Detection of human rhinovirus C in children with acute lower respiratory tract infections in South Korea

Understanding Rhinovirus Circulation and Impact on Illness

Rhinoviruses (RVs) have been reported as one of the main viral causes for severe respiratory illnesses that may require hospitalization, competing with the burden of other respiratory viruses such as influenza and RSV in terms of severity, economic cost, and resource utilization. With three species and 169 subtypes, RV presents the greatest diversity within the Enterovirus genus, and despite the efforts of the research community to identify clinically relevant subtypes to target therapeutic strategies, the role of species and subtype in the clinical outcomes of RV infection remains unclear. This review aims to collect and organize data relevant to RV illness in order to find patterns and links with species and/or subtype, with a specific focus on species and subtype diversity in clinical studies typing of respiratory samples.

Detection of Pathogenic Viruses in the Ambient Air in Seoul, Korea

The possible transport of pathogenic microorganisms during Asian dust events could be an important concern for health workers; however, this is still uncertain owing to a lack of supporting evidence. The present study aimed to investigate the presence of pathogenic microorganisms in air samples collected during the Asian and non-Asian dust periods. Between March and September 2016, air samples were collected at three weather observation stations in Seoul using a high-volume air sampler. Multiplex PCR was performed using the Allplex™ respiratory and gastrointestinal panel assay kits to detect 46 microorganisms. RT-PCR was performed for klassevirus, Aichivirus, and human parechovirus (HPeV) detection. In total, 71 air samples were collected during the Asian (8 samples) and non-Asian (63 samples) dust events. During an Asian dust event, only one human rhinovirus (HRV)-positive air sample was collected on April 23. During the non-Asian dust period, HRV, HPeV, norovirus (NoV), enteroaggregative Escherichia coli (EAEC), enterotoxigenic E. coli (ETEC), and Blastocystis hominis were detected in four, two, one, one, one, and one air samples, respectively. Pathogenic viruses were mostly detected in ambient air samples during the non-Asian dust period, which suggests a possible air-borne transmission of viral pathogens; however, the role of Asian dust in epidemics caused by pathogenic viruses is unclear.

Three-dimensional Culture of Human Airway Epithelium in Matrigel for Evaluation of Human Rhinovirus C and Bocavirus Infections

OBJECTIVE

Newly identified human rhinovirus C (HRV-C) and human bocavirus (HBoV) cannot propagate in vitro in traditional cell culture models; thus obtaining knowledge about these viruses and developing related vaccines are difficult. Therefore, it is necessary to develop a novel platform for the propagation of these types of viruses.

METHODS

A platform for culturing human airway epithelia in a three-dimensional (3D) pattern using Matrigel as scaffold was developed. The features of 3D culture were identified by immunochemical staining and transmission electron microscopy. Nucleic acid levels of HRV-C and HBoV in 3D cells at designated time points were quantitated by real-time polymerase chain reaction (PCR). Levels of cytokines, whose secretion was induced by the viruses, were measured by ELISA.

RESULTS

Properties of bronchial-like tissues, such as the expression of biomarkers CK5, ZO-1, and PCK, and the development of cilium-like protuberances indicative of the human respiration tract, were observed in 3D-cultured human airway epithelial (HAE) cultures, but not in monolayer-cultured cells. Nucleic acid levels of HRV-C and HBoV and levels of virus-induced cytokines were also measured using the 3D culture system.

CONCLUSION

Our data provide a preliminary indication that the 3D culture model of primary epithelia using a Matrigel scaffold in vitro can be used to propagate HRV-C and HBoV.

Clinical characteristics and outcomes of human rhinovirus positivity in hospitalized children

BACKGROUND:

The clinical relevance of positive human rhinovirus (HRV) in hospitalized patients is unclear. Our objective was to describe the clinical characteristics and outcomes of HRV positivity in a heterogeneous population of hospitalized children, compared to those positive for another respiratory virus and those where no respiratory virus was detected.

METHODS:

A retrospective case–control study of children hospitalized between January 2014 to April 2015 who had a respiratory viral specimen collected. Clinical and laboratory data were collected, and baseline characteristics and clinical variables were compared.

RESULTS:

During the study period, there were 671 specimens obtained from 577 patients that were processed for the respiratory viral polymerase chain reaction assay, of which 198 were positive for HRV, 167 positive for another respiratory virus, and 306 where no respiratory virus was detected. A history of asthma was significantly associated with HRV-positive patients (odds ratio [OR] 3.71; P < 0.001). On multivariate analysis, HRV-positive patients had a higher requirement for mechanical ventilation (OR 1.44), lower rates of readmission (OR 0.53), and lower mortality (OR 0.35) compared to patients with no respiratory virus isolated; however, none were statistically significant. HRV-positive patients did have a significantly shorter length of stay (LOS) compared with patients with no respiratory virus isolated (difference–0.35; P = 0.001). Similar outcomes were seen in patients positive for other respiratory viruses.

CONCLUSIONS:

HRV-positive hospitalized pediatric patients with a heterogeneous set of clinical diagnoses had higher association with asthma compared to patients who had another, or no, respiratory virus isolated. HRV-positive patients had shorter LOS compared to patients who had no respiratory viruses isolated. These findings suggest that HRV positivity in hospitalized pediatric patients may not lead to adverse clinical outcomes, although asthma is a risk factor regardless of clinical comorbidities and diagnoses. Further research is warranted to understand the predisposition of asthma to HRV positivity.

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.

[An epidemiological study on human rhinovirus C in hospitalized children with respiratory tract infections]

OBJECTIVE

To investigate the detection rates, epidemical characteristics, and clinical features of human rhinovirus C (HRV-C) in hospitalized children with respiratory tract infections (RTIs) in Suzhou, China.

METHODS

A total of 1 702 hospitalized children with RTIs from January to December, 2014 were enrolled, and 1 702 nasopharyngeal aspirate samples were collected from all children. RT-PCR was used to measure HRV mRNA, and quantitative real-time PCR combined with high-resolution melting curve was used to measure HRV-C.

RESULTS

Of all children, 244 (14.34%) were detected to have HRV infection, among whom 69 (69/244, 28.3%) had HRV-C infection. The rate of mixed infection of HRV-C with other viruses and bacteria was 61% (42/69). HRV-C was detected in each month of the year, and the detection rate of HRV-C in autumn was significantly higher than that in spring, summer, and winter (P<0.05). The children aged 2-5 years had a significantly higher detection rate of HRV-C than those in the other age groups (P<0.05). Compared with HRV-A/B infection, HRV-C infection led to significantly higher proportions of patients with lobar pneumonia and acute exacerbation of asthma (P<0.05), as well as patients with increased neutrophil count and CRP level (P<0.05). There were no significant differences in sex distribution or other clinical manifestations (P>0.05).

CONCLUSIONS

HRV-C infection accounts for about 1/3 of HRV infection, with a high incidence rate in autumn. The rate of mixed infection of HRV-C with other viruses and bacteria is high, and children aged 2-5 years have the highest detection rate of HRV-C. Children with HRV-C infection have similar clinical manifestations as those with HRV-A/B infection.

[An epidemiological study on human rhinovirus C in hospitalized children with respiratory tract infections]

OBJECTIVE

To investigate the detection rates, epidemical characteristics, and clinical features of human rhinovirus C (HRV-C) in hospitalized children with respiratory tract infections (RTIs) in Suzhou, China.

METHODS

A total of 1 702 hospitalized children with RTIs from January to December, 2014 were enrolled, and 1 702 nasopharyngeal aspirate samples were collected from all children. RT-PCR was used to measure HRV mRNA, and quantitative real-time PCR combined with high-resolution melting curve was used to measure HRV-C.

RESULTS

Of all children, 244 (14.34%) were detected to have HRV infection, among whom 69 (69/244, 28.3%) had HRV-C infection. The rate of mixed infection of HRV-C with other viruses and bacteria was 61% (42/69). HRV-C was detected in each month of the year, and the detection rate of HRV-C in autumn was significantly higher than that in spring, summer, and winter (P<0.05). The children aged 2-5 years had a significantly higher detection rate of HRV-C than those in the other age groups (P<0.05). Compared with HRV-A/B infection, HRV-C infection led to significantly higher proportions of patients with lobar pneumonia and acute exacerbation of asthma (P<0.05), as well as patients with increased neutrophil count and CRP level (P<0.05). There were no significant differences in sex distribution or other clinical manifestations (P>0.05).

CONCLUSIONS

HRV-C infection accounts for about 1/3 of HRV infection, with a high incidence rate in autumn. The rate of mixed infection of HRV-C with other viruses and bacteria is high, and children aged 2-5 years have the highest detection rate of HRV-C. Children with HRV-C infection have similar clinical manifestations as those with HRV-A/B infection.

Rhinoviruses and Their Receptors: Implications for Allergic Disease

Human rhinoviruses (RVs) are picornaviruses that can cause a variety of illnesses including the common cold, lower respiratory tract illnesses such as bronchitis and pneumonia, and exacerbations of asthma. RVs are classified into three species, RV-A, B, and C, which include over 160 types. They utilize three major types of cellular membrane glycoproteins to gain entry into the host cell: intercellular adhesion molecule 1 (ICAM-1) (the majority of RV-A and all RV-B), low-density lipoprotein receptor (LDLR) family members (12 RV-A types), and cadherin-related family member 3 (CDHR3) (RV-C). CDHR3 is a member of cadherin superfamily of transmembrane proteins with yet unknown biological function, and there is relatively little information available about the mechanisms of RV-C interaction with CDHR3. A coding single nucleotide polymorphism (rs6967330) in CDHR3 could promote RV-C infections and illnesses in infancy, which could in turn adversely affect the developing lung to increase the risk of asthma. Further studies are needed to determine how RV infections contribute to pathogenesis of asthma and to develop the optimal treatment approach to control asthma exacerbations.

Rhinovirus is an important pathogen in upper and lower respiratory tract infections in Mexican children

Background

Most of the studies characterizing the incidence of rhinovirus (RV) have been carried out in hospitalized children and in developed countries. In those studies, RV-C has been associated with more severe respiratory tract infections than RV species A and B. In this study we determined the frequency and diversity of RV strains associated with upper and lower respiratory tract infections (URTI, LRTI) in Mexico, and describe the clinical characteristics of the illness associated with different RV species.

Methods

A prospective surveillance of 526 and 250 children with URTI and LRTI was carried out. Respiratory samples were analyzed by RT-PCR for viruses. The 5′ untranslated region of the RV genome was amplified and sequenced.

Results

In the case of URTI, 17.5% were positive for RV, while this virus was found in 24.8% of LRTI. The RV species was determined in 73 children with URTI: 61.6% were RV-A, 37% RV-C and, 1.4% RV-B; and in 43 children with LRTI: 51.2% were RV-A, 41.8% RV-C, and 7% RV-B. No significant differences in clinical characteristics were found in patients with RV-A or RV-C infections. A high genetic diversity of RV strains was found in both URTI and LRTI.

Conclusions

Both RV-A and RV-C species were frequently found in hospitalized as well as in outpatient children. This study underlines the high prevalence and genetic diversity of RV strains in Mexico and the potential severity of disease associated with RV-A and RV-C infections.

Molecular Epidemiology of the Human Rhinovirus Infection in Mongolia during 2008-2013

Rhinovirus infections are common in all age groups world-wide, and they occur throughout the year. In this study, we examined 2,689 nasopharyngeal swabs collected in Mongolia during 2008-2013. Human rhinoviruses (HRVs) were detected in 295 (11.0%) samples, and 85 (28.8%) patients were co-infected with other respiratory viruses. HRV was co-detected with bocavirus, human coronavirus, and respiratory syncytial virus in 21 (24.7%), 17 (20.0%), and 14 (16.5%), respectively. We tested 170 (57.6%) of the 295 HRV-positive samples: 117 HRV strains were typed by using the VP4/VP2 method and 53 by using 5' UTR method. We found HVR-A, HVR-C, and HVR-B infections in 80 (47.1%), 76 (44.7%), and 14 (8.2%) samples, respectively.

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.

Prevalence of human rhinovirus in children admitted to hospital with acute lower respiratory tract infections in Changsha, China

Human rhinovirus (HRV) is a causative agent of acute respiratory tract infections. This study analyzed the prevalence and clinical characteristics of three HRV groups (HRV‐A, ‐B, and ‐C) among 1,165 children aged 14 years or younger who were hospitalized with acute lower respiratory tract infection in China. PCR or reverse transcription‐PCR was performed to detect 14 respiratory viruses in nasopharyngeal aspirates collected from September 2007 to August 2008 in Changsha, China. HRV was detected in 202 (17.3%) of the 1,165 children; 25.3% of the HRV‐positive children were 13–36 months of age (χ² = 22.803, P = 0.000). HRV was detected year round and peaked between September and December. Fifty‐three percent of the HRV‐positive samples were also positive for other respiratory viruses; respiratory syncytial virus (RSV) was the most common secondary virus. Phylogenetic analysis using the VP4/VP2 region grouped the HRV‐positive strains as follows: 101 HRV‐A (50.0%), 21 HRV‐B (10.4%), and 80 HRV‐C (39.6%). HRV‐A infections occurred predominantly in spring and autumn, and the peak prevalence of HRV‐C was in early winter and late autumn. HRV‐B infections were less common in spring (χ² = 31.914, P = 0.000). No significant difference in clinical severity or presentation was found between patients with HRV single infection and HRV co‐detections. Furthermore, the clinical characterizations did not differ among the three HRV species. These results suggest that HRV‐C is an important viral agent along with HRV‐A and HRV‐B and that among hospitalized children with acute lower respiratory tract infection in China, the three HRV genotypes have similar clinical characteristics. J. Med. Virol. 86:1983–1989, 2014. © 2014 Wiley Periodicals, Inc.

Patient characteristics and severity of human rhinovirus infections in children

BACKGROUND

It is increasingly recognized that human rhinoviruses (HRV) can be associated with severe infections. However, conflicting results have been reported on the relative prevalence and severity of the three HRV species.

OBJECTIVES

The relative prevalence and clinical characteristics of HRV-A, B and C, in children attending a South London teaching hospital were investigated retrospectively.

STUDY DESIGN

Children aged<16 years with episodes of respiratory tract infections and detectable entero/rhinovirus RNA in respiratory samples between November 2009 and December 2010 were investigated. Retrospective case review was performed and patients' characteristics recorded.

RESULTS

Entero/rhinoviruses were the commonest viral pathogens (498/2316; 21.5%). Amongst 204 infection episodes associated with entero/rhinovirus, 167 were typed HRV, HRV-C was the most prevalent (99/167, 59.3%) followed by HRV-A (60/167; 35.9%) and HRV-B (8/167, 4.8%). The severity spectrum of HRV-A and HRV-C infections were similar and affected all parts of the respiratory tract. Co-pathogens were observed in 54 (26.5%) episodes. Severity was increased in patients with non-viral co-pathogens and those with an underlying respiratory condition. Univariate and multiple regression analyses of potential prognostic variables including age, co-pathogens and underlying respiratory illnesses showed that mono-infection with HRV-C, as compared with other HRV species, was associated with more severe disease in young children<3 years.

CONCLUSIONS

HRV-C was the most prevalent species and on its own was associated with severe disease in children<3 years. The association between infection with HRV species and clinical presentation is complex and affected by many confounding factors.

From sneeze to wheeze: what we know about rhinovirus Cs

While the discovery of HRV-Cs is recent, there are no indications that they are new viruses, or that they are emerging in real-time. Genetically, HRV-Cs are most closely related to the members of HRV-A and HRV-B but even a small genetic difference can impart encompass significant changes to their clinical impact, complicated by a diverse human background of prior virus exposure and underlying host immune and disease variability. It is well known that HRVs are a major trigger of asthma exacerbations and HRV-Cs are now under investigation for their potential involvement in asthma inception. The newly described HRV-Cs account for a large proportion of HRV-related illness, including common colds and wheezing exacerbations. HRV-Cs are genetically diverse and appear to circulate with seasonal variation, exchanging dominance with HRV-A. Whether HRV-Cs are consistently more pathogenic or "asthmagenic" is unproven. Antigenic diversity complicates passive and active prophylactic interventions (i.e. antibodies or vaccines), so further identification and characterisation of individual types (and their neutralising antigens) is likely to inform future preventive strategies. In the meantime, new antivirals should benefit groups at risk of the most severe disease.

Proposals for the classification of human rhinovirus species A, B and C into genotypically assigned types

Human rhinoviruses (HRVs) frequently cause mild upper respiratory tract infections and more severe disease manifestations such as bronchiolitis and asthma exacerbations. HRV is classified into three species within the genus Enterovirus of the family Picornaviridae. HRV species A and B contain 75 and 25 serotypes identified by cross-neutralization assays, although the use of such assays for routine HRV typing is hampered by the large number of serotypes, replacement of virus isolation by molecular methods in HRV diagnosis and the poor or absent replication of HRV species C in cell culture. To address these problems, we propose an alternative, genotypic classification of HRV-based genetic relatedness analogous to that used for enteroviruses. Nucleotide distances between 384 complete VP1 sequences of currently assigned HRV (sero)types identified divergence thresholds of 13, 12 and 13 % for species A, B and C, respectively, that divided inter- and intra-type comparisons. These were paralleled by 10, 9.5 and 10 % thresholds in the larger dataset of >3800 VP4 region sequences. Assignments based on VP1 sequences led to minor revisions of existing type designations (such as the reclassification of serotype pairs, e.g. A8/A95 and A29/A44, as single serotypes) and the designation of new HRV types A101–106, B101–103 and C34–C51. A protocol for assignment and numbering of new HRV types using VP1 sequences and the restriction of VP4 sequence comparisons to type identification and provisional type assignments is proposed. Genotypic assignment and identification of HRV types will be of considerable value in the future investigation of type-associated differences in disease outcomes, transmission and epidemiology.

Recombination in the evolution of human rhinovirus genomes

Human rhinoviruses (HRV) are highly prevalent human respiratory pathogens that belong to the genus Enterovirus. Although recombination within the coding region is frequent in other picornavirus groups, most evidence of recombination in HRV has been restricted to the 5' untranslated region. We analysed the occurrence of recombination within published complete genome sequences of members of all three HRV species and additionally compared sequences from HRV strains spanning 14 years. HRV-B and HRV-C showed very little evidence of recombination within the coding region. In contrast, HRV-A sequences appeared to have undergone a large number of recombination events, typically involving whole type groups. This suggests that HRV-A may have been subject to extensive recombination during the period of diversification into types. This study demonstrates the rare and sporadic nature of contemporary recombination of HRV strains and contrasts with evidence of extensive recombination within HRV-A and between members of different species during earlier stages in its evolutionary diversification.

Human rhinoviruses including group C are common in stool samples of young Finnish children

BACKGROUND

Human rhinoviruses (HRVs) are common causes of viral respiratory infections. They have been widely studied in respiratory samples in hospital patient series but only a few studies have been performed to assess their occurrence in other sample types and their circulation in healthy children background population.

OBJECTIVES

To analyze the frequency of HRVs in the background population in Finland by screening HRV RNA from stool samples longitudinally collected in a cohort of young children.

STUDY DESIGN

Altogether 4184 stool samples were collected regularly from a cohort of children who were observed from birth. Samples were screened for the presence of RNA of HRVs using RT-PCR. HRV specific sequences were identified by sequencing the VP1 or VP4/VP2 coding region. Virus isolation was performed using four different cell lines and the result was confirmed by real time PCR.

RESULTS

A total of 9% of the stool samples were positive for HRV RNA. Sequence analysis indicated that the most prevalent species was HRV-A, and the most prevalent serotype was HRV61. HRV-B and HRV-C species were also detected. One of the six tested rhinovirus positive samples retained its infectivity and was able to grow in RD and GMK cells.

CONCLUSIONS

Our study shows that HRVs are frequently detected in the stool samples from the population of young children. We also show that HRV-C, which can cause severe illnesses in children, is commonly circulating in young children in Finland.

Infection and propagation of human rhinovirus C in human airway epithelial cells

Human rhinovirus species C (HRV-C) was recently discovered using molecular diagnostic techniques and is associated with lower respiratory tract disease, particularly in children. HRV-C cannot be propagated in immortalized cell lines, and currently sinus organ culture is the only system described that is permissive to HRV-C infection ex vivo. However, the utility of organ culture for studying HRV-C biology is limited. Here, we report that a previously described HRV-C derived from an infectious cDNA, HRV-C15, infects and propagates in fully differentiated human airway epithelial cells but not in undifferentiated cells. We demonstrate that this differentiated epithelial cell culture system supports infection and replication of a second virus generated from a cDNA clone, HRV-C11. We show that HRV-C15 virions preferentially bind fully differentiated airway epithelial cells, suggesting that the block to replication in undifferentiated cells is at the step of viral entry. Consistent with previous reports, HRV-C15 utilizes a cellular receptor other than ICAM-1 or LDLR for infection of differentiated epithelial cells. Furthermore, we demonstrate that HRV-C15 replication can be inhibited by an HRV 3C protease inhibitor (rupintrivir) but not an HRV capsid inhibitor previously under clinical development (pleconaril). The HRV-C cell culture system described here provides a powerful tool for studying the biology of HRV-C and the discovery and development of HRV-C inhibitors.

Clinical and molecular features of human rhinovirus C

A newly discovered group of human rhinoviruses (HRVs) has been classified as the HRV-C species based on distinct genomic features. HRV-Cs circulate worldwide, and are important causes of upper and lower respiratory illnesses. Methods to culture and produce these viruses have recently been developed, and should enable identification of unique features of HRV-C replication and biology.

Detection of human rhinovirus C viral genome in blood among children with severe respiratory infections in the Philippines

Human rhinovirus (HRV) C was recently identified as the third species of HRV using a molecular technique. Infections caused by previously identified HRVs (A and B) are thought to be limited to the respiratory tract; however, pathogenesis of HRVC is still largely unknown. A total of 816 nasopharyngeal swabs from hospitalized children with severe respiratory infections in the Philippines (May 2008-May 2009) were tested for HRV by reverse transcription polymerase chain reaction (RT-PCR), and 243 samples (29.8%) were positive for HRV. Among these patients, serum samples were also tested to determine whether specific HRV species were associated with viremia. Only 30 serum samples (12.3%) were positive for HRV. However, the HRV positive rates were different among HRV species, 3% (4/135) for HRVA, 0% (0/25) for HRVB, and 31% (26/83) for HRVC, and were the highest on 2 days after the onset of symptoms. These results suggest that HRVC may have a different pathogenicity and can more commonly cause viremia than HRVA and HRVB. Serum positive rates for HRV are affected by age, i.e., higher positive rates for those aged 1 year or more. HRVC that were detected from serum exhibited the same level of sequence diversity as those positive only for nasopharyngeal samples in phylogenetic analysis. However, all HRVA which were detected from serum were clustered in a monophyletic clade based on their 5' non-coding region (NCR) sequences, which is closely related with a certain HRVC genotype (A2) in 5'-NCR. This finding suggests that the 5'NCR region may be associated with viremia.

Host and viral factors associated with severity of human rhinovirus-associated infant respiratory tract illness

BACKGROUND

Risk factors for severe human rhinovirus (HRV)-associated infant illness are unknown.

OBJECTIVES

We sought to examine the role of HRV infection in infant respiratory tract illness and assess viral and host risk factors for HRV-associated disease severity.

METHODS

We used a prospective cohort of term, previously healthy infants enrolled during an inpatient or outpatient visit for acute upper or lower respiratory tract illness during the fall-spring months of 2004-2008. Illness severity was determined by using an ordinal bronchiolitis severity score, with higher scores indicating more severe disease. HRV was identified by means of real-time RT-PCR. The VP4/VP2 region from HRV-positive specimens was sequenced to determine species.

RESULTS

Of 630 infants with bronchiolitis or upper respiratory tract illnesses (URIs), 162 (26%) had HRV infection; HRV infection was associated with 18% of cases of bronchiolitis and 47% of cases of URI. Among infants with HRV infection, 104 (64%) had HRV infection alone. Host factors associated with more severe HRV-associated illness included a maternal and family history of atopy (median score of 3.5 [interquartile range [IQR], 1.0-7.8] vs 2.0 [IQR, 1.0-5.2] and 3.5 [IQR, 1.0-7.5] vs 2.0 [IQR, 0-4.0]). In adjusted analyses maternal history of atopy conferred an increase in the risk for more severe HRV-associated bronchiolitis (odds ratio, 2.39; 95% CI, 1.14-4.99; P = .02). In a similar model maternal asthma was also associated with greater HRV-associated bronchiolitis severity (odds ratio, 2.49, 95% CI, 1.10-5.67; P = .03). Among patients with HRV infection, 35% had HRVA, 6% had HRVB, and 30% had HRVC.

CONCLUSION

HRV infection was a frequent cause of bronchiolitis and URIs among previously healthy term infants requiring hospitalization or unscheduled outpatient visits. Substantial viral genetic diversity was seen among the patients with HRV infection, and predominant groups varied by season and year. Host factors, including maternal atopy, were associated with more severe infant HRV-associated illness.

Human rhinovirus C: a newly discovered human rhinovirus species

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

New human rhinovirus species and their significance in asthma exacerbation and airway remodeling

Asthma is the most common chronic disease of childhood, affecting 10% to 15% of all children. Several different stimuli including allergens, tobacco smoke, certain drugs, and viral or bacterial infections are known to exacerbate asthma symptoms. Among these triggers, viruses are frequent inducers of asthma exacerbations, with human rhinoviruses being the most common in children and adults. This article describes the different species of this virus and their roles as major triggers of asthma exacerbations.

Association between human rhinovirus C and severity of acute asthma in children

A new and potentially more pathogenic group of human rhinovirus (HRV), group C (HRVC), has recently been discovered. We hypothesised that HRVC would be present in children with acute asthma and cause more severe attacks than other viruses or HRV groups. Children with acute asthma (n = 128; age 2-16 yrs) were recruited on presentation to an emergency department. Asthma exacerbation severity was assessed, and respiratory viruses and HRV strains were identified in a nasal aspirate. The majority of the children studied had moderate-to-severe asthma (85.2%) and 98.9% were admitted to hospital. HRV was detected in 87.5% and other respiratory viruses in 14.8% of children, most of whom also had HRV. HRVC was present in the majority of children with acute asthma (59.4%) and associated with more severe asthma. Children with HRVC (n = 76) had higher asthma severity scores than children whose HRV infection was HRVA or HRVB only (n = 34; p = 0.018), and all other children (n = 50; p = 0.016). Of the 19 children with a non-HRV virus, 13 had HRV co-infections, seven of these being HRVC. HRVC accounts for the majority of asthma attacks in children presenting to hospital and causes more severe attacks than previously known HRV groups and other viruses.

Analysis of genetic diversity and sites of recombination in human rhinovirus species C

Human rhinoviruses (HRVs) are a highly prevalent and diverse group of respiratory viruses. Although HRV-A and HRV-B are traditionally detected by virus isolation, a series of unculturable HRV variants have recently been described and assigned as a new species (HRV-C) within the picornavirus Enterovirus genus. To investigate their genetic diversity and occurrence of recombination, we have performed comprehensive phylogenetic analysis of sequences from the 5' untranslated region (5' UTR), VP4/VP2, VP1, and 3Dpol regions amplified from 89 HRV-C-positive respiratory samples and available published sequences. Branching orders of VP4/VP2, VP1, and 3Dpol trees were identical, consistent with the absence of intraspecies recombination in the coding regions. However, numerous tree topology changes were apparent in the 5' UTR, where >60% of analyzed HRV-C variants showed recombination with species A sequences. Two recombination hot spots in stem-loop 5 and the polypyrimidine tract in the 5' UTR were mapped using the program GroupingScan. Available HRV-C sequences showed evidence for additional interspecies recombination with HRV-A in the 2A gene, with breakpoints mapping precisely to the boundaries of the C-terminal domain of the encoded proteinase. Pairwise distances between HRV-C variants in VP1 and VP4/VP2 regions fell into two separate distributions, resembling inter- and intraserotype distances of species A and B. These observations suggest that, without serological cross-neutralization data, HRV-C genetic groups may be equivalently classified into types using divergence thresholds derived from distance distributions. The extensive sequence data from multiple genome regions of HRV-C and analyses of recombination in the current study will assist future formulation of consensus criteria for HRV-C type assignment and identification.

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

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

Human rhinoviruses in Chinese adults with acute respiratory tract infection

Objective

To evaluate the roles of human rhinoviruses (HRVs) in acute respiratory tract infections (ARTIs) in Chinese adults and determine the association between species of HRV and clinical presentations.

Methods

RT-PCR methods were used to detect HRVs in throat and nasal swabs collected from 6104 adult patients with ARTIs from December 2005 to April 2008 in Beijing, China.

Results

HRV strains were detected in 271 ARTIs cases, 65% of which tested positive for HRV-A, 25% for HRV-B, and 10% for HRV-C. Aside from fever, pharyngeal congestion and headache were the most common clinical symptoms observed in the HRVs infected patients. HRV-A infected patients had a higher percentage of upper respiratory symptoms than patients infected by the two other HRV species. Systemic symptoms such as chilliness and myalgia were more frequent in people infected by HRV-B. The three HRV species exhibited unique infection timing when analyzed monthly.

Conclusion

HRV-C can be detected in adult patients with acute upper respiratory tract infections, but is not the predominant species in this population.

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

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

Genetics, recombination and clinical features of human rhinovirus species C (HRV-C) infections; interactions of HRV-C with other respiratory viruses

To estimate the frequency, molecular epidemiological and clinical associations of infection with the newly described species C variants of human rhinoviruses (HRV), 3243 diagnostic respiratory samples referred for diagnostic testing in Edinburgh were screened using a VP4-encoding region-based selective polymerase chain reaction (PCR) for HRV-C along with parallel PCR testing for 13 other respiratory viruses. HRV-C was the third most frequently detected behind respiratory syncytial virus (RSV) and adenovirus, with 141 infection episodes detected among 1885 subjects over 13 months (7.5%). Infections predominantly targeted the very young (median age 6–12 months; 80% of infections in those <2 years), occurred throughout the year but with peak incidence in early winter months. HRV-C was detected significantly more frequently among subjects with lower (LRT) and upper respiratory tract (URT) disease than controls without respiratory symptoms; HRV-C mono-infections were the second most frequently detected virus (behind RSV) in both disease presentations (6.9% and 7.8% of all cases respectively). HRV variants were classified by VP4/VP2 sequencing into 39 genotypically defined types, increasing the current total worldwide to 60. Through sequence comparisons of the 5′untranslated region (5′UTR), the majority grouped with species A (n = 96; 68%, described as HRV-Ca), the remainder forming a phylogenetically distinct 5′UTR group (HRV-Cc). Multiple and bidirectional recombination events between HRV-Ca and HRV-Cc variants and with HRV species A represents the most parsimonious explanation for their interspersed phylogeny relationships in the VP4/VP2-encoding region. No difference in age distribution, seasonality or disease associations was identified between HRV-Ca and HRV-Cc variants. HRV-C-infected subjects showed markedly reduced detection frequencies of RSV and other respiratory viruses, providing evidence for a major interfering effect of HRV-C on susceptibility to other respiratory virus infections. HRV-C's disease associations, its prevalence and evidence for interfering effects on other respiratory viruses mandates incorporation of rhinoviruses into future diagnostic virology screening.

All known human rhinovirus species are present in sputum specimens of military recruits during respiratory infection

Human rhinoviruses (HRV) are known to cause common cold as well as more complicated respiratory infections. HRV species -A, -B and -C have all been associated with lower respiratory infections and exacerbations of asthma. However, the type distribution of strains connected to different kinds of lower respiratory conditions is not clearly known. We have analysed the presence of HRV in sputum specimens derived from military recruits with and without pre-diagnosed asthma at times of acute respiratory infection (CIAS Study, 2004-2005). The analysis was performed with HRV and HEV real-time RT-PCR assays. Subsequently we studied type distribution of HRV strains by genetic typing in the VP4/VP2 genomic region. In total 146 (38.8%) specimens were HRV-positive and 36 (9.3%) HEV-positive. No difference was found in HRV detection between the asthmatic vs. non-asthmatic patients. Most of the genetically typed strains, 18 (62.1%), belonged to HRV-A, while HRV-B strains constituted five (17.2%) of the HRV-positive strains. HRV-C strain was typed four times from the HRV-positive cases and a HEV-D strain twice. We further typed six HEV positive strains in the partial VP1 region. Three of these belonged to HRV-A and three to HEV-D. HRV-A strains were discovered throughout the study period, while HRV-C strains originated from winter and spring specimens. Interestingly, four out of five typed HRV-B strains originated from the summer season specimens.

Screening respiratory samples for detection of human rhinoviruses (HRVs) and enteroviruses: comprehensive VP4-VP2 typing reveals high incidence and genetic diversity of HRV species C

Rhinovirus infections are the most common cause of viral illness in humans, and there is increasing evidence of their etiological role in severe acute respiratory tract infections (ARTIs). Human rhinoviruses (HRVs) are classified into two species, species A and B, which contain over 100 serotypes, and a recently discovered genetically heterogeneous third species (HRV species C). To investigate their diversity and population turnover, screening for the detection and the genetic characterization of HRV variants in diagnostic respiratory samples was performed by using nested primers for the efficient amplification of the VP4-VP2 region of HRV (and enterovirus) species and serotype identification. HRV species A, B, and C variants were detected in 14%, 1.8%, and 6.8%, respectively, of 456 diagnostic respiratory samples from 345 subjects (6 samples also contained enteroviruses), predominantly among children under age 10 years. HRV species A and B variants were remarkably heterogeneous, with 22 and 6 different serotypes, respectively, detected among 73 positive samples. Similarly, by using a pairwise distance threshold of 0.1, species C variants occurring worldwide were provisionally assigned to 47 different types, of which 15 were present among samples from Edinburgh, United Kingdom. There was a rapid turnover of variants, with only 5 of 43 serotypes detected during both sampling periods. By using divergence thresholds and phylogenetic analysis, several species A and C variants could provisionally be assigned to new types. An initial investigation of the clinical differences between rhinovirus species found HRV species C to be nearly twice as frequently associated with ARTIs than other rhinovirus species, which matches the frequencies of detection of respiratory syncytial virus. The study demonstrates the extraordinary genetic diversity of HRVs, their rapid population turnover, and their extensive involvement in childhood respiratory disease.