Human bocavirus in Italian patients with respiratory diseases

Simultaneous detection and characterization of common respiratory pathogens in wastewater through genomic sequencing

Genomic surveillance of SARS-CoV-2 has given insight into the evolution and epidemiology of the virus and its variant lineages during the COVID-19 pandemic. Expanding this approach to include a range of respiratory pathogens can better inform public health preparedness for potential outbreaks and epidemics. Here, we simultaneously sequenced 38 pathogens including influenza viruses, coronaviruses and bocaviruses, to examine the abundance and seasonality of respiratory pathogens in urban wastewater. We deployed a targeted bait capture method and short-read sequencing (Illumina Respiratory Virus Oligos Panel; RVOP) on composite wastewater samples from 8 wastewater treatment plants (WWTPs) and one associated hospital site. By combining seasonal sampling with whole genome sequencing, we were able to concurrently detect and characterise a range of common respiratory pathogens, including SARS-CoV-2, adenovirus and parainfluenza virus. We demonstrated that 38 respiratory pathogens can be detected at low abundances year-round, that hospital pathogen diversity is higher in winter vs. summer sampling events, and that significantly more viruses are detected in raw influent compared to treated effluent samples. Finally, we compared detection sensitivity of RT-qPCR vs. next generation sequencing for SARS-CoV-2, enteroviruses, influenza A/B, and respiratory syncytial viruses. We conclude that both should be used in combination; RT-qPCR allowed accurate quantification, whilst genomic sequencing detected pathogens at lower abundance. We demonstrate the valuable role of wastewater genomic surveillance and its contribution to the field of wastewater-based epidemiology, gaining rapid understanding of the seasonal presence and persistence for common respiratory pathogens. By simultaneously monitoring seasonal trends and early warning signs of many viruses circulating in communities, public health agencies can implement targeted prevention and rapid response plans.

Prevalence of human bocavirus infections in Europe. A systematic review and meta-analysis

Human bocaviruses (HBoVs) are recently described as human emergent viruses, especially in young children. In this study, we undertook a systematic review and meta-analysis to estimate their prevalence in Europe. PubMed, Web of Science and Scopus databases were systematically screened for clinical studies, up to October 2020. Study eligibility criteria were primary full-text articles from clinical studies, conducted using valid screening test methods and published in peer-reviewed journals, in English or Spanish and from European countries. The overall pooled prevalence, prevalence by country as well as the prevalence of HBoV as a single or co-pathogen were estimated using a random-effects model. Sub-group and meta-regression analyses explored potential sources of heterogeneity in the data. A total of 35 studies involving 32,656 subjects from 16 European countries met the inclusion criteria. Heterogeneity (I²  = 97.0%, p < .01) was seen among studies; HBoV prevalence varied from 2.0 to 45.69% with a pooled estimate of 9.57% (95%CI 7.66-11.91%). The HBoV prevalence both as a single infection (3.99%; 95%CI 2.99-5.31%) or as co-infection with other viruses (5.06%; 95%CI 3.88-6.58%) was also analysed. On a geographic level, prevalence by country did not show statistical differences, ranging from 3.24% (Greece) to 21.05% (Denmark). An odds ratio analysis was also included in order to evaluate the relevance of the variable 'age' as a risk factor of HBoV infection in children <5 years old. The OR value of 1.77 (95%CI 1.13-2.77; p < .01) indicated that being <5 years old is a risk factor for HBoV infection. This study showed that HBoV has a moderate prevalence among European countries.

Hospital utilization rates for influenza and RSV: a novel approach and critical assessment

BACKGROUND

Influenza and respiratory syncytial virus (RSV) contribute significantly to the burden of acute lower respiratory infection (ALRI) inpatient care, but heterogeneous coding practices and availability of inpatient data make it difficult to estimate global hospital utilization for either disease based on coded diagnoses alone.

METHODS

This study estimates rates of influenza and RSV hospitalization by calculating the proportion of ALRI due to influenza and RSV and applying this proportion to inpatient admissions with ALRI coded as primary diagnosis. Proportions of ALRI attributed to influenza and RSV were extracted from a meta-analysis of 360 total sources describing inpatient hospital admissions which were input to a Bayesian mixed effects model over age with random effects over location. Results of this model were applied to inpatient admission datasets for 44 countries to produce rates of hospital utilization for influenza and RSV respectively, and rates were compared to raw coded admissions for each disease.

RESULTS

For most age groups, these methods estimated a higher national admission rate than the rate of directly coded influenza or RSV admissions in the same inpatient sources. In many inpatient sources, International Classification of Disease (ICD) coding detail was insufficient to estimate RSV burden directly. The influenza inpatient burden estimates in older adults appear to be substantially underestimated using this method on primary diagnoses alone. Application of the mixed effects model reduced heterogeneity between countries in influenza and RSV which was biased by coding practices and between-country variation.

CONCLUSIONS

This new method presents the opportunity of estimating hospital utilization rates for influenza and RSV using a wide range of clinical databases. Estimates generally seem promising for influenza and RSV associated hospitalization, but influenza estimates from primary diagnosis seem highly underestimated among older adults. Considerable heterogeneity remains between countries in ALRI coding (i.e., primary vs non-primary cause), and in the age profile of proportion positive for influenza and RSV across studies. While this analysis is interesting because of its wide data utilization and applicability in locations without laboratory-confirmed admission data, understanding the sources of variability and data quality will be essential in future applications of these methods.

Human bocavirus (HBoV) in Kuwait: molecular epidemiology and clinical outcome of the virus among patients with respiratory diseases

Introduction. Globally, human bocavirus (HBoV) has been detected in respiratory samples from patients suffering from upper and lower respiratory diseases. In Kuwait, little is known about the epidemiological and clinical characterization of the virus and genetic characterization of the virus as a respiratory pathogen is unknown.Aim. This study aims to explore the molecular epidemiology and clinical features of HBoV isolates in patients with respiratory diseases.Methodology. Retrospectively, between 2018 and 2020, 5941 respiratory samples from patients with respiratory diseases were screened for respiratory viruses using multiplex real-time PCR. Samples that were positive for HBoV were then subjected to NP1 and VP1/PV2 phylogenetic analysis.Results. HBoV was detected in 1.9 % of the patients, with a peak incidence of infection among children <1 year old. Co-infection with other respiratory viruses was observed in 56.8 % of HBoV-positive patients. Fever, cough and respiratory distress were the most common clinical features of HBoV infection. Phylogenetic analysis of the Kuwaiti HBoV isolates revealed that all the isolates were of the HBoV-1 genotype, with slight sequence variations among the isolates.Conclusion. This study illustrated the predominance of the HBoV-1 genotype in patients with respiratory diseases in Kuwait with minimal genetic variability. It also highlighted the clinical features of HBoV-1 infection, verifying its role in respiratory diseases.

Human Bocavirus Infection in Adults: Clinical Features and Radiological Findings

OBJECTIVE

Human bocavirus (HBoV) is a newly identified pathogen that can cause upper and lower respiratory infections usually in children; however, its clinical characteristics and significance in respiratory infections in adults have not been well known. Our objective was to evaluate the clinical features of respiratory HBoV infection and to describe the CT findings of HBoV pneumonia in adults.

MATERIALS AND METHODS

A total of 185 adult patients diagnosed with HBoV infection at a tertiary referral center between January 2010 and December 2017 were retrospectively evaluated with respect to the clinical characteristics of HBoV infection and its risk factors for pneumonia. Chest CT findings for 34 patients with HBoV pneumonia without co-infection were analyzed and compared between immunocompetent (n = 18) and immunocompromised (n = 16) patients.

RESULTS

HBoV infections were predominantly noted between February and June. Among the 185 patients with HBoV infection, 119 (64.3%) had community-acquired infections and 110 (59.5%) had pneumonia. In multivariable analysis, older age (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.00-1.04; p = 0.045) and nosocomial infection (OR, 2.07; 95% CI, 1.05-4.10; p = 0.037) were associated with HBoV pneumonia. The main CT findings were bilateral consolidation (70.6%) and/or ground-glass opacities (64.7%); centrilobular nodules (14.7%) were found less frequently. The pattern of CT findings were not significantly different between immunocompetent and immunocompromised patients (all, p > 0.05).

CONCLUSION

HBoV infection can be a potential respiratory tract infection in adults. The most frequent CT findings of HBoV pneumonia were bilateral consolidation and/or ground-glass opacities.

Fatal Primary Human Bocavirus Pneumonia in an Immunocompetent Adult

A 70-year-old woman was admitted to our hospital for dyspnea and a fever of 2 weeks duration. Chest imaging showed bilateral infiltration, and a rapid diagnostic test for influenza virus, Mycoplasma pneumoniae, Streptococcus pneumoniae, and Legionella spp. was negative. She was intubated and mechanically ventilated and underwent bronchoalveolar lavage. Bronchoalveolar lavage fluid yielded no significant pathogens, and the multiplex polymerase chain reaction test was positive only for human bocavirus. Specific antibodies against significant pathogens were not increased in paired sera, so we diagnosed her with primary human bocavirus pneumonia.

The effects of human parvovirus VP1 unique region in a mouse model of allergic asthma

Evidence has indicated that viral infection increases the risk of developing asthma. Although the association of human parvovirus B19 (B19V) or human bocavirus (HBoV) with respiratory diseases has been reported, little is known about the influence of the B19V-VP1u and HBoV-VP1u proteins on the symptoms of asthma. Herein, we investigated the systemic influence of subcutaneously injected B19V-VP1u and HBoV-VP1u recombinant proteins in an OVA-sensitized asthmatic mouse model. A significantly higher Penh ratio and IgE level were detected in the serum, bronchoalveolar lavage fluid (BALF) and the supernatant of a lymphocyte culture from mice treated with HBoV-VP1u or B19V-VP1u than in a lymphocyte culture from OVA-sensitized mice. Significantly higher levels of serum and BALF IgE, total IgG, IgG1, OVA-specific IgE and OVA-specific IgG1 were detected in mice treated with HBoV-VP1u or B19V-VP1u than in OVA-sensitized mice. Conversely, a significantly lower IgG2a level was detected in mice from the HBoV-VP1u or B19V-VP1u groups than in mice from the OVA group. The mice treated with HBoV-VP1u or B19V-VP1u exhibited more significant lung inflammatory indices, including elevated serum and BALF IL-4, IL-5, IL-10 and IL-13 levels; BALF lymphocyte, neutrophil and eosinophil counts, MMP-9 and MMP-2 activity; and the amount of lymphocyte infiltration, relative to those in the control mice or in those sensitized with OVA. These findings demonstrate that the subcutaneous injection of HBoV-VP1u or B19V-VP1u proteins in OVA-sensitized mice result in elevated asthmatic indices and suggest that human parvoviruses may increase the risk of developing airway inflammation in a mouse model of asthma.

Prevalence of Human Bocavirus in Africa and Other Developing Countries between 2005 and 2016: A Potential Emerging Viral Pathogen for Diarrhea

BACKGROUND

Human Bocavirus (HBoV) is an emerging virus discovered in 2005 from individuals suffering gastroenteritis and respiratory tract infections. Numerous studies related to the epidemiology and pathogenesis of HBoV have been conducted worldwide. This review reports on HBoV studies in individuals with acute gastroenteritis, with and without respiratory tract infections in Africa between 2005 and 2016.

MATERIAL AND METHOD

The search engines of PubMed, Google Scholar, and Embase database for published articles of HBoV were used to obtain data between 2005 and 2016. The search words included were as follows: studies performed in Africa or/other developing countries or/worldwide; studies for the detection of HBoV in patients with/without diarrhea and respiratory tract infection; studies using standardized laboratory techniques for detection.

RESULTS

The search yielded a total of 756 publications with 70 studies meeting the inclusion criteria. Studies included children and individuals of all age groups. HBoV prevalence in Africa was 13% in individuals suffering gastroenteritis with/without respiratory tract infection.

CONCLUSION

Reports suggest that HBoV infections are increasingly being recognized worldwide. Therefore, surveillance of individuals suffering from infections in Africa is required to monitor the prevalence of HBoV and help understand the role of HBoV in individuals suffering from gastroenteritis with/without respiratory tract infection.

The VP1 unique region of human parvovirus B19 and human bocavirus induce lung injury in naïve Balb/c mice

Both human parvovirus B19 (B19V) and human bocavirus (HBoV) are known to be important human pathogens of the Parvoviridae family. Our earlier investigation demonstrated that both B19V-VP1u and HBoV-VP1u have a significantly disruptive effect on tight junctions (TJs) in A549 cells, implying the essential role of parvovirus in airway infection and lung injury. However, no direct evidence that B19V-VP1u and HBoV-VP1u induce lung injury exists. The present study further investigates the induction of lung injury by B19V-VP1u and HBoV-VP1u in naïve Balb/c mice following subcutaneous injection of PBS, recombinant B19V-VP1u or HBoV-VP1u. The experimental results reveal significantly increased activity, protein expression and ratio of matrix metalloproteinase-9 (MMP-9) to MMP-2 in Balb/c mice that received B19V-VP1u or HBoV-VP1u compared to those that received PBS. Significantly higher levels of inflammatory cytokines, including IL-6 and IL-1β, and greater lymphocyte infiltration in lung tissue sections were detected in mice that received B19V-VP1u or HBoV-VP1u. Additionally, significantly increased levels of phosphorylated p65 (NF-κB) and MAPK signaling proteins were observed in lung tissue of mice that received B19V-VP1u or HBoV-VP1u compared to those of mice that received PBS. These findings demonstrate for the first time that B19V-VP1u and HBoV-VP1u proteins induce lung inflammatory reactions through p65 (NF-κB) and MAPK signaling.

Whole-genome sequencing analysis of human bocavirus detected in South Korea

Human bocaviruses (HBoVs) have been detected in human gastrointestinal infections worldwide. In 2005, HBoV was also discovered in infants and children with infections of the lower respiratory tract. Recently, several genotypes of this parvovirus, including HBoV genotype 2 (HBoV2), genotype 3 (HBoV3) and genotype 4 (HBoV4), were discovered and found to be closely related to HBoV. HBoV2 was first detected in stool samples from children in Pakistan, followed by detection in other countries. HBoV3 was detected in Australia and HBoV4 was identified in stool samples from Nigeria, Tunisia and the USA. Recently, HBoV infection has been on the rise throughout the world, particularly in countries neighbouring South Korea; however, there have been very few studies on Korean strains. In this study, we characterised the whole genome and determined the phylogenetic position of CUK-BC20, a new clinical HBoV strain isolated in South Korea. The CUK-BC20 genome of 5184 nucleotides (nt) contains three open-reading frames (ORFs). The genotype of CUK-BC20 is HBoV2, and 98.77% of its nt sequence is identical with those of other HBoVs, namely Rus-Nsc10-N386. Especially, the ORF3 amino acid sequences from positions 212-213 and 454 corresponding to a variable region (VR)1 and VR5, respectively, showed genotype-specific substitutions that distinguished the four HBoV genotypes. As the first whole-genome sequence analysis of HBoV in South Korea, this information will provide a valuable reference for the detection of recombination, tracking of epidemics and development of diagnosis methods for HBoV.

Prevalence and clinical profile of human bocavirus in children with acute gastroenteritis in Chengdu, West China, 2012-2013

Viral acute gastroenteritis (AGE) is a major cause of mortality in childhood and leads to hospitalization in developing countries. Human bocavirus (HBoV) is a newly described virus associated with gastroenteritis. However, little is known about the clinical and epidemiological profile of human bocavirus (HBoV) in pediatric population in Chengdu, China. Between January 2012 and December 2013, 346 fecal samples from children admitted to hospital with acute gastroenteritis were tested for the presence of HBoV as well as other gastroenteritis viruses. Additionally, laboratory test results, clinical features and epidemiological characters were also collected to assess the correlation between HBoV and acute gastroenteritis in pediatric patients in Chengdu, China. Of the 346 tested fecal samples, 60 (17.34%) were positive for HBoV. The rate of co-detection of HBoV with other gastroenteritis viruses was 43.33% (26/60). HBoV was most detected in the summer/early fall months. Sequence analysis of the VP1/VP2 gene showed that both HBoV1 and HBoV2 circulated in Chengdu, China. No obvious difference was found between the clinical features of the HBoV1 mono-detected patients and HBoV2 mono-detected patients. Besides, in diarrheic children, positive correlation was found between detection of HBoV and diagnose of respiratory disease. Furthermore, blood cells were detected more frequently in fecal samples of patients with HBoV mono-detected. Though HBoV was detected frequently in Children with diarrhea in Chengdu, no statistical association was found between HBoV and disease severity.

Alternative Polyadenylation of Human Bocavirus at Its 3' End Is Regulated by Multiple Elements and Affects Capsid Expression

Alternative processing of human bocavirus (HBoV) P5 promoter-transcribed RNA is critical for generating the structural and nonstructural protein-encoding mRNA transcripts. The regulatory mechanism by which HBoV RNA transcripts are polyadenylated at proximal [(pA)p] or distal [(pA)d] polyadenylation sites is still unclear. We constructed a recombinant HBoV infectious clone to study the alternative polyadenylation regulation of HBoV. Surprisingly, in addition to the reported distal polyadenylation site, (pA)d, a novel distal polyadenylation site, (pA)d2, which is located in the right-end hairpin (REH), was identified during infectious clone transfection or recombinant virus infection. (pA)d2 does not contain typical hexanucleotide polyadenylation signal, upstream elements (USE), or downstream elements (DSE) according to sequence analysis. Further study showed that HBoV nonstructural protein NS1, REH, and cis elements of (pA)d were necessary and sufficient for efficient polyadenylation at (pA)d2. The distance and sequences between (pA)d and (pA)d2 also played a key role in the regulation of polyadenylation at (pA)d2. Finally, we demonstrated that efficient polyadenylation at (pA)d2 resulted in increased HBoV capsid mRNA transcripts and protein translation. Thus, our study revealed that all the bocaviruses have distal poly(A) signals on the right-end palindromic terminus, and alternative polyadenylation at the HBoV 3′ end regulates its capsid expression.

IMPORTANCE The distal polyadenylation site, (pA)d, of HBoV is located about 400 nucleotides (nt) from the right-end palindromic terminus, which is different from those of bovine parvovirus (BPV) and canine minute virus (MVC) in the same genus whose distal polyadenylation is located in the right-end stem-loop structure. A novel polyadenylation site, (pA)d2, was identified in the right-end hairpin of HBoV during infectious clone transfection or recombinant virus infection. Sequence analysis showed that (pA)d2 does not contain typical polyadenylation signals, and the last 42 nt form a stem-loop structure which is almost identical to that of MVC. Further study showed that NS1, REH, and cis elements of (pA)d are required for efficient polyadenylation at (pA)d2. Polyadenylation at (pA)d2 enhances capsid expression. Our study demonstrates alternative polyadenylation at the 3′ end of HBoV and suggests an additional mechanism by which capsid expression is regulated.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Human Bocavirus in Korean Children with Gastroenteritis and Respiratory Tract Infections

Human bocaviruses (HBoVs) are suggested to be etiologic agents of childhood respiratory and gastrointestinal infections. There are four main recognized genotypes of HBoVs (HBoV1–4); the HBoV-1 genotype is considered to be the primary etiologic agent in respiratory infections, whereas the HBoV2–4 genotypes have been mainly associated with gastrointestinal infections. The aim of the present study was to determine the distribution of HBoV genotypes in children with respiratory or gastrointestinal infections in a hospital in Korea. A total of 662 nasopharyngeal swabs (NPSs) and 155 fecal specimens were collected from children aged 5 years or less. Polymerase chain reaction (PCR) was conducted to detect the NS1 HBoV gene. The VP1 gene of HBoV was further amplified in samples that were positive for the NS1 gene. The PCR products of VP1 gene amplification were genotyped by sequence analysis. HBoV was detected in 69 (14.5%) of 662 NPSs and in 10 (6.5%) of 155 fecal specimens. Thirty-three isolates from NPSs and five isolates from fecal specimens were genotyped, and all 38 sequenced isolates were identified as the HBoV-1 genotype. HBoV-1 is the most prevalent genotype in children with respiratory or gastrointestinal HBoV infections in a hospital in Korea.

Human bocavirus: Current knowledge and future challenges

Human bocavirus (HBoV) is a parvovirus isolated about a decade ago and found worldwide in both respiratory samples, mainly from early life and children of 6-24 mo of age with acute respiratory infection, and in stool samples, from patients with gastroenteritis. Since then, other viruses related to the first HBoV isolate (HBoV1), namely HBoV2, HBoV3 and HBoV4, have been detected principally in human faeces. HBoVs are small non-enveloped single-stranded DNA viruses of about 5300 nucleotides, consisting of three open reading frames encoding the first two the non-structural protein 1 (NS1) and nuclear phosphoprotein (NP1) and the third the viral capsid proteins 1 and 2 (VP1 and VP2). HBoV pathogenicity remains to be fully clarified mainly due to the lack of animal models for the difficulties in replicating the virus in in vitro cell cultures, and the fact that HBoV infection is frequently accompanied by at least another viral and/or bacterial respiratory and/or gastroenteric pathogen infection. Current diagnostic methods to support HBoV detection include polymerase chain reaction, real-time PCR, enzyme-linked immunosorbent assay and enzyme immunoassay using recombinant VP2 or virus-like particle capsid proteins, although sequence-independent amplification techniques combined with next-generation sequencing platforms promise rapid and simultaneous detection of the pathogens in the future. This review presents the current knowledge on HBoV genotypes with emphasis on taxonomy, phylogenetic relationship and genomic analysis, biology, epidemiology, pathogenesis and diagnostic methods. The emerging discussion on HBoVs as true pathogen or innocent bystander is also emphasized.

A novel primer set for improved direct gene sequencing of human bocavirus genotype-1 from clinical samples

Human bocavirus genotype (HBoV-1) is a parvovirus associated with respiratory tract infections in children with different degrees of severity. The current study intended to improve the direct gene sequencing of the HBoV-1 using a newly developed primer set. Screening the presence of human bocavirus infection among in-patients children suffering from lower respiratory tract infections was another aim of the current study. Nasopharyngeal swab samples from in-patients children suffering from lower respiratory tract infections were examined. The real-time polymerase chain reaction was used for the initial screening as a highly sensitive method to detect the HBoV. Genotyping of real-time positive samples was attempted by direct sequencing of PCR amplicons using NP, VP1/2 and the newly developed VP/NC primers. HBoV-1 was present in 56.8% of the examined children. The newly developed primer set successfully amplified all real-time PCR positive samples, however, the other primer pairs did not reliably detect real-time PCR positive samples. The gene sequences of the detected HBoV-1 showed conserved sequences to each other with a low rate of discrepancies. The high rate of infection and the similarity between the detected strains strongly suggest nosocomial infections.

Detection of human bocavirus in nasopharyngeal aspirates versus in broncho-alveolar lavage fluids in children with lower respiratory tract infections

To compare the presence of human bocavirus (HBoV) in nasopharyngeal aspirates (NPA) versus broncho-alveolar lavage fluids (BAL) in children with lower respiratory tract infections (LRTIs), as revealed by real-time PCR, in order to confirm the diagnostic validity of NPA samples. A retrospective 5-year study was performed from 2009 to 2014 in 1,194 patients under the age of 17 years (mean age of 3 years) that were diagnosed with LRTIs and from whom both NPA and BAL were obtained. Clinical and demographic data were recorded, and NPA and BAL samples were analyzed for HBoV-positivity by real-time PCR. Of the 1,194 patients enrolled, 65 (5.4%) patients had HBoV detected from NPA, and 61 (5.1%) had HBoV detected from BAL. For HBoV, there was a significant association between the NPA and BAL samples (P < 0.001), but the diagnostic validity was relatively low (kappa = 0.414). When real-time PCR-positivity for HBoV in BAL was used as a reference for diagnosis, NPA had a good specificity and better positive predictive validity in male patients or those younger than 3 years of age. NPA has a similar yield and a good specificity for diagnosis of LRTIs with HBoV compared to BAL. The best diagnostic validity for NPA was detected in male patients or those younger than 3 years old.

Detection of Human Bocavirus DNA by Multiplex PCR Analysis: Postmortem Case Report

BACKGROUND

Human bocavirus (HBoV) is a virus belonging to the Parvoviridae family, which has been newly discovered to be associated with respiratory tract infections in children. There are many reports worldwide on the endemicity of this virus. Since it is relatively new, it is not routinely detected in clinical laboratory investigations.

CASE REPORT

We demonstrated that HBoV infection caused the death of a 5-month-old girl with a history of high fever and wheezing. Human bocavirus (HBoV 1/2/3/4) was found in a nasopharyngeal swab, paraffin-embedded lung tissue and stool samples by multiplex PCR methods using postmortem microbiological analysis.

CONCLUSION

This case suggests that lower respiratory tract infections due to HBoV may cause severe and life-threatening diseases. Postmortem microbiology is useful in both clinical and forensic autopsies, and allows a suspected infection to be confirmed. To our knowledge, this report is the first document of a HBoV postmortem case in Turkey.

Epidemiology characteristics of respiratory viruses found in children and adults with respiratory tract infections in southern China

Background

The World Health Organization (WHO) ranks respiratory tract infection (RTI) as the second leading cause of death worldwide for children under 5 years of age. The aim of this work was to evaluate the epidemiology characteristics of respiratory viruses found in children and adults with RTI from July 2009 to June 2012 in southern China.

Methods

In this work, a total of 14 237 nasopharyngeal swabs (14 237 patients from 25 hospitals) were analyzed, and seven respiratory viruses (influenza virus, respiratory syncytial virus, parainfluenza virus, adenovirus, human metapneumovirus, human coronavirus, human bocavirus) were detected using PCR/RT-PCR from nasopharyngeal swabs.

Results

The demographic characteristics, viral prevalence, age distribution, seasonal distribution, and pathogen spectrum of the patients with RTIs were analyzed. Co-infection was observed in 483 specimens, but it was more common in male patients, inpatients, children, and young adults. It varied by season, being more prevalent in the spring and summer and less so in the winter. Human coronavirus and human bocavirus were the most common pathogens, tending to occur in co-infection with other respiratory viruses.

Conclusions

This work adds to our knowledge of the epidemiology characteristics of these seven common respiratory viruses among patients with RTI in southern China. The detection of the specific viral causes of infection provides a useful starting point for an understanding of illness attributable to respiratory infection, and might also provide data relevant to the development of prevention strategies.

Human bocavirus isolated from children with acute respiratory tract infections in Korea, 2010-2011

Human bocavirus (HBoV) was first recognized in respiratory samples in 2005. The clinical importance of HBoV infection remains unclear. This report describes the clinical features and molecular phylogeny of HBoV isolates in children with acute respiratory infections. Nasopharyngeal aspirates were obtained from 1,528 children with acute respiratory infections between 2010 and 2011. Respiratory samples were screened for HBoV by multiplex PCR. A phylogenetic analysis of the HBoV VP1/VP2 gene was also undertaken. HBoV was detected in 187 (12.2%) of the 1,528 patients with a peak incidence of infection observed in patients aged 12–24 months. Coinfection with other respiratory viruses was observed in 107 (57.2%) of the HBoV‐positive children. The peak of HBoV activity occurred during the month of June in both 2010 and 2011. A higher previous history of wheezing (P = 0.016), a higher frequency of chest retraction (P < 0.001) and wheezing (P = 0.022), a higher respiratory symptom score (P = 0.002), and a longer duration of hospital stay (P = 0.021) were observed in HBoV‐positive children compared with the HBoV‐negative group. Phylogenetic analysis showed all 187 HBoV‐positive isolates were identified as HBoV 1, indicating minimal sequence variations among the isolates. A single lineage of HBoV 1 was found to have circulated in children with acute respiratory infections between 2010 and 2011 and was associated with several clinical characteristics including age, seasonality, and clinical severity with retraction, wheezing, and longer hospitalization. The clinical relevance of the minimal sequence variations of HBoV remains to be determined. J. Med. Virol. 86:2011–2018, 2014. © 2014 The Authors. Journal of Medical Virology published by Wiley Periodicals, Inc.

Human Bocavirus

Human bocavirus 1 (HBoV1), family Parvoviridae, subfamily Parvovirinae, genus Bocavirus, is a recently described respiratory virus with a worldwide distribution. It is recognized as one of the most frequently detected respiratory viruses in hospitalized children below 5 years of age and mainly detected in children between 6 and 24 months of age. The severe clinical course of HBoV1 infection can be seen in prematurely born children or children, but rarely adults, with other underlying medical conditions. The seroepidemiological studies show that most of the children are infected with HBoV1 by the age of 6 and that the IgG antibodies remain for life. The routine laboratory diagnostics of HBoV1 infections is almost exclusively based on detection of HBoV1 DNA in respiratory samples by PCR. Due to frequent coinfections with other respiratory viruses, PCR of plasma samples and detection of specific IgM might aid in determining the etiology of infection.

Viral load of human bocavirus-1 in stools from children with viral diarrhoea in Paraguay

Since their discovery, four species of human bocavirus (HBoV) have been described in patients with respiratory and gastrointestinal diseases. However, a clear causal association between HBoV-1 and gastroenteritis has not been demonstrated. In this study, we describe the detection and quantification of HBoV-1 in stools from children with acute non-bacterial gastroenteritis using quantitative polymerase chain reaction. HBoV-1 genome was detected in 10.6% of stools with frequent association with rotavirus and norovirus. The median of HBoV-1 viral load was 1.88 × 104 genome/ml, lower than previously shown in secretions of patients with respiratory infections, without any obvious association between high viral load and presence of HBoV as single agent. Thus, although HBoV-1 was frequently detected in these patients, there is no clear causal association of this agent with diarrhoea. Indeed, HBoV-1 DNA in stools of patients with gastroenteritis without respiratory symptoms may be a remnant of previous infections or associated with prolonged shedding of virus in the respiratory or digestive tracts.

Genetic variability of human metapneumo- and bocaviruses in children with respiratory tract infections

OBJECTIVES

The genotypic analysis of human metapneumo-(HMPV) and boca-(HBoV) viruses circulating in Greece and their comparison to reference and other clinical strains.

DESIGN

Genetic analysis of representative strains over three consecutive winter seasons of the years 2005-2008.

SETTING

Representative positive specimens for HMPV and HBoV from paediatric patients of healthcare units and hospitals in Southern Greece with influenza-like illness or other respiratory tract infections.

SAMPLE

Seven to ten positive specimens for either HMPV or HBoV from each winter period. In total, 24 specimens positive for HMPV and 26 for HBoV, respectively.

MAIN OUTCOME MEASURES

Sequence diversity of HMPV and HBoV strains by sequencing the complete G and VP1/VP2 genes, respectively.

RESULTS

In total, 24 HMPV strains were found to have a 92-100% nucleotide and a 85.9-100% amino acid identity. Phylogenetic analysis based on the number of amino acid differences, revealed circulation of 4 different subclusters belonging to genetic lineage B2. Similarly, analysis of 26 HBoV strains indicated that 22 clustered within genotype St2, 2 into genotype St1 and the remaining 2 formed a third cluster derived from potential recombination between different St1 genotype strains. St2 HBoV genotype was observed throughout the whole observation period whereas St1 only during the second and the third winter period. Higher levels of heterogeneity were observed between HMPV compared to HBoV strains.

CONCLUSIONS

Phylogenetic analysis revealed circulation of one single lineage (B2) for HMPV viruses and predominance of St2 genotype for HBoV viruses. A possible recombination between St1 genotype strains of HBoV was observed.

Clinical and epidemiologic profile of lower respiratory tract infections associated with human bocavirus

BACKGROUND

Acute viral bronchiolitis (AVB) remains the leading cause of lower respiratory tract infection (LRTI) in infants under 2 years of age. Advances in molecular methods for virus detection have led to the identification of new infectious agents implicated in the development of AVB, such as human bocavirus (HBoV).

OBJECTIVES

To ascertain the frequency, seasonality, and clinical behavior of HBoV detection in a series of episodes of LRTI.

STUDY DESIGN

The frequency of HBoV was assessed in children with LRTI episodes, aged 1-24 months, seen at the emergency department of Hospital da Criança Santo Antônio, Porto Alegre, Brazil, between May 2007 and July 2008. Virus-specific polymerase chain reaction was used for detection.

RESULTS

A total of 455 nasal secretion samples were collected from 433 patients over a 14-month period. Of these, 60 were positive for HBoV (13.2%). Mean age was 7.9 months and 55% of patients were male. Just over half of patients were under 6 months of age (53.3%). Wheezing was the presenting respiratory complaint in 51.7%. Of the 60 patients, 80% were admitted to a pediatric ward. Diarrhea was present in nine patients (18%). Co-detection was a frequent finding in our sample, occurring in 95% of cases. In our series, the distribution of HBoV was clearly seasonal and was influenced by temperature, relative humidity, and precipitation.

CONCLUSIONS

We conclude that HBoV detection in infants with AVB and recurrent wheezing of viral etiology in Brazil is similar to that reported in other countries. The clinical course of HBoV detection is no different from that of other respiratory viruses commonly found in this age range.

Human bocavirus in children with acute respiratory infections in Vietnam

Acute respiratory infections are the major cause of morbidity and mortality globally. Human bocavirus (HBoV), a novel virus, is recognized to increasingly associate with previously unknown etiology respiratory infections in young children. In this study, the epidemiological, clinical, and molecular characteristics of HBoV infections were described in hospitalized Vietnamese pediatric patients. From April 2010 to May 2011, 1,082 nasopharyngeal swab samples were obtained from patients with acute respiratory infections at the Children's Hospital 2, Ho Chi Minh City, Vietnam. Samples were screened for HBoV by PCR and further molecularly characterized by sequencing. HBoV was found in 78 (7.2%) children. Co‐infection with other viruses was observed in 66.7% of patients infected with HBoV. Children 12–24 months old were the most affected age group. Infections with HBoV were found year‐round, though most cases occurred in the dry season (December–April). HBoV was possible to cause severe diseases as determined by higher rates of hypoxia, pneumonia, and longer hospitalization duration in patients with HBoV infection than in those without (P‐value <0.05). Co‐infection with HBoV did not affect the disease severity. The phylogenetic analysis of partial VP1 gene showed minor variations and all HBoV sequences belonged to species 1 (HBoV1). In conclusion, HBoV1 was circulating in Vietnam and detected frequently in young children during dry season. Acute respiratory infections caused by HBoV1 were severe enough for hospitalization, which implied that HBoV1 may have an important role in acute respiratory infections among children. J. Med. Virol. 86:988–994, 2014. © 2013 Wiley Periodicals, Inc.

Frequency of human bocavirus respiratory infections among at-risk patients in São Paulo, Brazil

BACKGROUND AND OBJECTIVES

Human Bocavirus (HBoV) has been described since 2005 as an etiological agent of respiratory virus infections. From 2001 to 2008 we investigated the etiology of HBoV among adults and children in different groups at risk of presenting complications arising from acute respiratory infection, the investigation was carried out in a tertiary hospital health care system in Brazil.

METHODS

HBoV DNA was assayed in 598 respiratory samples from community and hospitalized patients by PCR.

RESULTS

Of the 598 tested samples, 2.44% (8/328) of children, including five children with heart disease, and 0.4% (1/270) of adult bone-marrow-transplant were HBoV positive.

CONCLUSIONS

These data suggested lower HBoV frequency among different at-risk patients and highlights the need to better understand the real role of HBoV among acute respiratory symptomatic patients.

Detection of bocavirus in children suffering from acute respiratory tract infections in Saudi Arabia

Human bocavirus (HBoV) was recently discovered in children with respiratory distress and/or diarrhea. To our knowledge, no previous study has reported the existence of bocavirus in Saudi Arabia. Swabs samples from 80 children with respiratory tract infections were examined for the presence of HBoV. Real-time polymerase chain reaction was used as a sensitive method to detect the HBoV. Direct gene sequencing was used to determine the genotype of the detected virus isolates. HBoV was detected in 22.5% of the examined patients. The NP1 partial gene sequence from all patients showed that the circulated strains were related to HBoV-1 genotype. Most of HBoV infected patients showed evidence of mixed coinfection with other viral pathogens. The current study clearly demonstrated that genetically conserved HBoV1 circulates in Saudi Arabia. Interestingly, most of the HBoV1 infected cases were associated with high rates of co-infections with other viruses.

The role of infections and coinfections with newly identified and emerging respiratory viruses in children

Acute respiratory infections are a major cause of morbidity in children both in developed and developing countries. A wide range of respiratory viruses, including respiratory syncytial virus (RSV), influenza A and B viruses, parainfluenza viruses (PIVs), adenovirus, rhinovirus (HRV), have repeatedly been detected in acute lower respiratory tract infections (LRTI) in children in the past decades. However, in the last ten years thanks to progress in molecular technologies, newly discovered viruses have been identified including human Metapneumovirus (hMPV), coronaviruses NL63 (HcoV-NL63) and HKU1 (HcoV-HKU1), human Bocavirus (HBoV), new enterovirus (HEV), parechovirus (HpeV) and rhinovirus (HRV) strains, polyomaviruses WU (WUPyV) and KI (KIPyV) and the pandemic H1N1v influenza A virus. These discoveries have heavily modified previous knowledge on respiratory infections mainly highlighting that pediatric population is exposed to a variety of viruses with similar seasonal patterns. In this context establishing a causal link between a newly identified virus and the disease as well as an association between mixed infections and an increase in disease severity can be challenging. This review will present an overview of newly recognized as well as the main emerging respiratory viruses and seek to focus on the their contribution to infection and co-infection in LRTIs in childhood.

Occurrence of human bocaviruses and parvovirus 4 in solid tissues

Human bocaviruses 1-4 (HBoV1-4) and parvovirus 4 (PARV4) are recently discovered human parvoviruses. HBoV1 is associated with respiratory infections of young children, while HBoV2-4 are enteric viruses. The clinical manifestations of PARV4 remain unknown. The objective of this study was to determine whether the DNAs of HBoV1-4 and PARV4 persist in human tissues long after primary infection. Biopsies of tonsillar tissue, skin, and synovia were examined for HBoV1-4 DNA and PARV4 DNA by PCR. Serum samples from the tissue donors were assayed for HBoV1 and PARV4 IgG and IgM antibodies. To obtain species-specific seroprevalences for HBoV1 and for HBoV2/3 combined, the sera were analyzed after virus-like particle (VLP) competition. While HBoV1 DNA was detected exclusively in the tonsillar tissues of 16/438 individuals (3.7%), all of them ≤8 years of age. HBoV2-4 and PARV4 DNAs were absent from all tissue types. HBoV1 IgG seroprevalence was 94.9%. No subject had HBoV1 or PARV4 IgM, nor did they have PARV4 IgG. The results indicate that HBoV1 DNA occurred in a small proportion of tonsils of young children after recent primary HBoV1 infection, but did not persist long in the other tissue types studied, unlike parvovirus B19 DNA. The results obtained by the PARV4 assays are in line with previous results on PARV4 epidemiology.

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study

BACKGROUND

Viral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients.

METHODS

Bronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid.

RESULTS

There was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536).

CONCLUSIONS

This study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out.

TRIALS REGISTRATION

Current Controlled Trials ISRCTN62337037 & ISRCTN40147207.

Surveillance and genome analysis of human bocavirus in patients with respiratory infection in Guangzhou, China

Human bocavirus (HBoV) is a novel parvovirus associated with respiratory tract diseases and gastrointestinal illness in adult and pediatric patients throughout the world. To investigate the epidemiological and genetic variation of HBoV in Guangzhou, South China, we screened 3460 throat swab samples from 1686 children and 1774 adults with acute respiratory infection symptoms for HBoV between March 2010 and February 2011, and analyzed the complete genome sequence of 2 HBoV strains. Specimens were screened for HBoV by real-time PCR and other 6 common respiratory viruses by RT-PCR or PCR. HBoV was detected in 58 (1.68%) out of 3460 samples, mostly from pediatric patients (52/58) and inpatient children (47/58). Six adult patients were detected as HBoV positive and 5 were emergency cases. Of these HBoV positive cases, 19 (32.76%) had co-pathogens including influenza virus (n = 5), RSV (n = 5), parainfluenza (n = 4), adenovirus (n = 1), coronavirus (n = 7). The complete genome sequences of 2 HBoVs strains (Genbank no. JN794565 and JN794566) were analyzed. Phylogenetic analysis showed that the 2 HBoV strains were HBoV1, and were most genetically close to ST2 (GenBank accession number DQ0000496). Recombination analysis confirmed that HBoV strain GZ9081 was an intra–genotype recombinant strain among HBoV1 variants.

Seroepidemiology of human bocavirus infection in Jamaica

BACKGROUND

Human bocavirus (HBoV) is a newly identified human parvovirus. HBoV is associated with upper and lower respiratory tract infections and gastroenteritis in children. Little is known about the seroepidemiology of HBoV in populations in the Caribbean.

METHODS

In a cross-sectional study conducted at the University Hospital of the West Indies in Kingston, Jamaica, 287 blood samples were collected from pediatric patients and tested for the presence of HBoV-specific antibody using a virus-like-particle based enzyme-linked immunosorbent assay (ELISA).

RESULTS

HBoV-specific antibodies were found to be present in 220/287 (76.7%) of samples collected from the pediatric population. Seroprevalence of HBoV was highest in those ≥2 years old. The seroepidemiological profile suggests that most children are exposed to HBoV during the first two years of life in Jamaica.

CONCLUSION

HBoV infection is common in children in Jamaica. HBoV seroprevalence rates in the Caribbean are similar to those previously reported in other areas of the world.

Association of human bocavirus 1 infection with respiratory disease in childhood follow-up study, Finland

Since its discovery in 2005, human bocavirus type 1 has often been found in the upper airways of young children with respiratory disease. But is this virus the cause of the respiratory disease or just an innocent bystander? A unique study in Finland, which examined follow-up blood samples of 109 healthy children with no underlying illness starting at birth and until they were 13 years of age, found that acute bocavirus infection resulted in respiratory disease. All children had been infected by age 6. Most retained their antibodies to this virus; some lost them. Children who were later re-exposed to bocavirus did not get sick from this virus. Thus, human bocavirus type 1 is a major cause of respiratory disease in childhood.

Human bocavirus 1 (HBoV1) DNA is frequently detected in the upper airways of young children with respiratory symptoms. Because of its persistence and frequent co-detection with other viruses, however, its etiologic role has remained controversial. During 2009–2011, using HBoV1 IgM, IgG, and IgG-avidity enzyme immunoassays and quantitative PCR, we examined 1,952 serum samples collected consecutively at 3- to 6-month intervals from 109 constitutionally healthy children from infancy to early adolescence. Primary HBoV1 infection, as indicated by seroconversion, appeared in 102 (94%) of 109 children at a mean age of 2.3 years; the remaining 7 children were IgG antibody positive from birth. Subsequent secondary infections or IgG antibody increases were evident in 38 children and IgG reversions in 10. Comparison of the seroconversion interval with the next sampling interval for clinical events indicated that HBoV1 primary infection, but not secondary immune response, was significantly associated with acute otitis media and respiratory illness.

Molecular diagnosis of respiratory virus infections

The appearance of eight new respiratory viruses, including the SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009, in the human population in the past nine years has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid based amplification tests (NATs) for respiratory viruses were first introduced two decades ago and today are utilized for the detection of both conventional and emerging viruses. These tests are more sensitive than other diagnostic approaches, including virus isolation in cell culture, shell vial culture (SVC), antigen detection by direct fluorescent antibody (DFA) staining, and rapid enzyme immunoassay (EIA), and now form the backbone of clinical virology laboratory testing around the world. NATs not only provide fast, accurate and sensitive detection of respiratory viruses in clinical specimens but also have increased our understanding of the epidemiology of both new emerging viruses such as the pandemic H1N1 influenza virus of 2009, and conventional viruses such as the common cold viruses, including rhinovirus and coronavirus. Multiplex polymerase chain reaction (PCR) assays introduced in the last five years detect up to 19 different viruses in a single test. Several multiplex PCR tests are now commercially available and tests are working their way into clinical laboratories. The final chapter in the evolution of respiratory virus diagnostics has been the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance. These assays are now being multiplexed with primary detection and subtyping assays, especially in the case of influenza virus. These resistance assays, together with viral load assays, will enable clinical laboratories to provide physicians with new and important information for optimal treatment of respiratory virus infections.

High viral load of human bocavirus correlates with duration of wheezing in children with severe lower respiratory tract infection

Background

Human bocavirus (HBoV) is a newly discovered parvovirus and increasing evidences are available to support its role as an etiologic agent in lower respiratory tract infection (LRTI). The objective of this study is to assess the impact of HBoV viral load on clinical characteristics in children who were HBoV positive and suffered severe LRTI.

Methods

Lower respiratory tract aspirates from 186 hospitalized children with severe LRTI were obtained by bronchoscopy. HBoVs were detected by real-time PCR and other 10 infectious agents were examined using PCR and/or direct fluorescent assay.

Results

Thirty-one patients (24.6%) were tested positive for HBoV in the respiratory tract aspirates. Fifteen samples had a high viral load (>10⁴ copies/mL) and the other sixteen samples had a low viral load (<10⁴ copies/mL). The duration of presented wheezing and hospitalization was longer in children with high viral load of HBoV than that in children with low viral load. The days of wheezing showed a correlation with viral load of HBoV.

Conclusion

We confirmed that HBoV was frequently detected in patients with severe LRTI. Wheezing was one of the most common symptoms presented by patients with positive HBoV. A high HBoV viral load could be an etiologic agent for LRTI, which led to more severe lower respiratory tract symptom, longer duration of wheezing and hospitalization.

Human bocavirus in the nasopharynx of otitis-prone children

OBJECTIVES

Human bocavirus (HBoV) is frequently identified in children with respiratory tract infections, and its role in acute otitis media (AOM) has been suggested. The disease associations for the closely related bocaviruses HBoV2-4 remain unknown. Increasing evidence shows that probiotics may reduce the risk of AOM of viral origin. Objectives of the study was to examine the prevalence and persistence of bocaviruses in consecutive nasopharyngeal samples (NPS) of otitis-prone children, and whether an association exists between HBoV and the child's characteristics, respiratory symptoms, and AOM pathogens, and whether probiotics reduce the occurrence of HBoV.

METHODS

In a double-blind, placebo-controlled, randomized, 6-month intervention study, 269 otitis-prone children (aged 9 months to 5.6 years), consumed daily either one capsule of probiotics (Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Bifidobacterium breve 99 and Propionibacterium freudenreichii JS) or placebo. After a clinical examination and NPS collected at three-time points, the presence and persistence of HBoV1-4 DNA in NPS was determined by RT-qPCR at the baseline, after 3, and 6 months.

RESULTS

A high load (>10,000 copies/ml) of HBoV DNA was detected in 26 (17.1%) of 152 children, and 16 (10.5%) showed a prolonged presence of HBoV for at least 3 months. None had DNA of HBoV2-4. Higher number of siblings associated with increased HBoV prevalence (p=0.029). Prevalence or persistence of HBoV was not significantly associated with other characteristics, respiratory symptoms, or AOM pathogens. Probiotic intervention significantly reduced the number of HBoV DNA-positive samples (probiotic vs. placebo: 6.4% vs. 19.0%, OR=0.25, CI 95%=0.07-0.94, p=0.039).

CONCLUSIONS

HBoV, but not HBoV2-4, DNA occurs often in the nasopharynx of otitis-prone children, and may persist for 3-6 months. Probiotic treatment possibly reduced the presence of HBoV.

High prevelance of human parvovirus infection in patients with malignant tumors

It is well known that the immunity of patients with malignant tumors decreases significantly. An increased parvovirus B19 (B19) infection rate has been observed in immunocompromised hosts. However, only a small amount of literature regarding the risk of human parvovirus infection in patients with malignant tumors is available. To evaluate the correlation of human parvovirus infection with malignant tumors, 288 serum samples from patients with malignant tumors were screened for B19 DNA by nested-PCR. The serum samples, 156 of which were from known clinicopathological cancer patients, were subjected to analysis of the seropositive rate of human bocavirus (HBoV), hepatitis B virus (HBV) and transfusion transmitted virus (TTV) by PCR. A total of 800 normal population sera and 941 aspirate samples from children with respiratory tract infections were used as controls for the detection of B19 and HBoV, respectively. Pairwise comparison between cancerous serum and control samples, and the correlation between parvovirus infection and clinicopathological variables, including gender and cancer type, were evaluated using the χ2 test, Fisher's exact test or the t-test. P<0.05 was considered to indicate a statistically significant difference. The overall prevalence of B19 DNA in cancer patients was 50.69% (146/288), which was significantly higher than that of the healthy controls with 4.5% (36/800) (χ2 test, P<0.0001). Similar results were obtained for HBoV with a 39.74% (62/156) prevalence in cancer patients. However, the infection prevalence of HBV and TTV in the cancer patients was 5.13 (8/156) and 6.41% (10/156), respectively (P<0.0001), which was much less than that of B19 and HBoV. These results revealed that a high risk of B19 and HBoV infection occurred in cancer patients, and a potential correlation exists between parvovirus infection and occurrence of malignant tumors.

Detection of human bocavirus from children and adults with acute respiratory tract illness in Guangzhou, southern China

BACKGROUND

Human bocavirus (HBoV) is a newly discovered parvovirus associated with acute respiratory tract illness (ARTI) and gastrointestinal illness. Our study is the first to analyze the characteristics of HBoV-positive samples from ARTI patients with a wide age distribution from Guangzhou, southern China.

METHODS

Throat swabs (n=2811) were collected and analyzed from children and adults with ARTI over a 13-month period. The HBoV complete genome from a 60 year-old female patient isolate was also determined.

RESULTS

HBoV DNA was detected in 65/2811 (2.3%) samples, of which 61/1797 were from children (<18 years old) and 4/1014 from adults (≥18 years old). Seasonal peaks of 4.8% and 7.7% were detected in May and June, respectively. 28 of 65 (43.1%) HBoV-positive samples were co-detected with 11/16 other potential pathogens. Mycoplasma pneumoniae had the highest frequency of 16.9% (11/65). Upper and lower respiratory tract illness were common symptoms, with 19/65 (29.2%) patients diagnosed with pneumonia by chest radiography. All four adult patients had systemic influenza-like symptoms. Phylogenetic analysis of the complete genome revealed a close relationship with other HBoVs, and a more distant relationship with HBoV2 and HBoV3.

CONCLUSIONS

HBoV was detected from children and adults with ARTI from Guangzhou, southern China. Elderly people were also susceptive to HBoV. A single lineage of HBoV was detected among a wide age distribution of patients with ARTI.

Association of Human bocavirus with Respiratory Infections in Outpatients and in Patients Attended at a Reference Hospital

The role of Human bocavirus (HBoV) in human infectious disease is unclear due to the frequent detection of this virus in association with other respiratory viruses with a recognized pathogenic role in acute respiratory infection. We have analyzed the impact of HBoV in outpatients and in patients requiring hospitalisation or emergency attention for acute respiratory infections. Respiratory viruses were investigated by real-time PCR, direct antigen detection and/or viral culture by shell-vial assay. Nasopharyngeal aspirates, BAL and/or sputum samples from patients attended at a reference hospital, and nasal/throat swabs from outpatients were used. Respiratory viruses were detected in 660 samples (47%). HBoV detection rate was 12.6%, only preceded by respiratory syncytial virus (25%). Co-detections were observed in 12.9% of samples, and HBoV was present in 81% of them. Similar detection rates of HBoV were obtained in individuals with positive and negative results for other respiratory viruses (12.5% and 12.7%, respectively). The crossing point value was taken as a measure of HBoV viral load. Higher HBoV loads were observed in children, and in patients from the hospital. HBoV viral load was not associated with symptoms of upper respiratory tract infection or lower respiratory tract disease. Although HBoV is frequently detected in respiratory specimens, there is a poor association between HBoV-positive specimens and clinical parameters. A clinical impact of HBoV in respiratory infection probably occurs in few cases.

Human bocavirus-the first 5 years

Four species of human bocavirus (HBoV) have been recently discovered and classified in the Bocavirus genus (family Parvoviridae, subfamily Parvovirinae). Although detected both in respiratory and stool samples worldwide, HBoV1 is predominantly a respiratory pathogen, whereas HBoV2, HBoV3, and HBoV4 have been found mainly in stool. A variety of signs and symptoms have been described in patients with HBoV infection including rhinitis, pharyngitis, cough, dyspnea, wheezing, pneumonia, acute otitis media, fever, nausea, vomiting, and diarrhea. Many of these potential manifestations have not been systematically explored, and they have been questioned because of high HBoV co-infection rates in symptomatic subjects and high HBoV detection rates in asymptomatic subjects. However, evidence is mounting to show that HBoV1 is an important cause of lower respiratory tract illness. The best currently available diagnostic approaches are quantitative PCR and serology. This concise review summarizes the current clinical knowledge on HBoV species.

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. J. Med. Virol. 84:99–108, 2011. © 2011 Wiley Periodicals, Inc.

Seroepidemiology of human bocaviruses 1-4

BACKGROUND

Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBoV3), and human bocavirus 4 (HBoV4), were discovered. HBoV2-4 occur mainly in the gastrointestinal tract but rarely in the respiratory tract, contrary to human bocavirus 1 (HBoV1).

METHODS

To investigate HBoV1-4 seroepidemiology among 195 adults and 252 wheezing children, we conducted immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme immunoassays with recombinant viruslike particles (VLPs). The children's sera were also tested for HBoV1-4 DNA by quantitative polymerase chain reaction (qPCR).

RESULTS

Both rabbit and human antibodies to HBoV1-4 VP2 VLPs were found to be cross-reactive. After depletion of HBoV1-reactive antibodies, the HBoV2-4 approximate seroprevalences in adults were 34%, 15%, and 2% and in children aged 1-2 years 25%, 10%, and 5%, respectively. After depletion of HBoV2-4-reactive antibodies, the HBoV1 seroprevalence among adults decreased from 96% to 59%. No cross-reactivity of human anti-HBoV IgG was observed with bovine parvovirus1, parvovirus B19 or PARV4. No child was HBoV2-4 viremic.

CONCLUSIONS

HBoV2-4 infect humans less commonly and elicit weaker B-cell responses than HBoV1. In our study HBoV2-4 did not seem to have a major etiological role in wheezing. Cross-reactivity with HBoV2-4 IgG partially accounts for the high HBoV1 seroprevalences previously reported. Correction for cross-reactivity is a prerequisite for VLP-based HBoV seroepidemiology.

Human metapneumovirus and human bocavirus associated with respiratory infection in Apulian population

We have studied the occurrence of hBoV, hMPV and InfA-B in an Apulian population with respiratory tract infections. During influenza season 2008-2009, 116 oropharingeal swabs were collected from patients affected by Influenza-Like Illness (ILI). The PCR products of hMPV M and HBoV NP-1 genes were sequenced. 78 out of 116 samples were positive for at least one respiratory virus; hBoV was detected in 53, hMPV in 22 and InfA-B in 41 out of 116 swabs. A high rate of hBoV infection in adult (18.9%) and elderly (26.4%) subjects was found. The co-infection rate was higher for hMPV (18/22 cases, 81.8%) compared to hBoV (26/53 cases, 49.1%), and InfA-B (25/41 cases, 61.0%). Co-infections were common in children. hBoV positive samples shared a high level of genetic similarity with the hBoV1 genotype, and hMPV positive samples clustered with A2 subgroup. Our results suggest that hBoV and hMPV play a role in ILI.

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.

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.

Repeated virus identification in the airways of patients with mild and severe asthma during prospective follow-up

To cite this article: Turchiarelli V, Schinkel J, Molenkamp R, Foschino Barbaro MP, Carpagnano GE, Spanevello A, Lutter R, Bel EH, Sterk PJ. Repeated virus identification in the airways of patients with mild and severe asthma during prospective follow‐up. Allergy 2011; 66: 1099–1106.

Abstract

Background:  Respiratory viruses may persist in the airways of asthmatics between episodes of clinical worsening. We hypothesized that patients with clinically stable, severe asthma exhibit increased and more prolonged viral presence in the airways as compared to mild asthmatics and healthy controls.

Methods:  Thirty‐five subjects (no cold symptoms >4 weeks) entered a 12‐week prospective study using three groups: clinically stable mild asthma (GINA 2) (n = 12, age 34.1 ± 13.4 year), severe asthma (GINA 4) (n = 12, age 49.3 ± 14.8 year) and healthy controls (n = 11, age 37.9 ± 14.2 year). All subjects underwent spirometry and completed a written questionnaire on asthma symptoms at baseline. Nasal and throat swabs, induced sputum samples, exhaled breath condensate and gelatine‐filtered expired air were analysed at 0, 6 and 12 weeks by a multiplex real‐time PCR assay for 14 respiratory viruses using adequate positive and negative controls.

Results:  Thirty‐two of 525 patient assessments (6%) showed a virus‐positive sample. Among the 14 respiratory viruses examined, HRV, adenovirus, respiratory syncytial virus, parainfluenza 3&4, human bocavirus, influenza B and coronavirus were detected. When combining all sampling methods, on average 18% of controls and 30% of mild and severe asthmatics were virus positive, which was not different between the groups (P = 0.34). The longitudinal data showed a changing rather than persistent viral presence over time.

Conclusion:  Patients with clinically stable asthma and healthy controls have similar detection rates of respiratory viruses in samples from nasopharynx, sputum and exhaled air. This indicates that viral presence in the airways of stable (severe) asthmatics varies over time rather than being persistent.

New respiratory viruses and the elderly

The diagnostics of respiratory viral infections has improved markedly during the last 15 years with the development of PCR techniques. Since 1997, several new respiratory viruses and their subgroups have been discovered: influenza A viruses H5N1 and H1N1, human metapneumovirus, coronaviruses SARS, NL63 and HKU1, human bocavirus, human rhinoviruses C and D and potential respiratory pathogens, the KI and WU polyomaviruses and the torque teno virus. The detection of previously known viruses has also improved. Currently, a viral cause of respiratory illness is almost exclusively identifiable in children, but in the elderly, the detection rates of a viral etiology are below 40%, and this holds also true for exacerbations of chronic respiratory illnesses. The new viruses cause respiratory symptoms like the common cold, cough, bronchitis, bronchiolitis, exacerbations of asthma and chronic obstructive pulmonary disease and pneumonia. Acute respiratory failure may occur. These viruses are distributed throughout the globe and affect people of all ages. Data regarding these viruses and the elderly are scarce. This review introduces these new viruses and reviews their clinical significance, especially with regard to the elderly population.

Detection of human bocavirus mRNA in respiratory secretions correlates with high viral load and concurrent diarrhea

Human bocavirus (HBoV) is a parvovirus recently identified in association with acute respiratory infections (ARI). Despite its worldwide occurrence, little is known on the pathogenesis of HBoV infections. In addition, few systematic studies of HBoV in ARI have been conducted in Latin America. Therefore, in order to test whether active viral replication of human bocavirus is associated with respiratory diseases and to understand the clinical impact of this virus in patients with these diseases, we performed a 3-year retrospective hospital-based study of HBoV in outpatients and inpatients with symptoms of Acute Respiratory Infections (ARI) in Brazil. Nasopharyngeal aspirates (NPAs) from 1015 patients with respiratory symptoms were tested for HBoV DNA by PCR. All samples positive for HBoV were tested by PCR for all other respiratory viruses, had HBoV viral loads determined by quantitative real time PCR and, when possible, were tested by RT-PCR for HBoV VP1 mRNA, as evidence of active viral replication. HBoV was detected in 4.8% of patients, with annual rates of 10.0%, 3.0% and 3.0% in 2005, 2006 and 2007, respectively. The range of respiratory symptoms was similar between HBoV-positive and HBoV-negative ARI patients. However, a higher rate of diarrhea was observed in HBoV-positive patients. High HBoV viral loads (>10⁸ copies/mL) and diarrhea were significantly more frequent in patients with exclusive infection by HBoV and in patients with detection of HBoV VP1 mRNA than in patients with viral co-infection, detected in 72.9% of patients with HBoV. In summary, our data demonstrated that active HBoV replication was detected in a small percentage of patients with ARI and was correlated with concurrent diarrhea and lack of other viral co-infections.