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Human bocavirus in French children.



Human bocavirus (HBoV), a new member of the genus Bocavirus in the family Parvoviridae, has been recently associated with respiratory tract infections. We report the epidemiologic and clinical features observed from a 1-year retrospective study retrospective study,
a study in which a search is made for a relationship between one phenomenon or condition and another that occurred in the past (e.g.
 of HBoV infection in young children hopitalized with a respiratory tract infection.

**********

Viral respiratory tract infections cause a substantial amount of illness and death in children. Respiratory syncytial virus respiratory syncytial virus (sĭnsĭsh`əl): see cold, common.  (RSV RSV respiratory syncytial virus; Rous sarcoma virus.

RSV
abbr.
respiratory syncytial virus


RSV 1 Respiratory syncytial virus, see there 2 Rous sarcoma virus, see there
), influenza A influenza A
n.
Influenza caused by infection with a strain of influenza virus type A.


influenza A Infectious disease An avian virus, especially of ducks–which in China live near the pig reservoir and 'vector';
 and B viruses, parainfluenza viruses, human adenoviruses, rhinoviruses, corona viruses, and the more recently identified human metapneumovirus (HMPV) all cause respiratory tract infections. However, in a substantial proportion of respiratory tract infections, no etiologic agent is detected (1), which suggests unknown pathogens. A previously unknown virus likely involved in children's respiratory tract infections has been recently described in Sweden (2) and was also identified in Australia (3) and Japan (4). This newly identified virus shares a high sequence identity and a similar genomic organization with bovine parvovirus parvovirus (pär'vōvī`rəs), any of several small DNA viruses that cause several diseases in animals, including humans. In humans, parvoviruses cause fifth disease, or erythema infectiosum, an acute disease usually affecting young  and canine minute virus Canine minute virus is a type of virus of the family Parvoviridae that infects dogs. It is most similar to bovine parvovirus in its protein structure and DNA. , 2 related members of the Bocavirus genus in the Parvovirinae subfamily subfamily /sub·fam·i·ly/ (sub´fam-i-le) a taxonomic division between a family and a tribe.

sub·fam·i·ly
n.
A taxonomic category ranking between a family and a genus.
 of the Parvoviridae family, and it was provisionally named human bocavirus (HBoV).

To investigate epidemiologic features of this virus and further specify clinical signs associated with HBoV infections, we retrospectively tested respiratory specimens from children obtained during a 1-year period. We report the incidence and seasonal distribution of HBoV, provide a phylogenetic phy·lo·ge·net·ic
adj.
1. Of or relating to phylogeny or phylogenetics.

2. Relating to or based on evolutionary development or history.
 analysis of HBoV isolates, and describe clinical characteristics of HBoV infection.

The Study

The study sample comprised 589 children <5 years of age who were admitted to a pediatric pediatric /pe·di·at·ric/ (pe?de-at´rik) pertaining to the health of children.

pe·di·at·ric
adj.
Of or relating to pediatrics.
 unit of the University Hospital of Montpellier (France) for acute respiratory tract disease, from November 2003 to October 2004. They were 306 boys and 283 girls with a median age of 7 months (range 2 days-60 months). Nasopharyngeal nasopharyngeal

pertaining to the nasal and pharyngeal cavities.


nasopharyngeal meatus
see nasopharyngeal meatus.

nasopharyngeal spasm
see reverse sneeze.
 aspirates from these children were tested for common viral respiratory pathogens as previously described (5). Samples were tested for respiratory viruses by direct immunofluorescence Immunofluorescence

A technique that uses a fluorochrome to indicate the occurrence of a specific antigen-antibody reaction. The fluorochrome labels either an antigen or an antibody.
 assays with monoclonal antibodies to RSV; influenza A and B viruses; parainfluenza parainfluenza Infectious disease A virus that causes URIs–up to 50% of croup and 10–15% of bronchiolitis, bronchitis, pneumonias in toddlers Clinical Rhinorrhea, cold-like Sx Risk factors Preschool children; by school age most children have been exposed  type 1, 2, and 3 viruses; and human adenovirus adenovirus

Any of a group of spheroidal viruses, made up of DNA wrapped in a protein coat, that cause sore throat and fever in humans, hepatitis in dogs, and several diseases in fowl, mice, cattle, pigs, and monkeys.
. Samples were also injected into MRC See Maximum return criterion. 5 cell monolayers for virus isolation, and they were tested for HMPV by reverse transcription PCR PCR polymerase chain reaction.

PCR
abbr.
polymerase chain reaction


Polymerase chain reaction (PCR) 
. Aliquots of samples and of nucleic acid extracts were stored at -80[degrees]C.

Nucleic acid extracts were tested for HBoV DNA DNA: see nucleic acid.
DNA
 or deoxyribonucleic acid

One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes.
 by PCR with primers targeting the predicted NP1 gene (2). A negative control was included in each PCR run. All HBoV-positive samples were quantitated by real-time PCR with a second sample aliquot aliquot (al-ee-kwoh) adj. a definite fractional share, usually applied when dividing and distributing a dead person's estate or trust assets. (See: share) . For quantitating HBoV DNA in the positive samples, the 354-bp NP1 PCR fragment was cloned into pGEM-T Easy Vector (Promega, Charbonnieres, France). The obtained HBoV-NP1 plasmid was used as control in a subsequent 5'-exonuclease-based real-time PCR assay performed on a LightCycler 2.0 (Roche Diagnostics, Meylan, France) with 2 inner primers (BocaRT1, 5'-CGAAGATGAGCTCAGGGAAT-3' and BocaRT2, 5'-GCTGATTGGGTGTTCCTGAT-3') and a FAM/TAMRA dually labeled probe (5'-FAM-CACAGGAGCAGGAGCCGCAGTAMRA-3'). Amplification was performed on 10 gL nucleic acid extract with 0.5 [micro]mol/L both primers and probe and 3 mmol/L Mg[Cl.sub.2] with FastStart DNA Hybridization Mix (Roche Diagnostics). For quantitation, standard curves were generated by 10-fold dilutions of the pGEM-T HBoV NP1 plasmid. Sensitivity of the PCR assay was 50 copies per reaction as determined by dilutions of the plasmid. DNA level in the HboV-positive samples was measured by using the LightCycler control DNA kit (Roche Diagnostics). Results were expressed as log HBoV DNA copies per nanogram nanogram /nano·gram/ (ng) (nan?o-gram) one billionth (10-9) of a gram.

nan·o·gram
n. Abbr. ng
One billionth (10-9) of a gram.
 of extracted DNA.

We identified 268 viruses in 259 (44.0%) of the 589 children. Of the 589 children, 165 (28.0%) were infected with RSV, 50 (8.5%) with HMPV, 18 (3.1%) with influenza A viruses, 18 (3.1%) with rhinoviruses, 9 (1.5%) with parainfluenza type 3 viruses, and 8 (1.3%) with human adenoviruses.

Nasopharyngeal aspirates were positive for HBoV in 26 children (4.4%). Among these HBoV-infected children, 9 (34.6%) were coinfected with another respiratory virus: 5 with RSV, 2 with HMPV, and 2 with human adenovirus. The median HBoV viral load was 2.61 log copies/ng of DNA (range 1.26-4.26 log copies/ng of DNA). The seasonal distribution of respiratory viruses is shown in Figure 1; HBoV was detected from December to June.

[FIGURE 1 OMITTED]

Seven HBoV isolates (corresponding to 1 isolate per month) were selected for sequence analysis of a 1-kb DNA fragment encompassing the VP2 gene. Amplification and sequencing primers were as follows: BocaSEQ1 (5 '-AAAATGAACTAGCAGATCTTGATG3'), BocaSEQ4 (5'-GAACTTGTAAGCAGAAGCAAAA3'), BocaSEQ2 (5'-GTCTGGTTTCCTTTGTATAGGAGT3'), and BocaSEQ3 (5'-GACCCAACTCCTATACAAAGGAAAC-3'). These HBoV VP2 sequences were deposited in GenBank under accession numbers AM160609 to AM160615. The nucleotide sequences were aligned, and a phylogenetic tree was constructed to include the 2 previously deposited HBoV sequences ST1 and ST2 as well as the VP2 sequences of canine minute virus (NC_004442) and bovine parvovirus (NC_001540). The VP2 gene of human parvovirus B19 (NC_000883) was chosen as outgroup to root this tree (Figure 2). Our VP2 sequences shared 97.5%-100% nucleotide identity with the HBoV prototype strains ST1 and ST2, whereas amino acid identity was 98.9%-100%.

[FIGURE 2 OMITTED]

The 26 HBoV-infected children had a median age of 13 months, and the ratio of boys to girls was 1.9. The median duration of hospital stay was 4 days (range 2-39 days). Bronchiolitis Bronchiolitis Definition

Bronchiolitis is an acute viral infection of the small air passages of the lungs called the bronchioles.
Description

Bronchiolitis is extremely common.
 was the leading diagnosis, and upper respiratory pathologic features were uncommon. The clinical signs and symptoms among children with HBoV are shown in the Table. The predominant symptoms were dyspnea dyspnea /dysp·nea/ (disp-ne´ah) labored or difficult breathing.dyspne´ic

paroxysmal nocturnal dyspnea
, respiratory distress, and cough. Half of the children had fever (temperature >38[degrees]C). Chest radiographs were obtained for 18 HBoV-infected children, and 15 of them (83.3%) showed abnormal findings, such as hyperinflation Hyperinflation

Extremely rapid or out of control inflation.

Notes:
There is no precise numerical definition to hyperinflation. This is a situation where price increases are so out of control that the concept of inflation is meaningless.
 or interstitial infiltrates. History of asthma or previous bronchiolitis episodes were reported in 6 HBoV-infected children (23.0%). Three children (11.5%) had an underlying disease (1 congenital heart disease congenital heart disease, any defect in the heart present at birth. There is evidence that some congenital heart defects are inherited, but the cause of most cases is unknown.  and 2 chronic respiratory diseases), and 7 (26.9%) were born preterm preterm /pre·term/ (-term´) before completion of the full term; said of pregnancy or of an infant.

pre·term
adj.
 (<36 weeks). Laboratory parameters such as oxygen saturation, C-reactive protein level, or leukocyte count were not relevant in this context.

Conclusions

Our data indicate that among children <5 years of age hospitalized with a community-acquired respiratory tract infection, HBoV was detected in 4.4% and represented the third most likely etiologic agent after RSV and HMPV. This 4.4% incidence is in accordance with the values of 3.1%, 5.6%, and 5.7% reported by Allander et al. (2), Sloots et al. (3), and Ma et al. (4). HBoV was detected from December to June, which suggests an epidemiologic difference with respiratory viruses such as RSV, HMPV, or influenza A virus (Figure 1). The absence of HBoV circulation during summer and early fall needs further confirmation. Indeed, this finding might be in part explained by the low number of samples collected during this period.

We previously showed that the HBoV NP1 gene displayed limited sequence variation (6). In the present study, we also observed only minor sequence variations in the VP2 gene, which suggests that the diverse strains of HBoV belong to a unique lineage. This low genetic diversity of HboV was also reported by Sloots et al., who analyzed the NS1 gene (3).

HBoV infections were mainly identified in children with lower respiratory tract Noun 1. lower respiratory tract - the bronchi and lungs
lung - either of two saclike respiratory organs in the chest of vertebrates; serves to remove carbon dioxide and provide oxygen to the blood
 diseases such as bronchiolitis. HBoV was also found in children with asthma exacerbation and, less frequently, in children with upper respiratory infection Noun 1. upper respiratory infection - infection of the upper respiratory tract
respiratory infection, respiratory tract infection - any infection of the respiratory tract
, which suggests that HBoV shares clinical features with respiratory viruses such as RSV or HMPV (5,7). Underlying diseases, asthma, or previous bronchiolitis episodes as well as history of prematurity were observed in 61.5% of HBoV-infected children. Even though this feature may be explained by more systematic hospitalization of these children, HBoV pathogenicity may be facilitated by predisposing conditions.

In 9 (34.6%) instances, HBoV was detected concurrently with another respiratory virus. In the original description of HBoV, 17.6% of coinfections involved human adenovirus or RSV (2). More recently, a high rate of coinfection (55.6%) was seen in a population of children <3 years of age (3). Considering these high rates of coinfection, the exact role played by HBoV in respiratory tract diseases needs to be more precisely defined.

This work was supported by a grant from the Programme Hospitalier de Recherche Clinique of the Montpellier University Hospital.

References

(1.) Juven T, Mertsola J, Waris M, Leimonen M, Meurman O, Roivanen M, et al. Etiology of community-acquired pneumonia in 254 hospitalized children. Pediatr Infect Dis J. 2000;19:293-8.

(2.) Allander T, Tammi MT, Eriksson M, Bjerkner A, Tiveljung-Lindell A, Anderson B. Cloning of a human parvovirus by molecular screening of respiratory tract samples. Proc Natl Acad Sci U S A. 2005;102:12891-6.

(3.) Sloots TP, McErlean P, Speicher DJ, Arden K, Nissen MD, Mackay IA. Evidence of human coronavirus coronavirus /co·ro·na·vi·rus/ (ko-ro´nah-vi?rus) any virus belonging to the family Coronaviridae.
Coronavirus /Co·ro·na·vi·rus/ (ko-ro´nah-vi?rus 
 HKU HKU University of Hong Kong
HKU Hogeschool voor de Kunsten Utrecht (Utrecht School of The Arts, The Netherlands)
HKU Hot Key Users
1 and human bocavirus in Australian children. J Clin Virol. 2005;35:99-102.

(4.) Ma X, Endo R, Ishiguro N, Ebihara T, Ishiko H, Ariga T, et al. Detection of human bocavirus in Japanese children with lower respiratory tract infections. J Clin Microbiol. 2006;44:1132-4.

(5.) Foulongne V, Guyon G, Rodirre M, Segondy M. Human metapneumovirus infection in young children hospitalized with respiratory tract disease. Pediatr Infect Dis J. 2006;25:354-9.

(6.) Foulongne V, Rodiere M, Segondy M. Human bocavirus in children. Emerg Infect Dis. 2006; 12:862-3.

(7.) Iwane MK, Edwards KM, Szilagyi PG, Walker FJ, Griffin MR, Weinberg GA, et al. Population-based surveillance for hospitalizations associated with respiratory syncytial virus, influenza virus, and parainfluenza viruses among young children. Pediatrics. 2004;113:1758-64.

Vincent Foulongne, * Yann Olejnik, * Virginie Perez, * Stephane Elaerts, * Michel Rodiere, * and Michel Segondy *

* Montpellier University Hospital, Montpellier, France

Dr Foulongne is a virologist virologist

microbiologist specializing in virology.
 in the Department of Virology virology, study of viruses and their role in disease. Many viruses, such as animal RNA viruses and viruses that infect bacteria, or bacteriophages, have become useful laboratory tools in genetic studies and in work on the cellular metabolic control of gene expression , University Hospital of Montpellier, and associate professor in microbiology at Montpellier University, France. His primary research interests are in clinical virology and molecular diagnosis of viral infectious agents.

Address for correspondence: Vincent Foulongne, Laboratory of Virology, Hopital St-Eloi, 34295 Montpellier CEDEX 5, France; email: v-foulongne@chu-montpellier.fr
Table. Characteristics of 26 children infected with HBoV *

Characteristic                                      Value

Demographic data
  Age (mo), median (range)                         13(4-43)
  No. boys/no. girls                                 17/9
Virologic data
  HBoV viral load (log copies/ng DNA),         2.61 (1.26-4.26)
  median (range)
  Viral coinfection, ([dagger]) no. (%)            9 (34.6)
Laboratory findings
  CRP (mg/L), median (range), n = 22            13.5 (<5-166)
  Leukocytes (x [10.sup.3]/[micro]L), median   13.2 (7.7-32.0)
  (range), n = 24
  Sa[O.sub.2] (%), median (range), n = 17         93 (68-99)
Chest radiographic findings, no. (%), n = 18
  Hyperinflation                                  14 (72.2)
  Infiltrate                                       7 (38.8)
  Atelectasis                                      2 (11.1)
  Normal                                           3 (16.6)
Clinical findings, no. (%)
  Temperature >38[degrees]C                       13 (50.0)
  Cough                                           13 (50.0)
  Dyspnea, wheezing                               14 (53.8)
  Respiratory distress                            14 (53.8)
  Rhinorrhea, pharyngitis                          8 (30.7)
  Otitis                                           4 (15.4)
Final diagnosis, no. (%)
  Bronchiolitis                                   12 (46.1)
  Pneumonia                                        3 (11.5)
  Asthma                                           7 (26.9)
  Upper respiratory tract infection                4 915.4)

* HBoV, human bocavirus, CRP, C-reactive protein; Sa[O.sub.2],
arterial oxygen saturation.

([dagger]) Respiratory syncytial virus (n = 5), human
metapneumovirus (n = 2), and adenovirus (n = 2).
COPYRIGHT 2006 U.S. National Center for Infectious Diseases
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Title Annotation:DISPATCHES
Author:Segondy, Michel
Publication:Emerging Infectious Diseases
Geographic Code:4EUFR
Date:Aug 1, 2006
Words:1843
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