Human Bocavirus DNA Research Articles

Absence of human bocavirus from deceased fetuses and their mothers

Background The human bocavirus (HBoV), a newly discovered parvovirus, is closely related to the bovine parvovirus and the canine minute virus, which are known to cause adverse pregnancy outcomes. Another human parvovirus, B19, can lead to fetal hydrops, miscarriage and intrauterine fetal death (IUFD). Objectives To determine the prevalence of HBoV DNA in aborted fetuses and IUFDs. The HBoV serology of the mothers was also studied. Study design We retrospectively studied all available fetuses ( N = 535) autopsied during 7/1992–12/1995, and 1/2003–12/2005 in Helsinki, Finland. All available formalin-fixed paraffin-embedded fetal tissues – placenta, heart and liver – of 120 miscarriages, 169 IUFDs, and 246 induced abortions were studied by quantitative PCR. We also measured the HBoV IgM and IgG antibodies in the corresponding maternal sera ( N = 462) mostly of the first trimester. The IgM-positive sera underwent HBoV PCR. Results None of the fetal tissues harbored HBoV DNA. A total of 97% (448/462) of the mothers were positive for IgG antibodies to HBoV, while only 0.9% (4/462) exhibited HBoV-specific IgM antibodies without viremia or respiratory symptoms. One IgM-positive mother had an unexplained fetal loss. Conclusions We did not find HBoV DNA in any of the deceased fetuses. Almost all pregnant women were HBoV-IgG positive.

Correlation between bocavirus infection and humoral response, and co-infection with other respiratory viruses in children with acute respiratory infection

Background Human bocavirus (HBoV), a recently discovered virus, is prevalent among children with respiratory tract infection throughout the world. Co-infection was frequently found in HBoV-positive patients. Thus, whether HBoV is responsible for the respiratory disease is still arguable. Objectives A comprehensive study was carried out to integrate clinical and virological prevalence in HBoV-positive outpatient children, and to determine genetic and serologic characteristics of HBoV in Shanghai, China. Study design Nasal/throat swabs and sera were obtained over a 2-year period from 817 children with respiratory tract infection to examine the presence of HBoV and its co-infection. The seroepidemiology of HBoV was studied by ELISA and Western blot against the capsid protein VP2-based fragment. Persistence of HBoV was also analyzed in 12 pairs of return-visit cases. Results HBoV was identified in 96 samples (11.8%). The co-infection rate with other respiratory viruses was 51%. IgM was detected in 55.7% of HBoV RT-PCR-positive patients, and in 72.7% of those who had high viral genome load. In addition, persistent viral DNA positivity was detected in 10 of 12 HBoV-positive cases tested, an average of 14 days later, and one child was still HBoV-positive after 31 days. Conclusion HBoV was found frequently in children with respiratory tract symptoms associated with other respiratory viruses, and persisted in the respiratory tract and in serum and urine. The presence of IgM was significantly more prevalent in viremic patients and those diagnosed with high load of HBoV DNA in nasal/throat swabs.

Prevalence of Parvovirus B19 and Human Bocavirus DNA in the Heart of Patients with no Evidence of Dilated Cardiomyopathy or Myocarditis

Although the DNA of parvovirus B19 (B19V) is frequently detected in patients with dilated cardiomyopathy or myocarditis, whether the parvovirus causes disease is questionable, since even in healthy individuals the virus persists in various tissues. The same question applies to human bocavirus (HBoV). We have determined the prevalence and quantity of B19V and HBoV DNA in heart tissue of patients who were not experiencing virus-related heart diseases and analyzed whether the seroprevalence corresponded to DNA prevalence in the heart. Samples of left-atrium heart tissue and serum were obtained from 100 patients who underwent open-heart surgery. Serum immunoglobulin (Ig) G and IgM against proteins encoded by B19V and HBoV were detected by enzyme-linked immunoabsorption assay and immunoblotting. B19V and HBoV DNA concentrations were determined by quantitative real-time polymerase chain reaction (PCR) in heart tissue and serum samples. Nested PCRs for VP1, K71, and GT3 identified the B19V genotypes. The prevalences of serum IgG specific for B19V and HBoV were 85% and 96%, respectively. Of all the patients, 85% had B19V DNA detected in heart tissues, and 4% displayed low-level B19V viremia, whereas only 5% of heart tissue samples and none of the serum samples demonstrated HBoV DNA. The sensitivity of B19V serological testing for B19V DNA in heart samples was 0.96 (95% confidence interval, 0.92-1.0). Specificity was 0.8 (95% confidence interval, 0.6-1.0), and the positive predictive value was 0.96 (95% confidence interval, 0.92-1.0). B19V genotypes 1 and 2 were present in 11% and 89% of heart tissues samples, respectively. B19V genotype 3 was not detected in any of the samples. Our data suggest that B19V but not HBoV demonstrates a lifelong persistence in the heart. The detection of B19V DNA in heart tissue showed no correlation with clinical symptoms. We strongly recommend that serological testing become a standardized procedure for future studies, to obtain representative data concerning the prevalence of B19V in the heart.

Human Bocavirus DNA Detected in a Boy With Plastic Bronchitis

Human Bocavirus DNA Detected in a Boy With Plastic Bronchitis

Prevalence of Human Bocavirus in Human Tonsils and Adenoids

Prevalence of Human Bocavirus in Human Tonsils and Adenoids

No detection of human bocavirus in amniotic fluid samples from fetuses with hydrops or isolated effusions

Background Human bocavirus (HBoV) is a recently identified parvovirus associated with respiratory disease in infants. Animal bocaviruses have been shown to cause intrauterine infection, fetal anasarca and abortion in late gestation. Objectives To investigate whether HBoV infection is associated with fetal hydrops, fetal anemia or isolated fetal effusions. Study design We determined the prevalence of HBoV and parvovirus B19 (B19) DNA in amniotic fluid samples from fetuses with hydrops, anemia or isolated effusions using different real-time PCR protocols, and the HBoV IgG and IgM positivity rate in pregnant women with fetal hydrops or normal ultrasound findings by a non-commercial virus-like particle-based enzyme immunoassay. Results None of 87 amniotic fluid samples tested was HBoV DNA positive. Twelve of 60 fetuses with hydrops or anemia were found B19 DNA positive. Anti-HBoV IgG antibodies were detected in 100% (19/19) and 94% (47/50) of serum samples from pregnant women with fetal hydrops and normal ultrasound findings, respectively. All serum samples were found negative for anti-HBoV IgM. Conclusion We suggest that HBoV is not a common cause of fetal hydrops, anemia or isolated effusions. This has to be confirmed by further studies of proven gestational HBoV infection.

Absence of Parvoviral Genomes in Endothelial Cells of Kawasaki Disease Patients With Coronary Artery Lesions

To the Editors: Kawasaki disease (KD) is the most common systemic vasculitis syndrome primarily affecting small and medium-sized arteries, particularly the coronary artery.1 It is widely believed that KD is due to one or more common infectious agents. Since its initial description, identification of a definitive infectious agent has been elusive, including contradictory data on the role of parvovirus B19 (PVB19).2 Parvovirus infection of the cardiac vascular endothelium has been associated with impaired coronary microcirculation and with diastolic dysfunction and coexisting endothelial dysfunction.3 Human bocavirus (HBoV) is a new member of the Parvoviridae family and appears to be a common cause of acute upper and lower respiratory tract infection in children.4 Catalano-Pons et al5 recently reported the detection of HBoV DNA in nasopharyngeal, serum, or stool samples from 5 of 16 patients with KD, suggesting that this emerging virus may also play a pathogenic role in KD. One of the major limiting factors in efforts to identify etiologic agents in patients with KD is the lack of cardiac tissue samples; most studies have used peripheral samples to look for pathogens. We have previously shown that the number of circulating endothelial cells is higher in KD patients with coronary artery lesions (CAL).6 Therefore, we speculated that parvovirus infection of the coronary endothelium may result in the development of CAL leading to increased endothelial cell shedding into the circulation. In this investigation we studied 22 patients (10 boys and 12 girls), median age being 1.8 years (0.7–5.9 years), with acute KD. The patients were further classified as those with (n = 18) or without CAL (n = 4). From these 22 patients, 39 blood samples were collected up to 4 weeks after disease onset for cell preparations (mean = 1.70 ± 0.69). Endothelial cell smears were prepared and quantitated, as previously described.6 The peripheral blood samples from acute KD patients had elevated numbers of circulating endothelial cells at the time of diagnosis (1.21 ± 3.13/mL). They continued to increase, even after IVIG administration (15.1 ± 14.1/mL), and peaked at 2 weeks (44.2 ± 29.4/mL), which is the time when CAL usually develops, before falling (4.77 ± 2.89/mL; 4 weeks after treatment). The cells from each slide were resuspended in phosphate-buffered saline and then an aliquot was amplified by whole genome amplification using a REPLI-g kit (Qiagen, Valencia, CA). After purification, the DNA was amplified by nested PCR, as described previously for PVB197; primers and amplification conditions available on request. Verification of the presence of amplifiable DNA extracted was performed by single step PCR amplification of a fragment of a single copy gene. Although DNA was isolated for each of the samples, none of the 39 samples was positive for PVB19 or HBoV DNA. These data suggest that persistent infection of coronary endothelial cells with the parvoviruses PVB19 or HBoV does not cause endothelial cell shedding in KD patients. However, it is still not possible to definitively exclude PVB19 or HoBV as causative agents of KD. First, we have not proven that these are derived from the coronary endothelium. Second, if these viruses infected coronary endothelial cells, triggering the events that lead to cell shedding, it is possible that this infection was transient and the viral genome was already cleared. Finally, it is possible that the number of viral genomes present in the cell smears is below the detection limit of the assay. However, the combination of whole genome amplification and nested PCR increased sensitivity to less that 5 genome copies per sample. ACKNOWLEDGMENTS The authors thank Dr. Jeffrey Stevenson, ARUP, and Dr. Mark Poritz, Idaho Technology, Inc., for the PVB19 and HBoV positive DNA samples, respectively, used as PCR controls. Neil E. Bowles, PhD Dept. of Pediatrics (Div. of Cardiology) University of Utah School of Medicine Salt Lake City, UT Keiichi Hirono, MD Xianyi Yu, MD Fukiko Ichida, MD Dept. of Pediatrics University of Toyama Toyama, Japan

Human Bocavirus in Tonsillar Lymphocytes

Human Bocavirus in Tonsillar Lymphocytes

Human Bocavirus quantitative DNA detection in French children hospitalized for acute bronchiolitis

Background Human Bocavirus (HBoV) is a newly discovered parvovirus whose role as a causative agent of respiratory disease remains unclear. Study design We investigated the presence of HBoV by quantitative PCR in the nasopharyngeal samples of 192 French children consecutively hospitalized for acute bronchiolitis. Other common respiratory viruses were detected using immunofluorescence assays, cell culture detection, or RT-PCR assays. Results HBoV was detected in 24 (12.5%) of 192 study children. In 14/192 cases (7%) HBoV was the sole isolate and in 10/192 (5%) it was part of a mixed viral infection. HBoV was the third most common pathogen detected after respiratory syncytial virus (45/192; 23%) and rhinovirus (24/192; 12%). It occurred more often in infants aged 1–12 months ( P = 0.002). Median levels of HBoV DNA genome in respiratory samples were significantly higher in patients with single HBoV infection than in patients with mixed respiratory viral infection with HBoV (4 × 10 8 copies/ml vs. 2 × 10 3 copies/ml, P < 0.001). Conclusions Our data suggest that HBoV at a high viral load could be an etiologic agent of respiratory tract disease, whereas the exact role of HBoV at a low viral load, as etiological cause or as pathophysiological co-factor of respiratory diseases, remains to be determined.

Serodiagnosis of Human Bocavirus Infection

Background. A new human-pathogenic parvovirus, human bocavirus (HBoV), has recently been discovered and associated with respiratory disease in small children. However, many patients have presented with low viral DNA loads, suggesting HBoV persistence and rendering polymerase chain reaction-based diagnosis problematic. Moreover, nothing is known of HBoV immunity. We examined HBoV-specific systemic B cell responses and assessed their diagnostic use in young children with respiratory disease. Patients and methods. Paired serum samples from 117 children with acute wheezing, previously studied for 16 respiratory viruses, were tested by immunoblot assays using 2 recombinant HBoV capsid antigens: the unique part of virus protein 1 and virus protein 2. Results. Virus protein 2 was superior to the unique part of virus protein 1 with respect to immunoreactivity. According to the virus protein 2 assay, 24 (49%) of 49 children who were positive for HBoV according to polymerase chain reaction had immunoglobulin (Ig) M antibodies, 36 (73%) had IgG antibodies, and 29 (59%) exhibited IgM antibodies and/or an increase in IgG antibody level. Of 22 patients with an increase in antibody levels, 20 (91%) had a high load of HBoV DNA in the nasopharynx, supporting the hypothesis that a high HBoV DNA load indicates acute primary infection, whereas a low load seems to be of less clinical significance. In a subgroup of patients who were previously determined to have acute HBoV infection (defined as a high virus load in the nasopharynx, viremia, and absence of other viral infections), 9 (100%) of 9 patients had serological evidence of primary infection. In the control group of 68 children with wheezing who had polymerase chain reaction results negative for HBoV in the nasopharynx, 9 (13%) had IgM antibodies, including 5 who displayed an increase in IgG antibody levels and were viremic. No cross-reactivity with human parvovirus B19 was detected. Conclusions. Respiratory infections due to HBoV are systemic, elicit B cell immune responses, and can be diagnosed serologically. Serological diagnoses correlate with high virus loads in the nasopharynx and with viremia. Serological testing is an accurate tool for disclosing the association of HBoV infection with disease.

Human bocavirus: clinical significance and implications

Human bocavirus (HBoV), a parvovirus, was discovered in 2005 with the use of nonspecific genome amplification techniques. Since its discovery, HBoV has been identified worldwide. This review will focus on the epidemiology and clinical features associated with HBoV infection. Initial studies demonstrated the presence of HBoV DNA in respiratory specimens of individuals with respiratory tract disease. Data from some studies suggest that HBoV may be the etiological agent responsible for respiratory tract disease, particularly in young children. HBoV, however, is frequently detected in the presence of other common respiratory viruses. HBoV is not confined to the respiratory tract as evidence of the virus has been detected in serum and stool, the significance of which remains unclear. Presence of the virus in respiratory secretions, serum and stool suggests that this virus may cause systemic illness. HBoV is an emerging human parvovirus. The full spectrum of disease associated with HBoV remains to be defined.

Human Bocavirus Infections in Hospitalized Children and Adults

Studies have reported human bocavirus (HBoV) in children with respiratory tract infections (RTIs), but only occasionally in adults. We searched for HBoV DNA in nasopharyngeal aspirates (NPAs) from adults with exacerbations of chronic bronchitis or pneumonia, from children hospitalized for acute RTIs, and from asymptomatic children during the winter of 2002-2003 in Canada. HBoV was detected in NPAs of 1 (0.8%) of 126 symptomatic adults, 31 (13.8%) of 225 symptomatic children, and 43 (43%) of 100 asymptomatic children undergoing elective surgery. Another virus was detected in 22 (71%) of the 31 HBoV-positive NPAs from symptomatic children. Two clades of HBoV were identified. The pathogenic role of HBoV in RTIs is uncertain because it was frequently detected in symptomatic and asymptomatic children and was commonly found with other viruses in symptomatic children.

DETECTION OF HUMAN BOCAVIRUS IN CHINESE CHILDREN WITH RESPIRATORY TRACT INFECTION

INTRODUCTION: Human bocavirus (HBoV), a parvovirus discovered in 2005, was identified as a respiratory pathogen in a proportion of respiratory tract diseases with an unknown causative agent. OBJECTIVE: Our goal was to investigate the role of HBoV in acute lower respiratory tract infection in Chinese children. METHODS: Two hundred forty-five nasopharyngeal aspirates collected from January to December 2006 from hospitalized children with acute lower respiratory tract infection were tested for the presence of HBoV DNA by using polymerase chain reaction (PCR) that targeted the NP-1 gene. Bulk PCR products were subjected to nucleotide sequence analysis. Medical charts were reviewed for clinical features of HBoV infection. RESULTS: HBoV DNA was detected in 11 (4.5%) of the 245 nasopharyngeal aspirates. HBoV infection occurred year-round and peaked in winter. The age range of the children was from 48 days to 18 months. Coinfections of HBoV and respiratory syncytial virus were found in 2 (18.2%) of 11 samples. Nucleotide sequence of the NP-1 gene PCR products showed considerably high identity (99%). Clinical symptoms included cough and wheezing. CONCLUSIONS: HBoV seems to be one of the respiratory pathogens for acute respiratory tract infection in the Chongqing area, particularly in young children. Understanding of the clinical relevance of HBoV infection will require additional studies.

Clinical prospective study on maternal-fetal transmission of human bocavirus

To investigate maternal-fetal transmission at human bocavirus (HBoV). IgG antibody to HBoV in serum samples of 316 mothers were determined with ELISA and HBoV DNA was determined with real time PCR in the sera of the mothers and their infants. HBoV-IgG was positive in 40.20 percent (127/316) of the mothers, while it was positive in 29.43 percent (93/316) of the cord blood specimens of the infants. The difference between the two groups was significant (X2=8.12, P less than 0.005); 93 samples of both the mothers and the infants were positive for HBoV-IgG. HBoV-IgG can cross the placenta to the fetuses through placenta. Further study is needed to answer the question whether vertical maternal-fetal transmission occurs.

Human Bocavirus and Gastroenteritis

To the Editor: We read with great interest the recent study by Vicente and colleagues, who suspect the human bocavirus (HBoV), a newly detected parvovirus initially described as a respiratory pathogen, to be a possible causative agent of gastroenteritis in children (1). These researchers investigated the presence of HBoV DNA in 527 stool samples from ambulatory patients (<36 months of age) with unrelated respiratory symptoms. Of these stool samples, 48 (9.1%) were positive for HBoV DNA. Other enteric pathogens were found in 58% of all HBoV-positive fecal samples. A close taxonomic relationship exists between HBoV and bovine parvovirus, an animal virus capable of causing gastrointestinal symptoms in cattle (2). Taking into account the assumed high tenacity of this parvovirus against environmental factors and hospital-grade disinfectants (3,4), we believe the possibility of fecal-oral transmission, in addition to transmission via respiratory droplets, has to be considered in interpreting the observations of Vicente et al. (1). Gastroenteric symptoms have been described in up to 25% of all patients with respiratory HBoV infections (5–7). Although these observations suggest that HBoV may contribute to gastroenteritis or even be a causative agent, further studies are needed. Such studies should include control groups of asymptomatic patients and should test stool samples for HBoV. The correlation between detection of HBoV and clinical symptoms of gastroenteritis needs further confirmation in animal models, which are still not available. Nevertheless, the study by Vicente et al. did not clarify the extent of respiratory symptoms in patients with HBoV-positive stool samples. Taking into account the nature of parvovirus particles, we believe the virus likely passed through the gastrointestinal tract, as patients frequently swallow virus-containing sputum or nasal secretions. Thus, the observation that HBoV is an enteric pathogen should be considered a preliminary finding. Finally, we suggest that the role of HBoV should be investigated through histologic examination of mucosa biopsy specimens (e.g., from patients with chronic gastrointestinal diseases) to confirm pathogenicity.

Parvoviruses and blood transfusion

Parvoviruses and blood transfusion

Prospective study of Human Bocavirus (HBoV) infection in a pediatric university hospital in Germany 2005/2006

Background Human Bocavirus (HBoV), a new species of the genus parvovirus newly detected in 2005, seems to be a worldwide distributed pathogen among children with respiratory tract infection (prevalence 2%–18%). Recently published retrospective studies and one prospective birth cohort study suggest that HBoV-primary infection occurs in infants. Methods Prospective single center study over one winter season (November 2005–May 2006) with hospitalized children without age restriction using PCR-based diagnostic methods. Results HBoV DNA was detected in 11 (2.8%) of 389 nasopharyngeal aspirates from symptomatic hospitalized children (median age 9.0 months; range: 3–17 months). RSV, HMPV, HCoV, and Influenza B were detected in 13.9% ( n = 54), 5.1% ( n = 20), 2.6% ( n = 10), and 1.8% ( n = 7), respectively. There was no influenza A DNA detected in any of the specimens. The clinical diagnoses were acute wheezing (bronchitis) in four patients, radiologically confirmed pneumonia in six patients (55%) and croup syndrome in one patient. In five to six patients with pneumonia, HBoV was the only pathogen detected. While no patient had to be mechanically ventilated, 73% needed oxygen supplementation. In four (36.4%) patients at least one other viral pathogen was found (plus RSV n = 3; 27.3%; Norovirus n = 1; 9.1%). Conclusion HBoV causes severe respiratory tract infections in infants and young children. Its role as a copathogen and many other open questions has to be defined in further prospective studies.

Disseminated Bocavirus Infection after Stem Cell Transplant

Disseminated Bocavirus Infection after Stem Cell Transplant

Seroepidemiology of Human Bocavirus in Hokkaido Prefecture, Japan

A new human virus, provisionally named human bocavirus (HBoV), was discovered by Swedish researchers in 2005. A new immunofluorescence assay using Trichoplusia ni insect cells infected with a recombinant baculovirus expressing the VP1 protein of HBoV was developed, and the levels of immunoglobulin G antibody to the VP1 protein of HBoV in serum samples were measured. The overall seroprevalence rate of antibodies against the VP1 protein of HBoV in a Japanese population aged from 0 months to 41 years was 71.1% (145 of 204). The seropositive rate was lowest in the age group of 6 to 8 months and gradually increased with age. All of the children had been exposed to HBoV by the age of 6 years. A rise in titers of antibody against the VP1 protein of HBoV during the convalescent phase was observed for four patients with lower respiratory tract infections, and HBoV DNA was detected in nasopharyngeal swab and serum samples from all four patients. These results suggest that HBoV is a ubiquitous virus acquired early in life and that HBoV might play a role in the course of lower respiratory tract infections.

Electron Microscopy Observation of Human Bocavirus (HBoV) in Nasopharyngeal Samples from HBoV-Infected Children

The newly identified human bocavirus is frequently detected by molecular techniques in respiratory samples from children with respiratory tract infections, but virions have not been observed so far. We report the electron microscopy observation of viral particles in nasopharyngeal aspirates previously found to be positive for human bocavirus DNA. The virions presented the expected structural characteristics of a Parvoviridae family member.