Innate immune response to viral infection of the lungs

Viral respiratory tract infections are the most common infectious illnesses, though they are usually self-limiting and confined to the respiratory tract. The rapid identification of viruses and their effective elimination with minimal local and systemic inflammation is a testament to the efficiency of the innate immune response within the airways and lungs. A failure of this response appears to occur in those with asthma and chronic obstructive pulmonary disease, where viral infection is an important trigger for acute exacerbations. The innate immune response to viruses requires their early detection through pathogen recognition receptors and the recruitment of the efficient antiviral response that is centred around the release of type 1 interferons. The airway epithelium provides both a barrier and an early detector for viruses, and interacts closely with cells of the innate immune response, especially macrophages and dendritic cells, to eliminate infection and trigger a specific adaptive immune response.

[Clinical and genetic diversity of rhinoviruses]

Human rhinoviruses are the most common cause of viral respiratory infections across all age groups, from the neonate to the elderly patient. The benign nature of most of these infections as well as the difficulty to isolate the causative agent limits our perception of its real clinical impact. Molecular diagnostic tools have allowed to better characterize the variety of clinical presentations which are not limited to the common cold alone. It is now clearly established that rhinoviruses infect both the upper and lower tracheobronchial tree which may also be the site of viral replication. Moreover, the virus is the cause of significant complications in patients at risk such as those with asthma or highly immunocompromised hosts. The use of molecular screening techniques shows the very high diversity of circulating strains which are not only limited to known serotypes and has allowed the identification of new subgroups previously unknown. Detailed analysis of the genomic organization shows a common phylogeny between certain subgroups of rhinoviruses and enteroviruses and sheds light on the constraints modelling the evolution of human Picornaviridae. Furthermore, detailed analysis of the CRE structures shows that this structure is not only conserved for each species, but is also located on a specific region for each of these species.

Viral respiratory infection and the link to asthma

Viral respiratory infections are closely associated with wheezing illnesses and exacerbations of asthma throughout childhood, and yet there are a number of remaining questions pertaining to the specific nature of this relationship. Infection with an expanding list of respiratory viruses is an important cause of acute wheezing in infancy, and viruses are detected in most exacerbations of asthma throughout childhood. Furthermore, infants who develop severe viral respiratory infections are more likely to have asthma later in childhood. There has been progress in understanding the pathogenesis of viral respiratory illnesses, and this has led to new insights into how these processes might differ in asthma. Several host factors, including respiratory allergy and virus-induced interferon responses, modify the risk of virus-induced wheezing. In the absence of effective antiviral therapies, treatment of virus-induced wheezing and exacerbations of asthma can be challenging, and studies evaluating current treatment strategies are reviewed. Understanding the host-pathogen interactions that determine the severity of respiratory illnesses and long-term sequelae is likely to be of great help in identifying at-risk individuals, and in designing new and more effective treatments.

Cleavage of eukaryotic initiation factor eIF5B by enterovirus 3C proteases

The enteroviruses poliovirus (PV), Coxsackie B virus (CVB) and rhinovirus (HRV) are members of Picornaviridae that inhibit host cell translation early in infection. Enterovirus translation soon predominates in infected cells, but eventually also shuts off. This complex pattern of modulation of translation suggests regulation by a multifactorial mechanism. We report here that eIF5B is proteolytically cleaved during PV and CVB infection of cultured cells, beginning at 3 hours post-infection and increasing thereafter. Recombinant PV, CVB and HRV 3Cpro cleaved purified native rabbit eukaryotic initiation factor (eIF) 5B in vitro at a single site (VVEQG, equivalent to VMEQG479 in human eIF5B) that is consistent with the cleavage specificity of enterovirus 3C proteases. Cleavage separates the N-terminal domain of eIF5B from its essential conserved central GTPase and C-terminal domains. 3Cpro-mediated cleavage of eIF5B may thus play an accessory role in the shutoff of translation that occurs in enterovirus-infected cells.

The cis-acting replication elements define human enterovirus and rhinovirus species

Replication of picornaviruses is dependent on VPg uridylylation, which is linked to the presence of the internal cis-acting replication element (cre). Cre are located within the sequence encoding polyprotein, yet at distinct positions as demonstrated for poliovirus and coxsackievirus-B3, cardiovirus, and human rhinovirus (HRV-A and HRV-B), overlapping proteins 2C, VP2, 2A, and VP1, respectively. Here we report a novel distinct cre element located in the VP2 region of the recently reported HRV-A2 species and provide evolutionary evidence of its functionality. We also experimentally interrogated functionality of recently identified HRV-B cre in the 2C region that is orthologous to the human enterovirus (HEV) cre and show that it is dispensable for replication and appears to be a nonfunctional evolutionary relic. In addition, our mutational analysis highlights two amino acids in the 2C protein that are crucial for replication. Remarkably, we conclude that each genetic clade of HRV and HEV is characterized by a unique functional cre element, where evolutionary success of a new genetic lineage seems to be associated with an invention of a novel cre motif and decay of the ancestral one. Therefore, we propose that cre element could be considered as an additional criterion for human rhinovirus and enterovirus classification.

Wheezing due to rhinovirus infection in infancy: Bronchial hyperresponsiveness at school age

BACKGROUND

Characteristics related to decreased lung function and increased bronchial responsiveness after early childhood wheezing requiring hospitalization are not fully established.

METHODS

Seventy-nine children with wheezing requiring hospitalization at age <2 years were prospectively followed up and re-investigated at age 5.6-8.8 years when the measurements of baseline lung function and bronchial responsiveness to exercise were performed.

RESULTS

At early school age, 23% of children had decreased lung function, and 13% had increased bronchial responsiveness to exercise. Predictors of decreased lung function were maternal history of smoking during pregnancy (odds ratio [OR], 12.8; 95% confidence interval [CI]: 1.2-139.6), parental history of asthma (OR, 4.3; 95%CI: 1.1-17.1), and female gender (OR, 4.0; 95%CI: 1.2-13.7). Increased bronchial responsiveness was associated with rhinovirus infection-induced wheezing in infancy (OR, 6.5; 95%CI: 1.2-36.3), and early cat or dog exposure leading to sensitization (OR, 26.6; 95%CI: 1.3-525.2). Inhaled anti-inflammatory therapy was common in children with rhinovirus infection-induced wheezing in infancy (n = 13/19; P = 0.001 vs children with other/no confirmed virus infection etiology for wheezing in infancy, n = 16/60), which may have improved lung function and attenuated bronchial responsiveness in them.

CONCLUSIONS

After early childhood wheezing requiring hospitalization, one-fourth of children will have decreased lung function and one-eighth of children will show increased bronchial responsiveness at school age. Gender, heredity of asthma, and antenatal exposure to tobacco smoke are predictors of decreased lung function, whereas rhinovirus infection etiology of wheeze and early animal exposure leading to sensitization are associated with increased bronchial responsiveness later in childhood.

Atopic characteristics of wheezing children and responses to prednisolone

We wanted to test the hypothesis that the efficacy of systemic corticosteroid is associated with atopic characteristics in wheezing children. A randomized controlled trial comparing oral prednisolone (2 mg/kg/day in 3 divided doses for 3 days) with placebo in hospitalized wheezing children (n = 266, median 1.6 years, range 3 months to 15.2 years) was conducted. In this post-hoc analysis, we assessed the link between the efficacy of prednisolone and several atopic characteristics, such as atopy, aeroallergen sensitization, total IgE level, number of sensitizations, eczema, atopic eczema, blood or nasal eosinophils, exhaled nitric oxide, positive modified asthma predictive index/asthma, inhaled corticosteroid medication and parental asthma/allergy. Virology was studied comprehensively. Our primary endpoint was the time until ready for discharge, and the most important secondary endpoint was the occurrence of relapses during the following 2 months. For statistics, we used interaction analyses in uni- and multivariate regression models. Overall, prednisolone did not decrease any of our predefined clinical endpoints. Neither was the efficacy of prednisolone associated with atopy. However, prednisolone significantly decreased the time until ready for discharge in children with positive modified asthma predictive index/asthma, inhaled corticosteroids, or rhinovirus infection and/or in children without azithromycin treatment. Prednisolone significantly decreased relapses in children with eczema, nasal eosinophilia and rhinovirus infection. The multiple clinical, inflammatory and viral markers associating with the efficacy of prednisolone should be confirmed in prospective trials. It is important that corticosteroid intervention trials have strict design for these potentially confounding factors.

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.

Efficacy of prednisolone in children hospitalized for recurrent wheezing

Data on the efficacy of corticosteroids on respiratory picornavirus-induced wheezing are limited. To determine whether prednisolone is effective in rhinovirus- or enterovirus-induced recurrent wheezing, we conducted a controlled trial comparing oral prednisolone (2 mg/kg/day in three divided doses for 3 days) with placebo in hospitalized wheezing children and studied post hoc virus-specific efficacy in early wheezing (<3 episodes, reported elsewhere) and in recurrent wheezing (>or=3 episodes). Virus-negative children where excluded. Our primary endpoint was the time until children were ready for discharge. Secondary endpoints included oxygen saturation and exhaled nitric oxide during hospitalization, duration of symptoms, blood eosinophil count, and impulse oscillometry 2 wk after discharge, and occurrence of relapses during the following 2 months. Virus-specific effects were analyzed with interaction analysis in a multivariate regression model. During the study period, 661 patients were hospitalized, 293 randomized, and 59 were accepted in this analysis (mean age 2.6 yr, s.d. 1.3). Prednisolone did not significantly decrease the time until ready for discharge in all patients (prednisolone vs. placebo, medians, 18 vs. 24 h, p = 0.11). However, prednisolone decreased the time until ready for discharge in children with picornavirus infection (respectively, 12 vs. 24 h, p = 0.0022) and more specifically, in children with enterovirus infection (6 vs. 35 h, p = 0.0007). In the secondary endpoints, prednisolone decreased the duration of cough and dyspnea in rhinovirus-affected children (p = 0.033 for both). Prospectively designed clinical trial is needed to test the hypothesis that prednisolone reduces symptoms in picornavirus-affected wheezing children.

Infection-induced proinflammatory cytokines are associated with decreases in positive affect, but not increases in negative affect

Infection commonly triggers nonspecific psychological and behavioral changes including fatigue and malaise, anhedonia, inability to concentrate, and disturbed sleep that collectively are termed "sickness behaviors". Converging evidence from several lines of research implicate the activities of proinflammatory cytokines as a cause of sickness behaviors. Here we elaborate upon the findings of previous research by examining whether infection-associated elevations in local proinflammatory cytokines are associated with increased negative mood and decreased positive mood. One hundred and eighty-nine healthy adults were experimentally exposed to rhinovirus or influenza virus during a 6-day period of quarantine. Infection, objective signs of illness, nasal IL-1beta, IL-6, and TNF-alpha, and self-reported affect were assessed at baseline and on each of the five post-challenge quarantine days. In the 153 persons who became infected following exposure to the challenge virus, daily production of IL-6, but not IL-1beta or TNF-alpha, was associated with reduced concurrent daily positive affect. One-day lagged analyses showed that daily production of all three cytokines was related to lower positive affect on the next day. All lagged associations were independent of previous-day positive affect and objective signs of illness (mucus production, mucociliary clearance function). There were no associations between cytokines and negative affect. Findings support a causal association between pathogen-induced local cytokine production and changes in positive affect over a 24-h timeline.

NMR structure of stem-loop D from human rhinovirus-14

The 5'-cloverleaf of the picornavirus RNA genome is essential for the assembly of a ribonucleoprotein replication complex. Stem-loop D (SLD) of the cloverleaf is the recognition site for the multifunctional viral protein 3Cpro. This protein is the principal viral protease, and its interaction with SLD also helps to position the viral RNA-dependent RNA polymerase (3Dpol) for replication. Human rhinovirus-14 (HRV-14) is distinct from the majority of picornaviruses in that its SLD forms a cUAUg triloop instead of the more common uYACGg tetraloop. This difference appears to be functionally significant, as 3Cpro from tetraloop-containing viruses cannot bind the HRV-14 SLD. We have determined the solution structure of the HRV-14 SLD using NMR spectroscopy. The structure is predominantly an A-form helix, but with a central pyrimidine-pyrimidine base-paired region and a significantly widened major groove. The stabilizing hydrogen bonding present in the uYACGg tetraloop was not found in the cUAUg triloop. However, the triloop uses different structural elements to present a largely similar surface: sequence and underlying architecture are not conserved, but key aspects of the surface structure are. Important structural differences do exist, though, and may account for the observed cross-isotype binding specificities between 3Cpro and SLD.

Viral upper respiratory tract infections in young children with emphasis on acute otitis media

Viral upper respiratory infection is the most common reason for seeking medical care for children. Recurrent viral respiratory infections and subsequent complications (e.g. acute otitis media (AOM)) are a burden for children, their families and society. Over the past decade, our knowledge on the significance of respiratory viruses has broadened remarkably. Viruses cause large variety of respiratory diseases and cause alone diseases, which previously have been assumed to be bacterial only (e.g. AOM and pneumonia). Methods for detection analysis of respiratory viruses are developing making both the diagnosis and epidemiological investigations of respiratory infections easier. Accurate diagnosis of respiratory infections and awareness of possible viral etiology could reduce the use of antibiotics. Etiologic studies of viral infections are becoming increasingly important, with the emergence of new antiviral drugs and vaccines.

Teenage asthma after severe early childhood wheezing: an 11-year prospective follow-up

The role of factors related to early wheezing and their associations with subsequent development of asthma are controversial. We reevaluated 81 children who had been prospectively followed up since hospitalization for wheezing at less than 2 years of age. The baseline data on characteristics of the children, family-related factors, and viral causes of wheezing were collected on entry into the study. At the median age of 12.3 years, current symptoms suggestive of asthma and allergy were recorded. As part of the clinical examination, an outdoor exercise challenge test and skin prick tests to common inhalant allergens were performed. Asthma, as indicated by current inhaled anti-inflammatory medication or repeated wheezing and positive result in the challenge test, was present in 32 (40%) children, and 90% of them were sensitized to at least one allergen. Early asthma-predictive factors were atopic dermatitis (odds ratio (OR), 3.5; 95% confidence interval (CI), 1.2-10.1) and the presence of specific IgE to inhalant allergens (OR, 11.3; 95% CI, 1.9-67.6). Respiratory syncytial virus (RSV) identification during wheezing in infancy was relatively rare (20%) among later asthmatics compared with other or no viral identification (52%) or rhinovirus identification (58%). Since the prevalence of childhood asthma in our area is 4.0-5.0%, we conclude that the increased risk of asthma persists until the teenage years after hospitalization for wheezing in infancy. The risk was about 5-fold after respiratory syncytial virus-induced wheezing, and more than 10-fold after rhinovirus-induced wheezing in the present study.

Development of three multiplex RT-PCR assays for the detection of 12 respiratory RNA viruses

Three multiplex hemi-nested RT-PCR assays were developed to detect simultaneously 12 RNA respiratory viruses: influenza viruses A, B and C, human respiratory syncytial virus (hRSV), human metapneumovirus (hMPV), parainfluenza virus types 1-4 (PIV-1, -2, -3 and -4), human coronavirus OC43 and 229E (HCoV) and rhinovirus (hRV). An internal amplification control was included in one of the RT-PCR assays. The RT-PCR multiplex 1 and the hemi-nested multiplex 1 detected 1 and 0.1 TCID50 of RSV A, respectively, and 0.01 and 0.001 TCID50 of influenza virus A/H3N2, respectively. Two hundred and three nasal aspirates from hospitalised children were retrospectively tested in comparison with two conventional methods: direct immunofluorescence assay and viral isolation technique. Almost all samples (89/91) that were positive by immunofluorescence assay and/or viral isolation technique were detected by the multiplex assay. This method also detected an additional 85 viruses and 33 co-infections. The overall sensitivity (98%), rapidity and enhanced efficiency of these multiplex hemi-nested RT-PCR assays suggest that they would be a significant improvement over conventional methods for the detection of a broad spectrum of respiratory viruses.

Biochemical prevention and treatment of viral infections - a new paradigm in medicine for infectious diseases

For two centuries, vaccination has been the dominating approach to develop prophylaxis against viral infections through immunological prevention. However, vaccines are not always possible to make, are ineffective for many viral infections, and also carry certain risk for a small, yet significant portion of the population. In the recent years, FDA's approval and subsequent market acceptance of Synagis, a monoclonal antibody indicated for prevention and treatment of respiratory syncytial virus (RSV) has heralded a new era for viral infection prevention and treatment. This emerging paradigm, herein designated "Biochemical Prevention and Treatment", currently involves two aspects: (1) preventing viral entry via passive transfer of specific protein-based anti-viral molecules or host cell receptor blockers; (2) inhibiting viral amplification by targeting the viral mRNA with anti-sense DNA, ribozyme, or RNA interference (RNAi). This article summarizes the current status of this field.

Mechanisms of rhinovirus-induced asthma

Several epidemiological studies using sensitive detection methodologies have confirmed that the majority of acute asthma exacerbations follow upper respiratory tract infections--common colds. Most of these colds are due to human rhinoviruses (RVs). RVs are able to reach and replicate in epithelial cells of the lower airways and can activate these cells to produce pro-inflammatory mediators. Under some circumstances, RVs can also become cytotoxic to the epithelium. Atopic asthmatic individuals produce less interferon-gamma and more interleukin-10 than normal subjects in response to RV infection. Symptom severity as well as viral shedding after experimental RV infection, is inversely correlated with 'atopic' status, expressed as the interferon-gamma to interleukin-5 ratio. Expression of co-stimulatory molecules on immune cells is also affected in atopic asthmatics, suggesting an aberrant immune response to RV that may lead to suboptimal viral clearance and viral persistence. Some of the above effects can be reversed in vitro by corticosteroids, second-generation antihistamines or anti-oxidants; however, the optimal strategy for treating acute asthma exacerbations requires further research at both mechanistic and clinical levels.

Acute respiratory symptoms in adults in general practice

BACKGROUND

Community studies have shown that approximately 30% of patients with acute respiratory tract symptoms have no identifiable infective aetiology. This may not be applicable in general practice.

OBJECTIVE

The purpose of this study was to determine the infective aetiology in patients who presented to primary care doctors with acute respiratory symptoms.

METHODS

A prospective study was carried out in all nine primary care clinics belonging to the National Healthcare Group Polyclinics (NHGPs) in Singapore. The subjects comprised 594 consecutive patients (318 males, 276 females) aged > or = 21 years who presented with complaints of any one of cough, nasal or throat symptoms of <7 days duration. Data collection was through interview using structured questionnaire, physical examination, throat swabs for bacterial culture and nasal swabs for virus identification by immunofluorescence (IF) and polymerase chain reaction (PCR). Additional PCR was performed on a subsample of 100 patients. Patients were followed-up until resolution of symptoms.

RESULTS

The aetiological diagnosis by infective agent is as follows: 150 patients (25.2%) had virus infections, of which 90.7% (136/150) were by rhinovirus. Fourteen patients (2.4%) had bacterial infections, of which 10 were due to group G streptococcus. Group A streptococcus was not detected. Nineteen patients with new pathogens were identified by further PCR. These included parainfluenza 4, human coronavirus OC43, adenovirus, enterovirus and Chlamydia pneumoniae. No pathogen could be identified in 49% of patients. There were no differences in clinical presentation and socio-demographic variables between patients who had viral infections and those in whom no pathogen could be identified.

CONCLUSION

In about half of patients who presented at NHGPs, no pathogens could be identified even after PCR. A non-infective aetiology could be considered in these patients.

The common cold: a review of the literature

Respiratory viral infections, also known as the common cold, are the most common infections in humans. Despite their benign nature, they are a major cause of morbidity and mortality on a worldwide basis. Several viruses have been associated with such illness, of which rhinovirus is the most common. Symptom production is a combination of viral cytopathic effect and the activation of inflammatory pathways. Therefore, antiviral treatment alone may not be able to prevent these events. The optimal use of such agents also requires earlier initiation; therefore, it is important to develop accurate and rapid diagnostic techniques for respiratory viruses. Before any reliable and effective treatment is available, symptomatic therapies may remain the only possible choice of management.

Zinc lozenges: cold cure or candy? Solution chemistry determinations

Common colds were shortened by 7 days in a 1984 clinical trial using zinc gluconate throat lozenges each 2 h. Between then and 2004, 10 other double-blind, placebo-controlled clinical trials showed widely varying results. This re-analysis of these trials presents solution chemistry methods to elucidate differences in efficacy. Statistically significant correlation was shown between total daily dosages of positively charged zinc species and reductions in median (p = 0.005) and mean duration (p < 0.02) of common colds in these trials.

Predominance of rhinovirus in the nose of symptomatic and asymptomatic infants

Respiratory infections in infancy may protect against developing Th2-mediated allergic disease (hygiene hypothesis). To estimate the relative contribution of particular viruses to the development of the immune system and allergic disease, we investigated longitudinally the prevalence of respiratory viral infections in infants. One hundred and twenty-six healthy infants were included in this prospective birth cohort study in their first year of life. Physical examination was performed and nasal brush samples were taken during routine visits every 6 months and during an upper respiratory tract infection (URTI) (sick visits). The prevalence of respiratory viral infections in infants with URTI, infants with rhinitis without general malaise and infants without nasal symptoms was studied. Rhinovirus was the most prevalent pathogen during URTI and rhinitis in 0- to 2-year-old infants ( approximately 40%). During URTI, also respiratory syncytial virus ( approximately 20%) and coronavirus ( approximately 10%) infections were found, which were rarely detected in infants with rhinitis. Surprisingly, in 20% of infants who did not present with nasal symptoms, rhinovirus infections were also detected. During routine visits at 12 months, a higher prevalence of rhinovirus infections was found in infants who attended day-care compared with those who did not. We did not observe a relation between breast-feeding or smoking by one or both parents and the prevalence of rhinovirus infections. The parental history of atopy was not related to the prevalence of rhinovirus infection, indicating that the genetic risk of allergic disease does not seem to increase the chance of rhinovirus infections. In conclusion, rhinovirus infection is the most prevalent respiratory viral infection in infants. It may therefore affect the maturation of the immune system and the development of allergic disease considerably.

Inhibition of nucleo-cytoplasmic trafficking by RNA viruses: targeting the nuclear pore complex

Analysis of virus-host interactions has revealed a variety of ways in which viruses utilize and/or alter host functions in an effort to facilitate efficient replication. Recent work has suggested that certain RNA viruses that replicate in the cytoplasm disrupt the normal trafficking of cellular RNAs and proteins within the host cell. This review will examine the recent evidence showing that poliovirus and vesicular stomatitis virus (VSV) can inhibit nucleo-cytoplasmic transport within cells. Interestingly, the data indicate that inhibition by both viruses involves targeting components of the nuclear pore complex (NPC). Following this, several possible explanations for why viruses might disrupt nucleo-cytoplasmic transport are discussed. Finally, the possibility that disruption of nucleo-cytoplasmic trafficking may be a more common feature of RNA virus-host interactions than previously thought is examined.

Detection of rhinovirus RNA in middle turbinate of patients with common colds by in situ hybridization

Human rhinovirus 14 RNA was determined by in situ hybridization from middle turbinate biopsies in 32 patients with diagnosed common colds and in five control individuals. Twenty-two (69%) biopsies from common colds patients but none of the five control biopsies showed reactivity for human rhinovirus 14 antisense probe. The signal was detected both in the respiratory epithelium and in mucosal inflammatory cells. In situ hybridization of the middle turbinate tissue yielded more positive results than RT-PCR (47%) or virus culture (34%) assayed from nasopharyngeal aspirates, but no statistical significant differences were observed (P = 0.265, P = 0.425, respectively). The results indicated that in situ hybridization procedure was slightly more sensitive than PCR assays and classical culture for the detection of human rhinovirus infection of upper respiratory tract. However, in situ hybridization procedure appeared to be an interesting methodology to investigate the physiopathology of respiratory tract infection by rhinoviruses.

[Rhinovirus and acute respiratory infections in hospitalized children. Retrospective study 1998-2000]

OBJECTIVES

Rhinoviruses are the most common aetiological agents of colds, but the frequency and the severity of other locations of the infection are not well known. This study describes the clinical aspects and the severity of rhinovirus infections in hospitalised children.

METHODS

Isolation in culture and a RT-PCR were performed for the detection of rhinovirus in nasal aspirates from hospitalised children from September 1998 to October 2000. A group of 211 children found to be positive for rhinovirus was studied.

RESULTS

Rhinovirus-infected children suffered from the following clinical syndromes: 60 (28.4%) upper airway infections, 81 (38.4%) bronchiolitis, 25 (11.9%) pneumonias and 12 (4.7%) acute attacks of asthma. Clinical symptoms were wheezing (32%), ronchi (37%) and 29% of children presented with acute distress respiratory syndrome; 40% of the available chest X-Ray were abnormal. Eight children were hospitalised in the intensive care unit and two children died. Twenty-five children (10.9%) had a nosocomial infection; a dual infection was observed in 19 cases (9%) with the following viruses: RSV (3), influenza (2) parainfluenza (8), adenovirus (2), enterovirus (4); 19 (9%) children had a secondary bacterial infection. Rhinoviruses were detected in nasal aspirates in 112 cases (53%) according to the culture and in the rhinovirus culture-negative samples in 99 cases (47%) according to the RT-PCR assay.

CONCLUSION

After eliminating cases of bacterial or viral dual infections, the clinical aspects of rhinovirus infections in children are the following: upper respiratory tract infections (25.6%), bronchiolitis ou bronchitis (25.6%), pneumonia (6.2%), acute attack of asthma (5.7%). The virological diagnosis according to culture is mainly improved by molecular techniques.

Rhinovirus-induced wheezing in infancy--the first sign of childhood asthma?

BACKGROUND

Although known as common causes of upper respiratory infections, rhinoviruses, enteroviruses, and corona-viruses are poorly studied as inducers of wheezing in infants, and their possible role in the development of childhood asthma has not been investigated.

OBJECTIVE

The purposes of this study were to assess the occurrence of RV, enterovirus, and coronavirus infections in wheezing infants and to evaluate the association of these viral findings with early school-age asthma.

METHODS

In 1999, outcome in relation to asthma was studied in 82 of 100 initially recruited children who had been hospitalized for wheezing in infancy during the period 1992-1993. In 2000, etiologic viral studies regarding the index episode of wheezing were supplemented by rhinovirus, enterovirus, and coronavirus detection by RT-PCR from frozen nasopharyngeal aspirates in 81 of the children for whom adequate samples were available. Of these children, 66 had participated in the follow-up in 1999.

RESULTS

Rhinoviruses were identified in 27 (33%) of the 81 children, enteroviruses in 10 (12%), and coronaviruses in none. Rhinoviruses were present as single viral findings in 22 (81%) of the 27 rhinovirus-positive cases, and rhinovirus infections were associated with the presence of atopic dermatitis in infancy. Enteroviruses were commonly encountered in mixed infections and had no association with atopy. As single viral findings, rhinoviruses were associated with the development of asthma (P =.047; odds ratio, 4.14; 95% CI, 1.02-16.77 versus rhinovirus-negative cases [by logistic regression adjusted for age, sex, and atopic dermatitis on entry)].

CONCLUSION

Our results present rhinoviruses as important inducers of wheezing even in infancy. The association with atopy and subsequent asthma calls for reevaluation of the role of rhinoviruses in the development of asthma.

The seasonality of rhinovirus infections and its implications for clinical recognition

BACKGROUND

Rhinoviruses are the most common cause of acute respiratory infections. Isolation of rhinoviruses occurs in a distinct and consistent seasonal pattern that can be used to help determine whether an acute respiratory illness is caused by a rhinovirus.

OBJECTIVE

This article reviews information on the seasonality of rhinovirus infection derived from early and recent studies of rhinovirus occurrence and treatment.

METHODS

PubMed was searched from 1965 to the present to identify all potentially relevant papers. The search terms used were rhinovirus and seasonality. A total of 1998 papers were screened.

RESULTS

Rhinoviruses comprise more than three quarters of viruses circulating in early autumn. In some years and perhaps some geographic areas, spring is an even more important time for rhinovirus transmission. Although overall rates of respiratory illness are lower in summer, rhinoviruses are the most frequently isolated virus at this time of year. Other viral agents, including influenza viruses and respiratory syncytial virus (particularly with parainfluenza virus), predominate in the winter. Thus, for most of the year, rhinoviruses are the cause of the majority of acute viral respiratory infections.

CONCLUSION

Understanding the seasonal incidence of rhinovirus infection may help determine how best to employ currently available antirhinoviral agents in patients presenting with symptoms of an acute viral respiratory infection.