Human bocavirus in children.

To the Editor: Respiratory tract infection is a major cause of illness in children. Despite the availability of sensitive diagnostic methods, detecting infectious agents is difficult in a substantial proportion of respiratory samples from children with respiratory tract disease (1). This fact suggests the existence of currently unknown respiratory pathogens.

A new virus has been recently identified in respiratory samples from children with lower respiratory tract disease in Sweden (2). Analysis of the full-length genome sequence showed that this virus is closely related to bovine parvovirus and canine minute virus and is a member of the genus Bocavirus, subfamily Parvovirinae, family Parvoviridae. This virus has been provisionally named human Bocavirus (HBoV) (2). HBoV in respiratory samples from Australian children was also recently reported (3). Involvement of this new virus in respiratory tract diseases merits further investigation. We have therefore retrospectively tested for HBoV nasopharyngeal samples collected from children <5 years of age hospitalized with respiratory tract disease.

Samples were collected from 262 children from November 1, 2003, to January 31, 2004. The samples were tested for respiratory viruses by using direct immunofluorescence assays with monoclonal antibodies to respiratory syncytial virus; influenza virus types A and B; parainfluenza virus types 1, 2, and 3; and adenovirus. Samples were also placed on MRC5 cell monolayers for virus isolation and tested for human metapneumovirus by reverse transcription-polymerase chain reaction (RT-PCR). Nucleic acids were extracted from samples, stored at -80[degrees]C, and tested for HBoV DNA by PCR with primers specific for the predicted NP 1 gene as previously described (2). The expected product size was 354 bp. In each experiment, a negative control was included, and positive samples were confirmed by analyzing a second sample. Amplification specificity was verified by sequencing.

Nine (3.4%) samples were positive. Comparison of PCR product sequences of these 9 isolates (GenBank accession nos. AM 109958-AM109966) showed minor differences that occurred at 1 to 4 nucleotide positions, and a high level of sequence identity (99%-100%) was observed with the NP1 sequences of the previously identified ST1 and ST2 isolates (2). This finding indicates that HBoV is a highly conserved virus.

HBoV was the only virus identified in 6 children and was associated with respiratory syncytial virus in 3 other children. An infection with other respiratory viruses was detected among 153 (60.5%) of the 253 HBoV-negative children. The viruses identified were respiratory syncytial virus in 114 (43.5%) samples, human metapneumovirus in 27 (10.3%) samples, influenza A virus in 14 (5.4%) samples, rhinovirus in 4 (1.5%) samples, adenovirus in 2 (0.8%) samples, and parainfluenza virus type 3 in 1 (0.4%) sample. Respiratory syncytial virus was associated with human metapneumovirus in 9 (3.4%) samples.

Clinical characteristics of the HBoV-infected children are shown in the Table. Children infected with only HBoV had mild-to-moderate fevers. Leukocyte counts and C-reactive protein levels were normal or moderately elevated. Chest radiographs obtained for 7 children showed abnormalities such as hyperinflation and interstitial infiltrates. Bronchiolitis was the major diagnosis. Dyspnea, respiratory distress, and cough were the most common respiratory symptoms observed. Four (44%) HBoV-infected children were born preterm, which suggests that these children have an increased susceptibility to HBoV-associated diseases. All children recovered and were discharged within 1 to 6 days.

The 3.4% incidence of HBoV observed in our study is similar to that (3.1%) reported by Allander et al. (2). HBoV was the only infectious agent identified in 6 children, which suggests that it was the causative agent of the disease. However, more studies conducted in children with and without respiratory disease as well as in adults and elderly persons are needed to better assess the pathogenic role of HBoV.

This work was supported by a grant from the Programme Hospitalier de Recherche Clinique of the Montpellier University Hospital (AOI 2003).

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 USA. 2005;102:12891-6.

(3.) Sloots TP, McErlean P, Speicher DJ, Arden K, Nissen MD, Mackay IA. Evidence of human coronavirus HKU1 and human bocavirus in Australian children. J Clin Virol. 2005;35:99-102.

Vincent Foulongne, * Michel Rodiere , * and Michel Segondy *

* Montpellier University Hospital, Montpellier, France

Address for correspondence: Vincent Foulongne, Laboratory of Virology, Montpellier University Hospital, 80 Ave A. Fliche, Montpellier 34295, France; email: [e-mail]

Table. Characteristics of extended-spectrum [beta]-lactamase-producing
Enterobacteriaceae in Bangui, Central African Republic

                                        Results of sequencing
                      Patient
Strain ([dagger])   hospitalized   [bla.sub.CTX-M]   [bla.sub.SHV]

K. pneumoniae 022        N                              SHV-2a
K. pneumoniae 043        Y                              SHV-12
K. pneumoniae 106        Y            CTX-M-15
K. pneumoniae 047        Y                              SHV-2a
E. coli 272              Y            CTX-M-15
E. coli 065              Y            CTX-M-15
E. coli 047              N            CTX-M-15
E. coli 010              N            CTX-M-15
E. coli 073              N            CTX-M-15
E. coli 059              Y            CTX-M-15
E. coli 064              N            CTX-M-15
E. coli 070              N            CTX-M-15
E. coli 054              N            CTX-M-15
E. coli 026              N            CTX-M-15
E. cloacae 081           Y                              SHV-12
E. cloacae 106           Y                              SHV-12
E. aerogenes 014         Y             CTX-M-3          SHV-12

                     Results of     MICs of [beta]-lactams
                     sequencing        ([micro]g/mL) *

Strain ([dagger])   [bla.sub.TEM]   AMC   CTX   CAZ   CRO

K. pneumoniae 022       TEM-1       16    16    16    16
K. pneumoniae 043       TEM-1       16    16    256   32
K. pneumoniae 106       TEM-1        8    256   128   256
K. pneumoniae 047       TEM-1       64    16    16    16
E. coli 272             TEM-1       32    256   128   256
E. coli 065             TEM-1       20    256   128   256
E. coli 047             TEM-1       16    256   32    256
E. coli 010             TEM-1       32    256   128   256
E. coli 073             TEM-1       16    256   128   256
E. coli 059             TEM-1       19    256   128   256
E. coli 064             TEM-1       128   256   128   256
E. coli 070             TEM-1       128   256   128   256
E. coli 054             TEM-1       128   256   32    256
E. coli 026             TEM-1       32    256   64    256
E. cloacae 081          TEM-1       32    16    256   16
E. cloacae 106          TEM-1       128   16    256   16
E. aerogenes 014        TEM-1       128   256   256   256

                          MICs of
                      [beta]-lactams
                     ([micro]g/mL) *

Strain ([dagger])    FEP    CPO   ATM   Resistance

K. pneumoniae 022     8      8     2       KGT
K. pneumoniae 043     8      8    256     KGTNC
K. pneumoniae 106    64     256   64       None
K. pneumoniae 047     8     16    32       None
E. coli 272          128    256   128     KGTNC
E. coli 065          64     256   128       C
E. coli 047          32     128   64       KGTC
E. coli 010          128    256   256      KGT
E. coli 073          128    256   128      KGTC
E. coli 059           8     256   256       C
E. coli 064          64     256   64        C
E. coli 070          64     256   128       C
E. coli 054          64     256   32       KGTC
E. coli 026          128    256   256      KGTC
E. cloacae 081      0.125    1    256      KGTN
E. cloacae 106       32      8    256      KGT
E. aerogenes 014     32     256   128      KGTN

* AMC, amoxicillin + clavulanic acid (2 [micro]g/mL); CTX, cefotaxime;
CAZ, ceftazidime; CRO, ceftriaxone; FEP, cefepime; CPO, cefpirome;
ATM, aztreonam; K, kanamycin; G, gentamicin; T, tobramycin; N,
netilmicin; C, ciprofloxacin.

([dagger]) On Klebsiella pneumoniae strains, polymerase chain reaction
and sequencing for [blas.sub.SHV] genes were studied on Escherichia
coli transconjugant or electroporant.