5' noncoding region alone does not unequivocally determine genetic type of human rhinovirus strains

Whole genome sequencing of two human rhinovirus A types (A101 and A15) detected in Kenya, 2016-2018

Background: Virus genome sequencing is increasingly utilized in epidemiological surveillance. Genomic data allows comprehensive evaluation of underlying viral diversity and epidemiology to inform control. For human rhinovirus (HRV), genomic amplification and sequencing is challenging due to numerous types, high genetic diversity and inadequate reference sequences. Methods: We developed a tiled amplicon type-specific protocol for genome amplification and sequencing on the Illumina MiSeq platform of two HRV types, A15 and A101. We then assessed added value in analyzing whole genomes relative to the VP4/2 region only in the investigation of HRV molecular epidemiology within the community in Kilifi, coastal Kenya. Results: We processed 73 nasopharyngeal swabs collected between 2016-2018, and 48 yielded at least 70% HRV genome coverage. These included all A101 samples (n=10) and 38 (60.3%) A15 samples.  Phylogenetic analysis revealed that the Kilifi A101 sequences interspersed with global A101 genomes available in GenBank collected between 1999-2016. On the other hand, our A15 sequences formed a monophyletic group separate from the global genomes collected in 2008 and 2019. An improved phylogenetic resolution was observed with the genome phylogenies compared to the VP4/2 phylogenies. Conclusions: We present a type-specific full genome sequencing approach for obtaining HRV genomic data and characterizing infections.

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.

Duration of rhinovirus shedding in the upper respiratory tract in the first year of life

BACKGROUND

Current molecular diagnostic methods have detected rhinovirus RNA in a high proportion of asymptomatic infants and children, raising the question of the clinical significance of these findings. This study investigates the prevalence of prolonged rhinovirus RNA presence in the upper respiratory tract of infants during the first year of life.

METHODS

In a longitudinal study, infants were followed from birth up to 12 months. Nasopharyngeal specimens were collected monthly (months 1-6 and month 9) and during an upper respiratory infection. Rhinoviruses were detected by quantitative reverse-transcription polymerase chain reaction. Presence of repeated rhinovirus RNA was evaluated by nucleotide sequence analysis.

RESULTS

A total of 2153 specimens from 362 infants were studied; 341 distinct rhinovirus infections in 216 infants were identified. Follow-up specimens were available within 30 days for 179 infections, creating the sample set to assess prolonged rhinovirus presence. Of the 179 infections, 46 involved the detection of the same rhinovirus strain in repeated specimens, including 8 events of prolonged presence of the same strain (detected in specimens collected >30 days apart), representing 4.5% of the evaluable rhinovirus infections. There were 26 events in which a rhinovirus strain was replaced by a different strain within a 30-day interval, representing 14.5% of the 179 infections.

CONCLUSIONS

Although rhinovirus infections are common in healthy infants, prolonged presence of rhinovirus RNA in the respiratory tract after an upper respiratory infection was uncommon (<5%). Detection of rhinovirus RNA in an infant most likely represents an infection within a 30-day period.

Molecular epidemiology of human rhinovirus infections in the pediatric emergency department

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We analyzed rhinovirus (HRV) illness in children at a hospital emergency department.

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HRV-C was associated with lower respiratory tract illness (LRTI) compared to HRV-A.

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Specific HRV-A and C genotypes were more strongly associated with LRTI.

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Patients with multiple illness episodes had new HRV infections in each episode.

Background

Human rhinovirus (HRV) infections are highly prevalent, genetically diverse, and associated with both mild upper respiratory tract and more severe lower tract illnesses (LRTI).

Objective

To characterize the molecular epidemiology of HRV infections in young children seeking acute medical care.

Study design

Nasal swabs collected from symptomatic children <3 years of age receiving care in the Emergency and Urgent Care Departments at Seattle Children's Hospital were analyzed by a rapid polymerase chain reaction (PCR) system (FilmArray^®) for multiple viruses including HRV/enterovirus. HRV-positive results were confirmed by laboratory-developed real-time reverse transcription PCR (LD-PCR). Clinical data were collected by chart review. A subset of samples was selected for sequencing using the 5′ noncoding region. Associations between LRTI and HRV species and genotypes were estimated using logistic regression analysis.

Results

Of 595 samples with HRV/enterovirus detected by FilmArray, 474 (80%) were confirmed as HRV by LD-PCR. 211 (96%) of 218 selected samples were sequenced; HRV species A, B, and C were identified in 133 (63%), 6 (3%), and 72 (34%), respectively. LRTI was more common in HRV-C than HRV-A illness episodes (adjusted OR [95% CI] 2.35[1.03–5.35). Specific HRV-A and HRV-C genotypes detected in multiple patients were associated with a greater proportion of LRTI episodes. In 18 patients with >1 HRV-positive illness episodes, a distinct genotype was detected in each.

Conclusion

Diverse HRV genotypes circulated among symptomatic children during the study period. We found an association between HRV-C infections and LRTI in this patient population and evidence of association between specific HRV genotypes and LRTI.

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.

Analysis of a potential cluster of rhinovirus infections in patients and staff on two haemato-oncology wards

BACKGROUND

Human rhinoviruses (HRV) cause the common cold, increased mortality in patients attending elderly care facilities and significant morbidity as well as mortality in the post-transplantation setting.

OBJECTIVES

The aim of the study was to determine if there had been a breakdown in infection control practice in a large haemato-oncology centre. Molecular techniques had detected increased numbers of HRV in respiratory samples from patients and staff over a 6-week period. Typing was performed to investigate the possibility of transmission between individuals.

STUDY DESIGN

This was a retrospective study having detected HRV RNA in combined nose and throat swab samples that were collected from 13 individuals: 8 patients and 5 staff members, in the haemato-oncology wards of a tertiary referral centre in January and February 2011. The 5'NTR and the VP4/VP2 region were used for HRV typing.

RESULTS

All 3 HRV species were detected with 7 HRV-A, 1 HRV-B, 4 HRV-C and 1 untyped. None of the individuals were infected by the same HRV serotype. Three individuals had multiple samples collected: 1 patient had an HRV-B infection over a 4-week period, 1 patient had an HRV-A infection over 3 months and 1 staff member had an HRV-C infection over 1 week, each shedding an unchanged serotype throughout the whole period.

CONCLUSION

Nucleotide sequence analysis confirmed that there was no breakdown in infection control measures. No transmission incidents had occurred between patients and/or between staff and patients.

Human rhinoviruses and enteroviruses in influenza-like illness in Latin America

Background

Human rhinoviruses (HRVs) belong to the Picornaviridae family with high similarity to human enteroviruses (HEVs). Limited data is available from Latin America regarding the clinical presentation and strains of these viruses in respiratory disease.

Methods

We collected nasopharyngeal swabs at clinics located in eight Latin American countries from 3,375 subjects aged 25 years or younger who presented with influenza-like illness.

Results

Our subjects had a median age of 3 years and a 1.2:1.0 male:female ratio. HRV was identified in 16% and HEV was identified in 3%. HRVs accounted for a higher frequency of isolates in those of younger age, in particular children < 1 years old. HRV-C accounted for 38% of all HRVs detected. Phylogenetic analysis revealed a high proportion of recombinant strains between HRV-A/HRV-C and between HEV-A/HEV-B. In addition, both EV-D68 and EV-A71 were identified.

Conclusions

In Latin America as in other regions, HRVs and HEVs account for a substantial proportion of respiratory viruses identified in young people with ILI, a finding that provides additional support for the development of pharmaceuticals and vaccines targeting these pathogens.

Co-circulation of multiple genotypes of human rhinovirus during a large outbreak of respiratory illness in a veterans' long-term care home

Background

Human rhinoviruses (HRVs) are a well-recognized cause of long-term care home (LTCH) outbreaks of respiratory illness. However, there are limited data on the molecular epidemiology of the HRV types involved.

Objectives

To determine whether a large respiratory outbreak in a LTCH was caused by a single type of HRV, and to describe the clinical impact of the outbreak.

Study design

Nasopharyngeal swabs were collected from residents with one or more of the following: fever, cough, rhinitis, or congestion. Specimens were interrogated by multiplex PCR using the ResPlex II assay. Samples positive for HRV were then submitted for genotyping by partial sequence analysis of the 5′ untranslated (UTR) and viral protein (VP) 1 capsid regions.

Results

Of 71 screened, 56 residents were positive for a HRV during an outbreak that lasted 5.5 weeks; 27 healthcare workers also had respiratory symptoms. Three residents were transferred to hospital and 2 died. Seven units in two wings of the LTCH were affected, resulting in 3152.5 resident unit closure days. Three different HRV genotypes were identified, although HRV-A1 dominated.

Conclusions

This large outbreak of HRVs among residents and healthcare workers in a LTCH was associated with substantial resident and staff morbidity as well as significant unit closures. Multiple types of HRV were implicated but an HRV-A1 type dominated, warranting further investigation into viral determinants for virulence and transmission.

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.

Molecular epidemiology and genetic diversity of human rhinovirus affecting hospitalized children in Rome

Human rhinoviruses (HRV) have been re-classified into three species (A-C), but the recently discovered HRV-C strains are not fully characterized yet. This study aimed to undertake a molecular and epidemiological characterization of HRV strains infecting children hospitalized over one year in two large research hospitals in Rome. Nasal washings from single HRV infections were retrospectively subjected to phylogenetic analysis on two genomic regions: the central part of the 5'Untranslated Region (5'UTR) and the Viral Protein (VP) 4 gene with the 5' portion of the VP2 gene (VP4/2). Forty-five different strains were identified in 73 HRV-positive children: 55 % of the cases were HRV-A, 38 % HRV-C and only 7 % HRV-B. HRV-C cases were less frequent than HRV-A during summer months and more frequent in cases presenting wheezing with respect to HRV-A. Species distribution was similar with respect to patient age, and seasonality differed during summer months with fewer HRV-C than HRV-A cases. On admission, a significantly higher number of HRV-C cases presented with wheezing with respect to HRV-A. The inter- and intra-genotype variability in VP4/2 was higher than in 5'UTR; in particular, HRV-A patient VP4/2 sequences were highly divergent (8-14 %) at the nucleotide level from those of their reference strains, but VP4 amino acid sequence was highly conserved. In HRV-C isolates, the region preceding the initiator AUG, the amino acids involved in VP4 myristoylation, the VP4-VP2 cleavage site and the cis-acting replication element were highly conserved. Differently, VP4 amino acid conservation was significantly lower in HRV-C than in HRV-A strains, especially in the transiently exposed VP4 N-terminus. This study confirmed the high number of different HRV genotypes infecting hospitalized children over one year and reveals a greater than expected variability in HRV-C VP4 protein, potentially suggestive of differences in replication.

Detection of multiple viral and bacterial infections in acute exacerbation of chronic obstructive pulmonary disease: a pilot prospective study

Few studies have evaluated the contribution of multiple virus and bacterial infections in acute exacerbation of chronic obstructive pulmonary disease. This study estimated the burden of multiple viral and bacterial respiratory infections in moderate to very severe chronic obstructive pulmonary disease patients that were prospectively followed-up during a 12-month pilot study. Clinical data were collected monthly and sputum was collected at the time of each acute exacerbation event. Classical culture techniques for bacteria and multiplex polymerase chain reaction (PCR) and microarray detection assays were performed to identify viral and atypical bacterial pathogens in the sputum. Overall, 51 patients were included and 45 acute exacerbation events were investigated clinically and microbiologically. Among the 45 acute exacerbation events, 44% had evidence of viral infection involving human rhinovirus (HRV) and metapneumovirus (hMPV) in 20% and 18%, respectively. Intracellular bacteria were not found in sputum by PCR. Common bacterial pathogens were identified in 42% of acute exacerbation patients, most frequently Branhamella catarrhalis, Streptococcus pneumoniae and Haemophilus influenzae. Viral or virus and bacteria co-infections were detected in 27% of acute exacerbation events (n = 12) with HRV and hMPV involved in 92% of cases. Patients with co-infections did not present greater clinical severity scores at exacerbation and more recurrence of acute exacerbation events at 3 and 6 months than those with single infections (P > 0.4). These results suggest that HRV and hMPV may be contributors or cofactors of AECOPD. These findings indicate that viral or virus and bacterial co-infections do not impact significantly on the clinical severity of acute exacerbation of chronic obstructive pulmonary disease and recurrence at 3 and 6 months.

Rhinovirus detection using different PCR-based strategies

Human rhinoviruses (HRVs) are the major cause of the common cold. HRVs were recently reclassified into the Enterovirus genus (HEV) in the Picornaviridae family. HRVs and other members of the HEV genus share many common features, including sense RNA genomes and partial nucleotide sequence identity. The aim of this study was to evaluate different HRV detection strategies. Samples from adults with acute respiratory infection (n = 291) who were treated in Sao Paulo Hospital (2001-2003) were tested using three assays. The first assay detected picornaviruses by RT-PCR and hybridization, the second detected rhinoviruses using RT-PCR/sequencing, and the third differentiated HRV from HEV using duplex semi-nested-RT-PCR. Analysis of the results obtained from the first two strategies revealed 83% concordance. Discordant samples were then evaluated by the third protocol, and 82% were negative. The picornavirus detection protocol was more sensitive but less specific than the rhinovirus detection protocols. The semi-nested protocol utilized in the present study was less sensitive and was not useful in differentiating HRV from HEV. Sequencing assays examining different genes would address the best strategy of confirming rhinovirus and enterovirus infections.

Respiratory viral pathogens associated with lower respiratory tract disease among young children in the highlands of Papua New Guinea

Background

Acute lower respiratory tract infections (ALRI) commonly result in fatal outcomes in the young children of Papua New Guinea (PNG). However, comprehensive studies of the viral aetiology of ALRI have not been conducted in PNG for almost 30 years.

Objectives

To determine the viruses associated with ALRI among children living in the PNG highlands using sensitive molecular detection techniques.

Study design

Pernasal swabs were collected routinely between 1 week and 18 months of age and also during episodes of ALRI, as part of a neonatal pneumococcal conjugate vaccine trial. A tandem multiplex real-time PCR assay was used to test for a comprehensive range of respiratory viruses in samples collected from 221 young children. Picornavirus typing was supported by DNA sequence analysis.

Results

Recognized pathogenic respiratory viruses were detected in 198/273 (73%) samples collected from children with no evidence of ALRI and 69/80 (86%) samples collected during ALRI episodes. Human rhinoviruses (HRV) species A, B and C were detected in 152 (56%) samples from non-ALRI children and 50 (63%) samples collected during ALRI episodes. Partial structural region sequences for two new species C rhinoviruses were added to the GenBank database. ALRI was associated with detection of adenovirus species B (p < 0.01) or C (p < 0.05), influenza A (p < 0.0001) or respiratory syncytial virus (p < 0.0001). Multiple viruses were detected more often during ALRI episodes (49%) than when children displayed no symptoms of ALRI (18%) (p < 0.0001).

Conclusions

The burden of infection with respiratory viruses remains significant in young children living in the PNG highlands.

Enterovirus 68 among children with severe acute respiratory infection, the Philippines

Enterovirus 68 (EV68) is a rare enterovirus associated with respiratory illness that, unlike other enteroviruses, has been identified only from respiratory specimens. We identified EV68 from respiratory specimens of children hospitalized with a diagnosis of severe pneumonia in Leyte, Republic of the Philippines. Twenty-one samples showed high similarity with EV68 by sequencing of 5' nontranslated region; 17 of these samples were confirmed as EV68 by sequencing of viral protein 1 capsid coding region. Most previously reported EV68 cases had been identified as sporadic cases. All 21 patients we identified had severe illness, and 2 died, possibly the first reported fatal cases associated with EV68 infection. Our study suggests that EV68 may be a possible causative agent of severe respiratory illnesses.

Clinical spectrum of human rhinovirus infections in hospitalized Hong Kong children

BACKGROUND

Human rhinovirus (HRV) is classified into A, B, and C genogroups. HRVs cause mild upper respiratory infections, but HRV-C was recently found to be a major cause of asthma exacerbation in whites. This study elucidated disease spectrum of HRV infections among Hong Kong children hospitalized with respiratory illnesses.

METHODS

This retrospective study recruited 128 children with asthma exacerbations and 192 inpatient controls without allergy and hospitalized for respiratory illnesses within the same week. Their clinical information was retrieved from case records. HRVs in nasopharyngeal aspirates were detected by molecular assays using primers targeting consensus VP4/VP2 coding regions, and their genogroups identified by sequencing.

RESULTS

The mean (standard deviation) age of cases and controls was 5.6 (3.6) years and 5.4 (3.8) years, respectively (P = 0.601). HRV was detected in 107 (84.9%) cases and 63 (33.0%) controls (P < 0.0001), and HRV-C in 69.8% and 18.8% of these groups, respectively (P < 0.0001). Detection of HRV-A and -B was similar between these groups (P > 0.15). More subjects with HRV-C needed oxygen supplementation (11.1% vs. 2.6%; P = 0.043). Among controls, HRV infection was associated with acute bronchiolitis (P < 0.001) and bronchitis (P = 0.04), which paralleled those of HRV-C. HRV-A was associated with acute bronchiolitis (P = 0.005). Phylogenetic analysis revealed a diverse group of HRV serotypes (21 for HRV-A, 2 for HRV-B, and 32 for HRV-C).

CONCLUSIONS

HRV-C is associated with asthma exacerbation, whereas the presence of all HRVs, or either HRV-A or HRV-C alone, is associated with wheezing respiratory infections in nonasthmatic children. HRV is an important respiratory virus responsible for childhood wheezing illnesses.

Evolution of newly described enteroviruses

Several new enterovirus serotypes and a new human rhinovirus species have been characterized in the Enterovirus genus recently, raising a question about the origin of the new viruses. In this article we attempt to outline the general patterns of enterovirus evolution, ultimately leading to the emergence of new serotypes or species. Different evolutionary and epidemiological patterns can be deduced between different enterovirus species, between entero- and rhino-viruses and between different serotypes within a species. This article presents a hypothesis that the divergent evolution leading to a new serotype is likely to involve adaptation to a new ecological niche either within a single host species or due to interspecies transmission. By contrast, evolution within a serotype appears to occur primarily by genetic drift.

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.

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.

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.

Evidence of recombination and genetic diversity in human rhinoviruses in children with acute respiratory infection

Background

Human rhinoviruses (HRVs) are a highly prevalent cause of acute respiratory infection in children. They are classified into at least three species, HRV-A, HRV-B and HRV-C, which are characterized by sequencing the 5′ untranslated region (UTR) or the VP4/VP2 region of the genome. Given the increased interest for novel HRV strain identification and their worldwide distribution, we have carried out clinical and molecular diagnosis of HRV strains in a 2-year study of children with acute respiratory infection visiting one district hospital in Shanghai.

Methodology/Findings

We cloned and sequenced a 924-nt fragment that covered part of the 5′UTR and the VP4/VP2 capsid genes. Sixty-four HRV-infected outpatients were diagnosed amongst 827 children with acute low respiratory tract infection. Two samples were co-infected with HRV-A and HRV-B or HRV-C. By comparative analysis of the VP4/VP2 sequences of the 66 HRVs, we showed a high diversity of strains in HRV-A and HRV-B species, and a prevalence of 51.5% of strains that belonged to the recently identified HRV-C species. When analyzing a fragment of the 5′ UTR, we characterized at least two subspecies of HRV-C: HRV-Cc, which clustered differently from HRV-A and HRV-B, and HRV-Ca, which resulted from previous recombination in this region with sequences related to HRV-A. The full-length sequence of one strain of each HRV-Ca and HRV-Cc subspecies was obtained for comparative analysis. We confirmed the close relationship of their structural proteins but showed apparent additional recombination events in the 2A gene and 3′UTR of the HRV-Ca strain. Double or triple infections with HRV-C and respiratory syncytial virus and/or bocavirus were diagnosed in 33.3% of the HRV-infected patients, but no correlation with severity of clinical outcome was observed.

Conclusion

Our study showed a high diversity of HRV strains that cause bronchitis and pneumonia in children. A predominance of HRV-C over HRV-A and HRV-B was observed, and two subspecies of HRV-C were identified, the diversity of which seemed to be related to recombination with former HRV-A strains. None of the HRV-C strains appeared to have a higher clinical impact than HRV-A or HRV-B on respiratory compromise.

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

BACKGROUND

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

OBJECTIVES

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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