Complete coding sequence characterization and comparative analysis of the putative novel human rhinovirus (HRV) species C and B

Exploration of Potential Broad-Spectrum Antiviral Targets in the Enterovirus Replication Element: Identification of Six Distinct 5' Cloverleaves

Enterovirus genomic replication initiates at a predicted RNA cloverleaf (5'CL) at the 5' end of the RNA genome. The 5'CL contains one stem (SA) and three stem-loops (SLB, SLC, SLD). Here, we present an analysis of 5'CL conservation and divergence for 209 human health-related serotypes from the enterovirus genus, including enterovirus and rhinovirus species. Phylogenetic analysis indicates six distinct 5'CL serotypes that only partially correlate with the species definition. Additional findings include that 5'CL sequence conservation is higher between the EV species than between the RV species, the 5'CL of EVA and EVB are nearly identical, and RVC has the lowest 5'CL conservation. Regions of high conservation throughout all species include SA and the loop and nearby bases of SLB, which is consistent with known protein interactions at these sites. In addition to the known protein binding site for the Poly-C binding protein in the loop of SLB, other conserved consecutive cytosines in the stems of SLB and SLC provide additional potential interaction sites that have not yet been explored. Other sites of conservation, including the predicted bulge of SLD and other conserved stem, loop, and junction regions, are more difficult to explain and suggest additional interactions or structural requirements that are not yet fully understood. This more intricate understanding of sequence and structure conservation and variability in the 5'CL may assist in the development of broad-spectrum antivirals against a wide range of enteroviruses, while better defining the range of virus isotypes expected to be affected by a particular antiviral.

Molecular evolution of the VP1, VP2, and VP3 genes in human rhinovirus species C

Human rhinovirus species C (HRV-C) was recently discovered, and this virus has been associated with various acute respiratory illnesses (ARI). However, the molecular evolution of the major antigens of this virus, including VP1, VP2, and VP3, is unknown. Thus, we performed complete VP1, VP2, and VP3 gene analyses of 139 clinical HRV-C strains using RT-PCR with newly designed primer sets and next-generation sequencing. We assessed the time-scale evolution and evolutionary rate of these genes using the Bayesian Markov chain Monte Carlo method. In addition, we calculated the pairwise distance and confirmed the positive/negative selection sites in these genes. The phylogenetic trees showed that the HRV-C strains analyzed using these genes could be dated back approximately 400 to 900 years, and these strains exhibited high evolutionary rates (1.35 to 3.74 × 10⁻³ substitutions/site/year). Many genotypes (>40) were confirmed in the phylogenetic trees. Furthermore, no positively selected site was found in the VP1, VP2, and VP3 protein. Molecular modeling analysis combined with variation analysis suggested that the exterior surfaces of the VP1, VP2 and VP3 proteins are rich in loops and are highly variable. These results suggested that HRV-C may have an old history and unique antigenicity as an agent of various ARI.

Epidemiologic, clinical, and virologic characteristics of human rhinovirus infection among otherwise healthy children and adults: rhinovirus among adults and children

BACKGROUND

human rhinovirus (HRV) is a major cause of influenza-like illness (ILI) in adults and children. Differences in disease severity by HRV species have been described among hospitalized patients with underlying illness. Less is known about the clinical and virologic characteristics of HRV infection among otherwise healthy populations, particularly adults.

OBJECTIVES

to characterize molecular epidemiology of HRV and association between HRV species and clinical presentation and viral shedding.

STUDY DESIGN

observational, prospective, facility-based study of ILI was conducted from February 2010 to April 2012. Collection of nasopharyngeal specimens, patient symptoms, and clinical information occurred on days 0, 3, 7, and 28. Patients recorded symptom severity daily for the first 7 days of illness in a symptom diary. HRV was identified by RT-PCR and genotyped for species determination. Cases who were co-infected with other viral respiratory pathogens were excluded from the analysis. We evaluated the associations between HRV species, clinical severity, and patterns of viral shedding.

RESULTS

eighty-four HRV cases were identified and their isolates genotyped. Of these, 62 (74%) were >18 years. Fifty-four were HRV-A, 11HRV-B, and 19HRV-C. HRV-C infection was more common among children than adults (59% vs. 10%, P<0.001). Among adults, HRV-A was associated with higher severity of upper respiratory symptoms compared to HRV-B (P=0.02), but no such association was found in children. In addition, adults shed HRV-A significantly longer than HRV-C (P trend=0.01).

CONCLUSIONS

among otherwise healthy adults with HRV infection, we observed species-specific differences in respiratory symptom severity and duration of viral shedding.

Rhinovirus and the developing lung

Human rhinovirus (HRV) infections are now widely accepted as the commonest cause of acute respiratory illnesses (ARIs) in children. Advanced PCR techniques have enabled HRV infections to be identified as causative agents in most common ARIs in childhood including bronchiolitis, acute asthma, pneumonia and croup. However, the long-term implications of rhinovirus infections are less clear. The aim of this review is to examine the relationship between rhinovirus infections and disorders of the lower airways in childhood.

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.

Spread of different rhinovirus B genotypes in hospitalized children in Spain

Please cite this paper as: Cuevas et al. (2013) Spread of different rhinovirus B genotypes in hospitalized children in Spain. Influenza and Other Respiratory Viruses 7(5), 623–628.

Human Rhinovirus (HRV) classification is an evolving process. New genotypes have been described within HRV‐A and HRV‐C species, but only one has been accepted related to HRV‐B. From 2003 to 2010, a total of 3987 nasopharyngeal aspirate samples were taken from pediatric patients admitted to the Severo Ochoa Hospital in Madrid (Spain). After viral analysis, 949 (23·8%) tested positive to HRV. A random selection of 397 (42%) positive samples showed that 39 (9·8%) were HRV‐B. The sequencing of partial VP4/VP2 coding region revealed the spread of 13 of 25 defined HRV‐B serotypes and three putative new genotypes. Such results remark the high diversity of HRV‐B.

Biological characteristics and propagation of human rhinovirus-C in differentiated sinus epithelial cells

Information about the basic biological properties of human rhinovirus-C (HRV-C) viruses is lacking due to difficulties with culturing these viruses. Our objective was to develop a cell culture system to grow HRV-C. Epithelial cells from human sinuses (HSEC) were differentiated at air–liquid interface (ALI). Differentiated cultures supported 1–2  logs growth of HRV-C15 as detected by quantitative RT-PCR. Two distinguishing features of HRVs are acid lability and optimal growth at 33–34  °C. We used this system to show that HRV-C15 is neutralized by low pH (4.5). In contrast to most HRV types, replication of HRV-C15 and HRV-C41 was similar at 34 and 37 °C. The HSEC ALI provides a useful tool for quantitative studies of HRV-C replication. The ability of HRV-C to grow equally well at 34 °C and 37 °C may contribute to the propensity for HRV-C to cause lower airway illnesses in infants and children with asthma.

Molecular epidemiology and evolution of human enterovirus serotype 68 in Thailand, 2006-2011

Background

Publications worldwide have reported on the re-occurrence of human enterovirus 68 (EV68), a rarely detected pathogen usually causing respiratory illness. However, epidemiological data regarding this virus in particular on the Asian continent has so far been limited.

Methodology/Findings

We investigated the epidemiology and genetic variability of EV68 infection among Thai children with respiratory illnesses from 2006–2011 (n = 1810). Semi-nested PCR using primer sets for amplification of the 5′-untranslated region through VP2 was performed for rhino-enterovirus detection. Altogether, 25 cases were confirmed as EV68 infection indicating a prevalence of 1.4% in the entire study population. Interestingly, the majority of samples were children aged >5 years (64%). Also, co-infection with other viruses was found in 28%, while pandemic H1N1 influenza/2009 virus was the most common co-infection. Of EV68-positive patients, 36% required hospitalizations with the common clinical presentations of fever, cough, dyspnea, and wheezing. The present study has shown that EV68 was extremely rare until 2009 (0.9%). An increasing annual prevalence was found in 2010 (1.6%) with the highest detection frequency in 2011 (4.3%). Based on analysis of the VP1 gene, the evolutionary rate of EV68 was estimated at 4.93×10⁻³ substitutions/site/year. Major bifurcation of the currently circulating EV68 strains occurred 66 years ago (1945.31 with (1925.95–1960.46)95% HPD). Among the current lineages, 3 clusters of EV68 were categorized based on the different molecular signatures in the BC and DE loops of VP1 combined with high posterior probability values. Each cluster has branched off from their common ancestor at least 36 years ago (1975.78 with (1946.13–1984.97)95% HPD).

Conclusion

Differences in epidemiological characteristic and seasonal profile of EV68 have been found in this study. Results from Bayesian phylogenetic investigations also revealed that EV68 should be recognized as a genetically diverse virus with a substitution rate identical to that of enterovirus 71 genotype B (4.2×10⁻³ s/s/y).

PCR for detection of respiratory viruses: seasonal variations of virus infections

Real-time PCR and related methods have revolutionized the laboratory diagnosis of viral respiratory infections because of their high detection sensitivity, rapidness and potential for simultaneous detection of 15 or more respiratory agents. Results from studies with this diagnostic modality have significantly expanded our knowledge about the seasonality of viral respiratory diseases, pinpointed the difficulties to make a reliable etiologic diagnosis without the aid of an unbiased multiplex molecular assay for respiratory viruses, and revealed previously unknown details as to possible infections with multiple agents as aggravating factors. The scope of this article is to review and discuss this new knowledge and its implications for diagnostic strategies and other measures essential for the clinical management of respiratory viral infections and for epidemiological surveillance of seasonal respiratory infections.