Impact of rhinovirus nasopharyngeal viral load and viremia on severity of respiratory infections in children

Rhinovirus characteristics associated with viremia in childhood asthma

Although rhinoviruses play a major role in exacerbations of childhood asthma, the presence of rhinovirus (RV) RNA in plasma, referred to as viremia, has been investigated in a few studies. The aim of the study was to investigate the presence of rhinovirus viremia at the time of asthma exacerbation and to describe the molecular characteristics of rhinoviruses associated with viremia. We conducted an observational, prospective, multicenter study in eight pediatric hospitals (VIRASTHMA2). Preschool-aged recurrent wheezers (1-5 years) hospitalized for a severe exacerbation were included. Reverse-transcription polymerase chain reaction (RT-PCR) and molecular typing for RV/enteroviruses (EV) were performed on nasal swabs and plasma. Plasma specimens were available for 105 children with positive RT-PCR for RV/EV in respiratory specimens. Thirty-six (34.3%) had positive viremia. In plasma, 28 (82.4%) of the typable specimens were RV-C, five (14.7%) were EV-D68, and one was RV-A (2.9%). In all cases, the RV/EV type was identical in the plasma and respiratory specimens. In conclusion, RV/EV viremia is frequent in severe exacerbations of preschool recurrent wheezers, particularly in RV-C infections.

Epidemiology of Respiratory Infections during the COVID-19 Pandemic

To face the COVID-19 outbreak, a wide range of non-pharmaceutical interventions (NPIs) aimed at limiting the spread of the virus in communities, such as mask-wearing, hand hygiene, social distancing, travel restrictions, and school closures, were introduced in most countries. Thereafter, a significant reduction of new asymptomatic and symptomatic COVID-19 cases occurred, although there were differences between countries according to the type and duration of the NPIs. In addition, the COVID-19 pandemic has been accompanied by significant variations in the global incidence of diseases due to the most common non-SARS-CoV-2 respiratory viruses and some bacteria. In this narrative review, the epidemiology of the most common non-SARS-CoV-2 respiratory infections during the COVID-19 pandemic is detailed. Moreover, factors that could have had a role in modifying the traditional circulation of respiratory pathogens are discussed. A literature analysis shows that NPIs were the most important cause of the general reduction in the incidence of influenza and respiratory syncytial virus infection in the first year of the pandemic, although the different sensitivity of each virus to NPIs, the type and duration of measures used, as well as the interference among viruses may have played a role in modulating viral circulation. Reasons for the increase in the incidences of Streptococcus pneumoniae and group A Streptococcus infections seem strictly linked to immunity debt and the role played by NPIs in reducing viral infections and limiting bacterial superimposed infections. These results highlight the importance of NPIs during pandemics, the need to monitor the circulation of infectious agents that cause diseases similar to those caused by pandemic agents, and the need to make efforts to improve coverage with available vaccines.

Association of viral load with TRAIL, IP-10, CRP biomarker signature and disease severity in children with respiratory tract infection or fever without source: A prospective, multicentre cohort study

BACKGROUND

To investigate the association of viral load (VL) with (i) tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-induced protein-10, C-reactive protein, and a combinatorial score (BV score), and (ii) clinical severity.

STUDY DESIGN

In this prospective, multicentre cohort substudy, children with respiratory tract infection or fever without source were enrolled. VL for influenza virus, rhinovirus, respiratory syncytial virus, and adenovirus was measured from nasopharyngeal swabs. The reference standard diagnosis was established based on expert panel adjudication.

RESULTS

Of 1140 recruited patients, 333 had a virus monodetection. VL for the aggregated data set correlated with TRAIL and IP-10 levels, with the length of oxygen therapy, and inversely with the BV score. At a single viral level, only the influenza VL yielded a correlation with TRAIL, IP-10 levels, and the BV score. Children with a viral reference standard diagnosis had significantly higher VL than those with bacterial infection (p = 0.0005). Low TRAIL (incidence rate ratio [IRR] 0.6, 95% confidence interval [CI] 0.39-0.91) and young age (IRR 0.62, 95% CI 0.49-0.79) were associated with a longer hospital stay, while young age (IRR 0.33, 95% CI 0.18-0.61), low TRAIL (IRR 0.25, 95% CI 0.08-0.76), and high VL (IRR 1.16, 95% CI 1.00-1.33) were predictive of longer oxygen therapy.

CONCLUSION

These findings indicate that VL correlates with biomarkers and may serve as a complementary tool pertaining to disease severity.

SARS-CoV-2 Transmission Risk Model in an Urban Area of Mexico, Based on GIS Analysis and Viral Load

The COVID-19 pandemic highlighted health systems vulnerabilities, as well as thoughtlessness by governments and society. Due to the nature of this contingency, the use of geographic information systems (GIS) is essential to understand the SARS-CoV-2 distribution dynamics within a defined geographic area. This work was performed in Tepic, a medium-sized city in Mexico. The residence of 834 COVID-19 infected individuals was georeferenced and categorized by viral load (Ct). The analysis took place during the maximum contagion of the first four waves of COVID-19 in Mexico, analyzing 158, 254, 143, and 279 cases in each wave respectively. Then heatmaps were built and categorized into five areas ranging from very low to very high risk of contagion, finding that the second wave exhibited a greater number of cases with a high viral load. Additionally, a spatial analysis was performed to measure urban areas with a higher risk of contagion, during this wave this area had 19,203.08 km² (36.11% of the city). Therefore, a kernel density spatial model integrated by meaningful variables such as the number of infected subjects, viral load, and place of residence in cities, to establish geographic zones with different degrees of infection risk, could be useful for decision-making in future epidemic events.

Viral Induced Effects on a Vulnerable Epithelium; Lessons Learned From Paediatric Asthma and Eosinophilic Oesophagitis

The epithelium is integral to the protection of many different biological systems and for the maintenance of biochemical homeostasis. Emerging evidence suggests that particular children have epithelial vulnerabilities leading to dysregulated barrier function and integrity, that resultantly contributes to disease pathogenesis. These epithelial vulnerabilities likely develop in utero or in early life due to various genetic, epigenetic and environmental factors. Although various epithelia are uniquely structured with specific function, prevalent allergic-type epithelial diseases in children potentially have common or parallel disease processes. These include inflammation and immune response dysregulation stemming from atypical epithelial barrier function and integrity. Two diseases where aetiology and pathogenesis are potentially linked to epithelial vulnerabilities include Paediatric Asthma and Eosinophilic Oesophagitis (EoE). For example, rhinovirus C (RV-C) is a known risk factor for paediatric asthma development and is known to disrupt respiratory epithelial barrier function causing acute inflammation. In addition, EoE, a prevalent atopic condition of the oesophageal epithelium, is characterised by similar innate immune and epithelial responses to viral injury. This review examines the current literature and identifies the gaps in the field defining viral-induced effects on a vulnerable respiratory epithelium and resulting chronic inflammation, drawing from knowledge generated in acute wheezing illness, paediatric asthma and EoE. Besides highlighting the importance of epithelial structure and barrier function in allergic disease pathogenesis regardless of specific epithelial sub-types, this review focuses on the importance of examining other parallel allergic-type disease processes that may uncover commonalities driving disease pathogenesis. This in turn may be beneficial in the development of common therapeutics for current clinical management and disease prevention in the future.

Epidemiology and Seasonality of Endemic Human Coronaviruses in South African and Zambian Children: A Case-Control Pneumonia Study

Endemic human coronaviruses (HCoV) are capable of causing a range of diseases from the common cold to pneumonia. We evaluated the epidemiology and seasonality of endemic HCoVs in children hospitalized with clinical pneumonia and among community controls living in countries with a high HIV burden, namely South Africa and Zambia, between August 2011 to October 2013. Nasopharyngeal/oropharyngeal swabs were collected from all cases and controls and tested for endemic HCoV species and 12 other respiratory viruses using a multiplex real-time PCR assay. We found that the likelihood of detecting endemic HCoV species was higher among asymptomatic controls than cases (11% vs. 7.2%; 95% CI: 1.2–2.0). This was however only observed among children > 6 months and was mainly driven by the Betacoronavirus endemic species (HCoV-OC43 and –HKU1). Endemic HCoV species were detected through the year; however, in Zambia, the endemic Betacoronavirus species tended to peak during the winter months (May–August). There was no association between HIV status and endemic HCoV detection.

Epidemiology of the Rhinovirus (RV) in African and Southeast Asian Children: A Case-Control Pneumonia Etiology Study

Rhinovirus (RV) is commonly detected in asymptomatic children; hence, its pathogenicity during childhood pneumonia remains controversial. We evaluated RV epidemiology in HIV-uninfected children hospitalized with clinical pneumonia and among community controls. PERCH was a case-control study that enrolled children (1–59 months) hospitalized with severe and very severe pneumonia per World Health Organization clinical criteria and age-frequency-matched community controls in seven countries. Nasopharyngeal/oropharyngeal swabs were collected for all participants, combined, and tested for RV and 18 other respiratory viruses using the Fast Track multiplex real-time PCR assay. RV detection was more common among cases (24%) than controls (21%) (aOR = 1.5, 95%CI:1.3–1.6). This association was driven by the children aged 12–59 months, where 28% of cases vs. 18% of controls were RV-positive (aOR = 2.1, 95%CI:1.8–2.5). Wheezing was 1.8-fold (aOR 95%CI:1.4–2.2) more prevalent among pneumonia cases who were RV-positive vs. RV-negative. Of the RV-positive cases, 13% had a higher probability (>75%) that RV was the cause of their pneumonia based on the PERCH integrated etiology analysis; 99% of these cases occurred in children over 12 months in Bangladesh. RV was commonly identified in both cases and controls and was significantly associated with severe pneumonia status among children over 12 months of age, particularly those in Bangladesh. RV-positive pneumonia was associated with wheezing.

Enhanced Neutralizing Antibody Responses to Rhinovirus C and Age-Dependent Patterns of Infection

Rationale: Rhinovirus (RV) C can cause asymptomatic infection and respiratory illnesses ranging from the common cold to severe wheezing.Objectives: To identify how age and other individual-level factors are associated with susceptibility to RV-C illnesses.Methods: Longitudinal data from the COAST (Childhood Origins of Asthma) birth cohort study were analyzed to determine relationships between age and RV-C infections. Neutralizing antibodies specific for RV-A and RV-C (three types each) were determined using a novel PCR-based assay. Data were pooled from 14 study cohorts in the United States, Finland, and Australia, and mixed-effects logistic regression was used to identify factors related to the proportion of RV-C versus RV-A detection.Measurements and Main Results: In COAST, RV-A and RV-C infections were similarly common in infancy, whereas RV-C was detected much less often than RV-A during both respiratory illnesses and scheduled surveillance visits (P < 0.001, χ2) in older children. The prevalence of neutralizing antibodies to RV-A or RV-C types was low (5-27%) at the age of 2 years, but by the age of 16 years, RV-C seropositivity was more prevalent (78% vs. 18% for RV-A; P < 0.0001). In the pooled analysis, the RV-C to RV-A detection ratio during illnesses was significantly related to age (P < 0.0001), CDHR3 genotype (P < 0.05), and wheezing illnesses (P < 0.05). Furthermore, certain RV types (e.g., C2, C11, A78, and A12) were consistently more virulent and prevalent over time.Conclusions: Knowledge of prevalent RV types, antibody responses, and populations at risk based on age and genetics may guide the development of vaccines or other novel therapies against this important respiratory pathogen.

Clinically Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion Associated with Rhinovirus

A 2-year-old girl with fever and seizures was diagnosed as having clinically mild encephalitis/encephalopathy with a reversible splenial lesion, as indicated by magnetic resonance imaging. Virologic analysis identified human rhinovirus A49 in her serum. Although human rhinovirus rarely involves the central nervous system, such involvement could result in mild encephalitis/encephalopathy with a reversible splenial lesion.

Viral Loads and Disease Severity in Children with Rhinovirus-Associated Illnesses

The role of rhinoviruses (RVs) in children with clinical syndromes not classically associated with RV infections is not well understood. We analyzed a cohort of children ≤21 years old who were PCR+ for RV at a large Pediatric Hospital from 2011 to 2013. Using univariate and multivariable logistic regression, we analyzed the associations between demographic, clinical characteristics, microbiology data, and clinical outcomes in children with compatible symptoms and incidental RV detection. Of the 2473 children (inpatients and outpatients) with an RV+ PCR, 2382 (96%) had compatible symptoms, and 91 (4%) did not. The overall median age was 14 months and 78% had underlying comorbidities. No differences in RV viral loads were found according to the presence of compatible symptoms, while in children with classic RV symptoms, RV viral loads were higher in single RV infections versus RV viral co-infections. Bacterial co-infections were more common in RV incidental detection (7.6%) than in children with compatible symptoms (1.9%, p < 0.001). The presence of compatible symptoms independently increased the odds ratio (OR, 95% CI) of hospitalization 4.8 (3.1-7.4), prolonged hospital stays 1.9 (1.1-3.1), need for oxygen 12 (5.8-25.0) and pediatric intensive care unit (PICU) admission 4.13 (2.0-8.2). Thus, despite comparable RV loads, disease severity was significantly worse in children with compatible symptoms.

Uses of pathogen detection data to estimate vaccine direct effects in case-control studies

The fact that many pathogens can be carried or shed without causing symptoms complicates the interpretation of microbiological data when diagnosing certain infectious disease syndromes. Diagnostic criteria that attribute symptoms to a pathogen which is detectable, whether it is or is not the aetiological agent of disease, may lead to outcome misclassification in epidemiological studies. Case-control studies are commonly undertaken to estimate vaccine effectiveness (VE) and present an opportunity to compare pathogen detection among individuals with and without clinically relevant symptoms. Considering this study context, we present a mathematical framework yielding simple estimators for the direct effects of vaccination on various aspects of host susceptibility. These include protection against acquisition of the pathogen of interest and protection against progression of this pathogen to disease following acquisition. We assess the impact of test sensitivity on these estimators and extend our framework to identify a 'vaccine probe' estimator for pathogen-specific aetiological fractions. We also derive biases affecting VE estimates under the test-negative design, a special case enrolling only symptomatic persons. Our results provide strategies for estimating pathogen-specific VE in the absence of a diagnostic gold standard. These approaches can inform the design and analysis of studies addressing numerous pathogens and vaccines.

Rhinovirus Infection Drives Complex Host Airway Molecular Responses in Children With Cystic Fibrosis

Early-life viral infections are responsible for pulmonary exacerbations that can contribute to disease progression in young children with cystic fibrosis (CF). The most common respiratory viruses detected in the CF airway are human rhinoviruses (RV), and augmented airway inflammation in CF has been attributed to dysregulated airway epithelial responses although evidence has been conflicting. Here, we exposed airway epithelial cells from children with and without CF to RV in vitro. Using RNA-Seq, we profiled the transcriptomic differences of CF and non-CF airway epithelial cells at baseline and in response to RV. There were only modest differences between CF and non-CF cells at baseline. In response to RV, there were 1,442 and 896 differentially expressed genes in CF and non-CF airway epithelial cells, respectively. The core antiviral responses in CF and non-CF airway epithelial cells were mediated through interferon signaling although type 1 and 3 interferon signaling, when measured, were reduced in CF airway epithelial cells following viral challenge consistent with previous reports. The transcriptional responses in CF airway epithelial cells were more complex than in non-CF airway epithelial cells with diverse over-represented biological pathways, such as cytokine signaling and metabolic and biosynthetic pathways. Network analysis highlighted that the differentially expressed genes of CF airway epithelial cells' transcriptional responses were highly interconnected and formed a more complex network than observed in non-CF airway epithelial cells. We corroborate observations in fully differentiated air–liquid interface (ALI) cultures, identifying genes involved in IL-1 signaling and mucin glycosylation that are only dysregulated in the CF airway epithelial response to RV infection. These data provide novel insights into the CF airway epithelial cells' responses to RV infection and highlight potential pathways that could be targeted to improve antiviral and anti-inflammatory responses in CF.

A prospective case-control study on the association of Rhinovirus nasopharyngeal viral load and viremia in South African children hospitalized with severe pneumonia

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Rhinovirus role during severe childhood respiratory disease remains unknown.

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Rhinovirus prevalence was similar between children with pneumonia and controls.

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Rhinovirus-viremia was 4-fold more prevalent amongst cases than controls.

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Viremia could be helpful in attributing causality to rhinovirus during pneumonia episodes.

Rhinovirus (RV) role in pathogenesis of severe childhood disease remains controversial. We aimed to explore the association between RV molecular subtyping, nasopharyngeal viral loads and viremia with childhood pneumonia. Nasopharyngeal and blood samples from cases and controls were tested for RV and the 5′ non-coding region sequenced. The cases compared to controls had a similar prevalence of RV detection in the nasopharynx (23 % vs. 22 %, P = 0.66), similar RV species distribution (A, B, C = 44 %, 8%, 44 % vs. 48 %, 7%, 38 %; respectively; P = 0.66) and similar viral load (4.0 and 3.7 log10 copies/mL, P = 0.062). However, RV-viremia was 4.01-fold (aOR 95 % CI: 1.26–12.78) more prevalent among cases (7%) than controls (2%), P = 0.019. Furthermore, among cases and controls RV-C was more commonly associated with viremia (14 % and 4%, P = 0.023), than RV-A (2% and 1%; P = 0.529). Thus RV-viremia could be used as a measure for attributing causality to RV in children hospitalized for pneumonia.

[Rhinoviruses]

Human rhinoviruses (RV) belong to the Picornaviridae and are divided into three species: rhinovirus A, B and C. As causative viruses of upper airway infections (common cold), they possess enormous epidemiological and clinical importance. Furthermore, rhinoviruses are significant pathogens of acute exacerbations of chronic airway diseases such as asthma and chronic obstructive pulmonary disease. Their role as a cofactor in the development of pneumonia and their relevance in critically ill patients is still unclear and the focus of current research. Due to the unspecific clinical symptoms, diagnosis is difficult. Laboratory detection is sophisticated and a distinction between clinically relevant infection and contamination not always possible. Specific therapeutic antiviral strategies against rhinovirus infection do not exist as yet and, due to the large variety of subtypes, the development of vaccines remains a considerable challenge.

Community-Acquired Respiratory Viruses in Transplant Patients: Diversity, Impact, Unmet Clinical Needs

Patients undergoing solid-organ transplantation (SOT) or allogeneic hematopoietic cell transplantation (HCT) are at increased risk for infectious complications. Community-acquired respiratory viruses (CARVs) pose a particular challenge due to the frequent exposure pre-, peri-, and posttransplantation. Although influenza A and B viruses have a top priority regarding prevention and treatment, recent molecular diagnostic tests detecting an array of other CARVs in real time have dramatically expanded our knowledge about the epidemiology, diversity, and impact of CARV infections in the general population and in allogeneic HCT and SOT patients. These data have demonstrated that non-influenza CARVs independently contribute to morbidity and mortality of transplant patients. However, effective vaccination and antiviral treatment is only emerging for non-influenza CARVs, placing emphasis on infection control and supportive measures. Here, we review the current knowledge about CARVs in SOT and allogeneic HCT patients to better define the magnitude of this unmet clinical need and to discuss some of the lessons learned from human influenza virus, respiratory syncytial virus, parainfluenzavirus, rhinovirus, coronavirus, adenovirus, and bocavirus regarding diagnosis, prevention, and treatment.

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

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Risk factors for rhinovirus lower respiratory tract infection are not well characterized.

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Several risk factors in hematopoietic cell transplant recipients were identified.

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A risk score for progression to lower respiratory tract infection was developed.

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

Elucidating the Interaction of CF Airway Epithelial Cells and Rhinovirus: Using the Host-Pathogen Relationship to Identify Future Therapeutic Strategies

Chronic lung disease remains the primary cause of mortality in cystic fibrosis (CF). Growing evidence suggests respiratory viral infections are often more severe in CF compared to healthy peers and contributes to pulmonary exacerbations (PEx) and deterioration of lung function. Rhinovirus is the most prevalent respiratory virus detected, particularly during exacerbations in children with CF <5 years old. However, even though rhinoviral infections are likely to be one of the factors initiating the onset of CF lung disease, there is no effective targeted treatment. A better understanding of the innate immune responses by CF airway epithelial cells, the primary site of infection for viruses, is needed to identify why viral infections are more severe in CF. The aim of this review is to present the clinical impact of virus infection in both young children and adults with CF, focusing on rhinovirus infection. Previous in vitro and in vivo investigations looking at the mechanisms behind virus infection will also be summarized. The review will finish on the potential of transcriptomics to elucidate the host-pathogen responses by CF airway cells to viral infection and identify novel therapeutic targets.

Clinical characteristics and cytokine profiles of children with acute lower respiratory tract infections caused by human rhinovirus

The clinical profile of human rhinovirus (HRV) with regard to lower respiratory infections remains unclear. We analyzed the clinical features and cytokine responses of HRV isolates in children with respiratory infections. Quantitative analysis and genotyping of the HRV-positive samples from 601 nasopharyngeal aspirates (NPAs) were performed using VP4/VP2 sequencing. To compare T-helper1 (Th1) type (IFN-γ, TNF-α) and Th2 type (IL-4, IL-10) cytokine responses between HRV-A, B and C, the levels of the four cytokines were measured. The HRV-positive children had shorter fever duration (P = 0.018), and higher frequencies of chest retraction (P = 0.002) and wheezing (P = 0.022) than did the HRV-negative group. HRV-A was identified in 55 cases (58.5%), HRV-B in 8 (8.5%), and HRV-C in 31 (33.0%). There were no significant differences in the clinical data or NPA cytokines levels between patients with HRV-A and HRV-C infections. HRV is an important pathogen of the lower respiratory tract in young children. HRV-A and HRV-C are the dominant species that cause respiratory difficulty in young children.

Antiviral drug screening by assessing epithelial functions and innate immune responses in human 3D airway epithelium model

Respiratory viral infections cause mild to severe diseases, such as common cold, bronchiolitis and pneumonia and are associated with substantial burden for society. To test new molecules for shortening, alleviating the diseases or to develop new therapies, relevant human in vitro models are mandatory. MucilAir™, a human standardized air-liquid interface 3D airway epithelial culture holds in vitro specific mechanisms to counter invaders comparable to the in vivo situation, such as mucus production, mucociliary clearance, and secretion of defensive molecules. The objective of this study was to test the relevance of such a model for the discovery and validation of antiviral drugs. Fully differentiated 3D nasal epithelium cultures were inoculated with picornaviruses, a coronavirus and influenza A viruses in the absence or in the presence of reference antiviral drugs. Results showed that, rupintrivir efficiently inhibits the replication of respiratory picornaviruses in a dose dependent manner and prevents the impairment of the mucociliary clearance. Similarly, oseltamivir reduced the replication of influenza A viruses in a dose dependent manner and prevented the impairment of the epithelial barrier function and cytotoxicity until 4 days of infection. In addition we found that Rhinovirus B14, C15 and influenza A(H1N1) induce significant increase of β Defensins 2 and Cathelicidin release with different time course. These results reveal that a large panel of epithelial functions is modified upon viral infection and validate MucilAir™ as a pertinent tool for pre-clinical antiviral drug testing.

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Reference antivirals inhibit in a dose-dependent manner the respiratory virus production in MucilAir™.

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Respiratory viruses induce specific antimicrobial peptide expression and functional changes in MucilAir™.

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Antivirals prevent virus-induced dysfunctions, the disruption of epithelial barrier and the decrease of mucociliary clearance.

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MucilAir™ is a suitable model to produce clinical respiratory virus isolates and to perform antiviral drugs screening.

Rhinovirus - not just the common cold

Rhinoviruses (RV) are ubiquitous respiratory tract pathogens. They affect both the upper and lower respiratory tract and cause colds but have also been associated with wheezing, asthma exacerbations and pneumonia. New blood transcription profiling techniques of the host immune response are becoming available to characterise the pathogenesis of RV in humans. This review will outline the clinical impact of RVs in children.

Rhinovirus Viremia in Patients Hospitalized With Community-Acquired Pneumonia

Background

Rhinoviruses (RVs) are ubiquitous respiratory pathogens that often cause mild or subclinical infections. Molecular detection of RVs from the upper respiratory tract can be prolonged, complicating etiologic association in persons with severe lower respiratory tract infections. Little is known about RV viremia and its value as a diagnostic indicator in persons hospitalized with community-acquired pneumonia (CAP).

Methods

Sera from RV-positive children and adults hospitalized with CAP were tested for RV by real-time reverse-transcription polymerase chain reaction. Rhinovirus species and type were determined by partial genome sequencing.

Results

Overall, 57 of 570 (10%) RV-positive patients were viremic, and all were children aged <10 years (n = 57/375; 15.2%). Although RV-A was the most common RV species detected from respiratory specimens (48.8%), almost all viremias were RV-C (98.2%). Viremic patients had fewer codetected pathogens and were more likely to have chest retractions, wheezing, and a history of underlying asthma/reactive airway disease than patients without viremia.

Conclusions

More than 1 out of 7 RV-infected children aged <10 years hospitalized with CAP were viremic. In contrast with other RV species, RV-C infections were highly associated with viremia and were usually the only respiratory pathogen identified, suggesting that RV-C viremia may be an important diagnostic indicator in pediatric pneumonia.

Epidemiological analysis and follow-up of human rhinovirus infection in children with asthma exacerbation

To determine the prevalence of human rhinovirus (HRV) infection in children with acute asthma exacerbations, investigation of HRV viral load and severity of asthma exacerbations is also required. Nasopharyngeal aspirates and swabs were collected and assessed for respiratory viruses. HRV-positive samples were sequenced to identify types and determine viral load. Outpatients with asthma exacerbations underwent follow-up evaluations, their swabs were collected and clinical outcomes were recorded at their next clinic visit 4 weeks later. One hundred forty-three inpatients and 131 outpatients, including 88 patients with asthma exacerbations and 43 controls with stable asthma were recruited. HRV-A was mainly detected in September and February (45.5% and 33.3%, respectively), while HRV-C was mainly detected in November and April (70.0% and 55.6%, respectively). HRV-C was the primary type and was primarily found in inpatients with severe asthma exacerbations. HRV-A viral load in the group of inpatients with severe exacerbations was higher than in the mild and moderate groups (P < 0.001 and P = 0.022). The HRV-A viral load of both inpatients and outpatients was higher than that of HRV-C (P < 0.001 and P = 0.036). The main genotypes were HRV-C53 and HRV-A20 among inpatients, and this genotype caused more severe clinical manifestations. HRV persisted for no more than 4 weeks, and their symptoms or signs of disease were well-controlled well. HRV-C was most frequently detected in asthma exacerbations. HRV-A with high viral load led to severe asthma exacerbations.

Rhinovirus viremia in adult patients with high viral load in bronchoalveolar lavages

BACKGROUND

In children, rhinovirus viremia has been associated with higher nasopharyngeal loads and increase in severity of clinical signs and symptoms.

OBJECTIVES

This study aims to detect rhinovirus viremia in adult patients and to establish potential correlations with the clinical course.

STUDY DESIGN

Adult patients with rhinovirus strongly positive bronchoalveolar lavages (BAL, quantitation cycle, Cq values <25) detected between 2008 and 2014 were studied retrospectively. Blood sampled between two weeks before and two weeks after BAL sampling was tested for rhinovirus RNA. Underlying conditions, symptoms, radiography, microbiological data, and disease outcome were analysed.

RESULTS

Twenty-seven of 43 patients with rhinovirus positive BAL at Cq values <25 had blood samples available within the prespecified time-frame (mean blood 3-4 samples per patient). Four of these 27 patients (15%) tested rhinovirus RNA positive in their blood (of whom one patient twice). Genotyping demonstrated rhinovirus A01, A24, B52 and B92 in these four immunocompromised patients. Viremic patients were not significantly different with regard to underlying conditions, respiratory symptoms, radiological findings, co-pathogens nor the number of blood samples tested for RV. However, patients with rhinovirus viremia had significant higher mortality rates compared to patients without viremia, as all four died as a consequence of respiratory problems (100%) versus 22% (5/23), p=0.007 (Fisher's exact).

CONCLUSIONS

Rhinovirus viremia can occur in adult patients with a high viral load in BAL fluid. Rhinovirus viremia may be considered a negative prognostic factor, although a causative role with regard to the adverse outcome has yet to be demonstrated.

Prednisolone for the first rhinovirus-induced wheezing and 4-year asthma risk: A randomized trial

BACKGROUND

Previous findings show that corticosteroid treatment during the first acute wheezing episode may reduce recurrent wheezing in children with high rhinovirus genome load at 12-month follow-up. Longer-term effects have not been investigated prospectively.

METHODS

After PCR confirmation of rhinovirus from nasopharyngeal aspirate, 79 children with the first acute wheezing episode were randomized to receive orally prednisolone or placebo for 3 days. The initiation of asthma control medication before the age of 5 years was confirmed from medical record and/or from parental interview. The outcome was the time to initiation of regular asthma control medication. Interaction analysis examined rhinovirus genome load.

RESULTS

Fifty-nine (75%) children completed the follow-up. Asthma control medication was initiated in 40 (68%) children at the median age of 20 months. Overall, prednisolone did not affect the time to initiation of asthma control medication when compared to placebo (P=.99). Rhinovirus load modified the effect of prednisolone regarding the time to initiation of asthma control medication (P-value for interaction=.04). In children with high rhinovirus load (>7000 copies/mL; n=23), the risk for initiation of medication was lower in the prednisolone group compared to the placebo group (P=.05). In the placebo group, asthma medication was initiated to all children with high rhinovirus load (n=9) during the 14 months after the first wheezing episode.

CONCLUSIONS

Overall, prednisolone did not affect the time to initiation of asthma control medication when compared to placebo. However, prednisolone may be beneficial in first-time wheezing children whose episode was severe and associated with high rhinovirus load. (ClinicalTrials.gov, NCT00731575).

Viral Pathogen Detection by Metagenomics and Pan-Viral Group Polymerase Chain Reaction in Children With Pneumonia Lacking Identifiable Etiology

Background.

Community-acquired pneumonia (CAP) is a leading cause of pediatric hospitalization. Pathogen identification fails in approximately 20% of children but is critical for optimal treatment and prevention of hospital-acquired infections. We used two broad-spectrum detection strategies to identify pathogens in test-negative children with CAP and asymptomatic controls.

Methods.

Nasopharyngeal/oropharyngeal (NP/OP) swabs from 70 children <5 years with CAP of unknown etiology and 90 asymptomatic controls were tested by next-generation sequencing (RNA-seq) and pan viral group (PVG) PCR for 19 viral families. Association of viruses with CAP was assessed by adjusted odds ratios (aOR) and 95% confidence intervals controlling for season and age group.

Results.

RNA-seq/PVG PCR detected previously missed, putative pathogens in 34% of patients. Putative viral pathogens included human parainfluenza virus 4 (aOR 9.3, P = .12), human bocavirus (aOR 9.1, P < .01), Coxsackieviruses (aOR 5.1, P = .09), rhinovirus A (aOR 3.5, P = .34), and rhinovirus C (aOR 2.9, P = .57). RNA-seq was more sensitive for RNA viruses whereas PVG PCR detected more DNA viruses.

Conclusions.

RNA-seq and PVG PCR identified additional viruses, some known to be pathogenic, in NP/OP specimens from one-third of children hospitalized with CAP without a previously identified etiology. Both broad-range methods could be useful tools in future epidemiologic and diagnostic studies.

Propagation of respiratory viruses in human airway epithelia reveals persistent virus-specific signatures

Background

The leading cause of acute illnesses, respiratory viruses, typically cause self-limited diseases, although severe complications can occur in fragile patients. Rhinoviruses (RVs), respiratory enteroviruses (EVs), influenza virus, respiratory syncytial viruses (RSVs), and coronaviruses are highly prevalent respiratory pathogens, but because of the lack of reliable animal models, their differential pathogenesis remains poorly characterized.

Objective

We sought to compare infections by respiratory viruses isolated from clinical specimens using reconstituted human airway epithelia.

Methods

Tissues were infected with RV-A55, RV-A49, RV-B48, RV-C8, and RV-C15; respiratory EV-D68; influenza virus H3N2; RSV-B; and human coronavirus (HCoV)–OC43. Replication kinetics, cell tropism, effect on tissue integrity, and cytokine secretion were compared. Viral adaptation and tissue response were assessed through RNA sequencing.

Results

RVs, RSV-B, and HCoV-OC43 infected ciliated cells and caused no major cell death, whereas H3N2 and EV-D68 induced ciliated cell loss and tissue integrity disruption. H3N2 was also detected in rare goblet and basal cells. All viruses, except RV-B48 and HCoV-OC43, altered cilia beating and mucociliary clearance. H3N2 was the strongest cytokine inducer, and HCoV-OC43 was the weakest. Persistent infection was observed in all cases. RNA sequencing highlighted perturbation of tissue metabolism and induction of a transient but important immune response at 4 days after infection. No majority mutations emerged in the viral population.

Conclusion

Our results highlight the differential in vitro pathogenesis of respiratory viruses during the acute infection phase and their ability to persist under immune tolerance. These data help to appreciate the range of disease severity observed in vivo and the occurrence of chronic respiratory tract infections in immunocompromised hosts.

The liver is a metabolic and immunologic organ: A reconsideration of metabolic decompensation due to infection in inborn errors of metabolism (IEM)

Metabolic decompensation in inborn errors of metabolism (IEM) is characterized by a rapid deterioration in metabolic status leading to life-threatening biochemical perturbations (e.g. hypoglycemia, hyperammonemia, acidosis, organ failure). Infection is the major cause of metabolic decompensation in patients with IEM. We hypothesized that activation of the immune system during infection leads to further perturbations in end-organ metabolism resulting in increased morbidity. To address this, we established model systems of metabolic decompensation due to infection. Using these systems, we have described the pathologic mechanisms of metabolic decompensation as well as changes in hepatic metabolic reserve associated with infection. First and foremost, our studies have demonstrated that the liver experiences a significant local innate immune response during influenza infection that modulates hepatic metabolism. Based on these findings, we are the first to suggest that the role of the liver as a metabolic and immunologic organ is central in the pathophysiology of metabolic decompensation due to infection in IEM. The dual function of the liver as a major metabolic regulator and a lymphoid organ responsible for immunosurveillance places this organ at risk for hepatotoxicity. Mobilization of hepatic reserve and the regenerative capacity of a healthy liver compensates for this calculated risk. However, activation of the hepatic innate immune system may be deleterious in IEM. Based on this assertion, strategies aimed at modulating the innate immune response may be a viable target for intervention in the treatment of hepatic metabolic decompensation.

Rhinovirus - From bench to bedside

Rhinovirus has been neglected in the past because it was generally perceived as a respiratory virus only capable of causing mild common cold. Contemporary epidemiological studies using molecular assays have shown that rhinovirus is frequently detected in adult and pediatric patients with upper or lower respiratory tract infections. Severe pulmonary and extrapulmonary complications are increasingly recognized. Contrary to popular belief, some rhinoviruses can actually replicate well at 37 °C and infect the lower airway in humans. The increasing availability of multiplex PCR panels allows rapid detection of rhinovirus and provides the opportunity for timely treatment and early recognition of outbreaks. Recent advances in the understanding of host factors for viral attachment and replication, and the host immunological response in both asthmatic and non-asthmatic individuals, have provided important insights into rhinovirus infection which are crucial in the development of antiviral treatment. The identification of novel drugs has been accelerated by repurposing clinically-approved drugs. As humoral antibodies induced by past exposure and vaccine antigen of a particular serotype cannot provide full coverage for all rhinovirus serotypes, novel vaccination strategies are required for inducing protective response against all rhinoviruses.

Viruses in cystic fibrosis patients' airways

Although bacteria have historically been considered to play a major role in cystic fibrosis (CF) airway damage, a strong impact of respiratory viral infections (RVI) is also now recognized. Emerging evidence confirms that respiratory viruses are associated with deterioration of pulmonary function and exacerbation and facilitation of bacterial colonization in CF patients. The aim of this review is to provide an overview of the current knowledge on respiratory viruses in CF airways, to discuss the resulting inflammation and RVI response, to determine how to detect the viruses, and to assess their clinical consequences, prevalence, and interactions with bacteria. The most predominant are Rhinoviruses (RVs), significantly associated with CF exacerbation. Molecular techniques, and especially multiplex PCR, help to diagnose viral infections, and the coming rise of metagenomics will extend knowledge of viral populations in the complex ecosystem of CF airways. Prophylaxis and vaccination are currently available only for Respiratory syncytial and Influenza virus (IV), but antiviral molecules are being tested to improve CF patients' care. All the points raised in this review highlight the importance of taking account of RVIs and their potential impact on the CF airway ecosystem.

Superiority of Digital Reverse Transcription-PCR (RT-PCR) over Real-Time RT-PCR for Quantitation of Highly Divergent Human Rhinoviruses

Human rhinoviruses (HRV) comprise 3 species representing more than 150 genotypes. As an important human respiratory pathogen, molecular detection is an indispensable tool for diagnosis and surveillance. However, the sequence diversity of HRV genotypes poses challenges for developing robust molecular methods that detect all genotypes with equal efficiencies. This study compares the accuracies of reverse transcription-quantitative PCR (RT-qPCR) and reverse transcription-digital PCR (RT-dPCR) for quantifying HRV RNA using genotype-specific primers and probes and a consensus primer/probe set targeting the 5' noncoding region of HRV. When using consensus primers and probes for the quantification of HRV, RT-dPCR outperformed RT-qPCR by consistently and accurately quantifying HRV RNAs across more genotype groups, despite the presence of up to 2 target-sequence mismatches within the primer or probe binding region. Because it does not rely on amplification efficiency, which can be affected by sequence mismatches in primer/probe binding regions, RT-dPCR may be the optimal molecular method for future HRV quantification studies and for quantitating other viruses with high sequence diversity.

The plasma virome of febrile adult Kenyans shows frequent parvovirus B19 infections and a novel arbovirus (Kadipiro virus)

Viral nucleic acids present in the plasma of 498 Kenyan adults with unexplained fever were characterized by metagenomics analysis of 51 sample pools. The highest to lowest fraction of plasma pools was positive for parvovirus B19 (75 %), pegivirus C (GBV-C) (67 %), alpha anellovirus (59 %), gamma anellovirus (55 %), beta anellovirus (41 %), dengue virus genotype 2 (DENV-2) (16 %), human immunodeficiency virus type 1 (6 %), human herpesvirus 6 (6 %), HBV (4 %), rotavirus (4 %), hepatitis B virus (4 %), rhinovirus C (2 %), Merkel cell polyomavirus (MCPyV; 2 %) and Kadipiro virus (2 %). Ranking by overall percentage of viral reads yielded similar results. Characterization of viral nucleic acids in the plasma of a febrile East African population showed a high frequency of parvovirus B19 and DENV infections and detected a reovirus (Kadipiro virus) previously reported only in Asian Culex mosquitoes, providing a baseline to compare with future virome studies to detect emerging viruses in this region.

Performance of a Taqman Assay for Improved Detection and Quantification of Human Rhinovirus Viral Load

Human rhinovirus (HRV) is the major aetiology of respiratory tract infections. HRV viral load assays are available but limitations that affect accurate quantification exist. We developed a one-step Taqman assay using oligonucleotides designed based on a comprehensive list of global HRV sequences. The new oligonucleotides targeting the 5′-UTR region showed high PCR efficiency (E = 99.6%, R² = 0.996), with quantifiable viral load as low as 2 viral copies/μl. Assay evaluation using an External Quality Assessment (EQA) panel yielded a detection rate of 90%. When tested on 315 human enterovirus-positive specimens comprising at least 84 genetically distinct HRV types/serotypes (determined by the VP4/VP2 gene phylogenetic analysis), the assay detected all HRV species and types, as well as other non-polio enteroviruses. A commercial quantification kit, which failed to detect any of the EQA specimens, produced a detection rate of 13.3% (42/315) among the clinical specimens. Using the improved assay, we showed that HRV sheds in the upper respiratory tract for more than a week following acute infection. We also showed that HRV-C had a significantly higher viral load at 2–7 days after the onset of symptoms (p = 0.001). The availability of such assay is important to facilitate disease management, antiviral development, and infection control.

Viruses as Sole Causative Agents of Severe Acute Respiratory Tract Infections in Children

Background

Respiratory syncytial virus (RSV) and influenza A viruses are known to cause severe acute respiratory tract infections (SARIs) in children. For other viruses like human rhinoviruses (HRVs) this is less well established. Viral or bacterial co-infections are often considered essential for severe manifestations of these virus infections.

Objective

The study aims at identifying viruses that may cause SARI in children in the absence of viral and bacterial co-infections, at identifying disease characteristics associated with these single virus infections, and at identifying a possible correlation between viral loads and disease severities.

Study Design

Between April 2007 and March 2012, we identified children (<18 year) with or without a medical history, admitted to our paediatric intensive care unit (PICU) with SARI or to the medium care (MC) with an acute respiratory tract infection (ARTI) (controls). Data were extracted from the clinical and laboratory databases of our tertiary care paediatric hospital. Patient specimens were tested for fifteen respiratory viruses with real-time reverse transcriptase PCR assays and we selected patients with a single virus infection only. Typical bacterial co-infections were considered unlikely to have contributed to the PICU or MC admission based on C-reactive protein-levels or bacteriological test results if performed.

Results

We identified 44 patients admitted to PICU with SARI and 40 patients admitted to MC with ARTI. Twelve viruses were associated with SARI, ten of which were also associated with ARTI in the absence of typical bacterial and viral co-infections, with RSV and HRV being the most frequent causes. Viral loads were not different between PICU-SARI patients and MC-ARTI patients.

Conclusion

Both SARI and ARTI may be caused by single viral pathogens in previously healthy children as well as in children with a medical history. No relationship between viral load and disease severity was identified.

Rhinovirus Disease in Children Seeking Care in a Tertiary Pediatric Emergency Department

BACKGROUND

Rhinovirus is the most common cause of viral respiratory tract infections in children. Virologic predictors of lower respiratory tract infection (LRTI), such as viral load and the presence of another respiratory virus (coinfection), are not well characterized in pediatric outpatients.

METHODS

Mid-nasal turbinate samples were collected from children presenting for care to the Seattle Children's Hospital emergency department (ED) or urgent care with a symptomatic respiratory infection between December 2011 and May 2013. A subset of samples was tested for rhinovirus viral load by real-time polymerase chain reaction. Clinical data were collected by chart reviews. Multivariate logistic regression was used to evaluate the relationship between viral load and coinfection and the risk for LRTI.

RESULTS

Rhinovirus was the most frequent respiratory virus detected in children younger than 3 years. Of 445 patients with rhinovirus infection, 262 (58.9%) had LRTIs, 231 (51.9%) required hospital admission and 52 (22.5%) were hospitalized for 3 days or longer. Children with no comorbidities accounted for 142 (54%) of 262 rhinovirus LRTIs. Higher viral load was significantly associated with LRTI among illness episodes with rhinovirus alone (OR, 2.11; 95% confidence interval [CI], 1.24-3.58). Coinfection increased the risk of LRTI (OR, 1.83; 95% CI, 1.01-3.32).

CONCLUSIONS

Rhinovirus was the most common pathogen detected among symptomatic young children in a pediatric ED who had respiratory viral testing performed, with the majority requiring hospitalization. Higher rhinovirus viral load and coinfection increased disease severity. Virologic data may assist clinical decision making for children with rhinovirus infections in the pediatric ED.

Rhinoviruses and Respiratory Enteroviruses: Not as Simple as ABC

Rhinoviruses (RVs) and respiratory enteroviruses (EVs) are leading causes of upper respiratory tract infections and among the most frequent infectious agents in humans worldwide. Both are classified in the Enterovirus genus within the Picornaviridae family and they have been assigned to seven distinct species, RV-A, B, C and EV-A, B, C, D. As viral infections of public health significance, they represent an important financial burden on health systems worldwide. However, the lack of efficient antiviral treatment or vaccines against these highly prevalent pathogens prevents an effective management of RV-related diseases. Current advances in molecular diagnostic techniques have revealed the presence of RV in the lower respiratory tract and its role in lower airway diseases is increasingly reported. In addition to an established etiological role in the common cold, these viruses demonstrate an unexpected capacity to spread to other body sites under certain conditions. Some of these viruses have received particular attention recently, such as EV-D68 that caused a large outbreak of respiratory illness in 2014, respiratory EVs from species C, or viruses within the newly-discovered RV-C species. This review provides an update of the latest findings on clinical and fundamental aspects of RV and respiratory EV, including a summary of basic knowledge of their biology.

Detection of respiratory viruses and bacteria in children using a twenty-two target reverse-transcription real-time PCR (RT-qPCR) panel

BACKGROUND

Rapid detection of the wide range of viruses and bacteria that cause respiratory infection in children is important for patient care and antibiotic stewardship. We therefore designed and evaluated a ready-to-use 22 target respiratory infection reverse-transcription real-time polymerase chain reaction (RT-qPCR) panel to determine if this would improve detection of these agents at our pediatric hospital.

METHODS

RT-qPCR assays for twenty-two target organisms were dried-down in individual wells of 96 well plates and saved at room temperature. Targets included 18 respiratory viruses and 4 bacteria. After automated nucleic acid extraction of nasopharyngeal aspirate (NPA) samples, rapid qPCR was performed. RT-qPCR results were compared with those obtained by the testing methods used at our hospital laboratories.

RESULTS

One hundred fifty-nine pediatric NPA samples were tested with the RT-qPCR panel. One or more respiratory pathogens were detected in 132/159 (83%) samples. This was significantly higher than the detection rate of standard methods (94/159, 59%) (P<0.001). This difference was mainly due to improved RT-qPCR detection of rhinoviruses, parainfluenza viruses, bocavirus, and coronaviruses. The panel internal control assay performance remained stable at room temperature storage over a two-month testing period.

CONCLUSION

The RT-qPCR panel was able to identify pathogens in a high proportion of respiratory samples. The panel detected more positive specimens than the methods in use at our hospital. The pre-made panel format was easy to use and rapid, with results available in approximately 90 minutes. We now plan to determine if use of this panel improves patient care and antibiotic stewardship.

Impact of Human Rhinovirus Types and Viral Load on the Severity of Illness in Hospitalized Children With Lower Respiratory Tract Infections

BACKGROUND

Human rhinovirus (HRV) is not only responsible for at least one-half of all common colds but also associated with bronchitis, bronchiolitis, pneumonia and acute asthma exacerbation. However, the impact of different HRV types and viral load on disease severity has not been thoroughly elucidated.

METHODS

From January 2012 to September 2014, 1742 nasopharyngeal aspirate specimens from hospitalized children with lower respiratory tract infections were analyzed by quantitative HRV-specific real-time polymerase chain reaction.

RESULTS

Among these 1742 children, HRV (407/1742, 23%) was the second most common viral agent after respiratory syncytial virus. HRV-A, HRV-B, HRV-C and HRV untyped were detected in 229 (56%), 27 (7%), 100 (25%) and 51 (13%) specimens, respectively. Children except who experienced wheezing were more common in the HRV-C detection group than in the HRV-A detection group; there were no other significant differences between the 2 groups, including the percent of children diagnosed with severe diseases. Logistic regression models demonstrated that there was no difference in disease severity among HRV types. In HRV-A detection group, in children younger than 2 years, the viral load was higher in the severe group than in the nonsevere group; but in the HRV-C detection group, there was no difference.

CONCLUSIONS

HRV was frequently present in hospitalized children with lower respiratory tract infections in Chongqing, China. The disease severity for HRV-C and HRV-A was similar. A high load of HRV-A in the lower respiratory tract might be connected with disease severity in children younger than 2 years.

Prospective evaluation of rhinovirus infection in healthy young children

BACKGROUND

Although the incidence of human rhinovirus (HRV) infection is highest in young, no study has yet been published concerning the types of HRV circulating in this population, the incidence of symptomatic infections due to the different types, or duration of shedding

OBJECTIVES

This prospective study evaluated the circulation of HRV species and types, and established the incidence of asymptomatic and symptomatic infections in young children.

STUDY DESIGN

The study enrolled 93 healthy children aged <2 years, 88 of whom completed the follow-up of weekly household visits from November 2013 to February 2014. At each visit, a record was made of any signs and symptoms of acute infection, and a nasopharyngeal (NP) swab was taken in order to identify the HRVs by means of RT-polymerase chain reaction and to construct the phylogenetic tree of the HRV-positive cases.

RESULTS

A total of 1408 NP samples were obtained and 326 HRV infections were diagnosed (23.1%), leading to a mean number of 3.7 ± 2.3 infections per child: HRV-A in 72 cases (22.1%), HRV-B in 29 (8.9%), HRV-C in 122 (37.4%), and non-typeable HRV in 103 (31.6%). Shedding was significantly longer for HRV-A (14 days) and HRV-B (14 days) than HRV-C (7 days; p = 0.002 and p = 0.012). Most of the HRV infections (209/326, 64.1%) remained asymptomatic and, when symptomatic, were of marginal clinical relevance.

CONCLUSIONS

In healthy young children, HRV infection is extremely frequent, generally asymptomatic or with a mild clinical presentation, and viral shedding is limited in time.

Role of rhinovirus load in the upper respiratory tract and severity of symptoms in lung transplant recipients

BACKGROUND

Rhinovirus is the most common cause of respiratory viral infections and leads to frequent respiratory symptoms in lung transplant recipients. However, it remains unknown whether the rhinovirus load correlates with the severity of symptoms.

OBJECTIVES

This study aimed to better characterize the pathogenesis of rhinoviral infection and the way in which viral load correlates with symptoms.

STUDY DESIGN

We assessed rhinovirus load in positive upper respiratory specimens of patients enrolled prospectively in a cohort of 116 lung transplant recipients. Rhinovirus load was quantified according to a validated in-house, real-time, reverse transcription polymerase chain reaction in pooled nasopharyngeal and pharyngeal swabs. Symptoms were recorded in a standardised case report form completed at each screening/routine follow-up visit, or during any emergency visit occurring during the 3-year study.

RESULTS

Rhinovirus infections were very frequent, including in asymptomatic patients not seeking a specific medical consultation. Rhinovirus load ranged between 4.1 and 8.3 log copies/ml according to the type of visit and clinical presentation. Patients with highest symptom scores tended to have higher viral loads, particularly those presenting systemic symptoms. When considering symptoms individually, rhinovirus load was significantly higher in the presence of symptoms such as sore throat, fever, sputum production, cough, and fatigue. There was no association between tacrolimus levels and rhinovirus load.

CONCLUSIONS

Rhinovirus infections are very frequent in lung transplant recipients and rhinoviral load in the upper respiratory tract is relatively high even in asymptomatic patients. Patients with the highest symptom scores tend to have a higher rhinovirus load.

Pathophysiology of Clinical Symptoms in Acute Viral Respiratory Tract Infections

In this article we discuss the pathophysiology of common symptoms of acute viral respiratory infections (e.g., sneezing, nasal discharge, sore throat, cough, muscle pains, malaise, and mood changes). Since clinical symptoms are not sufficient to determine the etiology of viral respiratory tract infections, we believe that the host defense mechanisms are critical for the symptomatology. Consequently, this review of literature is focused on the pathophysiology of respiratory symptoms regardless of their etiology. We assume that despite a high prevalence of symptoms of respiratory infection, their pathogenesis is not widely known. A better understanding of the symptoms' pathogenesis could improve the quality of care for patients with respiratory tract infections.

Emerging respiratory viruses other than influenza

Non-influenza respiratory virus infections are common worldwide and contribute to morbidity and mortality in all age groups. The recently identified Middle East respiratory syndrome coronavirus has been associated with rapidly progressive pneumonia and high mortality rate. Adenovirus 14 has been increasingly recognized in severe acute respiratory illness in both military and civilian individuals. Rhinovirus C and human bocavirus type 1 have been commonly detected in infants and young children with respiratory tract infection and studies have shown a positive correlation between respiratory illness and high viral loads, mono-infection, viremia, and/or serologically-confirmed primary infection.

Human rhinoviruses and severe respiratory infections: is it possible to identify at-risk patients early?

Molecular methods of viral screening have demonstrated that human rhinoviruses (HRVs) are associated with lower respiratory tract infections (LRTIs, including bronchiolitis and pneumonia), exacerbations of chronic pulmonary disease and the development of asthma. Patients with severe chronic diseases are at greater risk of developing major clinical problems when infected by HRVs, particularly if they are immunocompromised or have a chronic lung disease. Analysing the characteristics of HRVs does not provide any certainty concerning the risk of a poor prognosis and, although viremia seems to be associated with an increased risk of severe HRV infection, the available data are too scanty to be considered conclusive. However, a chest x-ray showing alveolar involvement suggests the potentially negative evolution of a bacterial superinfection. There is therefore an urgent need for more effective diagnostic, preventive and therapeutic measures in order to prevent HRV infection, and identify and treat the patients at highest risk.

Phylogenetic analysis of human rhinovirus isolates collected from otherwise healthy children with community-acquired pneumonia during five successive years

In order to evaluate the circulation of the different human rhinovirus (HRV) species and genotypes in Italian children with radiographically confirmed community-acquired pneumonia (CAP), a nasopharyngeal swab was obtained from 643 children admitted to hospital because of CAP during five consecutive winter and early spring seasons (2007-2012). Real-time reverse transcriptase polymerase chain reaction (RT-PCR) was used to identify HRV, and the HRV-positive samples were used for sequencing analysis and to reconstruct the phylogenetic tree. HRV was identified in 198 samples (42.2%), and the VP4/VP2 region was successfully amplified in 151 (76.3%). HRV-A was identified in 78 samples (51.6%), HRV-B in 14 (9.3%) and HRV-C in 59 (39.1%). Forty-seven (31.1%) of the children with HRV infection were aged <1 year, 71 (47.0%) were aged 1-3 years, and 33 (21.9%) were aged ≥4 years. Blast and phylogenetic analyses showed that the HRV strains were closely related to a total of 66 reference genotypes, corresponding to 29 HRV-A, 9 HRV-B and 28 HRV-C strains. Nucleotide variability was 37% between HRV-A and HRV-B, 37.3% between HRV-A and HRV-C, and 39.9% between HRV-B and HRV-C. A number of sequences clustered with known serotypes and, within these clusters, there were strains circulating during several seasons. The most frequently detected genotypes were HRV-A78 (n=17), HRV-A12 (n=9) and HRV-C2 (n=5). This study shows that, although it is mainly associated with HRV-A, pediatric CAP can also be diagnosed in subjects infected by HRV-C and, more rarely, by HRV-B. Moreover, a large number of genotypes may be involved in causing pediatric CAP and can be different from year to year. Although the prolonged circulation of the same genotypes can sometimes be associated with a number of CAP episodes in different years.