-sensitive bronchospasm, and nasal polyposis. While the aetiology is not understood, we propose that persistent respiratory infections play a central role in the development of intrinsic asthma.

Community-acquired respiratory viral infections in lung transplant recipients: a single season cohort study

BACKGROUND

The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated.

METHODS

A single-center prospective cohort study was performed in LTx-outpatients between October 31, 2005 and April 30, 2006. Symptoms of respiratory tract infections were recorded and nasopharyngeal and oropharyngeal swabs were obtained. Lower respiratory sampling was performed when indicated. Immunofluorescence testing, cultures, and polymerase chain reaction for 12 different CARV were applied. Patients were followed up until December 31, 2007. New onset and BOS-stage was recorded 1 year after presentation.

RESULTS

Three hundred eighty-eight LTx-recipients were screened. Fifty-one percent reported of symptoms of respiratory tract infection. Seven hundred seventy upper and 180 lower respiratory samples were obtained. Thirty-four CARV were detected in 30 patients (7.7%): 12 parainfluenza, 7 respiratory syncytial virus, 6 metapneumovirus, 5 coronavirus, 3 rhinovirus, and 1 influenza virus. At 1 year, 43 new cases of BOS developed. One-year incidence of BOS was 25.0% in CARV-positive versus 9.0% in CARV-negative patients (log-rank P=0.01). Symptomatic CARV-infection proved to be a significant covariate for 1-year BOS-free survival in multivariate analysis (P=0.002, adjusted hazard ratio 4.13). CARV-infection did not influence BOS progression in 88 patients with prior BOS (P 0.45). After paramyxovirus infection, 8 of 24 patients developed new-onset BOS, whereas no case was recorded after rhinovirus and coronavirus infection.

DISCUSSION

Surveillance detected CARV in LTx outpatients infrequently. Symptomatic CARV-infection increases the risk for new onset of BOS, but not progression. Risk to develop BOS was especially increased after paramyxovirus infection.

Rapid detection of respiratory picornaviruses in nasopharyngeal aspirates by immunofluorescence assay

BACKGROUND

Respiratory picornaviruses (enteroviruses and rhinoviruses) are commonly cited as causes of self-limited upper respiratory tract infection. However, it has recently been suggested that they may cause more severe respiratory disease. Immunofluorescence (IF) assays are rapid and inexpensive and are often used for the detection of respiratory viruses.

OBJECTIVES

We sought to develop an IF procedure, using commercially available reagents, for the detection of respiratory picornaviruses directly from nasopharyngeal aspirates (NPA).

STUDY DESIGN

From 1st November 2006 until 31st October 2007 all NPA from patients with respiratory infection were stained with the Light Diagnostic Pan-Enterovirus Reagent - "Blend" by IF (IF-ENVPAN). Those specimens which tested positive with this stain were further tested (subject to the availability of frozen specimen) with the xTAG respiratory viral panel, a multiplex PCR directed against respiratory picornaviruses, adenovirus (ADV), respiratory sincytial virus (RSV), influenza viruses A and B (IFA and IFB), parainfluenza virus (PIV) 1-4, human metapneumovirus (HMPV) and coronaviruses.

RESULTS

241/1122 NPA tested positive by IF-ENVPAN. 143 NPA were available for testing by xTAG respiratory viral panel. The multiplex PCR detected respiratory picornaviruses in 139 NPA, in 126 as the sole viral pathogen.

CONCLUSIONS

Our results indicate the potential of IF-ENVPAN for the laboratory detection of respiratory picornaviruses in clinical specimens. As far as we are aware, this is the first publication of such a method.

Clinical severity and molecular typing of human rhinovirus C strains during a fall outbreak affecting hospitalized patients

BACKGROUND

The circulation rate and the clinical severity of infections caused by members of the new human rhinovirus C (HRV-C) species remain to be defined.

OBJECTIVES

To investigate the epidemiologic and clinical impact of HRV-C strains in a fall outbreak interesting hospitalized patients.

STUDY DESIGN

HRV species (A-C) were determined by phylogenetic analysis following amplification of two genome regions (5'NCR and VP4/VP2) by RT-PCR. HRV species were correlated with age, respiratory tract involvement, clinical symptoms, and HRV load in respiratory secretions.

RESULTS

During the first week of the period October-November 2008, single HRV infections were associated with 95% of all respiratory syndromes affecting hospitalized patients. Then, HRV infections (single+coinfections) interested about 90% of positive samples until the end of October, when they declined in frequency until reaching about 30% at the end of November. Overall, 104 HRV strains were detected and, of these, 90 could be classified by phylogenetic analysis, as follows: 45 HRV-A, 12 HRV-B, 28 HRV-C, and 5 human enterovirus D strains. HRV-C identity was confirmed by detection of cis-acting replication elements (cre) in 23/23 strains. As for severity of respiratory syndromes, unlike HRV-A and HRV-B strains, HRV-C strains were responsible for a significantly higher rate (p<0.05) of lower respiratory tract infections in the pediatric as compared to adult patient population.

CONCLUSIONS

HRV-C strains have been shown to circulate at a rate intermediate between HRV-A and HRV-B strains, showing a greater degree of clinical severity in the pediatric population.

Respiratory viral infections within one year after pediatric lung transplant

Abstract: To characterize epidemiology and risk factors for respiratory viral infections (RVI) in pediatric lung transplant recipients within the first post‐transplant year, a retrospective multicenter study of pediatric lung transplant recipients from 1988 to 2005 was conducted at 14 centers in the United States and Europe. Data were recorded for 1 year post transplant. Associations between RVI and continuous and categorical risk factors were assessed using Wilcoxon's rank‐sum and χ² tests, respectively. Associations between time to RVI and risk factors or survival were assessed by multivariable Cox proportional hazards models. Of 576 subjects, 79 subjects (14%) had 101 RVI in the first year post transplant. Subjects with RVI were younger than those without RVI (median ages 9.7, 13; P<0.01). Viruses detected included adenovirus (n=25), influenza (n=9), respiratory syncytial virus (n=21), parainfluenza virus (n=19), enterovirus (n=4), and rhinovirus (n=22). In a multivariable model for time to first RVI, etiology other than cystic fibrosis (CF), younger age, and no induction therapy were independently associated with risk of RVI. Cytomegalovirus serostatus and acute rejection were not associated with RVI. RVI was independently associated with decreased 12‐month survival (hazard ratio 2.6, 95% confidence interval 1.6–4.4). RVI commonly occurs after pediatric lung transplantation with risk factors including younger age and non‐CF diagnosis. RVI is associated with decreased 1‐year survival.

Development of a RT real-time PCR for the detection and quantification of human rhinoviruses

Human Rhinoviruses (HRV) are the most common viral agents, being responsible for upper as well as lower respiratory tract infections. Evidence demonstrating that HRV disease is not exclusively limited to the upper airways and may cause lower respiratory complications, together with the frequency of HRV infections and the increasing number of immunocompromised patients underline the need for including HRV in virological diagnostics of acute lower respiratory tract illness. This article describes the development and optimization of a reverse transcription (RT) real-time PCR assay for quantification of HRV RNA in clinical samples. Efficiency, sensitivity, specificity, inter- and intra-assay variability, and dynamic range have been determined. Subsequently, the assay has been validated on bronchoalveolar lavage (BAL) specimens obtained from immunocompetent and immunocompromised patients.

Etiology of community-acquired pneumonia in hospitalized children based on WHO clinical guidelines

Community-acquired pneumonia (CAP) is a major cause of death in developing countries and of morbidity in developed countries. The objective of the study was to define the causative agents among children hospitalized for CAP defined by WHO guidelines and to correlate etiology with clinical severity and surrogate markers. Investigations included an extensive etiological workup. A potential causative agent was detected in 86% of the 99 enrolled patients, with evidence of bacterial (53%), viral (67%), and mixed (33%) infections. Streptococcus pneumoniae was accounted for in 46% of CAP. Dehydration was the only clinical sign associated with bacterial pneumonia. CRP and PCT were significantly higher in bacterial infections. Increasing the number of diagnostic tests identifies potential causes of CAP in up to 86% of children, indicating a high prevalence of viruses and frequent co-infections. The high proportion of pneumococcal infections re-emphasizes the importance of pneumococcal immunization.

Epidemiology

The common cold is the result of an upper respiratory tract infection causing an acute syndrome characterised by a combination of non-specific symptoms, including sore throat, cough, fever, rhinorrhoea, malaise, headache, and myalgia. Respiratory viruses, alone or in combination, are the most common cause. The course f illness can be complicated by bacterial agents, causing pharyngitis or sinusitis, but the are a rare cause of cold and flu-like illnesses (CFLIs). Our understanding of CFLI epidemiology has been enhanced by molecular detection methods, particularly polymerase chain reaction (PCR) testing. PCR has not only improved detection of previously known viruses, but within the last decade has resulted in the detection of many divergent novel respiratory virus species. Human rhinovirus (HRV) infections cause nearly all CFLIs and they can be responsible for asthma and chronic obstructive pulmonary disease exacerbations. HRVs are co-detected with other respiratory viruses in statistically significant patterns, with HRVs occurring in the lowest proportion of co-detections, compared to most other respiratory viruses. Some recently identified rhinoviruses may populate an entirely new putative HRV species; HRV C. Further work is required to confirm a causal role for these newly identified viruses in CFLIs. The burden of illness associated with CFLIs is poorly documented, but where data are available, the impact of CFLIs is considerable. Individual infections, although they do not commonly result in more severe respiratory tract illness, are associated with substantial direct and indirect resource use. The product of frequency and burden for CFLIs is likely to be greater in magnitude than for any other respiratory syndrome, but further work is required to document this. Our understanding of the viral causes of CLFIs, although incomplete, has improved in recent years. Documenting burden is also an important step in progress towards improved control and management of these illnesses.

Development and implementation of a molecular diagnostic platform for daily rapid detection of 15 respiratory viruses

Acute respiratory tract infections are caused by a large number of viruses. Diagnostic methods have until recently been available only for a limited number of these viruses. With the objective to achieve sensitive assays for all respiratory viruses, a rational workflow in the laboratory, and a short turn-around time, a real-time PCR diagnostic platform for daily rapid detection of 15 respiratory viruses was developed. The system was evaluated on 585 stored nasopharyngeal aspirates from hospitalized children. Previous analysis by immunofluorescence and virus isolation identified viruses in 37% of the samples while the new PCR diagnostic panel detected 57% virus positive samples. The new platform was introduced in the laboratory in October 2007 and has then fully replaced the standard immunofluorescence assay for rapid detection of viruses and virus isolation.

Identification of respiratory viruses in asymptomatic subjects: asymptomatic respiratory viral infections

The medical literature of the past 4 decades was searched regarding respiratory virus detection by polymerase chain reaction and conventional methods (culture, antigen detection, serology) in asymptomatic subjects in an attempt to determine the prevalence and clinical significance of such viruses in normal persons.

Respiratory viral infections in children with leukemia

BACKGROUND

Respiratory viruses occur frequently in the community and are a common cause of fever in children. Data on respiratory viral infections in children with cancer are limited.

METHODS

A long-term, prospective, multicenter study was carried out in Finland searching for respiratory viruses in febrile children with leukemia. For this purpose, 138 febrile episodes in 51 children with leukemia were analyzed. Twelve types of respiratory viruses were searched for by viral culture, antigen detection, and polymerase chain reaction tests.

RESULTS

Evidence of a respiratory viral infection was found in 61 of 138 febrile episodes (44%), accounting for an incidence of 0.8 (range, 0-2.4) per person year at risk during the treatment of leukemia. The most common viruses detected were rhinovirus (22%), respiratory syncytial virus (11%), human bocavirus (5%), and influenza A virus (4%). Dual viral infections were detected in 12 cases (9%). Half of the children had respiratory symptoms with cough being the most common symptom. Two children developed pneumonia. The mean duration of fever was 2.6 (SD 1.7) days in children with respiratory viral infection and 2.1 (SD 1.3) days in children without evidence of viral infection (P = 0.44).

CONCLUSIONS

Respiratory viruses are found commonly during febrile episodes in children with leukemia. The detection of viruses permits the use of available antiviral agents, may explain a poor response to antimicrobial agents, and minimizes the proportion of febrile episodes without possible etiologic agents in children with leukemia.

Clinical effects of rhinovirus infections

Rhinovirus is the major cause of common cold and frequently associates with acute wheezing, otitis media, sinusitis, and pneumonia. High prevalence of rhinovirus in hospitalized children and adults has been documented recently. We screened children > or =1 month of age, hospitalized for any infection, for the presence of rhinoviruses and recruited 24 families with > or =2 children for a 3-week follow-up study. Rhinovirus was detected in 46 (28%) of 163 hospitalizations by study children. Most rhinovirus-positive children (85%) had respiratory symptoms. During the follow-up, rhinoviruses were detected in virtually all children and in one-half of adults in families with a rhinovirus-positive index child, but commonly also in families with a rhinovirus-negative index child. Melting temperature and sequence analysis revealed the transmission routes of the viruses and showed that several virus types could circulate in the families simultaneously. Our studies corroborate the major contribution of rhinovirus to hospitalization of children, most often because of wheezing. Young children with respiratory symptoms are major spreaders of rhinovirus in family setting.

Human rhinoviruses: the cold wars resume

BACKGROUND

Human rhinoviruses (HRVs) are the most common cause of viral illness worldwide but today, less than half the strains have been sequenced and only a handful examined structurally. This viral super-group, known for decades, has still to face the full force of a molecular biology onslaught. However, newly identified viruses (NIVs) including human metapneumovirus and bocavirus and emergent viruses including SARS-CoV have already been exhaustively scrutinized. The clinical impact of most respiratory NIVs is attributable to one or two major strains but there are 100+ distinct HRVs and, because we have never sought them independently, we must arbitrarily divide the literature's clinical impact findings among them. Early findings from infection studies and use of inefficient detection methods have shaped the way we think of 'common cold' viruses today.

OBJECTIVES

To review past HRV-related studies in order to put recent HRV discoveries into context.

RESULTS

HRV infections result in undue antibiotic prescriptions, sizable healthcare-related expenditure and exacerbation of expiratory wheezing associated with hospital admission.

CONCLUSION

The finding of many divergent and previously unrecognized HRV strains has drawn attention and resources back to the most widespread and frequent infectious agent of humans; providing us the chance to seize the advantage in a decades-long cold war.

Serial viral infections in infants with recurrent respiratory illnesses

To better understand the viral aetiology of recurrent and prolonged illnesses, nasal secretions were prospectively collected from 285 infants at increased risk of developing asthma. Of these, 27 infants had recurrent (at least five) moderate-to-severe respiratory illnesses (MSIs). The viral aetiology of the 150 MSIs and 86 scheduled visits was analysed by molecular diagnostics. The demographic and clinical data were compared with infants who had 0-4 MSIs. Frequently ill infants had higher exposure to other children and more wheezing illnesses than less symptomatic children. Viruses were detected in 136 (91%) out of 150 MSIs, 14 (67%) out of 21 mild illnesses and 29 (45%) out of 65 asymptomatic visits. Human rhinovirus was the most common aetiological agent (61, 43 and 35% in MSIs, mild illnesses and asymptomatic visits, respectively). Mixed viral infections were generally associated with more severe illnesses (27, 0 and 5%, respectively). Among the 27 frequently ill infants, only eight (5.3%) out of 150 MSIs were prolonged (> or =2 weeks duration). Considering all samples, detection of the same virus strain > or =2 weeks apart was unusual (5.3% of all 244 positive findings). Human rhinovirus infections occur early, pervasively and repetitively in these high-risk infants. Infants with prolonged or recurrent respiratory illnesses most often have a series of infections rather than persistent infection with one virus strain.

[Infection in lung transplantation]

Actualmente, el trasplante de pulmón se considera un tratamiento válido para un buen número de pacientes con insuficiencia respiratoria grave. De todas formas, las complicaciones son muy frecuentes y pueden llevar a fracaso del injerto a medio y largo plazo y menor supervivencia. De acuerdo con el registro de la International Society for Heart and Lung Transplantation, las tasas de supervivencia al primer, segundo y quinto año fueron, en 2006, del 74, 65 y 47%, respectivamente. El principal obstáculo para el éxito a largo plazo del trasplante de pulmón es el rechazo crónico, caracterizado histológicamente como bronquiolitis obliterante, que acontece en cerca de dos terceras partes de los pacientes. Uno de los factores más importantes para el desarrollo de bronquiolitis obliterante, además del número de rechazos agudos, es la infección y la enfermedad por citomegalovirus (CMV). Recientemente, se ha destacado el papel de la infección por diferentes virus respiratorios como factores de riesgo para el desarrollo de rechazo crónico en receptores de un trasplante de pulmón. Las complicaciones infecciosas son una causa frecuente de morbimortalidad en este tipo de pacientes, y la causa de muerte de cerca de la mitad de ellos. La infección bacteriana es la complicación más frecuente de un receptor de un trasplante de pulmón. Del total, el 35-66% son bacterianas y el 50-85% de los pacientes presentan como mínimo un episodio de infección bacteriana. La segunda causa más frecuente de infección, después de la bacteriana, es la infección por CMV. A pesar de utilizar diferentes estrategias de prevención, la incidencia sigue siendo elevada, y se sitúa alrededor del 7% el primer año postrasplante. Es el único tipo de trasplante de órgano sólido en el cual la etiología más frecuente de la infección fúngica es Aspergillus spp., a diferencia del resto, en que típicamente se deben a Candida spp. La incidencia de aspergilosis invasora se cifra en alrededor del 4%.

Respiratory viruses other than influenza virus: impact and therapeutic advances

Though several antivirals have been developed and marketed to treat influenza virus infections, the development of antiviral agents with clinical activity against other respiratory viruses has been more problematic. Here we review the epidemiology of respiratory viral infections in immunocompetent and immunocompromised hosts, examine the evidence surrounding the currently available antivirals for respiratory viral infections other than influenza, highlight those that are in the pipeline, and discuss the hurdles for development of such agents.

The presence of rhinovirus in lower airways of patients with bronchial asthma

RATIONALE

The common cold virus, human rhinovirus (HRV), is the most frequent cause of asthma exacerbations. However, a possible contribution of HRV to the pathogenesis of chronic, persistent asthma has not been defined.

OBJECTIVES

To determine if patients with stable asthma, who are free of clinical signs of a respiratory infection for at least 3 weeks, harbor HRV in their bronchi more frequently than nonasthmatic control subjects, and whether clinical features of asthma are associated with the presence of HRV.

METHODS

Immunohistochemistry and the indirect in situ reverse transcription-polymerase chain reaction method were used to detect the presence of HRV in bronchial mucosal biopsies in patients with asthma and nonasthmatic control subjects.

MEASUREMENTS AND MAIN RESULTS

HRV was found by immunohistochemistry in 9 of 14 bronchial biopsies from subjects with asthma (64.3%) and 2 of 6 nonasthmatic control subjects (33.3%) (P = 0.38). With the more sensitive indirect in situ reverse transcription-polymerase chain reaction method, HRV was found in the mucosal biopsies of 73% of patients with asthma and 22% of nonasthmatic control subjects (P < 0.001). Subjects positive for HRV had lower pulmonary function, higher numbers of blood eosinophils and leukocytes, and eosinophilic infiltration in bronchial mucosa.

CONCLUSIONS

HRV was detected in the lower airway tissue of patients with asthma significantly more often than in nonasthmatic subjects, and its presence was associated with clinical features of more severe disease.

RNA-containing cytoplasmic inclusion bodies in ciliated bronchial epithelium months to years after acute Kawasaki disease

Background

Kawasaki Disease (KD) is the most common cause of acquired heart disease in children in developed nations. The KD etiologic agent is unknown but likely to be a ubiquitous microbe that usually causes asymptomatic childhood infection, resulting in KD only in genetically susceptible individuals. KD synthetic antibodies made from prevalent IgA gene sequences in KD arterial tissue detect intracytoplasmic inclusion bodies (ICI) resembling viral ICI in acute KD but not control infant ciliated bronchial epithelium. The prevalence of ICI in late-stage KD fatalities and in older individuals with non-KD illness should be low, unless persistent infection is common.

Methods and Principal Findings

Lung tissue from late-stage KD fatalities and non-infant controls was examined by light microscopy for the presence of ICI. Nucleic acid stains and transmission electron microscopy (TEM) were performed on tissues that were strongly positive for ICI. ICI were present in ciliated bronchial epithelium in 6/7 (86%) late-stage KD fatalities and 7/27 (26%) controls ages 9–84 years (p = 0.01). Nucleic acid stains revealed RNA but not DNA within the ICI. ICI were also identified in lung macrophages in some KD cases. TEM of bronchial epithelium and macrophages from KD cases revealed finely granular homogeneous ICI.

Significance

These findings are consistent with a previously unidentified, ubiquitous RNA virus that forms ICI and can result in persistent infection in bronchial epithelium and macrophages as the etiologic agent of KD.

New developments in the epidemiology and clinical spectrum of rhinovirus infections

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent changes in our understanding of the epidemiology and clinical manifestations of rhinovirus infection that have occurred as a result of the improved diagnostic sensitivity provided by the reverse transcriptase PCR assays.

RECENT FINDINGS

Rhinovirus infection is now recognized as an important cause of acute exacerbations of asthma in school-aged children. Along with other respiratory viruses, rhinovirus infection is also a cause of exacerbations of cystic fibrosis. There is evidence that rhinovirus can infect the lower airways and may be associated with bronchiolitis and pneumonia in immunocompetent children and with lower respiratory tract disease in the immunocompromised host.

SUMMARY

The use of nucleic acid hybridization-based assays has expanded our understanding of the spectrum of clinical illness that is associated with rhinovirus infection. The prevalence of rhinovirus infection in children is high and presents a risk for coincidental detection of rhinovirus in the face of other infectious syndromes. The detection of rhinovirus from patients with new or unusual clinical syndromes does not permit the assumption that rhinovirus is playing a causal role in the illness.

Mouse models of rhinovirus-induced disease and exacerbation of allergic airway inflammation

Rhinoviruses cause serious morbidity and mortality as the major etiological agents of asthma exacerbations and the common cold. A major obstacle to understanding disease pathogenesis and to the development of effective therapies has been the lack of a small-animal model for rhinovirus infection. Of the 100 known rhinovirus serotypes, 90% (the major group) use human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor and do not bind mouse ICAM-1; the remaining 10% (the minor group) use a member of the low-density lipoprotein receptor family and can bind the mouse counterpart. Here we describe three novel mouse models of rhinovirus infection: minor-group rhinovirus infection of BALB/c mice, major-group rhinovirus infection of transgenic BALB/c mice expressing a mouse-human ICAM-1 chimera and rhinovirus-induced exacerbation of allergic airway inflammation. These models have features similar to those observed in rhinovirus infection in humans, including augmentation of allergic airway inflammation, and will be useful in the development of future therapies for colds and asthma exacerbations.

Human bocavirus in children with acute lymphoblastic leukemia

A new human parvovirus, human bocavirus, has recently been identified in respiratory secretions, feces and serum. It is associated with lower and most likely also upper respiratory tract infections. Most commonly reported symptoms are cough, rhinorrhea, expiratory wheezing and fever, and the virus is preferentially detected in young children. We report three children with acute lymphoblastic leukemia who had acute febrile episodes with concomitant detection of human bocavirus in their respiratory secretions. One of them had five consecutive febrile episodes during 6 months, all associated with the presence of human bocavirus at varying viral loads, suggesting prolonged shedding or reactivation of the virus.

Real-time reverse transcription-PCR assay for comprehensive detection of human rhinoviruses

Human rhinoviruses (HRVs) are important contributors to respiratory disease, but their healthcare burden remains unclear, primarily because of the lack of sensitive, accurate, and convenient means of determining their causal role. To address this, we developed and clinically validated the sensitivity and specificity of a real-time reverse transcription-PCR (RT-PCR) assay targeting the viral 5' noncoding region defined by sequences obtained from all 100 currently recognized HRV prototype strains and 85 recently circulating field isolates. The assay successfully amplified all HRVs tested and could reproducibly detect 50 HRV RNA transcript copies, with a dynamic range of over 7 logs. In contrast, a quantified RNA transcript of human enterovirus 68 (HEV68) that showed the greatest sequence homology to the HRV primers and probe set was not detected below a concentration of 5 x 10(5) copies per reaction. Nucleic acid extracts of 111 coded respiratory specimens that were culture positive for HRV or HEV were tested with the HRV real-time RT-PCR assay and by two independent laboratories that used different in-house HRV/HEV RT-PCR assays. Eighty-seven HRV-culture-positive specimens were correctly identified by the real-time RT-PCR assay, and 4 of the 24 HEV-positive samples were positive for HRV. HRV-specific sequences subsequently were identified in these four specimens, suggesting HRV/HEV coinfection in these patients. The assay was successfully applied in an investigation of a coincidental outbreak of HRV respiratory illness among laboratory staff.

Mixed bacterial-viral infections in septic children with leukemia

BACKGROUND

Febrile infections in children with leukemia are common. The occurrence of possible mixed bacterial-viral infections is unknown.

METHODS

We searched for viruses in leukemic children with blood culture-positive bacterial infections. The prospective multicenter survey included 156 febrile episodes in 51 children with acute leukemia. The mean follow-up time was 1.5 years per patient (27,743 patient-days at risk). Sixteen viruses were searched for from nasal swab and stool samples using virus culture, virus antigen detection, and polymerase chain reaction tests.

RESULTS

Bacterial blood cultures were positive in 19 (11%) febrile episodes among 17 children. In half of the septic episodes (11 of 19), a virus was also found. Rhinovirus and respiratory syncytial virus were the most common viruses detected.

CONCLUSIONS

Our findings suggest that invasive bacterial infections are commonly associated with viral infections in children with leukemia.

[Pneumonias and immunosuppression]

Pneumonias are common, life threatening complications in immunodeficient patients. A rapid, targeted diagnosis and therapy are decisive for the course of the disease. The etiological spectrum is substantially broader than for immunocompetent patients. Important indications are provided by the type and intensity of the immunosuppression, gaps in the prophylactic concept and particular exposures. For diagnostic planning, high resolution computed tomogram of the thorax is necessary. The standard method for isolating the pathogen is flexible bronchoscopy with bronchoalveolar lavage. Indications for invasive bioptic measures depend on the individual situation, the expected spectrum of pathogens as well as risk factors and adverse effects. Non-invasive antigen and PCR tests complement the diagnostic spectrum, especially for difficult to cultivate pathogens such as fungi and Herpes viruses. The selection of the initial, targeted antimicrobial therapy is based on guidelines. The treatment should be followed after obtaining the relevant microbiological data.

Microbial manipulation of immune function for asthma prevention: inferences from clinical trials

The "hygiene hypothesis" proposes that the increase in allergic diseases in developing countries reflects a decrease in infections during childhood. Cohort studies suggest, however, that the risks of asthma are increased in children who suffer severe illness from a viral respiratory infection in infancy. This apparent inconsistency can be reconciled through consideration of epidemiologic, clinical, and animal studies. The elements of this line of reasoning are that viral infections can predispose to organ-specific expression of allergic sensitization, and that the severity of illness is shaped by the maturity of immune function, which in turn is influenced by previous contact with bacteria and viruses, whether pathogenic or not. Clinical studies of children and interventional studies of animals indeed suggest that the exposure to microbes through the gastrointestinal tract powerfully shapes immune function. Intestinal microbiota differ in infants who later develop allergic diseases, and feeding Lactobacillus casei to infants at risk has been shown to reduce their rate of developing eczema. This has prompted studies of feeding probiotics as a primary prevention strategy for asthma. We propose that the efficacy of this approach depends on its success in inducing maturation of immune function important in defense against viral infection, rather than on its effectiveness in preventing allergic sensitization. It follows that the endpoints of studies of feeding probiotics to infants at risk for asthma should include not simply tests of responsiveness to allergens, but also assessment of intestinal flora, immune function, and the clinical response to respiratory viral infection.

Clinical features and complete genome characterization of a distinct human rhinovirus (HRV) genetic cluster, probably representing a previously undetected HRV species, HRV-C, associated with acute respiratory illness in children

Although human rhinoviruses (HRVs) are common causes of respiratory illness, their molecular epidemiology has been poorly investigated. Despite the recent findings of new HRV genotypes, their clinical disease spectrum and phylogenetic positions were not fully understood. In this study, 203 prospectively collected nasopharyngeal aspirates (NPAs), negative for common respiratory viruses (83 were human bocavirus [HBoV] positive and 120 HBoV negative), from hospitalized children during a 1-year period were subjected to reverse transcription-PCR for HRV. HRV was detected in 14 NPAs positive and 12 NPAs negative for HBoV. Upon VP4 gene analysis, 5 of these 26 HRV strains were found to belong to HRV-A while 21 belonged to a genetic clade probably representing a previously undetected HRV species, HRV-C, that is phylogenetically distinct from the two known HRV species, HRV-A and HRV-B. The VP4 sequences of these HRV-C strains were closely related to the newly identified HRV strains from the United States and Australia. Febrile wheeze or asthma was the most common presentation (76%) of HRV-C infection, which peaked in fall and winter. Complete genome sequencing of three HRV-C strains revealed that HRV-C represents an additional HRV species, with features distinct from HRV-A and HRV-B. Analysis of VP1 of HRV-C revealed major deletions in regions important for neutralization in other HRVs, which may be signs of a distinct species, while within-clade amino acid variation in potentially antigenic regions may indicate the existence of different serotypes among HRV-C strains. A newly identified HRV species, HRV-C, is circulating worldwide and is an important cause of febrile wheeze and asthmatic exacerbations in children requiring hospitalization.

New complete genome sequences of human rhinoviruses shed light on their phylogeny and genomic features

Background

Human rhinoviruses (HRV), the most frequent cause of respiratory infections, include 99 different serotypes segregating into two species, A and B. Rhinoviruses share extensive genomic sequence similarity with enteroviruses and both are part of the picornavirus family. Nevertheless they differ significantly at the phenotypic level. The lack of HRV full-length genome sequences and the absence of analysis comparing picornaviruses at the whole genome level limit our knowledge of the genomic features supporting these differences.

Results

Here we report complete genome sequences of 12 HRV-A and HRV-B serotypes, more than doubling the current number of available HRV sequences. The whole-genome maximum-likelihood phylogenetic analysis suggests that HRV-B and human enteroviruses (HEV) diverged from the last common ancestor after their separation from HRV-A. On the other hand, compared to HEV, HRV-B are more related to HRV-A in the capsid and 3B-C regions. We also identified the presence of a 2C cis-acting replication element (cre) in HRV-B that is not present in HRV-A, and that had been previously characterized only in HEV. In contrast to HEV viruses, HRV-A and HRV-B share also markedly lower GC content along the whole genome length.

Conclusion

Our findings provide basis to speculate about both the biological similarities and the differences (e.g. tissue tropism, temperature adaptation or acid lability) of these three groups of viruses.

Characterisation of a newly identified human rhinovirus, HRV-QPM, discovered in infants with bronchiolitis

BACKGROUND

Human rhinoviruses (HRVs) are some of the earliest identified and most commonly detected viruses associated with acute respiratory tract infections (ARTIs) and yet the molecular epidemiology and genomic variation of individual serotypes remains undefined.

OBJECTIVES

To molecularly characterise a novel HRV and determine its prevalence and clinical impact on a predominantly paediatric population.

STUDY DESIGN

Nucleotide sequencing was employed to determine the complete HRV-QPM coding sequence. Two novel real-time RT-PCR diagnostic assays were designed and employed to retrospectively screen a well-defined population of 1244 specimen extracts to identify the prevalence of HRV-QPM during 2003.

RESULTS

Phylogenetic studies of complete coding sequences defined HRV-QPM as a novel member the genus Rhinovirus residing within the previously described HRV-A2 sub-lineage. Investigation of the relatively short VP1 sequence suggest that the virus is resistant to Pleconaril, setting it apart from the HRV A species. Sixteen additional HRV-QPM strains were detected (1.4% of specimens) often as the sole micro-organism present among infants with suspected bronchiolitis. HRV-QPM was also detected in Europe during 2006, and a closely related virus circulated in the United States during 2004.

CONCLUSIONS

We present the molecular characterisation and preliminary clinical impact of a newly identified HRV along with sequences representing additional new HRVs.