Epidemiological profile and clinical associations of human bocavirus and other human parvoviruses

Demographic and clinical characteristics of human bocavirus-1 infection in patients with acute respiratory tract infections during the COVID-19 pandemic in the Central Province of Sri Lanka

BACKGROUND

Human bocavirus-1 (hBoV-1) was first detected in respiratory specimens in 2005. Due to high co-infection rates and prolonged shedding of the virus, the pathogenic role of hBoV-1 as a primary causative agent of respiratory infections is still under discussion. This study aimed to determine the prevalence of hBoV-1 infection in patients with acute respiratory tract infections (ARTIs) during the COVID-19 pandemic in the Central Province of Sri Lanka.

METHODS

A total of 1021 patients (Age 12 days to ≤ 85 years) with ARTI symptoms including fever, cough, cold, sore throat and shortness of breath within first 7 days of the illness were included. The study was carried out at the National Hospital, Kandy, Sri Lanka from January 2021 to October 2022. Respiratory specimens were tested to detect 23 pathogens including hBoV-1 using a real time PCR. Prevalence of hBoV-1 co-infections with other respiratory pathogens and distribution of hBoV-1 infection among different age groups were determined. Moreover, clinical and demographic characteristics of hBoV-1 mono-infection associated ARTI were compared with that of the hBoV-1 co-infections.

RESULTS

Respiratory infections were detected in 51.5% (526/1021) of the patients and of these 82.5% were mono- and 17.1% were co-infections. hBoV-1 was detected in 66 patients and this was the most prevalent respiratory virus associated with 40% co-infections. Of the 66 hBoV-1 positive patients, 36 had co-infections and of these 33 had dual and 3 had triple infections. Most of the hBoV-1 co-infections were identified in children aged 2-<5 years. hBoV-1 co-infections were most frequently detected with respiratory syncytial virus (RSV) and Rhino/ Entero viruses (Rh/EnV). No differences were observed in age, gender and clinical presentations in those with hBoV-1 mono- compared to co-infections. Intensive care admissions were less among hBoV-1 mono-infected than hBoV-1 co-infected patients.

CONCLUSION

This study shows a prevalence of 12.5% for hBoV-1 infections in patients with ARTI. RSV and Rh/EnV were the most common co-infecting pathogens with hBoV-1. Clinical features of hBoV-1 mono-infections were not different to that of the hBoV-1 co-infections. Interactions between hBoV-1 and other respiratory pathogens need investigation to identify the role of hBoV-1 in clinical severity of co-infections.

HBoV-1: virus structure, genomic features, life cycle, pathogenesis, epidemiology, diagnosis and clinical manifestations

The single-stranded DNA virus known as human bocavirus 1 (HBoV-1) is an icosahedral, linear member of the Parvoviridae family. In 2005, it was discovered in nasopharyngeal samples taken from kids who had respiratory tract illnesses. The HBoV genome is 4.7-5.7 kb in total length. The HBoV genome comprises three open-reading frames (ORF1, ORF2, and ORF3) that express structural proteins (VP1, VP2, and VP3), viral non-coding RNA, and non-structural proteins (NS1, NS1-70, NS2, NS3, and NP1) (BocaSR). The NS1 and NP1 are crucial for viral DNA replication and are substantially conserved proteins. Replication of the HBoV-1 genome in non-dividing, polarized airway epithelial cells. In vitro, HBoV-1 infects human airway epithelial cells that are strongly differentiated or polarized. Young children who have HBoV-1 are at risk for developing a wide range of respiratory illnesses, such as the common cold, acute otitis media, pneumonia, and bronchiolitis. The most common clinical symptoms are wheezing, coughing, dyspnea, and rhinorrhea. After infection, HBoV-1 DNA can continue to be present in airway secretions for months. The prevalence of coinfections is considerable, and the clinical symptoms can be more severe than those linked to mono-infections. HBoV-1 is frequently detected in combination with other pathogens in various reports. The fecal-oral and respiratory pathways are more likely to be used for HBoV-1 transmission. HBoV-1 is endemic; it tends to peak in the winter and spring. This Review summarizes the knowledge on HBoV-1.

Identification of the Viral Pathogens in School Children With Acute Otitis Media in Central Java, Indonesia

Acute otitis media (AOM) is one of the most common infectious diseases in pediatric clinical facilities and has a significant impact on health care. It is a polymicrobial disease and is usually preceded by a viral upper respiratory tract infection. Data on the spectrum of viruses that cause AOM in Indonesia are still limited. This study analyzed nasopharynx (NP) samples collected from 119 school children with AOM in Banyumas Regency, Central Java, Indonesia. Viral RNA was extracted for cDNA synthesis, followed by PCR and sequencing tools for detection of a panel of respiratory viruses using family-level primers for Coronaviridae, Enterovirus, Bocavirus, and Pneumovirinae for bocavirus. In total, 37 out of 119 NP samples (31.1%) tested positive for viruses. Human rhinovirus B was the predominant virus identified (32.4%) followed by rhinovirus C (29.7%), human rhinovirus A (27%), and human bocavirus (5.4%). Rhinovirus are predominant viral pathogens within school children with AOM in Central Java, Indonesia.

Association among sentinel surveillance, meteorological factors, and infectious disease in Gwangju, Korea

The outbreak of new infectious diseases is threatening human survival. Transmission of such diseases is determined by several factors, with climate being a very important factor. This study was conducted to assess the correlation between the occurrence of infectious diseases and climatic factors using data from the Sentinel Surveillance System and meteorological data from Gwangju, Jeollanam-do, Republic of Korea. The climate of Gwangju from June to September is humid, with this city having the highest average temperature, whereas that from December to February is cold and dry. Infection rates of Salmonella (temperature: r = 0.710**; relative humidity: r = 0.669**), E. coli (r = 0.617**; r = 0.626**), rotavirus (r =  - 0.408**; r =  - 0.618**), norovirus (r =  - 0.463**; r =  - 0.316**), influenza virus (r =  - 0.726**; r =  - 0.672**), coronavirus (r =  - 0.684**; r =  - 0.408**), and coxsackievirus (r = 0.654**; r = 0.548**) have been shown to have a high correlation with seasonal changes, specifically in these meteorological factors. Pathogens showing distinct seasonality in the occurrence of infection were observed, and there was a high correlation with the climate characteristics of Gwangju. In particular, viral diseases show strong seasonality, and further research on this matter is needed. Due to the current COVID-19 pandemic, quarantine and prevention have become important to block the spread of infectious diseases. For this purpose, studies that predict infectivity through various types of data related to infection are important.

Human Bocavirus 1 Infection of Well-Differentiated Human Airway Epithelium

Human bocavirus 1 (HBoV1) is a small DNA virus that belongs to the Bocaparvovirus genus of the Parvoviridae family. HBoV1 is a common respiratory pathogen that causes mild to life-threatening acute respiratory tract infections in children and immunocompromised individuals, infecting both the upper and lower respiratory tracts. HBoV1 infection causes death of airway epithelial cells, resulting in airway injury and inflammation. In vitro, HBoV1 only infects well-differentiated (polarized) human airway epithelium cultured at an air-liquid interface (HAE-ALI), but not any dividing human cells. A full-length HBoV1 genome of 5543 nucleotides has been cloned from DNA extracted from a human nasopharyngeal swab into a plasmid called HBoV1 infectious clone pIHBoV1. Transfection of pIHBoV1 replicates efficiently in human embryonic kidney 293 (HEK293) cells and produces virions that are highly infectious. This article describes protocols for production of HBoV1 in HEK293 cells, generation of HAE-ALI cultures, and infection with HBoV1 in HAE-ALI. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Human bocavirus 1 production in HEK293 cells Support Protocol 1: HEK293 cell culture and transfection Support Protocol 2: Quantification of human bocavirus 1 using real-time quantitative PCR Basic Protocol 2: Differentiation of human airway cells at an air-liquid interface Support Protocol 3: Expansion of human airway epithelial cell line CuFi-8 Support Protocol 4: Expansion of human airway basal cells Support Protocol 5: Coating of plastic dishes and permeable membranes of inserts Support Protocol 6: Transepithelial electrical resistance measurement Basic Protocol 3: Human bocavirus 1 infection in human airway epithelium cultured at an air-liquid interface Support Protocol 7: Isolation of infected human airway epithelium cells from inserts Basic Protocol 4: Transduction of airway basal cells with lentiviral vector.

Human parvovirus 4: An emerging etiological agent in cases presenting with influenza like illness

This study was planned to study the association of parvovirus 4 (PARV4) with Influenza-like illness (ILI). A total of 1111 patients with a clinical diagnosis of ILI and 220 healthy controls were tested for Influenza A/HINI/and H3N2, Influenza B, and PARV4. Further sequencing was done to analyze the genotype distribution of parvovirus 4. Influenza A/HINI, A/H3N2, and B were detected in 334 (30.06%), 9 (0.81%), and 10 (0.9%) cases respectively. PARV4 was detected in 135 (12.15%) cases and one healthy control. Parvovirus 4 was significantly higher in cases as compared to controls (relative risk, 30.77%; p < .0006). Sequencing of 20 isolates suggests the dominance of genotype 2 in our region.

Development and evaluation of a panel of multiplex one-tube nested real time PCR assay for simultaneous detection of 14 respiratory viruses in five reactions

Multiplex real-time quantitative polymerase chain reaction (mRT-qPCR) assay is commonly used to detect respiratory viruses, however, the sensitivity is limited for most reports. A panel of locked nucleic acid based multiplex closed one-tube nested real-time PCR (mOTNRT-PCR) assay consisting of five separate internally controlled RT-qPCR assays was developed for detection of 14 respiratory viruses. The sensitivity and reproducibility of mOTNRT-PCR panel were evaluated using plasmid standards and the specificity was evaluated using clinical samples. The clinical performance of mOTNRT-PCR panel was further evaluated with 468 samples collected from patients with an acute respiratory infection and compared with individual real-time PCR (RT-qPCR) assay. The analytical sensitivities of mOTNRT-PCR panel ranged from 2 to 20 copies/reaction, and no cross-reaction with common respiratory viruses was observed. The coefficients of variation of intra-assay and inter-assay were between 0.35% and 8.29%. Totally 35 clinical samples detected by mOTNRT-PCR assay panel were missed by RT-qPCR and confirmed true positive by sequencing of nested PCR products. The mOTNRT-PCR assay panel provides a more sensitive and high-throughput method for the detection of 14 respiratory viruses.

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.

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.

Human Parvovirus 4: A harmless bystander or a pathogen of severe acute respiratory illness

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Severe Acute Respiratory Infection (SARI) is an important cause of morbidity and mortality worldwide.

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We investigated the association of PARV4 virus with SARI.

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PARV4 was detected in 26.55% of cases and only in one healthy control (0.68%).

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Detection of PARV4 is seen in a significantly large number of SARI cases.

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PARV4 genotype 2 was the only genotype detected from cases as well as controls.

Introduction

Severe Acute Respiratory Infection (SARI) is an important cause of morbidity and mortality worldwide, caused by a large number of viral and bacterial agents. PARV4 is a recently identified virus detected in human blood and variety of tissues, but its disease association with SARI could not be established.

Objective

In the present case control study, we aim to investigate the association of PARV4 with SARI.

Methods

The Nasal and Throat swab (NS/TS) samples of 241 cases and 146 healthy controls were tested for most common respiratory viruses and PARV4 by real-time PCR.

Results

PARV4 was detected in 64(26.55%) SARI cases and only one healthy control (0.68%). PARV4 was the most common viral agent detected in SARI cases. A strong association of PARV4 is seen with severe respiratory illness.

Conclusion

Detection of PARV4 in a significantly higher number of SARI cases, in comparison with controls, suggests association of PARV4 with SARI. PARV4 genotype 2 is the only circulating strain detected in our study.

Comparison of viral and epidemiological profiles of hospitalized children with severe acute respiratory infection in Beijing and Shanghai, China

Background

No comparison data have been reported on viral and epidemiological profiles of hospitalized children with severe acute respiratory infection (SARI) in Beijing or Shanghai, China.

Methods

We collected 700 nasopharyngeal aspirates (NPA) from hospitalized children with SARI in Beijing (northern China) and Shanghai (southern China). Multiple respiratory viruses (including 15 common viruses) were screened by validated polymerase chain reaction (PCR) or real-time reverse transcription-PCR assays and confirmed by sequencing. Demographic data and the distribution of viral infections were also examined.

Results

Of 700 samples, 547 (78.1%) tested positive for viral infections. The picornaviruses (PIC), which included rhinovirus (RV) and enterovirus (EV), were the most common (34.0%), followed by respiratory syncytial virus (RSV) (28.3%), human bocavirus (HBoV) (19.1%), adenovirus (ADV) (13.7%), human coronaviruses (HCoV) (10.7%), influenza A and B (8.9%), parainfluenza virus (PIV 1–3) (7.9%), and human metapneumovirus (HMPV) (5.0%). PIC (RV/EV) and RSV were the most prevalent etiological agents of SARI in both cities. The total and age-matched prevalence of RSV, HCoV, and hMPV among SARI children under 5 years old were significantly higher in Beijing than in Shanghai. Different age and seasonal distribution patterns of the viral infections were found between Beijing and Shanghai.

Conclusions

Viral infection was tested and shown to be the most prevalent etiological agent among children with SARI in either the Beijing or the Shanghai area, while showing different patterns of viral and epidemiological profiles. Our findings provide a better understanding of the roles of geographic location and climate in respiratory viral infections in hospitalized children with SARI.

Rare and Emerging Viral Infections in the Transplant Population

Viral infections account for a large proportion of emerging infectious diseases, and the agents included in this group consist of recently identified viruses as well as previously identified viruses with an apparent increase in disease incidence. In transplant recipients, this group can include viruses with no recognized pathogenicity in immunocompetent patients and those that result in atypical or more severe disease presentations in the immunocompromised host. In this chapter, we begin by discussing viral diagnostics and techniques used for viral discovery, specifically as they apply to emerging and rare infections in this patient population. Focus then shifts to specific emerging and re-emerging viruses in the transplant population, including human T-cell leukemia virus 1, rabies, lymphocytic choriomeningitis virus, human bocavirus, parvovirus 4, measles, mumps, orf, and dengue. We have also included a brief discussion on emerging viruses and virus families with few or no reported cases in transplant recipients: monkeypox, nipah and hendra, chikungunya and other alphaviruses, hantavirus and the Bunyaviridae, and filoviruses. Finally, concerns regarding infectious disease complications in xenotransplantation and the reporting of rare viral infections are addressed. With the marked increase in the number of solid organ and hematopoietic stem cell transplants performed worldwide, we expect a corresponding rise in the reports of emerging viral infections in transplant hosts, both from known viruses and those yet to be identified.

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.

Impact of RSV Coinfection on Human Bocavirus in Children with Acute Respiratory Infections

OBJECTIVE

The objective of this study was to assess epidemiological and clinical features of human bocavirus (HBoV) coinfection with other viruses.

METHOD

Children coinfected with HBoV between January 2012 and December 2014 were enrolled and retrospectively reviewed.

RESULT

A total of 984 patients were stratified into five groups: HBoV infection alone (n = 249), respiratory syncytial virus (RSV) infection alone (n = 649), HBoV coinfection with RSV (n = 28), with human rhinovirus (HRV) (n = 39) and with other virus (n = 19). Length of hospitalization was longer in HBoV coinfection with RSV group than HBoV (9.0 days vs. 7.0 days, p = 0.001), RSV (9.0 days vs. 8.0 days, p = 0.016) infection alone group. Pneumonia was more common in the HBoV coinfection with RSV group compared with the HBoV, RSV infection alone group, respectively (75.0% vs. 44.2%, 31.3%, p < 0.001). HBoV DNA copy numbers (383 000 copies/ml) were positively correlated with the length of hospitalization (r = 0.334, p < 0.001).

CONCLUSION

HBoV coinfection with RSV increases HBoV infection severity.

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.

Structural Insights into Human Bocaparvoviruses

Bocaparvoviruses are emerging pathogens of the Parvoviridae family. Human bocavirus 1 (HBoV1) causes severe respiratory infections and HBoV2 to HBoV4 cause gastrointestinal infections in young children. Recent reports of life-threatening cases, lack of direct treatment or vaccination, and a limited understanding of their disease mechanisms highlight the need to study these pathogens on a molecular and structural level for the development of therapeutics. Toward this end, the capsid structures of HBoV1, HBoV3, and HBoV4 were determined to a resolution of 2.8 to 3.0 Å by cryo-electron microscopy and three-dimensional image reconstruction. The bocaparvovirus capsids, which display different tissue tropisms, have features in common with other parvoviruses, such as depressions at the icosahedral 2-fold symmetry axis and surrounding the 5-fold symmetry axis, protrusions surrounding the 3-fold symmetry axis, and a channel at the 5-fold symmetry axis. However, unlike other parvoviruses, densities extending the 5-fold channel into the capsid interior are conserved among the bocaparvoviruses and are suggestive of a genus-specific function. Additionally, their major viral protein 3 contains loops with variable regions at their apexes conferring capsid surface topologies different from those of other parvoviruses. Structural comparisons at the strain (HBoV) and genus (bovine parvovirus and HBoV) levels identified differences in surface loops that are functionally important in host/tissue tropism, pathogenicity, and antigenicity in other parvoviruses and likely play similar roles in these viruses. This study thus provides a structural framework to characterize determinants of host/tissue tropism, pathogenicity, and antigenicity for the development of antiviral strategies to control human bocavirus infections.IMPORTANCE Human bocaviruses are one of only a few members of the Parvoviridae family pathogenic to humans, especially young children and immunocompromised adults. There are currently no treatments or vaccines for these viruses or the related enteric bocaviruses. This study obtained the first high-resolution structures of three human bocaparvoviruses determined by cryo-reconstruction. HBoV1 infects the respiratory tract, and HBoV3 and HBoV4 infect the gastrointestinal tract, tissues that are likely targeted by the capsid. Comparison of these viruses provides information on conserved bocaparvovirus-specific features and variable regions resulting in unique surface topologies that can serve as guides to characterize HBoV determinants of tissue tropism and antigenicity in future experiments. Based on the comparison to other existing parvovirus capsid structures, this study suggests capsid regions that likely control successful infection, including determinants of receptor attachment, host cell trafficking, and antigenic reactivity. Overall, these observations could impact efforts to design antiviral strategies and vaccines for HBoVs.

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: 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.

Mapping Antigenic Epitopes on the Human Bocavirus Capsid

Human bocaviruses (HBoV1 to -4) are emerging pathogens associated with pneumonia and/or diarrhea in young children. Currently, there is no treatment or vaccination, so there is a need to study these pathogens to understand their disease mechanisms on a molecular and structural level for the development of control strategies. Here, we report the structures of six HBoV monoclonal antibody (MAb) fragment complexes, HBoV1-15C6, HBoV2-15C6, HBoV4-15C6, HBoV1-4C2, HBoV1-9G12, and HBoV1-12C1, determined by cryo-electron microscopy and three-dimensional image reconstruction to 18.0- to 8.5-Å resolution. Of these, the 15C6 MAb cross-reacted with HBoV1, HBoV2, and HBoV4, while the 4C2, 12C1, and 9G12 MAbs recognized only HBoV1. Pseudoatomic modeling mapped the 15C6 footprint to the capsid surface DE and HI loops, at the 5-fold axis and the depression surrounding it, respectively, which are conserved motifs in Parvoviridae The footprints for 4C2, 12C1, and 9G12 span the surface loops that assemble portions of the 2-/5-fold wall (a raised surface feature between the 2-fold and 5-fold axes of symmetry) and the shoulder of the 3-fold protrusions. The MAb footprints, cross reactive and strain specific, coincide with regions with high and low sequence/structural identities, respectively, on the capsid surfaces of the HBoVs and identify potential regions for the development of peptide vaccines for these viruses.

IMPORTANCE

Human bocaviruses (HBoVs) may cause severe respiratory and gastrointestinal infections in young children. The nonenveloped parvovirus capsid carries determinants of host and tissue tropism, pathogenicity, genome packaging, assembly, and antigenicity important for virus infection. This information is currently unavailable for the HBoVs and other bocaparvoviruses. This study identifies three strain-specific antigenic epitopes on the HBoV1 capsid and a cross-reactive epitope on the HBoV1, HBoV2, and HBoV4 capsids using structures of capsid-antibody complexes determined using cryo-electron microscopy and image reconstruction. This is the first study to report the highly conserved parvovirus DE loop at the 5-fold axis as a determinant of antigenicity. Additionally, knowledge of the strain-specific and conserved antigenic epitopes of the bocaviruses can be instrumental in characterization of the virus life cycle, development of peptide vaccines, and generation of gene delivery vectors for cystic fibrosis given the strict tropism of HBoV1 for human airway epithelial cells.

Update of the human parvovirus B19 biology

Since its discovery, the human parvovirus B19 (B19V) has been associated with many clinical situations in addition to the prototype clinical manifestations, i.e. erythema infectiosum and erythroblastopenia crisis. The clinical significance of the viral B19V DNA persistence in sera after acute infection remains largely unknown. Such data may constitute a new clinical entity and is discussed in this manuscript. In 2002, despite the genetic diversity among B19V viruses has been reported to be very low, the description of markedly distinct sequences showed a new organization into three genotypes. The most recent common ancestor for B19V genotypes was estimated at early 1800s. B19V replication is enhanced by hypoxia and this might to explain the high viral load detected by quantitative PCR in the sera of infected patients. The minimum infectious dose necessary to transmit B19V infection by the transfusion of labile blood products remains unclear. At the opposite, the US Food and Drug Administration proposed a limit of 10(4)IU/mL of viral DNA in plasma pools used for the production of plasma derivatives. Recently, a new human parvovirus (PARV4) has been discovered. The consequences on blood transfusion of this blood-borne agent and its pathogenicity are still unknown.

[Detection and analysis of bocavirus in hospitalized children with respiratory infection]

OBJECTIVE

To detect human bocavirus (HBoV) and investigate its genetic and evolutionary characteristics in children with acute respiratory infection in Tianjin, China.

METHODS

A total of 1,259 samples of nasopharyngeal aspirates were collected from children with a confirmed diagnosis of acute respiratory infection between January and December, 2012. Viral nucleic acid was extracted, HBoV was detected by real-time quantitative PCR, and the gene segments of nucleocapsid protein of HBoV in positive samples were amplified by PCR. Several products were randomly selected and sequenced.The sequence obtained was compared with the known sequence of HBoV, and a phylogenetic analysis was performed. All the samples were examined to detect for other common respiratory tract viruses.

RESULTS

Among the 1,259 samples, the positive rate of HBoV was 4.53% (57/1,259), and among the 57 samples with positive HBoV, 75% (43/57) were positive in children with an age of 6-36 months. The positive rate of HBoV in children peaked in summer (from June to August), and there was a mixed infection with other viruses. Sequence analysis was performed for the PCR products from 36 positive samples, and the presence of HBoV was confirmed, with a higher homology to the known sequence of HBoV.

CONCLUSIONS

In Tianjin, acute respiratory infection in some children may be associated with HBoV infection, which is commonly seen in infants with an age of 6-36 months. The peak of HBoV infection occurs in summer. The phylogenetic analysis shows a high homology to the known sequence of HBoV, with few gene sequence variations.

[Detection and analysis of bocavirus in hospitalized children with respiratory infection]

OBJECTIVE

To detect human bocavirus (HBoV) and investigate its genetic and evolutionary characteristics in children with acute respiratory infection in Tianjin, China.

METHODS

A total of 1,259 samples of nasopharyngeal aspirates were collected from children with a confirmed diagnosis of acute respiratory infection between January and December, 2012. Viral nucleic acid was extracted, HBoV was detected by real-time quantitative PCR, and the gene segments of nucleocapsid protein of HBoV in positive samples were amplified by PCR. Several products were randomly selected and sequenced.The sequence obtained was compared with the known sequence of HBoV, and a phylogenetic analysis was performed. All the samples were examined to detect for other common respiratory tract viruses.

RESULTS

Among the 1,259 samples, the positive rate of HBoV was 4.53% (57/1,259), and among the 57 samples with positive HBoV, 75% (43/57) were positive in children with an age of 6-36 months. The positive rate of HBoV in children peaked in summer (from June to August), and there was a mixed infection with other viruses. Sequence analysis was performed for the PCR products from 36 positive samples, and the presence of HBoV was confirmed, with a higher homology to the known sequence of HBoV.

CONCLUSIONS

In Tianjin, acute respiratory infection in some children may be associated with HBoV infection, which is commonly seen in infants with an age of 6-36 months. The peak of HBoV infection occurs in summer. The phylogenetic analysis shows a high homology to the known sequence of HBoV, with few gene sequence variations.

Emerging and Rare Viral Infections in Transplantation

Immunocompromised patients such as those undergoing solid organ or hematopoietic stem cell transplantation are at substantial risk for infection with numerous pathogens. Infections with cytomegalovirus (CMV), herpes simplex virus (HSV), Epstein–Barr virus (EBV), and human herpesvirus-6 (HHV-6) are well-described complications of transplantation. As viruses previously believed to be quiescent through widespread vaccination (e.g., measles and mumps) reemerge and molecular diagnostic techniques are refined, rare and emerging viral infections are increasingly diagnosed in transplant recipients. This chapter will review the clinical manifestations, diagnosis, and potential antiviral therapies for these viruses in the transplant population.

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.

Viral Co-Infections in Pediatric Patients Hospitalized with Lower Tract Acute Respiratory Infections

BACKGROUND

Molecular techniques can often reveal a broader range of pathogens in respiratory infections. We aim to investigate the prevalence and age pattern of viral co-infection in children hospitalized with lower tract acute respiratory infection (LT-ARI), using molecular techniques.

METHODS

A nested polymerase chain reaction approach was used to detect Influenza (A, B), metapneumovirus, respiratory syncytial virus (RSV), parainfluenza (1-4), rhinovirus, adenovirus (A-F), bocavirus and coronaviruses (NL63, 229E, OC43) in respiratory samples of children with acute respiratory infection prospectively admitted to any of the GENDRES network hospitals between 2011-2013. The results were corroborated in an independent cohort collected in the UK.

RESULTS

A total of 204 and 97 nasopharyngeal samples were collected in the GENDRES and UK cohorts, respectively. In both cohorts, RSV was the most frequent pathogen (52.9% and 36.1% of the cohorts, respectively). Co-infection with multiple viruses was found in 92 samples (45.1%) and 29 samples (29.9%), respectively; this was most frequent in the 12-24 months age group. The most frequently observed co-infection patterns were RSV-Rhinovirus (23 patients, 11.3%, GENDRES cohort) and RSV-bocavirus / bocavirus-influenza (5 patients, 5.2%, UK cohort).

CONCLUSION

The presence of more than one virus in pediatric patients admitted to hospital with LT-ARI is very frequent and seems to peak at 12-24 months of age. The clinical significance of these findings is unclear but should warrant further analysis.

Seroepidemiology of human bocaviruses 1 and 2 in China

Seroepidemiology studies had been used to research the newly discovered human bocaviruses (HBoVs). Antibodies against the HBoV1–4 VP2 protein virus-like particles (VLPs) were found to be cross-reactive. The aim of the present study was to characterize the seroprevalence of HBoV1 and 2 among healthy populations in China. Recombinant HBoV1 and 2 VLPs were used to establish enzyme-linked immunosorbent assays (ELISAs) for detection of cross-reactivity between HBoV1 and HBoV2 in 1391 serum samples collected from healthy individuals in China. Of these, 884 samples were collected from Beijing and 507 were from Nanjing. Infection with HBoV1 and 2 was prevalent in healthy Chinese people, with the seroprevalence of HBoV1 and 2 in Beijing at 69.2 (612/884) and 64.4% (569/884), respectively. Highest seroprevalence was observed in 3–5-year-olds. The seroprevalence of HBoV1 was significantly decreased between 10–13-year-olds (80.3%) and 14–20-year-olds (62.3%, p< 0.05). For individuals over 20 years, seroprevalence was relatively constant at about 60%. Similar trends were observed in children from Nanjing, with seroprevalence of HBoV1 and 2 for healthy children at 80.7% (409/507) and 81.3% (412/507), respectively. Moreover, both mouse and human antibodies against HBoV1 and HBoV2 VLPs were found to be cross-reactive and 58.4% (813/1391) serum samples were seropositive for both HBoV1 and HBoV2. This finding suggests HBoV is highly prevalent in China and the antibodies produced as a result of infection with either HBoV1 or HBoV 2 will offer future protection. The cross-reactivity between HBoVs is crucial for accurately determining HBoV seroepidemiology.

Identification of new respiratory viruses in the new millennium

The rapid advancement of molecular tools in the past 15 years has allowed for the retrospective discovery of several new respiratory viruses as well as the characterization of novel emergent strains. The inability to characterize the etiological origins of respiratory conditions, particularly in children, led several researchers to pursue the discovery of the underlying etiology of disease. In 2001, this led to the discovery of human metapneumovirus (hMPV) and soon following that the outbreak of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) promoted an increased interest in coronavirology and the latter discovery of human coronavirus (HCoV) NL63 and HCoV-HKU1. Human bocavirus, with its four separate lineages, discovered in 2005, has been linked to acute respiratory tract infections and gastrointestinal complications. Middle East Respiratory Syndrome coronavirus (MERS-CoV) represents the most recent outbreak of a completely novel respiratory virus, which occurred in Saudi Arabia in 2012 and presents a significant threat to human health. This review will detail the most current clinical and epidemiological findings to all respiratory viruses discovered since 2001.

Poor outcome of acute respiratory infection in young children with underlying health condition in Brazil

Objectives

It is well established that respiratory viruses are an important cause of hospitalizations in young children worldwide, but data are limited on the contribution of specific viruses to severe illness in South America. We describe clinical and laboratory findings from prospective surveillance for acute respiratory infections at a tertiary hospital in São Paulo, Brazil.

Methods

We screened children < 2 years old with acute respiratory tract infections admitted to an urban tertiary hospital for respiratory viruses from March 2008 through February 2010, using polymerase chain reaction assays.

Results

Respiratory viruses were identified in 378 (53%) of the 715 samples analyzed. Respiratory syncytial virus was the most commonly identified virus (52%), followed by adenovirus (27%) and Human metapneumovirus (12%). More than one virus was identified in 19% of specimens. Almost half of the samples (46%) were from children with underlying health conditions. We demonstrated that compared to the previously healthy group, those with comorbidities had a worse outcome in terms of severity, with prolonged hospital stay and more need of intensive care.

Conclusion

Identification of this high-risk population along with strategies for fast diagnosis might each help to reduce morbidity and mortality in this group.

'Human bocavirus in Pakistani children with gastroenteritis'

Human Bocaviruses (HBoV) have been detected in human respiratory and gastrointestinal infections worldwide. Four genotypes of HBoV (HBoV1-4) have been described; HBoV-1 is associated with respiratory tract infections while HBoV-2, -3, and -4 genotypes are considered as entero-pathogenic although the exact role largely remains unclear. The global prevalence of HBoV has been reported, but the epidemiological data from Pakistan is largely unavailable to date. This study was conducted to understand the genetic diversity and disease prevalence of HBoV in hospitalized Pakistani children with acute diarrhea. During 2009, a total of 365 stool samples were collected from children hospitalized with gastrointestinal symptoms (as per WHO case definitions) at Rawalpindi General Hospital, Pakistan. Demographic and clinical data were recorded using a standardized questionnaire. The samples were tested for HBoV and rotavirus using real-time RT-PCR and ELISA, respectively. There were 47 (13%) samples positive for HBoV with 98% (n = 46) showing co-infection with rotavirus. HBoV-1 was the most frequently detected and was found in 94% samples followed by HBoV-2 and HBoV-3 genotypes. The mean age of infected children was 7.57 ± 5.4 months while detection was more frequent in males (n = 32, 68%). All cases recovered after 2.43 ± 1.0 mean days of treatment. On phylogenetic analysis, HBoV strains from Pakistan clustered closely with viruses from neighboring Bangladesh and China. These findings represent the first known epidemiological study in Pakistan to investigate the role of HBoV in acute gastroenteritis. The clinical data demonstrates that HBoV is not significantly associated with gastroenteritis alone and predominantly co-infections with rotavirus are found.

The Prevalence of Human Bocavirus, Human Coronavirus-NL63, Human Metapneumovirus, Human Polyomavirus KI and WU in Respiratory Tract Infections in Kuwait

OBJECTIVE

The aim of this study was to investigate the prevalence of human coronavirus (HCoV)-NL63, human metapneumovirus (hMPV), human bocavirus (Boca), human polyomavirus KI (KIV) and human polyomavirus WU (WUV) in respiratory tract infections (RTI) in Kuwait.

MATERIALS AND METHODS

Respiratory samples from 735 hospitalized patients with RTI from September 2010 to April 2013 were evaluated for the presence of HCoV-NL63, hMPV, Boca, KIV and WUV using molecular assays, polymerase chain reaction (PCR) and reverse-transcription PCR.

RESULTS

Of the 735 patients, 285 (38.8%) were diagnosed with viral RTI. The distribution of respiratory viruses was hMPV: 15 (5.3%), Boca: 14 (4.9%), WUV: 10 (3.5%) and KIV: 4 (1.4%). HCoV-NL63 was not detected in any of the samples.

CONCLUSIONS

These newly discovered viruses were associated with the development of RTI in Kuwait. The rapid identification of these viral infections could aid in the control of nosocomial transmission, reduce the use of antibiotics and improve treatment and management strategies.

Acute nonbacterial gastroenteritis in hospitalized children: a cross sectional study

Background:

Viral acute gastroenteritis (AGE) is a major cause of morbidity in childhood and leads to hospitalization in developed countries, such as Iran.

Objectives:

The aim of this study was to determine the prevalence and viral types (rotavirus, adenovirus, human parechoviruses-1, and human bocavirus) of acute nonbacterial gastroenteritis in hospitalized children.

Patients and Materials:

This was a across-sectional prospective study performed at the Pediatric Department of Rasoul Hospital, Tehran, Iran (2009-2011) on 80 hospitalized children with viral AGE. All Stool samples were collected on viral transport media. Human bocavirus (HBoV) was detected using the Real-time PCR TaqMan method. Molecular detection of human parechovirus type 1 (HPeV-1) RNA in stool samples was done using a specific nested reverse transcription PCR (RT-PCR). Rota and adeno virus antigens were sought by rapid chromatographic tests. P values less than 0.05 were considered statistically significant.

Results:

Fever was determined in 47.5% of cases (38), nausea and vomiting in 42.5% (34), respiratory symptoms in 16.3% (13), abdominal pain in 76%. Duration of diarrhea was 1-30 days (mean = 6.3 + 4.3 days). No dehydration was observed in 43.5% of subjects, mild dehydration in 33.8%, moderate dehydration in 17.5% and severe dehydration in 5% of cases. Positive rotavirus was found in 48.8% of cases (39), adenovirus in 20% (16), HBoV in 8% (6) and HPeV-1 in 23.2% (19), and adeno and rotaviruses co-infection in 6% (4). The frequency of positive HBoV was significantly lower than adeno and rotaviruses infection (P value = 0.0001). Rotavirus was more frequent in males (P value = 0.003) and in young children (17.49 months vs. 21.44 months) [P value = 0.03, CI = -13.4, 5.5]. Rotavirus infection was related to the degree of dehydration (P value = 0.001) but was not related to the presence of vomiting or fever (P value > 0.5).

Conclusions:

This study indicates that viral agents, especially rotavirus (48.8%), HPeV-1 (23.2%) and adenovirus (20%) are the most important causes for viral AGE in children while HBoV (8%) is infrequent during childhood. Determination of various viral pathogens of AGE is very important in planning diarrhea disease control strategies in our country where rotavirus vaccination in not routinely used.

Comorbidity and high viral load linked to clinical presentation of respiratory human bocavirus infection

Human bocavirus (HBoV) is a new parvovirus associated with acute respiratory tract infection (ARTI). In order to evaluate HBoV significance as an agent of acute respiratory disease, we screened 1,135 respiratory samples from children and adults with and without symptoms during two complete calendar years. HBoV1 prevalence in patients with ARTI was 6.33 % in 2011 and 11.64 % in 2012, including neonatal and adult patients. HBoV1 was also detected in 3.77 % of asymptomatic individuals. The co-detection rate was 78.1 %. Among children, 87 % were clinically diagnosed with lower respiratory infection (no significant differences between patients with and without coinfection), and 31 % exhibited comorbidities. Pediatric patients with comorbidities were significantly older than patients without comorbidities. Patients with ARTI had either high or low viral load, while controls had only low viral load, but there were no clinical differences between patients with high or low viral load. In conclusion, we present evidence of the pathogenic potential of HBoV1 in young children with ARTI. Since patients with HBoV1-single infection are not significantly different from those with coinfection with respect to clinical features, the virus can be as pathogenic by itself as other respiratory agents are. Furthermore, an association between high HBoV1 load and disease could not be demonstrated in this study, but all asymptomatic individuals had low viral loads. Also, children with comorbidities are susceptible to HBoV1 infection at older ages than previously healthy children. Thus, the clinical presentation of infection may occur depending on both viral load and the particular interaction between the HBoV1 and the host.

Clinical and epidemiological profiles of lower respiratory tract infection in hospitalized children due to human bocavirus in a subtropical area of China

Lower respiratory tract infection is a major cause of morbidity and mortality in children. Human bocavirus (HBoV) is confirmed to have an association with pediatric lower respiratory tract infection. Seasonal and meteorological factors may play a key role in the epidemiology of HBoV. The purpose of this study was to ascertain the frequency, season, and clinical characteristics of hospitalized children with HBoV infection. In addition, an evaluation of the effects of meteorological factors on the incidence of HBoV in a subtropical area in China will be conducted. Children were <14 years in age and hospitalized for lower respiratory tract infection between January 1, 2009 and December 31, 2012 in the Respiratory Disease Department at the Children's Hospital affiliated to Soochow University. Multi‐pathogens were detected in nasopharyngeal aspirate samples. The association between HBoV activity and regional meteorological conditions was analyzed. The average incidence of HBoV infection was 6.6% (502/7,626). Of the 502 HBoV positive children, the median age was 13 months (range 1–156 months). The HBoV infection rate was highest among the 7–12 months groups (12.9%, 163/1,267). Seasonal distribution of HBoV was noted during June to November, especially during the summer season (June to August). HBoV activity was associated with temperature and humidity although the lag effect between temperature and HBoV activity observed. HBoV is one of the most common viral pathogens in children with lower respiratory tract infection. HBoV infection occurs throughout the year with a peak during the summer. Temperature and humidity may affect the incidence of HBoV. J. Med. Virol. 86:2154–2162, 2014. © 2014 Wiley Periodicals, Inc.

High prevalence and genetic diversity of porcine bocaviruses in pigs in the USA, and identification of multiple novel porcine bocaviruses

Viruses in the genus Bocavirus are associated with respiratory and enteric disease in dogs and cattle. In addition, novel porcine bocaviruses (PBoVs) have been identified in domestic and wild pigs in recent years, but are of unknown relevance to date. The objectives of this study were to determine the prevalence ra

tes and genetic diversity of PBoVs in pigs in the USA. Using newly established multiplex real-time PCR assays, 385 lung, lymph node, serum and faecal samples from pigs with various disease conditions were investigated. A high PBoV prevalence rate ranging from 21.3 to 50.8 % was identified in the investigated samples and often two or more PBoV species were detected in the same sample. Cloning and sequencing analysis of the partial non-structural protein NS1 and the capsid proteins VP1 and VP2 of DNA samples positive for PBoV groups 1 (n = 6), 2 (n = 16) and 3 (n = 42), including subgroups 3A, 3B or 3C, revealed a high genetic diversity especially for the PBoV G3 VP2 gene, whereas the PBoV group 1 VP1 gene displayed a low nucleotide polymorphism. Using primer walking, 18 partial or nearly complete genomes of PBoVs were obtained and six of the 18 nearly complete genomes represented novel PBoV species. Recombination analysis using partial NS1, VP1 and VP2 genes and the nearly complete genomes indicated possible recombination events within and between PBoVs. Further studies will be required to reveal the possible pathogenic role of these diverse PBoVs.

Tools for detection of Mycoplasma amphoriforme: a primary respiratory pathogen?

Mycoplasma amphoriforme is a recently described organism isolated from the respiratory tracts of patients with immunodeficiency and evidence of chronic infection. Novel assays for the molecular detection of the organism by real-time quantitative PCRs (qPCRs) targeting the uracil DNA glycosylase gene (udg) or the 23S rRNA gene are described here. The analytical sensitivities are similar to the existing conventional M. amphoriforme 16S rRNA gene PCR, with the advantage of being species specific, rapid, and quantitative. By using these techniques, we demonstrate the presence of this organism in 17 (19.3%) primary antibody-deficient (PAD) patients, 4 (5%) adults with lower respiratory tract infection, 1 (2.6%) sputum sample from a patient attending a chest clinic, and 23 (0.21%) samples submitted for viral diagnosis of respiratory infection, but not in normal adult control subjects. These data show the presence of this microorganism in respiratory patients and suggest that M. amphoriforme may infect both immunocompetent and immunocompromised people. Further studies to characterize this organism are required, and this report provides the tools that may be used by other research groups to investigate its pathogenic potential.

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.

Prevalence of herpes and respiratory viruses in induced sputum among hospitalized children with non typical bacterial community-acquired pneumonia

Objective

Few comprehensive studies have searched for viruses in infants and young children with community-acquired pneumonia (CAP) in China. The aim of this study was to investigate the roles of human herpes viruses (HHVs) and other respiratory viruses in CAP not caused by typical bacterial infection and to determine their prevalence and clinical significance.

Methods

Induced sputum (IS) samples were collected from 354 hospitalised patients (infants, n = 205; children, n = 149) with respiratory illness (CAP or non-CAP) admitted to Wenling Hospital of China. We tested for HHVs and respiratory viruses using PCR-based assays. The epidemiological profiles were also analysed.

Results

High rate of virus detection (more than 98%) and co-infection (more than 80%) were found among IS samples from 354 hospitalised infants and children with respiratory illness in this study. Of 273 CAP samples tested, CMV (91.6%), HHV-6 (50.9%), RSV (37.4%), EBV (35.5%), HBoV (28.2%), HHV-7 (18.3%) and rhinovirus (17.2%) were the most commonly detected viruses. Of 81 non- CAP samples tested, CMV (63%), RSV (49.4%), HHV-6 (42%), EBV (24.7%), HHV-7 (13.6%) and HBoV (8.6%) were the dominant viruses detected. The prevalence of several viral agents (rhinovirus, bocavirus, adenovirus and CMV) among IS samples of CAP were significantly higher than that of non-CAP control group. We also found the prevalence of RSV coinfection with HHVs was also higher among CAP group than that of non-CAP control.

Conclusions

With sensitive molecular detection techniques and IS samples, high rates of viral identification were achieved in infants and young children with respiratory illness in a rural area of China. The clinical significance of rhinovirus, bocavirus, adenovirus and HHV (especially CMV) infections should receive greater attention in future treatment and prevention studies of CAP in infants and children.

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 1 infects commercially available primary human airway epithelium cultures productively

Human bocavirus 1 (HBoV1), a human parvovirus, belongs to the genus Bocavirus of the Parvoviridae family. It causes wheezing in young children with acute respiratory tract infections. HBoV1 has been shown to infect polarized human airway epithelium (HAE) made in house, and induces airway epithelial damage. In this study, two commercially available HAE cultures, EpiAirway and MucilAir HAE, were examined for HBoV1 infection. Both HAE cultures support fully productive HBoV1 infection. Infected EpiAirway and MucilAir HAE cultures showed loss of cilia, disruption of the tight junction barrier, and a significant decrease in transepithelial electrical resistance. Notably, HBoV1 persistent infection was demonstrated by maintaining HBoV1-infected EpiAirway HAE for as long as 50 days. After 2 days post-infection, progeny virus was produced consistently daily at a level of over 2×10(8) viral genome copies per culture (0.6 cm(2)). This study is the first to use commercial sources of HAE cultures for HBoV1 infection. The availability of these cultures will enable a wide range of laboratories to study HBoV1 infection.

Human Bocavirus in Iranian children with acute gastroenteritis

BACKGROUND

Human Bocavirus (HBoV) infection is of worldwide distribution. There is increasing evidencethat HBoV is pathogenic for the human gastroenteric tract. However, less data are available on the role of HBoVin gastroenteritis. The present study was aimed to determine the prevalence of HBoV in children with gastroenteritis.

METHODS

Real-time PCR TaqMan was used to screen 200 stool specimens that had been referred to the virologylaboratory for HBoV evaluation. All of samples were collected on viral transport media.

RESULTS

Of the 200 stool samples analyzed, 16 (8%) were positive for HBoV. Human Bocavirus positive samplesfrom patients aged between 1 to 5 years with acute gastroenteritis infection suggest a minor role of HBoVin gastroenteritis (p=0.0001).

CONCLUSION

The study showed a high prevalence of human Bocavirus in young children with acute gastroenteritisdiseases in Iran, suggesting that HBoV play a role in the pathogenesis of gastroenteritis.

Human bocavirus VP2 upregulates IFN-β pathway by inhibiting ring finger protein 125-mediated ubiquitination of retinoic acid-inducible gene-I

Precise regulation of innate immunity is crucial for maintaining optimal immune responses against infections. Whereas positive regulation of IFN signaling elicits rapid type I IFNs, negative regulation is equally important in preventing the production of superfluous IFNs that can be hazardous to the host. The positive regulators of IFN pathway are known to be the main targets of viruses to antagonize the innate immune system. Whether viruses target the negative regulators of IFN pathway remains to be fully investigated. In this study, we report that the structural protein VP2 of human Bocavirus modulates IFN pathway by targeting the ring finger protein 125 (RNF125), a negative regulator of type I IFN signaling, which conjugates Lys(48)-linked ubiquitination to retinoic acid-inducible gene-I (RIG-I) and subsequently leads to the proteasome-dependent degradation of RIG-I. VP2 not only upregulated Sendai virus (SeV)-induced IFNB promoter activity, but also enhanced SeV-induced IFN-β production at both mRNA and protein levels. In agreement, the level of Ser(396)-phosphorylated IFN regulatory factor 3 stimulated by SeV was enhanced in the presence of VP2. Furthermore, VP2 was demonstrated to physically interact with RNF125, resulting in the reduction of RNF125-mediated ubiquitination and proteasome-dependent degradation of RIG-I. Additional study indicated that endogenous RIG-I degradation was decreased in VP2-expressing cells. Our study delineates a unique phenomenon for aberrant activation of IFN regulatory factor 3 pathway and may represent a new mechanism underlying viral manipulation of the host immune system.

Prevalence of human parvovirus B19, bocavirus, and PARV4 in blood samples from the general population of China and lack of a correlation between parvovirus and hepatitis B co-infection

Few comprehensive studies have investigated viraemia caused by human parvoviruses (HPAVs) in China. A total of 1626 of blood samples were collected from non-HBV and HBV infected Chinese subjects (adults, N = 1279; children, N = 347) from south-western and south-eastern China. DNA from three HPAVs was detected in blood samples using PCR-based assays. The epidemiological profiles and association with HBV co-infection were also analysed. Of the 1626 blood samples tested, 138 (8.49%) were found to exhibit HPAV viraemia, including 3.51% with B19, 3.75% with HBoV and 2.52% with PARV4. The presence of B19 DNA in both child and adult, as well as that of PARV4 DNA in adult,from the south-western region was significantly higher than that from the south-eastern region (P = 0.006 for B19 in children; P = 0.026 for B19 in adults; and P = 0.014 for PARV4 in adult).However, the frequency of HBoV DNA in adults from the south-western region was significantly lower than that observed in adults from the south-eastern region (P = 0.001). Furthermore, HBoV was more prevalence in male (4.9%) than in female (1.4%) individuals. In addition, no significant correlation between HBV and HPAV co-infection was found using serum samples from Chinese adults. In conclusions,the molecular prevalence of three HPAVs in blood samples exhibited variation among different populations depending on area, age and gender; No association between HPAV and HBV infection in adults was found. Our data provide a basis for improving blood safety and preventing HPAV infection in China.

Human parvovirus 4 in nasal and fecal specimens from children, Ghana

Nonparenteral transmission might contribute to human parvovirus 4 (PARV4) infections in sub-Saharan Africa. PARV4 DNA was detected in 8 (0.83%) of 961 nasal samples and 5 (0.53%) of 943 fecal samples from 1,904 children in Ghana. Virus concentrations ≤6–7 log₁₀ copies/mL suggest respiratory or fecal–oral modes of PARV4 transmission.

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.