Detection of human bocavirus in Canadian children in a 1-year study

Detection and phylogenetic analysis of Human bocavirus in children diagnosed with acute respiratory tract infection

Introduction. Human bocavirus (HBoV) is a recently discovered parvovirus; it has been shown to be a common cause of respiratory infections and gastroenteritis in children. Since its identification, HBoV has been detected worldwide in nasopharyngeal swabs, serum and stool samples particularly those obtained from young children suffering from respiratory or gastrointestinal tract infections.Aim. The aim of this work was to determine HBoV prevalence among children with acute respiratory tract infection in Egypt, to detect the most prevalent HBoV genotype and to compare PCR and ELISA as diagnostic techniques for HBoV infection.Methods. Nasopharyngeal swabs and blood samples were obtained within the first day of admission from 75 children diagnosed with acute respiratory tract infection in El-Shatby University Hospital for Children in Alexandria, Egypt from October 2018 to March 2019. Conventional PCR was used to detect HBoV DNA, ELISA was used to detect HBoV IgM antibodies and sequencing of the VP1/2 genes was used for genotyping.Results. Seven (9.3%) of the 75 nasopharyngeal swabs obtained from patients with acute respiratory tract infection were positive for HBoV by PCR, while 5 (6.7 %) of the 75 serum samples were positive for HBoV IgM antibodies using ELISA. The correlation between PCR and ELISA results showed a highly significant association between PCR and ELISA techniques (X ²=52.041, P<0.01) and a highly significant agreement between the two methods (Kappa=81.9 %, P<0.01). Phylogenetic analysis showed that all positive samples were related to the HBoV-1 genotype.Conclusion. Human bocavirus was detected at 9.3 % prevalence in nasopharyngeal swabs obtained from children with acute respiratory tract infection. The HBoV-1 genotype was the only genotype detected, suggesting that a single genetic lineage of HBoV is circulating in Egypt. PCR and ELISA are two reliable methods for detection and diagnosis of HBoV.

Viral respiratory infections diagnosed by multiplex polymerase chain reaction in pediatric patients

Syndromic diagnosis by multiplex nucleic acid amplification tests is the most practical approach to respiratory tract infections since the symptoms are rarely agent‐specific. The aim of this study was to investigate the respiratory viruses in children admitted to a university hospital with acute respiratory tract infection during the last 8 years by a multiplex polymerase chain reaction (PCR) assay. A total of 3162 respiratory samples collected from children between April 2011 and April 2018 tested by a multiplex real‐time PCR assay. Two different commercial assays were used during the study period, "AusDiagnostics/Respiratory Pathogens 12 (AusDiagnostics)" used between April 2011 and December 2015, which changed to "Fast Track Diagnostics/Respiratory Pathogens 21 (Fast Track Diagnostics)" after January 2016 to cover more viruses. Nucleic acid extraction was done by EZ1 Advanced XL platform (QIAGEN). Respiratory pathogens detected in 1857 of the 3162 (58.7%) samples. The most prevalent viruses during the 8‐year period were rhinovirus/enterovirus (RV/EV; 36.2%), respiratory syncytial virus (RSV; 19%), and influenza virus A/B (14.7%). Rhinovirus was the main contributor to the RV/EV group as shown by the assay used during the 2016‐2018 period. RV/EV and adenoviruses detected throughout the year. Influenza virus was most frequently detected during January to March when both RSV and metapneumovirus were also in circulation. The coinfection percentage was 10.2%. Rhinovirus was the most common virus in coinfections while RSV plus rhinovirus/enterovirus were the most frequent combination. RSV and metapneumovirus showed a similar seasonal distribution to the influenza virus, which made it necessary to use a virological diagnostic assay during the influenza season.

Human bocavirus in hospitalized children under 5 years with acute respiratory infection, São Paulo, Brazil, 2010

The aims of this study were to investigate the human bocavirus (HBoV) frequency and genotypes in hospitalized children <5 years presenting acute respiratory infections (ARI) within the São Paulo metropolitan area. Nasopharyngeal samples from 300 patients, previously screened for common respiratory viruses, were tested by qPCR for the NSP1 and NP-1 genes. The VP1/2 gene in positive samples was then amplified by PCR and sequenced. A total of 49 positive HBoV cases (16.3%; mean Ct value of 34.41) were detected with the mean age being 18.1 months (range 1 month to 5 years) and the median age being 1 year of age. Children aged between 0 and 12 months had higher detection rates of HBoV (69.4%; 34/49; mean Ct = 34.45) than children from other age groups (30.6%; 15/49; mean Ct = 34.34). No significant differences were observed between HBoV Ct levels and clinical illness. The occurrence was more frequently associated with fall (38.8%; 19/49) and spring (36.7%; 18/49). All 12 sequenced isolates were identified as HBoV-1, displaying minor genetic variation compared to the Swedish reference strains ST1 and ST2 (99.1–99.7% nt). The sole identification of HBoV-1 supports the hypothesis that this particular genotype is strongly related to ARI, and contributes to the role of this virus in the aetiology of respiratory diseases.

Phylogenic analysis of human bocavirus detected in children with acute respiratory infection in Yaounde, Cameroon

Objective

Human Bocavirus (HBoV) was first identified in 2005 and has been shown to be a common cause of respiratory infections and gastroenteritis in children. In a recent study, we found that 10.7% of children with acute respiratory infections (ARI) were infected by HBoV. Genetic characterization of this virus remains unknown in Central Africa, particularly in Cameroon Leeding us to evaluate the molecular characteristics of HBoV strains in Cameroonian children with ARI.

Results

Phylogenetic analysis of partial HBoV VP1/2 sequences showed a low level of nucleotide variation and the circulation of HBoV genotype 1 (HBoV-1) only. Three clades were obtained, two clustering with each of the reference strains ST1 and ST2, and a third group consisting of only Cameroon strains. By comparing with the Swedish reference sequences, ST1 and ST2, Cameroon sequences showed nucleotide and amino acid similarities of respectively 97.36–100% and 98.35–100%. These results could help improve strategies for monitoring and control of respiratory infections in Cameroon.

Clinical significance of different virus load of human bocavirus in patients with lower respiratory tract infection

To assess the impact of human bocavirus (HBoV) virus load on epidemiologic and clinical characteristics in children with lower respiratory tract infection (LRTI). Clinical records of a total of 654 patients with HBoV infection during January 2013 and December 2014 were retrospectively reviewed. Patients with high HBoV virus load infection had a similar age distribution with the total HBoV infection, which had a peak age group of 6–24 months. Patients with high virus load are significantly younger (P < 0.01) than those with low load. The patients who had wheeze and tachypnea/dyspnea at presentation were more strongly affiliated with the patients with high virus load (both P < 0.01). Co-infection was found significantly more frequently among patients with low virus load than those with high virus load (57.0% vs 38.9%; P < 0.01). High virus load was a significant predictor of severe LRTI (P < 0.05). HBoV infections are found in an important proportion of the hospitalized children with respiratory illnesses (8.85% in our series). A high HBoV virus load could be an etiologic agent for LRTI, which may lead to more severe lower respiratory tract symptom and severe disease.

Human bocaviruses: Possible etiologic role in respiratory infection

Four species of human bocaviruses (HBoV) are currently included in the Bocavirus genus. There is satisfactory evidence demonstrating an association between HBoV1 and respiratory disease in children, and there is evidence that HBoV2 (and possibly the HBoV3 and HBoV4 species) are associated with gastroenteritis. In particular, HBoV1 has been associated with a prolonged period of persistence in the mucosa of the respiratory tract. Virus persistence does play a role in the high frequency of co-infections with proper pathogens of the upper and lower respiratory tracts. The high detection rate of multiple respiratory viruses in up to 83% of respiratory specimens and the presence of asymptomatic HBoV1 infections complicate the elucidation of the pathogenic role of the agent. Overall, a large amount of data are available concerning HBoV1, whereas little information is available about other bocavirus species. High viral loads are often associated with symptoms, and viremia may be associated with systemic manifestations such as encephalopathy. The effects and mechanisms of latency, persistence, reactivation, and reinfection are poorly understood. Thus, particularly in co-infections, the pathogenic contribution of the detected bocavirus species cannot be accurately stated. This review summarizes the current knowledge of HBoV species and provides perspectives for future clinical studies.

Atypical presentation of human bocavirus: Severe respiratory tract infection complicated with encephalopathy

Human bocavirus (HBOV) has been reported as a worldwide distributed respiratory pathogen. It has also been associated with encephalitis recently by detection of the virus in cerebrospinal fluid (CSF) of patients presented with encephalitis. This retrospective study aimed to present clinical features of HBOV infections in children with respiratory symptoms and describe unexplained encephalopathy in a subgroup of these patients. Results of 1,143 pediatric nasal samples from mid-December 2013 to July 2014 were reviewed for detection of HBOV. A multiplex real time polymerase chain reaction assay was used for viral detection. Medical records of the patients were retrospectively analyzed. HBOV was detected in 30 patients (2.6%). Median age was 14 months (5-80). Clinical diagnoses were upper respiratory tract infection (n = 10), bronchopneumonia (n = 9), acute bronchiolitis (n = 5), pneumonia (n = 4), acute bronchitis (n = 1), and asthma execarbation (n = 1). Hospitalization was required in 16 (53.3%) patients and 10 (62.5%) of them admitted to pediatric intensive care unit (PICU). Noninvasive mechanical ventilation modalities was applied to four patients and mechanical ventilation to four patients. Intractable seizures developed in four patients while mechanically ventilated on the 2nd-3rd days of PICU admission. No specific reason for encephalopathy was found after a thorough investigation. No mortality was observed, but two patients were discharged with neurological sequela. HBOV may lead to respiratory infections in a wide spectrum of severity. This report indicates its potential to cause severe respiratory infections requiring PICU admission and highlights possible clinical association of HBOV and encephalopathy, which developed during severe respiratory infection.

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.

Epidemic and molecular evolution of human bocavirus in hospitalized children with acute respiratory tract infection

Human bocavirus (HBoV) is a novel parvovirus, often associated with respiratory tract diseases in children. This study explored the epidemiological characteristics and molecular evolution of HBoV-1 in southeastern China. Nasopharyngeal aspirates were collected from children admitted to hospital with acute respiratory tract infections. HBoV-1 was detected using real-time reverse transcription polymerase chain reaction and further characterized by complete genome sequences analysis. Among the 3,022 recruited children, 386 (12.77 %) were HBoV-1-positive and 300 (77.72 %) had co-detection with other respiratory viruses. Seasonal prevalence peaked in summer. HBoV-1 presence was significantly associated with asthma attack [odds ratio = 1.74; 95 % confidence interval: 1.30, 2.31; p < 0.001]. Similar results were obtained when either single detection or co-detection of HBoV-1 was considered, demonstrating the minor impact of co-detection on the clinical characteristics or epidemic pattern. Phylogenetic analysis based on the complete genome sequences showed that all the HBoV-1 sequences clustered together and no branch was formed that was supported by bootstrap value ≥750. The overall evolutionary rate of the complete genome of HBoV-1 was estimated at 1.08 × 10⁻⁴ nucleotide substitutions per site per year (s/s/y) [95 % highest probability density: (0.40–1.86) × 10⁻⁴ s/s/y]. Selective pressure analysis showed that all the ω-values were less than 1, suggesting that HBoV-1 was under negative selective pressure. Site-by-site analysis identified the codon site 40 of the VP1 gene under positive selection. In conclusion, our study disclosed the epidemiological and genetic dynamics of HBoV-1 epidemics in southeastern China in the most recent 3 years, the information of which might help to further improve our understanding of HBoV-1 infection and guide better surveillance and control strategies in the future.

Respiratory virus infections among children in South China

Acute respiratory tract infection is an important cause of morbidity and mortality with a worldwide disease burden. This study aimed to determine the prevalence and clinical characteristics of children with viral-induced acute respiratory tract infection, in Southern China. Nasopharyngeal aspirate samples from 1,980 pediatric patients with suspected acute respiratory tract infection, and 82 samples from healthy subject controls were collected for routine examination at the Second Affiliated Hospital of Shantou University Medical College, from October 2007 to August 2011. Specimens were tested by multiplex polymerase chain reaction (mPCR). At least one or more viruses were detected from 1,087 samples (54.9%). These included laboratory confirmations for 446 respiratory syncytial virus (RSV), 386 influenza virus A (FluA), 315 human rhinovirus (HRV), 135 human bocavirus (HBoV), 119 Parainfluenza virus 3 (PIV3), 82 Parainfluenza virus 1 (PIV1), 66 adenovirus (ADV), 53 WU polyomavirus (WUPyV), 52 human metapneumovirus (hMPV), and 29 influenza virus B (FluB) samples. Samples from healthy subjects were negative for any virus. Of the patients with positive specimens, 107 (9.8%) were admitted to pediatric intensive care unit (PICU). Co-infection with at least two of the viral pathogens under study was observed in 325 of the 1,980 patients (16.4% of the total number of cases). These findings may help in the diagnosis of viral infections of the respiratory tract in children, and help to consider current and potential therapeutic approaches for the treatment of acute respiratory tract infection, and further respiratory complications.

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 bocaviruses are not significantly associated with gastroenteritis: results of retesting archive DNA from a case control study in the UK

Gastroenteritis is a common illness causing considerable morbidity and mortality worldwide. Despite improvements in detection methods, a significant diagnostic gap still remains. Human bocavirus (HBoV)s, which are associated with respiratory infections, have also frequently been detected in stool samples in cases of gastroenteritis, and a tentative association between HBoVs, and in particular type-2 HBoVs, and gastroenteritis has previously been made. The aim of this study was to determine the role of HBoVs in gastroenteritis, using archived DNA samples from the case-control Infectious Intestinal Disease Study (IID). DNA extracted from stool samples from 2,256 cases and 2,124 controls were tested for the presence of HBoV DNA. All samples were screened in a real time PCR pan-HBoV assay, and positive samples were then tested in genotype 1 to 3-specific assays. HBoV was detected in 7.4% but no significantly different prevalence was observed between cases and controls. In the genotype-specific assays 106 of the 324 HBoV-positive samples were genotyped, with HBoV-1 predominantly found in controls whilst HBoV-2 was more frequently associated with cases of gastroenteritis (p<0.01). A significant proportion of HBoV positives could not be typed using the type specific assays, 67% of the total positives, and this was most likely due to low viral loads being present in the samples. However, the distribution of the untyped HBoV strains was no different between cases and controls. In conclusion, HBoVs, including HBoV-2 do not appear to be a significant cause of gastroenteritis in the UK population.

Human bocavirus NP1 inhibits IFN-β production by blocking association of IFN regulatory factor 3 with IFNB promoter

Human bocavirus (HBoV) mainly infects young children. Although many infected children suffer from respiratory or gastroenteric tract diseases, an association between HBoV and these diseases is not definite. Because modulation of type I IFN is crucial for viruses to establish efficient replication, in this study, we tested whether HBoV modulates type I IFN production. We observed that a nearly full-length HBoV clone significantly reduced both Sendai virus (SeV)- and poly(deoxyadenylic-thymidylic) acid-induced IFN-β production. Further study showed that NP1 blocked IFN-β activation in response to SeV, poly(deoxyadenylic-thymidylic) acid, and IFN-β pathway inducers, including retinoic acid-inducible protein I, mitochondrial antiviral signaling protein, inhibitor of κB kinase ε, and TANK-binding kinase 1. In addition, NP1 interfered with IRF-3-responsive PRD(III-I) promoter activated by SeV and a constitutively active mutant of IRF-3 (IRF-3/5D). Although NP1 suppressed the IRF-3 pathway, it did not affect IRF-3 activation processes, including phosphorylation, dimerization, and nuclear translocation. Coimmunoprecipitation assays confirmed the interaction between NP1 and IRF-3. Additional deletion mutagenesis and coimmunoprecipitation assays revealed that NP1 bound to the DNA-binding domain of IRF-3, resulting in the interruption of an association between IRF-3 and IFNB promoter. Altogether, our results indicate that HBoV NP1 blocks IFN production through a unique mechanism. To our knowledge, this is the first study to investigate the modulation of innate immunity by HBoV. Our findings suggest a potential immune-evasion mechanism used by HBoV and provide a basis for better understanding HBoV pathogenesis.

Detection of human bocaviruses 1 to 4 from nasopharyngeal swab samples collected from patients with respiratory tract infections

Human bocaviruses (HBoV) 1, 2, 3, and 4 (HBoV1-4) were detected in 132 (15.5%), 5 (0.6%), 3 (0.4%), and 5 (0.6%) of 850 nasopharyngeal swab samples collected from children with respiratory tract infections, respectively. Out of the 145 HBoV1-4-positive samples, 62 (42.8%) were codetected with other respiratory viruses.

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.

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.

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.

Bocavirus episome in infected human tissue contains non-identical termini

Human bocaviruses (HBoV) are highly prevalent human infections whose pathogenic potential remains unknown. Recent identification of the first non-human primate bocavirus [1] in captive gorillas raised the possibility of the persistent nature of bocavirus infection. To characterize bocavirus infection in humans, we tested intestinal biopsies from 22 children with gastrointestinal disease for the presence of HBoV DNA. Four HBoV-positive tissue samples were analyzed to determine whether viral DNA was present in the linear genomic, the episomal closed circular or the host genome-integrated form. Whereas one tissue sample positive for HBoV3 contained the episomal form (HBoV3-E1), none had the genome-integrated form. The complete genome sequence of HBoV3-E1 contains 5319 nucleotides of which 513 represent the non-coding terminal sequence. The secondary structure of HBoV3-E1 termini suggests several conserved and variable features among human and animal bocaviruses. Our observation that HBoV genome exists as head-to-tail monomer in infected tissue either reflects the likely evolution of alternative replication mechanism in primate bocaviruses or a mechanism of viral persistence in their host. Moreover, we identified the HBoV genomic terminal sequences that will be helpful in developing reverse genetic systems for these widely prevalent parvoviruses.

Significance

HBoV have been found in healthy human controls as well as individuals with respiratory or gastrointestinal disease. Our findings suggest that HBoV DNA can exist as episomes in infected human tissues and therefore can likely establish persistent infection in the host. Previous efforts to grow HBoV in cell culture and to develop reverse genetic systems have been unsuccessful. Complete genomic sequence of the HBoV3 episome and its genomic termini will improve our understanding of HBoV replication mechanism and its pathogenesis.

Human bocavirus in patients with respiratory tract infection

BACKGROUND

Human bocavirus (HBoV) is a newly identified viral pathogen, and its clinical epidemiology and significance in respiratory infections have not yet been completely elucidated. We investigated the prevalence of HBoV infection and the association between viral (HBoV) load and clinical features of the infection in patients of all age-groups.

METHODS

Nasopharyngeal aspirates from patients with symptoms of respiratory infection were tested for presence of HBoV by using real-time polymerase chain reaction. HBoV-positive patients were categorized into low- and high-viral-load groups using 1.0×10(6) copies/mL as the threshold value of viral load.

RESULTS

Detection rate of HBoV was 4.8% (N=93) in a total of 1,926 samples with peak incidence of infection being observed in patients aged 6-12 months. HBoV infection was more frequently observed in young children, especially, in children aged less than 5 yr, and the HBoV load decreased with increase in age. HBoV was codetected with other respiratory viruses in 17 (18.3%) of the 93 HBoV-positive patients and 15 patients (88.2%) belonged to the low-viral-load group. Patients infected with HBoV alone showed a higher viral load than those patients in whom HBoV was codetected with other respiratory viruses (median load, 3.78×10(5) copies/mL vs. 1.94×10(4) copies/mL, P=0.014). Higher pulse rate (P=0.007) and respiratory rate (P=0.021) were observed in patients with a high-viral-load.

CONCLUSIONS

Our results suggest that HBoV may be the causative agent of respiratory infection in the high-viral-load group.

Human bocavirus (HBoV) in children with respiratory tract infection by enzyme linked immunosorbent assay (ELISA) and qualitative polymerase chain reaction (PCR)

BACKGROUND

Human bocavirus (HBoV) is a recently discovered parvovirus associated with mild to severe lower respiratory tract infections in children, the aim of the work was determination of human bocavirus in nasopharyngeal aspirate (NPA) of infants by qualitative PCR and determination of acute human bocavirus infection by estimation of immunoglobulin M (IgM) antibodies in serum by enzyme linked immunosorbent assay.

RESULTS

Twenty two (22%) out of the 100 NPA specimens of the patients with respiratory manifestations were positive for HBoV by qualitative PCR, while ELISA revealed positive HBoV IgM antibodies in 18 (18%) patients who were also positive by PCR. Non of the controls were positive by both techniques. The correlation study between ELISA and PCR revealed high significant association, (p < 0.001, X2 = 36 and agreement = 96%). Also PCR detected 4 (18.1%) NPA samples as HBoV positive cases among the patients that were not identified by ELISA. This could be due to high sensitivity and efficacy of PCR. ELISA being less sensitive than RT-PCR, sensitivity was (81.8% vs 100%), the efficacy was 97.7% in ELISA versus 99.7% for RT-PCR.

CONCLUSION

HBoV infections could be diagnosed in NPA of children by conventional PCR as a rapid and sensitive technique. While ELISA was a reliable serologic analysis for diagnosis of acute HBoV infection by estimation IgM antibodies in serum.

Genomic characterization and high prevalence of bocaviruses in swine

Using random PCR amplification followed by plasmid subcloning and DNA sequencing, we detected bocavirus related sequences in 9 out of 17 porcine stool samples. Using primer walking, we sequenced the nearly complete genomes of two highly divergent bocaviruses we provisionally named porcine bocavirus 1 isolate H18 (PBoV1-H18) and porcine bocavirus 2 isolate A6 (PBoV2-A6) which differed by 51.8% in their NS1 protein. Phylogenetic analysis indicated that PBoV1-H18 was very closely related to a ∼2 Kb central region of a porcine bocavirus-like virus (PBo-LikeV) from Sweden described in 2009. PBoV2-A6 was very closely related to the porcine bocavirus genomes PBoV-1 and PBoV2 from China described in 2010. Among 340 fecal samples collected from different age, asymptomatic swine in five Chinese provinces, the prevalence of PBoV1-H18 and PBoV2-A6 related viruses were 45-75% and 55-70% respectively, with 30-47% of pigs co-infected. PBoV1-A6 related strains were highly conserved, while PBoV2-H18 related strains were more diverse, grouping into two genotypes corresponding to the previously described PBoV1 and PBoV2. Together with the recently described partial bocavirus genomes labeled V6 and V7, a total of three major porcine bocavirus clades have therefore been described to date. Further studies will be required to elucidate the possible pathogenic impact of these diverse bocaviruses either alone or in combination with other porcine viruses.

Human bocavirus as an important cause of respiratory tract infection in Taiwanese children

BACKGROUND

Human bocavirus (HBoV), first described in September 2005, was considered a causative agent of previously unexplained respiratory tract diseases. However, only few reports provide the evidence for an association between HBoV and respiratory tract diseases. We conducted a prospective clinical and molecular study of HBoV in Taiwan.

METHODS

We enrolled 705 children who visited our outpatient pediatric clinics in a medical center because of symptoms and signs of respiratory tract infections from November 2008 to October 2009. Throat swab was performed and HBoV polymerase chain reaction and viral culture were done simultaneously.

RESULTS

Positive viral results were confirmed in 159 (22.6%) of the 705 children. HBoV was found in 35 samples and it was supposed to be as a single virus in 32 samples because viral isolation of these 32 samples did not identify other virus. The other three patients had coinfection with another virus. One child got HBoV reinfection 6 months after the first infection. Seventy-one percentage of these HBoV infections occurred between November and March. Of the 34 children with positive HBoV, 26 (76%) patients were younger than 5 years; their common symptoms were cough, rhinorrhea, and fever; the most common diagnoses were bronchitis (34%, 12/35) and sinusitis (31%, 11/35) followed by pharyngitis (29%, 10/35) and asthma exacerbation (26%, 9/35). Three of the 34 patients needed hospitalization.

CONCLUSION

HBoV is an emerging human parvovirus that may cause respiratory tract infection in young children. Diseases associated with HBoV may range from pharyngitis, sinusitis, acute otitis media to bronchitis, asthma, and even pneumonia.

Phylogenetic analysis of human bocavirus isolated from children with acute respiratory illnesses and gastroenteritis in Iran

Human bocavirus (hBoV) was first discovered in respiratory samples from children in 2005, and has been classified in the Parvoviridae family. hBoV has also been detected in children with acute gastroenteritis. This study was performed to analyze the frequency and phylogeny of hBoV in the respiratory and stool samples of children with acute respiratory tract illnesses and gastroenteritis during the time period beginning 2006 and ending 2008, at the Virology Research Centre, Masih Daneshvari Hospital, NRITLD, Tehran, Iran. Respiratory and stool samples were screened for hBoV by nested polymerase chain reaction with primers from the NS-1 gene. Nine out of 133 respiratory samples (6.8%) and 6 out of 47 stool samples (12.8%) were positive for hBoV. Ten positive samples (7 respiratory and 3 stool samples) were subjected to phylogenetic analysis by sequencing a fragment of the VP1/VP2 gene junction. The results showed a high similarity among isolates (>or=99%). It was found that hBoV isolates can be divided into 3 genetic groups.

Frequency of human bocavirus (HBoV) infection among children with febrile respiratory symptoms in Argentina, Nicaragua and Peru

BACKGROUND

Globally, respiratory infections are the primary cause of illness in developing countries, specifically among children; however, an etiological agent for many of these illnesses is rarely identified.

OBJECTIVES

Our study aimed to estimate the frequency of human bocavirus (HBoV) infection among pediatric populations in Argentina, Nicaragua and Peru.

METHODS

We conducted a cross-sectional study using stored samples of an influenza-like illness surveillance program. Irrespective of previous diagnosis, nasopharyngeal or nasal swab specimens were randomly selected and tested using real-time PCR from three sites during 2007 from patients younger than 6 years old.

RESULTS

A total of 568 specimens from Argentina (185), Nicaragua (192) and Peru (191) were tested. The prevalence of HBoV was 10·8% (95% CI: 6·3; 15·3) in Argentina, 33·3% in Nicaragua (95% CI: 26·6; 40·1) and 25·1% in Peru (95% CI: 18·9; 31·3).

CONCLUSIONS

These findings demonstrate circulation of HBoV in Argentina, Nicaragua and Peru among children with influenza-like symptoms enrolled in a sentinel surveillance program.

Identification and characterization of a new bocavirus species in gorillas

A novel parvovirus, provisionally named Gorilla Bocavirus species 1 (GBoV1), was identified in four stool samples from Western gorillas (Gorilla gorilla) with acute enteritis. The complete genomic sequence of the new parvovirus revealed three open reading frames (ORFs) with an organization similar to that of known bocaviruses. Phylogenetic analysis using complete capsid and non structural (NS) gene sequence suggested that the new parvovirus is most closely related to human bocaviruses (HBoV). However, the NS ORF is more similar in length to the NS ORF found in canine minute virus and bovine parvovirus than in HBoV. Comparative genetic analysis using GBoV and HBoV genomes enabled characterization of unique splice donor and acceptor sites that appear to be highly conserved among all four HBoV species, and provided evidence for expression of two different NS proteins in all primate bocaviruses. GBoV is the first non-human primate bocavirus identified and provides new insights into the genetic diversity and evolution of this highly prevalent and recently discovered group of parvoviruses.

Human bocavirus infection in children with acute respiratory tract infection in India

Human bocavirus (HBoV) is a new human parvovirus identified in children with respiratory tract disease. Nasopharyngeal aspirates were collected from 305 children <5 years of age with acute respiratory tract infection from April 2005 to March 2007 and screened for the presence of HBoV by two separate sets of a polymerase chain reaction (PCR) described previously. Twenty-two (7.2%) children who had acute respiratory infection were found to be positive for HBoV by both sets of PCR. The main clinical symptoms were cough (95%), runny nose (64%), and fever (59%). In two samples, HBoV was identified together with respiratory syncytial virus in one sample and influenza A virus in another. HBoV appeared to have no seasonal distribution and is associated with both upper and lower respiratory tract disease in young children in India.

Human bocavirus in very young infants hospitalized with acute respiratory infection in northeast Brazil

A cross-sectional study was carried out over a period of 12 months to investigate the occurrence of human bocavirus (HBoV) infection in infants hospitalized for respiratory infections in a teaching hospital in Salvador, Brazil, and to describe the clinical manifestations of this infection. Nasopharyngeal aspirates were collected from the children and immunofluorescence and polymerase chain reaction were performed to investigate the presence of respiratory viruses. HBoV was detected in 4 out of 66 patients. Two of the HBoV-positive infants were co-infected with other viruses. The principal clinical findings in HBoV-positive children were: nasal obstruction, catarrh, cough, fever and dyspnea. This study revealed HBoV infection in children aged <2 months, suggesting that the infection may occur at a very early age.

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

Human bocavirus (HBoV) is a recognized human parvovirus associated with acute respiratory tract infection. However, HBoV has yet to be established as a causative agent of respiratory disease. In this study, the epidemiological and virological characteristics of HBoV infection were studied in children with acute respiratory tract infection in China. In total, 406 children younger than 14 years of age with acute respiratory tract infection were included in this prospective 1-year study. HBoV was detected in 29 (7.1%) of the 406 children. No clear seasonal fluctuation was observed in infection rates of HBoV. Of the 29 children infected with HBoV, 16 (55.2%) were coinfected with other respiratory viruses, most commonly respiratory syncytial virus (RSV). Viral coinfection with HBoV did not affect the severity of the respiratory disease (P = 0.291). The number of HBoV genome copies ranged from 5.80 x 10(2) to 9.72 x 10(8) copies/ml in nasopharyngeal aspirates among HBoV-positive specimens by real-time PCR, and neither coinfection nor the severity of disease correlated with the viral load (P = 0.148, P = 0.354, respectively). The most common clinical features were cough and acute upper respiratory infection, and acute bronchopneumonia. Additionally, the NP-1 gene of HBoV showed minimal sequence variation. These data suggest that HBoV is frequent in young children with acute respiratory tract infection in Lanzhou, China, and RSV is the most common coinfecting virus. There was no apparent association between the viral load of HBoV and coinfection or disease severity. The NP-1 gene was highly conserved in HBoV.

Human bocavirus infections in hospitalized Greek children

INTRODUCTION

The epidemiology of human bocavirus (HBoV) infections has not been described in Greece, a south-eastern European country. To define the epidemiological profile and the clinical characteristics associated with HBoV infection in a population of children hospitalized with respiratory tract infection.

MATERIAL AND METHODS

During a one-year period throat swab samples were collected from 370 previously healthy children, aged 14 days to 13 years, admitted to two different paediatric wards because of respiratory tract infection. Samples were tested for HBoV by PCR amplifying a part of the NS1 gene.

RESULTS

Human bocavirus was detected in 12 children (3.2%). Four of the 12 cases were co-infections, 3 of them with influenza A and 1 with coronavirus OC43. Cases were observed only during the cold months. The mean age of children was 1.8 years (range 2 months to 4 years). The most common symptoms were fever, cough and various degrees of respiratory distress. All children were clinically diagnosed as having lower respiratory tract infections, mainly pneumonia and acute laryngotracheobronchitis, and recovered uneventfully.

CONCLUSIONS

HBoV infections occur in Greece mostly among very young children. They accounted for 3.2% of children hospitalized with acute respiratory disease. Cases were observed only in late autumn to early spring.

Serologically verified human bocavirus pneumonia in children

WORKING HYPOTHESIS

Human bocavirus (HBoV) is a newly identified parvovirus frequently found in children suffering from acute respiratory and intestinal infections. The aim of the present study was to evaluate, by using a newly developed antibody assay, the role of HBoV in pediatric community-acquired pneumonia (CAP) and the seropositivity rate to HBoV in a prospective study in North-Italian children.

MATERIALS/PATIENTS AND METHODS

During a 15-month study period, 124 children were admitted due to presumptive pneumonia, and in 101 of them, pneumonia was radiologically confirmed. The etiology of CAP was studied by antibody assays to 16 microbes, including the newly developed enzyme immunoassay for HBoV.

RESULTS

Serological evidence of acute HBoV infection was found in 12 (12%) children, being single in 7 and mixed in 5 cases (4 with other viruses and 3 with bacteria). IgM was positive in 11 cases. A diagnostic rise in IgG antibodies between paired sera was observed in six cases. HBoV was the second most common virus next to respiratory syncytial virus (17%). The seropositivity rate to HBoV increased with age, reaching nearly 100% before school age.

CONCLUSIONS

The present results show that HBoV is able to induce significant antibody responses and suggest that HBoV may be a fairly common cause of pneumonia in children. Seroconversion to HBoV in most children takes place in early childhood.

Human bocavirus in children with respiratory tract infection in Shanghai: a retrospective study

BACKGROUND

Human bocavirus (HBoV) was first reported in 2005. The worldwide presence of HBoV in children with acute respiratory tract infection (ARTI) has been confirmed. This study aimed to understand the prevalence and clinical features of HBoV in children with ARTI in Shanghai and explore the causative implication of HBoV in ARTI.

METHODS

We retrospectively reviewed the medical records of 349 hospitalized children with ARTI between November 2006 and January 2007. From these children, 351 nasopharyngeal aspirate samples were collected; 325 of the samples were obtained from those with community-acquired ARTI and 26 from those with hospital-acquired ARTI. All samples were routinely screened for seven common respiratory viruses by immunofluorescence and further tested for HBoV by polymerase chain reaction.

RESULTS

HBoV was detected in 16 (4.6%) of the 351 samples, and it was the second most commonly detected virus after respiratory syncytial virus. Three (19%) HBoV-positive samples were dual infection with respiratory syncytial virus or parainfluenza virus type 3. Of the 325 children with community-acquired ARTI, HBoV was identified to be positive in 11 (3.4%), of whom 6 were diagnosed with pneumonia with patchy or interstitial infiltrates in the lung indicated by chest radiography, 3 with bronchitis, and 2 with bronchial asthma exacerbation with attendant lung infection. Out of the 26 children with nosocomial ARTI, 5 (19.2%) had bronchitis which was found to be HBoV positive without co-detection of other viruses. The HBoV-positive children were aged 1.7 months to 43 months and their mean age was 13.7 months. Sixteen (100%) children had cough, 11 (68.8%) had wheezing, and 10 (62.5%) had fever.

CONCLUSIONS

HBoV was circulating in Shanghai during the study period, and which was detected frequently in children with ARTI. HBoV was found to be associated with community-acquired ARTI and may play a pathogenic role in nosocomial ARTI.

Newly recognized bocaviruses (HBoV, HBoV2) in children and adults with gastrointestinal illness in the United States

BACKGROUND

The human bocavirus (HBoV) is a newly recognized parvovirus associated with respiratory and gastrointestinal disease. Recently, two new members of the parvovirus family have been recognized, HBoV2 and HBoV3.

OBJECTIVES

Here we investigate stool and respiratory samples for the presence of HBoV, HBoV2 and HBoV3.

STUDY DESIGN

Stool samples collected from 12/1/2007 to 3/31/2008 were screened by PCR for the presence of HBoV, HBoV2, and HBoV3. Extracted DNA from respiratory specimens archived between 10/17/2005 and 3/29/2006 were screened by PCR for HBoV2 and HBoV3. Medical records for all bocavirus positive patients were reviewed.

RESULTS

Of 479 stool samples screened, 328 (68.5%) were from adults, and 151 (31.5%) were from children. Sixteen (3.4%) patients were positive for the presence of a bocavirus, including 10 (2.1%) HBoV and 6 (1.3%) HBoV2. No HBoV3 was detected in stool samples. Frequency of HBoV and HBoV2 in stool samples from children was 3.3% and 0.7%, and from adults was 1.5% and 1.5% respectively. Clinical findings in patients with HBoV and HBoV2 in stool include diarrhea (50% and 83.3%), abdominal pain (40%, 33.3%), and cough (10%, 50%). Of 868 respiratory samples screened, none were positive for either HBoV2 or HBoV3.

CONCLUSIONS

The newly recognized parvovirus HBoV2 circulates in the United States. Patients with bocaviruses in stool have evidence of gastrointestinal illness. HBoV2 was not detected in respiratory samples. HBoV3 was not detected in either stool or respiratory samples.

Review of new and newly discovered respiratory tract viruses in children

Respiratory tract viral infection continues to be among the most common reasons for emergency department visits and hospitalization of children, particularly infants younger than 1 year, in the United States. Throughout the years, clinicians have considered respiratory syncytial virus followed by influenza as the most common pathogens responsible. Over the past decade, new viruses have been discovered through both more specific testing and the finding of new agents causing infection. This includes human metapneumovirus, which leads to similar but often epidemiologically more severe clinical symptoms than respiratory syncytial virus. Other agents responsible for lower respiratory tract infection include Coronavirus (severe acute respiratory syndrome), Bocavirus, and others. This review serves to focus on some of the recent literature on these agents and the clinical impact they have on pediatric lung infection.

A newly identified bocavirus species in human stool

Viral metagenomic analysis was used to identify a previously uncharacterized parvovirus species, "HBoV2," whose closest phylogenetic relative is the human bocavirus (HBoV). HBoV2 has a genomic organization identical to that of HBoV but has only 78%, 67%, and 80% identity, respectively, with the latter's NS1, NP1, and VP1/VP2 proteins. The study used polymerase chain reaction to detect HBoV2 sequences in 5 of 98 stool samples from Pakistani children and in 3 of 699 stool samples from Edinburgh. Nearly-full-length genome sequencing revealed the presence of 3 HBoV2 genotypes and evidence of recombination between genotypes. Further studies are necessary to identify anatomical sites of HBoV2 replication and potential associations with clinical symptoms or disease.

Evidence of prior exposure to human bocavirus as determined by a retrospective serological study of 404 serum samples from adults in the United States

Recently, molecular screening for pathogenic agents has identified a partial genome of a novel parvovirus, called human bocavirus (HBoV). The presence of this newly described parvovirus correlated with upper and lower respiratory tract infections in children. Lower respiratory tract infections are a leading cause of hospital admission in children, and the etiological agent has not been identified in up to 39% of these cases. Using baculovirus expression vectors (BEVs) and an insect cell system, we produced virus-like particles (VLPs) of HBoV. The engineered BEVs express the HBoV capsid proteins stoichiometrically from a single open reading frame. Three capsid proteins assemble into the VLP rather than two proteins predicted from the HBoV genome sequence. The denatured capsid proteins VP1, VP2, and VP3 resolve on silver-stained sodium dodecyl sulfate-polyacrylamide gels as three bands with apparent molecular masses of 72 kDa, 68 kDa, and 62 kDa, respectively. VP2 apparently initiates at a GCT codon (alanine) 273 nucleotides downstream from the VP1 start site and 114 nucleotides upstream from the VP3 initiation site. We characterized the stable capsids using physical, biochemical, and serological techniques. We found that the density of the VLP is 1.32 g/cm(3) and is consistent with an icosahedral symmetry with approximately a 25-nm diameter. Rabbit antiserum against the capsid of HBoV, which did not cross-react with adeno-associated virus type 2, was used to develop enzyme-linked immunosorbent assays (ELISAs) for anti-HBoV antibodies in human serum. Using ELISA, we tested 404 human serum samples and established a range of antibody titers in a large U.S. adult population sample.

Molecular characterization of infectious clones of the minute virus of canines reveals unique features of bocaviruses

Minute virus of canines (MVC) is a member of the genus Bocavirus in the family Parvoviridae. We have molecularly cloned and sequenced the 5'- and 3'-terminal palindromes of MVC. The MVC genome, 5,404 nucleotides (nt) in length, shared an identity of 52.6% and 52.1% with that of human bocavirus and bovine parvovirus, respectively. It had distinct palindromic hairpins of 183 nt and 198 nt at the left-end and right-end termini of the genome, respectively. The left-end terminus was also found in two alternative orientations (flip or flop). Both termini shared extensive similarities with those of bovine parvovirus. Four full-length molecular clones constructed with different orientations of the left-end terminus proved to be infectious in Walter Reed canine cell/3873D (WRD) canine cells. Both MVC infection and transfection of the infectious clone in WRD cells revealed an identical RNA transcription profile that was similar to that of bovine parvovirus. Mutagenesis of the infectious clone demonstrated that the middle open reading frame encodes the NP1 protein. This protein, unique to the genus Bocavirus, was essential for MVC DNA replication. Moreover, the phospholipase A2 motif in the VP1 unique region was also critical for MVC infection. Thus, our studies revealed important information about the genus Bocavirus that may eventually help us to clone the human bocavirus and study its pathogenesis.

Clinical and genetic analysis of Human Bocavirus in children with lower respiratory tract infection in Taiwan

BACKGROUND

Human Bocavirus (HBoV) is a likely etiologic agent of acute respiratory disease in children. The prevalence of this virus has been studied in several sites worldwide. We conducted the first clinical and molecular study of HBoV in Taiwan at the Centers for Diseases Control, Taiwan.

OBJECTIVES

To investigate the genomic and epidemiologic profiles of HBoV infection in Taiwan.

STUDY DESIGN

Throat swabs or nasopharyngeal aspirates were obtained from hospitalized pediatric patients with acute lower respiratory tract infections. Specimens negative for other respiratory viruses by molecular screening were examined for HBoV.

RESULTS

HBoV was the only virus detected in 30 (5.6%) of 531 samples. Of these positive cases, 56.7% were from children less than 2 years old. Two groups of HBoV co-circulated in Taiwan during the study. Results of evolutionary networks evaluation suggest that HBoV might have had an opportunity for interbreeding of viruses and genetic recombinations among the different genes.

CONCLUSION

HBoV may have circulated in Taiwan for some time and it appears to be one of the etiological agents responsible for lower respiratory tract infection in children.

Comprehensive detection of causative pathogens using real-time PCR to diagnose pediatric community-acquired pneumonia

We have developed a real-time reverse transcription-PCR (RT-PCR) method to detect 13 respiratory viruses: influenza virus A and B; respiratory syncytial virus (RSV) subgroup A and B; parainfluenza virus (PIV) 1, 2, and 3; adenovirus; rhinovirus (RV); enterovirus; coronavirus (OC43); human metapneumovirus (hMPV); and human bocavirus (HBoV). The new method for detection of these viruses was applied simultaneously with real-time PCR for the detection of six bacterial pathogens in clinical samples from 1700 pediatric patients with community-acquired pneumonia (CAP). Of all the patients, 32.5% were suspected to have single bacterial infections; 1.9%, multiple bacterial infections; 15.2%, coinfections of bacteria and viruses; 25.8%, single viral infections; and 2.1%, multiple viral infections. In the remaining 22.6%, the etiology was unknown. The breakdown of suspected causative pathogens was as follows: 24.4% were Streptococcus pneumoniae, 14.8% were Mycoplasma pneumoniae, 11.3% were Haemophilus influenzae, and 1.4% were Chlamydophila pneumoniae. The breakdown of viruses was as follows: 14.5% were RV, 9.4% were RSV, 7.4% were hMPV, 7.2% were PIV, and 2.9% were HBoV. The new method will contribute to advances in the accuracy of diagnosis and should also result in the appropriate use of antimicrobials.

Clinical and epidemiologic characteristics of human bocavirus in Danish infants: results from a prospective birth cohort study

BACKGROUND

Human bocavirus (HBoV) is a recently discovered parvovirus that has been detected in respiratory samples from children with acute respiratory tract infection (ARTI) and in feces from children with gastroenteritis. However, its role as a causative agent of respiratory disease is not determined.

METHODS

We investigated the presence of HBoV by real-time polymerase-chain reaction of nasal swab specimens obtained from 228 healthy children followed in the community from birth to 1 year of age for a 2-year period from 2004 to 2006. Nasal swabs and symptom diaries were collected at monthly home visits.

RESULTS

HBoV was detected in 57 (8.2%) of 697 nasal swab specimens from children with ARTI, in 1 (2.3%) of 44 swabs from children with diarrhea, and in 13 (8.6%) of 152 swabs from asymptomatic children. HBoV was present mainly during the winter months. An additional respiratory virus was identified in 27 (47.4%) HBoV-positive samples. Thirty-four (68%) of 50 children with ARTI shed HBoV for less than 1 month, 13 (26%) for 2 months, 2 (4%) for 3 months, and 1 (2%) for 4 months. Seven asymptomatic children shed HBoV for less than 1 month, 2 children for 2 months, and 1 asymptomatic child had 5 HBoV-positive nasal swabs detected for 6 consecutive months. HBoV infection was associated with maternal smoking, being born in the winter, and predisposition to asthma.

CONCLUSIONS

Asymptomatic carriage of HBoV is common in infants <1 year of age, and an HBoV-positive test result does not imply that HBoV is the cause of the illness.

Clinical and epidemiological aspects of human bocavirus infection

Human bocavirus was recently described as a novel member of the Parvoviridae to infect humans. Based on accumulating clinical and epidemiological data the virus is currently being associated with respiratory infections in young children and infants and is furthermore discussed as causative agent of gastrointestinal illness.

Seroepidemiology of human bocavirus defined using recombinant virus-like particles

BACKGROUND

Human bocavirus (HBoV) is a newly identified human parvovirus for which seroepidemiology and antigenic properties remain undefined.

METHODS

The HBoV VP2 gene, expressed from a baculovirus vector, produced virus-like particles (VLPs), which were used to raise rabbit anti-HBoV antisera and to develop an enzyme-linked immunosorbent assay (ELISA). The VLP-based ELISA was used to screen for HBoV-specific immunoglobulin G antibodies in a convenience sample of 270 serum specimens, mostly from children, obtained at Yale-New Haven Hospital; 208 specimens were also screened for erythrovirus B19-specific antibodies by a B19 VLP-based ELISA.

RESULTS

Immunofluorescence and ELISA showed that human parvoviruses HBoV and B19 are antigenically distinct. By the HBoV VLP-based ELISA, 91.8% and 63.6% of serum specimens from infants in the first and second months of life, respectively, were found to be seropositive, as were 45.4% from 3-month-old infants and 25.0% from 4-month-old infants. The percentages of HBoV-seropositive children increased to 40.7%-60.0% for children 5-47 months of age and to >85% for individuals >or=48 months old. However, the overall percentage of B19-seropositive individuals was <40.5% for all age groups screened.

CONCLUSIONS

HBoV infection is common during childhood, but a minority of children and young adults screened have evidence of B19 infection.