Prevalence of human respiratory viruses in adults with acute respiratory tract infections in Beijing, 2005–2007

To determine the aetiological role and epidemiological profile of common respiratory viruses in adults with acute respiratory tract infections (ARTIs), a 2-year study was conducted in Beijing, China, from May 2005 to July 2007. Nose and throat swab samples from 5808 ARTI patients were analysed by PCR methods for common respiratory viruses, including influenza viruses (IFVs) A, B, and C, parainfluenza viruses (PIVs) 1–4, enteroviruses (EVs), human rhinoviruses (HRVs), respiratory syncytial virus (RSV), human metapneumovirus (HMPV), human coronaviruses (HCoVs) OC43, 229E, NL63, and HKU1, and adenoviruses (ADVs). Viral pathogens were detected in 34.6% of patient samples, and 1.6% of the patients tested positive for more than one virus. IFVs (19.3%) were the dominant agents detected, followed by HRVs (6.5%), PIVs (4.3%), EVs (3.2%), and HCoVs (1.1%). ADVs, RSV and HMPV were also detected (<1%). The viral detection rates differed significantly between infections of the lower and upper respiratory tracts in the sample population: PIVs, the second most commonly detected viral agents in lower acute respiratory tract infections (LRTIs), were more prevalent than in upper acute respiratory tract infections, indicating that the pathogenic role of PIVs in LRTIs should be investigated. Currently, this study is the largest-scale investigation of respiratory virus infections in China with multiple agent detection, providing baseline data for further studies of respiratory virus infections in adults with ARTIs.     

Newly identified respiratory viruses in children with asthma exacerbation not requiring admission to hospital

There are few data describing the comprehensive identification in and influence of newly identified respiratory viruses on asthma exacerbations. Most studies focus on inpatients. In this preliminary study, the point prevalence and the associations of picornavirus species described recently and human bocavirus (HBoV) with the recovery from exacerbations in non‐hospitalized asthmatic children (median age 5.1 years) were examined. Human rhinoviruses (HRVs) were present in 52.6% of specimens, HBoV‐1 was in 7.7%. Viral co‐detections occurred in 25.6% of children and were associated (P = 0.04) with lower asthma quality of life scores upon presentation than were single viral detections. The undifferentiated presence or absence of virus did not influence the severity of asthma or recovery however when virus species were examined individually, specific clinical associations emerged. HRV species C (HRV‐Cs) were the viruses most frequently detected as single virus detections. Among 41 genotyped HRVs, more HRV‐Cs (n = 23) were identified than HRV‐As (n = 16) however HRV‐A detection was associated (P = 0.01) with worse asthma symptoms and cough for longer than was HRV‐C detection. Larger, PCR‐based studies are required to elucidate further the true impact of HRV species in childhood asthma exacerbations of both hospitalized and non‐hospitalized cohorts. J. Med. Virol. 82:1458–1461, 2010. © 2010 Wiley‐Liss, Inc.     

Incidence,molecular epidemiology and clinical presentations of human metapneumovirus; assessment of its importance as a diagnostic screening target

BackgroundHuman metapneumovirus (HMPV) is a recently discovered human paramyxovirus associated with a spectrum of respiratory symptoms from the common cold to pneumonia and bronchiolitis.ObjectivesTo assess the clinical significance and epidemiology of HMPV, standardized comparison of frequencies of infection, age profiles and disease associations were made with other respiratory viruses in Scotland.Study design7091 respiratory samples collected in Scotland between 1 July 2006 and 30 June 2008 from 4282 individuals were screened by multiplex RT-PCR for respiratory syncytial virus (HRSV), adenovirus (AdV), parainfluenzaviruses 1–3 (PIV-1, -2 and -3), influenza A and B and by nested RT-PCR for HMPV.ResultsHMPV was the fifth most prevalent virus (2.0% of samples), found predominantly in young children in winter months. In the 2006–2007 respiratory season, 70% of HMPV isolates were genotype A, but a switch to predominantly type B infections occurred next winter. For samples with information on clinical presentations, 26% of HMPV infections were from subjects with lower respiratory tract presentations, lower than recorded for HRSV, but similar to adenovirus, parainfluenza viruses and influenza viruses A and B. Around 13% of HMPV infections were associated with upper respiratory tract symptoms or disease, comparable with other respiratory virus infections.ConclusionsNumerically and through its association with respiratory disease, HMPV represents a diagnostically significant target that should be included in PCR-based routine screening of respiratory samples. Understanding the biological basis of observed rapid turnover of HMPV variants, including the observed HMPV genotype change between respiratory seasons requires further longitudinal studies.     

Characterisation of a newly identified human rhinovirus, HRV-QPM, discovered in infants with bronchiolitis.

BACKGROUND: Human rhinoviruses (HRVs) are some of the earliest identified and most commonly detected viruses associated with acute respiratory tract infections (ARTIs) and yet the molecular epidemiology and genomic variation of individual serotypes remains undefined. OBJECTIVES: To molecularly characterise a novel HRV and determine its prevalence and clinical impact on a predominantly paediatric population. STUDY DESIGN: Nucleotide sequencing was employed to determine the complete HRV-QPM coding sequence. Two novel real-time RT-PCR diagnostic assays were designed and employed to retrospectively screen a well-defined population of 1244 specimen extracts to identify the prevalence of HRV-QPM during 2003. RESULTS: Phylogenetic studies of complete coding sequences defined HRV-QPM as a novel member the genus Rhinovirus residing within the previously described HRV-A2 sub-lineage. Investigation of the relatively short VP1 sequence suggest that the virus is resistant to Pleconaril, setting it apart from the HRV A species. Sixteen additional HRV-QPM strains were detected (1.4% of specimens) often as the sole micro-organism present among infants with suspected bronchiolitis. HRV-QPM was also detected in Europe during 2006, and a closely related virus circulated in the United States during 2004. CONCLUSIONS: We present the molecular characterisation and preliminary clinical impact of a newly identified HRV along with sequences representing additional new HRVs.     

Molecular characterization of a variant rhinovirus from an outbreak associated with uncommonly high mortality.

BACKGROUND: Human rhinoviruses (HRVs) are the most frequent cause of acute upper respiratory tract infection, however, they are also known to replicate in the lower respiratory tract and associate with more severe respiratory illnesses. An outbreak of HRV occurred in a long-term facility in Santa Cruz, California with unusually high morbidity and mortality. OBJECTIVES: To identify viral characteristics associated with this unique outbreak, genetic relationships between these clinical isolates (SCRVs) and prototype strains of rhinovirus were investigated. STUDY DESIGN: Sequence homology and phylogenetic analyses of the SCRV VP4/VP2 region were performed in conjunction with all HRV prototypes. Due to the importance of the 5'noncoding region (NCR) and the structural genes to viral replication and host immune responses, respectively, we focused on a segment of the HRV genome which includes these regions. Molecular models of SCRV were also assessed. RESULTS: SCRV showed closest similarity to HRV82 with some divergence from the prototype. Amino acid differences were concentrated within predicted neutralization epitopes within VP2, VP3 and VP1. CONCLUSION: Sequence analyses and differences in cell culture growth characteristics suggest that this virus is a variant of HRV which has distinctive properties from its respective prototype strain.     

Infection and maturation of monocyte-derived human dendritic cells by human respiratory syncytial virus, human metapneumovirus, and human parainfluenza virus type 3

Human respiratory syncytial virus (HRSV), human metapneumovirus (HMPV), and human parainfluenza virus type 3 (HPIV3) are common, important respiratory pathogens, but HRSV has a substantially greater impact with regard to acute disease, long-term effects on airway function, and frequency of re-infection. It has been reported to strongly interfere with the functioning of dendritic cells (DC). We compared HRSV to HMPV and HPIV3 with regard to their effects on human monocyte-derived immature DC (IDC). Side-by-side analysis distinguished between common effects versus those specific to individual viruses. The use of GFP-expressing viruses yielded clear identification of robustly infected cells and provided the means to distinguish between direct effects of robust viral gene expression versus bystander effects. All three viruses infected inefficiently based on GFP expression, with considerable donor-to donor-variability. The GFP-negative cells exhibited low, abortive levels of viral RNA synthesis. The three viruses induced low-to-moderate levels of DC maturation and cytokine/chemokine responses, increasing slightly in the order HRSV, HMPV, and HPIV3. Infection at the individual cell level was relatively benign, such that in general GFP-positive cells were neither more nor less able to mature compared to GFP-negative bystanders, and cells were responsive to a secondary treatment with lipopolysaccharide, indicating that the ability to mature was not impaired. However, there was a single exception, namely that HPIV3 down-regulated CD38 expression at the RNA level. Maturation by these viruses was anti-apoptotic. Inefficient infection of IDC and sub-optimal maturation might result in reduced immune responses, but these effects would be common to all three viruses rather than specific to HRSV.     

Human bocavirus infection in young children with acute respiratory tract infection in Lanzhou,China

Human bocavirus (HBoV) is a recognized human parvovirus associated with acute respiratory tract infection. However, HBoV has yet to be established as a causative agent of respiratory disease. In this study, the epidemiological and virological characteristics of HBoV infection were studied in children with acute respiratory tract infection in China. In total, 406 children younger than 14 years of age with acute respiratory tract infection were included in this prospective 1‐year study. HBoV was detected in 29 (7.1%) of the 406 children. No clear seasonal fluctuation was observed in infection rates of HBoV. Of the 29 children infected with HBoV, 16 (55.2%) were coinfected with other respiratory viruses, most commonly respiratory syncytial virus (RSV). Viral coinfection with HBoV did not affect the severity of the respiratory disease (P = 0.291). The number of HBoV genome copies ranged from 5.80 × 10² to 9.72 × 10⁸ copies/ml in nasopharyngeal aspirates among HBoV‐positive specimens by real‐time PCR, and neither coinfection nor the severity of disease correlated with the viral load (P = 0.148, P = 0.354, respectively). The most common clinical features were cough and acute upper respiratory infection, and acute bronchopneumonia. Additionally, the NP‐1 gene of HBoV showed minimal sequence variation. These data suggest that HBoV is frequent in young children with acute respiratory tract infection in Lanzhou, China, and RSV is the most common coinfecting virus. There was no apparent association between the viral load of HBoV and coinfection or disease severity. The NP‐1 gene was highly conserved in HBoV. J. Med. Virol. 82:282–288, 2010. © 2009 Wiley‐Liss, Inc.     

Prospective study of Human Bocavirus (HBoV) infection in a pediatric university hospital in Germany 2005/2006.

BACKGROUND: Human Bocavirus (HBoV), a new species of the genus parvovirus newly detected in 2005, seems to be a worldwide distributed pathogen among children with respiratory tract infection (prevalence 2%-18%). Recently published retrospective studies and one prospective birth cohort study suggest that HBoV-primary infection occurs in infants. METHODS: Prospective single center study over one winter season (November 2005-May 2006) with hospitalized children without age restriction using PCR-based diagnostic methods. RESULTS: HBoV DNA was detected in 11 (2.8%) of 389 nasopharyngeal aspirates from symptomatic hospitalized children (median age 9.0 months; range: 3-17 months). RSV, HMPV, HCoV, and Influenza B were detected in 13.9% (n=54), 5.1% (n=20), 2.6% (n=10), and 1.8% (n=7), respectively. There was no influenza A DNA detected in any of the specimens. The clinical diagnoses were acute wheezing (bronchitis) in four patients, radiologically confirmed pneumonia in six patients (55%) and croup syndrome in one patient. In five to six patients with pneumonia, HBoV was the only pathogen detected. While no patient had to be mechanically ventilated, 73% needed oxygen supplementation. In four (36.4%) patients at least one other viral pathogen was found (plus RSV n=3; 27.3%; Norovirus n=1; 9.1%). CONCLUSION: HBoV causes severe respiratory tract infections in infants and young children. Its role as a copathogen and many other open questions has to be defined in further prospective studies.     

Clinical and molecular epidemiology of human rhinovirus infections in patients with hematologic malignancy

BackgroundHuman rhinoviruses (HRVs) are common causes of upper respiratory tract infection (URTI) in hematologic malignancy (HM) patients. Predictors of lower respiratory tract infection (LRTI) including the impact of HRV species and types are poorly understood.ObjectivesThis study aims to describe the clinical and molecular epidemiology of HRV infections among HM patients.Study designFrom April 2012–March 2013, HRV-positive respiratory specimens from symptomatic HM patients were molecularly characterized by analysis of partial viral protein 1 (VP1) or VP4 gene sequence. HRV LRTI risk-factors and outcomes were analyzed using multivariable logistic regression.ResultsOne hundred and ten HM patients presented with HRV URTI (n = 78) and HRV LRTI (n = 32). Hypoalbuminemia (OR 3.0; 95% CI, 1.0–9.2; p = 0.05) was independently associated with LRTI, but other clinical and laboratory markers of host immunity did not differ between patients with URTI versus LRTI. Detection of bacterial co-pathogens was common in LRTI cases (25%). Among 92 typeable respiratory specimens, there were 58 (64%) HRV-As, 12 (13%) HRV-Bs, and 21 (23%) HRV-Cs, and one Enterovirus 68. LRTI rates among HRV-A (29%), HRV-B (17%), and HRV-C (29%) were similar. HRV-A infections occurred year-round while HRV-B and HRV-C infections clustered in the late fall and winter.ConclusionsHRVs are associated with LRTI in HM patients. Illness severity is not attributable to specific HRV species or types. The frequent detection of bacterial co-pathogens in HRV LRTIs further substantiates the hypothesis that HRVs predispose to bacterial superinfection of the lower airways, similar to that of other community-acquired respiratory viruses.     

Evidence of human coronavirus HKU1 and human bocavirus in Australian children.

Undiagnosed cases of respiratory tract disease suspected of an infectious aetiology peak during the winter months. Since studies applying molecular diagnostic assays usually report reductions in the number of undiagnosed cases of infectious disease compared to traditional techniques, we applied PCR assays to investigate the role of two recently described viruses, namely human coronavirus (HCoV) HKU1 and human bocavirus (HBoV), in a hospital-based paediatric population. Both viruses were found among Australia children with upper or lower respiratory tract disease during the autumn and winter of 2004, contributing to 21.1% of all microbial diagnoses, with individual incidences of 3.1% (HCoV-HKU1) and 5.6% (HBoV) among 324 specimens. HBoV was found to coincide with another virus in more than half of all instances and displayed a single genetic lineage, whilst HCoV-HKU1 was more likely to occur in the absence of another microbe and strains could be divided into two genetic lineages which we propose be termed HCoV-HKU1 type A and type B. Children under the age of 2 years were most at risk of infection by these viruses which contribute significantly to the microbial burden among patients with respiratory tract disease during the colder months.     

Human Rhinoviruses

Human rhinoviruses (HRVs), first discovered in the 1950s, are responsible for more than one-half of cold-like illnesses and cost billions of dollars annually in medical visits and missed days of work. Advances in molecular methods have enhanced our understanding of the genomic structure of HRV and have led to the characterization of three genetically distinct HRV groups, designated groups A, B, and C, within the genus Enterovirus and the family Picornaviridae. HRVs are traditionally associated with upper respiratory tract infection, otitis media, and sinusitis. In recent years, the increasing implementation of PCR assays for respiratory virus detection in clinical laboratories has facilitated the recognition of HRV as a lower respiratory tract pathogen, particularly in patients with asthma, infants, elderly patients, and immunocompromised hosts. Cultured isolates of HRV remain important for studies of viral characteristics and disease pathogenesis. Indeed, whether the clinical manifestations of HRV are related directly to viral pathogenicity or secondary to the host immune response is the subject of ongoing research. There are currently no approved antiviral therapies for HRVs, and treatment remains primarily supportive. This review provides a comprehensive, up-to-date assessment of the basic virology, pathogenesis, clinical epidemiology, and laboratory features of and treatment and prevention strategies for HRVs.     

Human bocavirus and other respiratory viral infections in a 2-year cohort of hospitalized children

Human bocavirus (HBoV) infection is reported worldwide and may cause severe respiratory tract infections. The aim of the present study was to assess the prevalence of HBoV, and other respiratory viral pathogens, in a 2-year retrospective study of children admitted to hospital, and to investigate whether viral loads of HBoV DNA were associated with severity of infection. Between April 2007 and March 2009, 891 respiratory samples from 760 children admitted to hospital with acute respiratory tract infection were tested for the presence of respiratory viruses by real-time PCR or direct immunofluorescence testing. HBoV DNA was detected by using internally controlled real-time quantitative PCR assay and 25 samples selected at random were sequenced. The virus detected most frequently was rhinovirus, followed by respiratory syncytial virus, HBoV, and human metapneumovirus. HBoV DNA was detected in 18.4% of children admitted to hospital. HBoV was the only viral pathogen detected in 66/164 (40.2%) of HBoV DNA-positive children and in 7.4% of all 891 samples. Ninety-seven percent (64/66) of children with an HBoV single infection were diagnosed as having lower respiratory tract infection. Median HBoV DNA viral load was significantly higher in children when HBoV was detected as a single pathogen. Higher HBoV DNA viral loads were associated with prematurity and age. HBoV seems to be an important and frequent pathogen in respiratory tract infections in children, and it is likely that the severity of illness is comparable to the severity of RSV illness.     

Seroepidemiology of human bocavirus in Hokkaido prefecture, Japan

A new human virus, provisionally named human bocavirus (HBoV), was discovered by Swedish researchers in 2005. A new immunofluorescence assay using Trichoplusia ni insect cells infected with a recombinant baculovirus expressing the VP1 protein of HBoV was developed, and the levels of immunoglobulin G antibody to the VP1 protein of HBoV in serum samples were measured. The overall seroprevalence rate of antibodies against the VP1 protein of HBoV in a Japanese population aged from 0 months to 41 years was 71.1% (145 of 204). The seropositive rate was lowest in the age group of 6 to 8 months and gradually increased with age. All of the children had been exposed to HBoV by the age of 6 years. A rise in titers of antibody against the VP1 protein of HBoV during the convalescent phase was observed for four patients with lower respiratory tract infections, and HBoV DNA was detected in nasopharyngeal swab and serum samples from all four patients. These results suggest that HBoV is a ubiquitous virus acquired early in life and that HBoV might play a role in the course of lower respiratory tract infections.     

Human bocavirus (HBoV)

The human bocavirus (HBoV) has been recently identified by means of molecular screening techniques in respiratory tract secretions from children with acute respiratory tract disease. This virus, which belongs to the Parvoviridae family, has been detected worldwide with a 5 to 10% prevalence among children with upper or lower respiratory tract infections, essentially during the winter period. A seroepidemiological study has shown that almost all the children have antibodies to HBoV by the age of five years, and HBoV infection seems to be rare in adults. HBoV is often detected in association with other respiratory viruses. This virus has also been detected in stools, but its role in gastroenteritis has not been yet established. Virological diagnostic of HBoV infection is based on the detection of viral DNA by PCR. Viral load determination by viral DNA quantitation in respiratory tract secretions could be a tool to differentiate between symptomatic HBoV infection and virus carriage.