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

Abstract

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.

Human bocavirus infection in Belgian children with respiratory tract disease

“…All but one of the children were younger than 3 years of age. This is in agreement with previous studies in which it was observed that most HBoV infections occur between the ages of 6 months and 3 years [5,23,29]. This distribution is compatible with protection from infection by maternal antibodies.…”

“…In this group, a relationship was observed between HBoV and LRTD. Some previous studies have found high viral loads to be associated with more-severe symptoms [9], while others have failed to find a clear relationship [5,7,23]. In our opinion, it is not possible to establish a clear relationship between viral load and severity of LRTD.…”

“…HBoV1 is predominantly found in respiratory tract secretions from children with RTD, and HBoV2-4 are found mainly in stool samples from patients with gastroenteritis [3,4]. HBoV is predominantly present in winter and spring [5]. The average prevalence of HBoV in respiratory tract samples ranges from 1.0% to 56.8%, depending on the country.…”

Influence of viral load in the outcome of hospitalized patients with influenza virus infection

“…Another potential limitation of the study is that the commercially available diagnostic methods for the detection of influenza virus are qualitative techniques that do not allow the performance of a viral load in a strict sense. However, the Ct value is routinely used in virology laboratories as a semi-quantitative measure of the amount of virus present in samples as has been shown in previous studies [21][22][23][24]. Our data would support the use of quantitative PCR for the management of hospitalized patients with influenza virus infection in order to discriminate the presence of abnormal findings on chest X-ray or lymphopenia.…”

“…Viral load was measured by real-time reverse-transcriptase-polymerase chain reaction (rRT-PCR) cycle threshold (Ct) value on upper respiratory tract samples. Its value was categorized into three groups (low Ct,≤ 20; intermediate Ct,(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) and high Ct, > 30). Two hundred thirty-nine patients were included.…”