Seroepidemiology of human bocavirus in Apulia, Italy

Exploring evidence from cells to clinics: is human bocavirus a gastrointestinal pathogen or just a risk factor?

Human bocaviruses (HBoVs), first identified in 2005 and composed of genotypes 1-4, have been increasingly detected worldwide in pediatric patients with acute gastroenteritis. HBoV-1 has been primarily associated with respiratory symptoms, while HBoV2-4 are mostly found in gastrointestinal (GI) samples. Results from case-control studies are still controversial; however, epidemiological evidence has shown a significant association between HBoV-2 and gastroenteritis. This review will primarily focus on this association, with a brief discussion of evidence related to other HBoV genotypes. Pathological and molecular studies on the pathogenesis of HBoV, particularly in GI cells, are very scarce, possibly due to the difficulties of in vitro HBoV culture. Nonetheless, some relevant findings from colorectal cancer samples have yielded valuable insights regarding the behavior of HBoV in the GI system. In the present review, we provide an updated overview of the epidemiological evidence for an association of HBoV infection with acute gastroenteritis and focus on the cellular and molecular perspectives of HBoV pathogenicity. Finally, we look at the knowledge gaps about how HBoV affects the GI system and explore future directions.

A Multi-Pathogen Retrospective Study in Patients Hospitalized for Acute Gastroenteritis

Acute gastroenteritis (AGE) is a gastrointestinal tract disease often caused by consuming food or water contaminated by bacteria, viruses, or parasites, that can lead to severe symptoms requiring hospitalization. A retrospective study on patients admitted for AGE between 2021 and 2023 at the Pediatrics and Infectious Diseases Departments of Lecce Hospital was conducted. Demographic characteristics, year and month of admission, length of hospital stay, etiological agents, co-infections, and blood chemistry data of patients were collected. The study included 103 patients ranging in age from 0 to 15 years, with 58.25% being male. A total of 78 bacterial, 35 viral, and 7 parasitic infections were identified. The most commonly detected pathogens were Escherichia coli (38.83%), Norovirus (28.16%), Campylobacter jejuni (22.33%), and Salmonella typhi/paratyphi (10.68%). Only a few cases of Cryptosporidium (5.83%) were identified. Additionally, 17 co-infections (16.50%) were detected. Viral infections are the primary cause of hospitalization for AGE in children <5 years, while bacterial infections are more common among older patients. The significantly higher number of children <5 years old with elevated creatinine compared to children ≥5 years suggested that young children are more susceptible to dehydration than older children. Few cases of AGE were attributed to pathogens for which a vaccine has already been licensed. AGE is a serious health concern that could be effectively prevented by implementing food-based and community-level sanitation systems, as well as by increasing vaccination coverage of available vaccines and developing new effective and safe vaccines.

Development of RPA-Cas12a-fluorescence assay for rapid and reliable detection of human bocavirus 1

Human bocavirus (HBoV) 1 is considered an important pathogen that mainly affects infants aged 6-24 months, but preventing viral transmission in resource-limited regions through rapid and affordable on-site diagnosis of individuals with early infection of HBoV1 remains somewhat challenging. Herein, we present a novel faster, lower cost, reliable method for the detection of HBoV1, which integrates a recombinase polymerase amplification (RPA) assay with the CRISPR/Cas12a system, designated the RPA-Cas12a-fluorescence assay. The RPA-Cas12a-fluorescence system can specifically detect target gene levels as low as 0.5 copies of HBoV1 plasmid DNA per microliter within 40 min at 37°C without the need for sophisticated instruments. The method also demonstrates excellent specificity without cross-reactivity to non-target pathogens. Furthermore, the method was appraised using 28 clinical samples, and displayed high accuracy with positive and negative predictive agreement of 90.9% and 100%, respectively. Therefore, our proposed rapid and sensitive HBoV1 detection method, the RPA-Cas12a-fluorescence assay, shows promising potential for early on-site diagnosis of HBoV1 infection in the fields of public health and health care. The established RPA-Cas12a-fluorescence assay is rapid and reliable method for human bocavirus 1 detection. The RPA-Cas12a-fluorescence assay can be completed within 40 min with robust specificity and sensitivity of 0.5 copies/μl.

Prevalence, molecular characterization, and clinical features of human bocavirus in children under 5 years of age with acute gastroenteritis admitted to a specialized children's hospital in Iran: A cross-sectional study

Background and Aims

Although some reports have confirmed the role of human bocavirus (HBoV) in respiratory infections, the importance of this virus in causing acute gastroenteritis has not yet been proven. This study aimed to determine the molecular prevalence of HBoV in children under 5 years old with gastroenteritis and to compare the clinical symptoms of HBoV-positive and -negative gastroenteritis cases.

Methods

A total of 100 stool samples were collected from children with gastroenteritis hospitalized in a pediatric hospital in Tehran, Iran. Demographic and clinical data were collected from patients' medical records. Viral genomic DNA was extracted from stool samples and amplified using the PCR assay. Finally, sequencing was used to determine the genotype of HBoV.

Results

The HBoV genome was detected in 14 samples (14%). The highest prevalence of HBoV was observed in the age range of 24-60 months (n = 5; 35.7%); However, no statistically significant relationship was observed between the prevalence of HBoV and age groups (p = 0.09). Nine (64.3%) and 5 (35.7%) HBoV-positive cases were boys and girls, respectively (p = 0.45). Fever, vomiting, and heartache were seen in 5 (35.7%), 3 (21.4%), and 1 (7.1%) HBoV-positive patients, respectively. Overall, no significant difference was observed in any of the investigated clinical manifestations between patients positive or negative for HBoV. Five HBoV-positive samples were subjected to sequencing and all five sequenced samples were genotype 3.

Conclusion

HBoV infections can be considered a risk factor for causing at least a portion of acute gastroenteritis cases in children under 5 years of age.

Unexpected Severe Bocavirus Infections among Hospitalized Children during the COVID-19 Pandemic

Objective Acute respiratory tract infections are one of the leading causes of morbidity and mortality in children. Although human bocavirus (HBoV) infections are not as common as other seasonal respiratory viruses, children who are infected with HBoV are more likely to suffer from a variety of respiratory conditions, including the common cold, acute otitis media, asthma exacerbations, bronchiolitis pneumonia, some of the affected children require pediatric intensive care unit stay. Here, we aimed to evaluate pediatric bocavirus (HBoV) cases presenting with severe respiratory tract symptoms during the coronavirus disease 2019 (COVID-19) pandemic.

Methods This retrospective study evaluated the medical records of children diagnosed with respiratory infections, followed up at the Faculty of Medicine, Eskisehir Osmangazi University between September 2021 and March 2022. In this study, patients with HBoV identified using nasopharyngeal polymerase chain reaction (PCR) were considered positive. Cases were analyzed retrospectively for their clinical characteristics.

Results This study included 54 children (29 girls and 25 boys) with HBoV in nasopharyngeal PCR samples. The cases ranged in age from 1 month to 72 months (median 25 months). At the time of presentation, cough, fever, and respiratory distress were the most prevalent symptoms. Hyperinflation (48%), pneumonic consolidation (42%), and pneumothorax–pneumomediastinum (7%) were observed on the chest X-ray; 54% of the children required intensive care unit stay. The median length of hospitalization was 6 days. Bacterial coinfection was detected in 7 (17%) children, while HBoV and other viruses were present in 20 (37%) children; 57% of children received supplemental oxygen by mask, 24% high-flow nasal oxygen, 7% continuous positive airway pressure, and 9% invasive mechanical ventilation support. Antibiotics were given to 34 (63%) cases, and systemic steroid treatment was given to 41 (76%) cases. Chest tubes were inserted in three out of the four cases with pneumothorax–pneumomediastinum. All patients were recovered and were discharged from the hospital.

Conclusion The COVID-19 pandemic changed the epidemiology of seasonal respiratory viruses and the clinical course of the diseases. Although it usually causes mild symptoms, severe respiratory symptoms can lead to life-threatening illnesses requiring intensive care admission.

Prevalence and Genetic Characteristics of Human Bocaviruses Detected in Patients with Acute Respiratory Infections in Bulgaria

Нuman bocaviruses (hBoVs) are often associated with acute respiratory infections (ARIs). Information on the distribution and molecular epidemiology of hBoVs in Bulgaria is currently limited. The objectives of this study were to investigate the prevalence and genetic characteristics of hBoVs detected in patients with ARIs in Bulgaria. From October 2016 to September 2019, nasopharyngeal/oropharyngeal swabs were prospectively collected from 1842 patients of all ages and tested for 12 common respiratory viruses using a real-time RT-PCR. Phylogenetic and amino acid analyses of the hBoV VP1/VP2 gene/protein were performed. HBoV was identified in 98 (5.3%) patients and was the 6^th most prevalent virus after respiratory-syncytial virus (20.4%), influenza A(H1N1)pdm09 (11.1%), A(H3N2) (10.5%), rhinoviruses (9.9%), and adenoviruses (6.8%). Coinfections with other respiratory viruses were detected in 51% of the hBoV-positive patients. Significant differences in the prevalence of hBoVs were found during the different study periods and in patients of different age groups. The detection rate of hBoV was the highest in patients aged 0-4 years (6.9%). In this age group, hBoV was the only identified virus in 9.7%, 5.8%, and 1.1% of the children diagnosed with laryngotracheitis, bronchiolitis, and pneumonia, respectively. Among patients aged ≥5 years, hBoV was detected as a single agent in 2.2% of cases of pneumonia. Phylogenetic analysis showed that all Bulgarian hBoV strains belonged to the hBoV1 genotype. A few amino acid substitutions were identified compared to the St1 prototype strain. This first study amongst an all-age population in Bulgaria showed a significant rate of hBoV detection in some serious respiratory illnesses in early childhood, year-to-year changes in the hBoV prevalence, and low genetic variability in the circulating strains.

Predominance of Human Bocavirus Genotypes 1 and 2 in Oysters in Thailand

Human bocavirus (HBoV) has been recognized as an important pathogen that causes respiratory infection and acute gastroenteritis in young children worldwide. HBoV is most likely transmitted by the respiratory route and by fecal-oral transmission. Recently, HBoV has been detected in several types of environmental water and in bivalve shellfish. However, study of the existence of HBoV in oysters is still undocumented in Thailand. In this study, 144 oyster samples collected from different markets in Chiang Mai, Thailand, in 2017 and 2018 were investigated for the presence of HBoV by nested PCR and sequencing. HBoV was detected in 11 out of 144 samples (7.6%). Nine HBoV-positive samples (81.8%) were identified as genotype 1 (HBoV1) and two (18.2%) as HBoV2. A monthly investigation of HBoV in oyster samples from July 2017 to June 2018 showed that HBoV was sporadically detected in particular months spanning the rainy and colder season, with a peak in January. This study demonstrates the presence and genotype diversity of HBoV in oyster samples in Thailand. The findings contribute to evaluating the risk of foodborne transmission of HBoV and to monitoring outbreaks of HBoV in Thailand and in other countries. IMPORTANCE Human bocavirus is recognized as an important cause of respiratory infection and of acute gastroenteritis in children worldwide. Human bocavirus has been widely detected in many clinical specimens, as well as in several types of environmental samples. Most previous studies describe the incidence of bocavirus infection in humans, whereas few data are available for the occurrence of human bocavirus in food materials, particularly that in bivalve shellfish. Our findings provide evidence for the existence and prevalence of human bocavirus in oysters, suggesting that further monitoring of the potential risk of food- and waterborne transmission of this virus to humans should be undertaken.

Molecular screening of the human parvoviruses B19 and bocavirus 1 in the study of congenital diseases as applied to symptomatic pregnant women and children

Introduction

B19 virus (B19V) and bocavirus 1 (HBoV1) are human pathogenic parvoviruses that are prevalent worldwide and are responsible for a diverse and not yet fully established spectrum of clinical manifestations.

Objective

To screen B19V and HBoV1 in patients with clinical manifestations associated with acquisition of the infection during gestation.

Methods

A retrospective, observational study was performed that included serum samples from patients without a previous known aetiology. B19V and HBoV1 were determined by end-point PCR. Positive samples were genotyped.

Results

A total of 106 serum samples were analysed, 61 from pregnant women and 45 from neonates and paediatric patients. None were positive for HBoV1, while B19V was detected in 37/106 [34.9 %, 95 % confidence interval (CI): 26.5–44.4] of the samples studied. In the group of pregnant women, 28/61 (45.9 %, 95 % CI: 34.0–58.3) were B19V-positive, and 2 of them had foetal anaemia followed by hydrops and foetal death, 3 were associated with a history of recurrent pregnancy loss and there was 1 case of spontaneous abortion. B19V was also detected in cases of maternal febrile exanthema, polyhydramnios, oligohydramnios and foetal ascites. In the group of children, 9/45 (20.0 %, 95 % CI: 10.9–33.8) neonatal patients were B19V-positive, and this was associated with foetal hydrops, TORCH syndrome and cardiac alterations. The nucleotide sequences analysed confirmed the identity of B19V genotype 1.

Conclusions

We found no evidence to indicate the presence of HBoV1 in maternal blood or in the newborns/paediatric patients (hence providing no support for the supposed vertical transmission). On the other hand, the high frequency of B19V in the pathologies studied indicates the importance of molecular diagnosis in both the mother and the child. Future efforts should contribute to early detection and characterization of infections.

The Role of the Human Bocavirus (HBoV) in Respiratory Infections

The human bocavirus is one of the most common respiratory viruses and occurs in all age groups. Because Koch’s postulates have been fulfilled unintendedly, it is currently accepted that the virus is a real pathogen associated with upper and lower respiratory tract infections causing clinical symptoms ranging from a mild common cold to life-threatening respiratory diseases. In order to exclude a viremia, serological analysis should be included during laboratory diagnostics, as acute and chronic infections cannot be differentiated by detection of viral nucleic acids in respiratory specimen alone due to prolonged viral shedding. Besides its ability to persist, the virus appears to trigger chronic lung disease and increases clinical symptoms by causing fibrotic lung diseases. Due to the lack of an animal model, clinical trials remain the major method for studying the long-term effects of HBoV infections.

Frequent Detection and Genetic Diversity of Human Bocavirus in Urban Sewage Samples

The prevalence and genetic diversity of human bocaviruses (HBoVs) in sewage water samples are largely unknown. In this study, 134 raw sewage samples from 25 wastewater treatment plants (WTPs) in Italy were analyzed by nested PCR and sequencing using species-specific primer pairs and broad-range primer pairs targeting the capsid proteins VP1/VP2. A large number of samples (106, 79.1 %) were positive for HBoV. Out of these, 49 were classified as HBoV species 2, and 27 as species 3. For the remaining 30 samples, sequencing results showed mixed electropherograms. By cloning PCR amplicons and sequencing, we confirmed the copresence of species 2 and 3 in 29 samples and species 2 and 4 in only one sample. A real-time PCR assay was also performed, using a newly designed TaqMan assay, for quantification of HBoVs in sewage water samples. Viral load quantification ranged from 5.51E+03 to 1.84E+05 GC/L (mean value 4.70E+04 GC/L) for bocavirus 2 and from 1.89E+03 to 1.02E+05 GC/L (mean value 2.27E+04 GC/L) for bocavirus 3. The wide distribution of HBoV in sewages suggests that this virus is common in the population, and the most prevalent are the species 2 and 3. HBoV-4 was also found, representing the first detection of this species in Italy. Although there is no indication of waterborne transmission for HBoV, the significant presence in sewage waters suggests that HBoV may spread to other water environments, and therefore, a potential role of water in the HBoV transmission should not be neglected.

Human bocavirus: Current knowledge and future challenges

Human bocavirus (HBoV) is a parvovirus isolated about a decade ago and found worldwide in both respiratory samples, mainly from early life and children of 6-24 mo of age with acute respiratory infection, and in stool samples, from patients with gastroenteritis. Since then, other viruses related to the first HBoV isolate (HBoV1), namely HBoV2, HBoV3 and HBoV4, have been detected principally in human faeces. HBoVs are small non-enveloped single-stranded DNA viruses of about 5300 nucleotides, consisting of three open reading frames encoding the first two the non-structural protein 1 (NS1) and nuclear phosphoprotein (NP1) and the third the viral capsid proteins 1 and 2 (VP1 and VP2). HBoV pathogenicity remains to be fully clarified mainly due to the lack of animal models for the difficulties in replicating the virus in in vitro cell cultures, and the fact that HBoV infection is frequently accompanied by at least another viral and/or bacterial respiratory and/or gastroenteric pathogen infection. Current diagnostic methods to support HBoV detection include polymerase chain reaction, real-time PCR, enzyme-linked immunosorbent assay and enzyme immunoassay using recombinant VP2 or virus-like particle capsid proteins, although sequence-independent amplification techniques combined with next-generation sequencing platforms promise rapid and simultaneous detection of the pathogens in the future. This review presents the current knowledge on HBoV genotypes with emphasis on taxonomy, phylogenetic relationship and genomic analysis, biology, epidemiology, pathogenesis and diagnostic methods. The emerging discussion on HBoVs as true pathogen or innocent bystander is also emphasized.

Mapping Antigenic Epitopes on the Human Bocavirus Capsid

Human bocaviruses (HBoV1 to -4) are emerging pathogens associated with pneumonia and/or diarrhea in young children. Currently, there is no treatment or vaccination, so there is a need to study these pathogens to understand their disease mechanisms on a molecular and structural level for the development of control strategies. Here, we report the structures of six HBoV monoclonal antibody (MAb) fragment complexes, HBoV1-15C6, HBoV2-15C6, HBoV4-15C6, HBoV1-4C2, HBoV1-9G12, and HBoV1-12C1, determined by cryo-electron microscopy and three-dimensional image reconstruction to 18.0- to 8.5-Å resolution. Of these, the 15C6 MAb cross-reacted with HBoV1, HBoV2, and HBoV4, while the 4C2, 12C1, and 9G12 MAbs recognized only HBoV1. Pseudoatomic modeling mapped the 15C6 footprint to the capsid surface DE and HI loops, at the 5-fold axis and the depression surrounding it, respectively, which are conserved motifs in Parvoviridae The footprints for 4C2, 12C1, and 9G12 span the surface loops that assemble portions of the 2-/5-fold wall (a raised surface feature between the 2-fold and 5-fold axes of symmetry) and the shoulder of the 3-fold protrusions. The MAb footprints, cross reactive and strain specific, coincide with regions with high and low sequence/structural identities, respectively, on the capsid surfaces of the HBoVs and identify potential regions for the development of peptide vaccines for these viruses.

IMPORTANCE

Human bocaviruses (HBoVs) may cause severe respiratory and gastrointestinal infections in young children. The nonenveloped parvovirus capsid carries determinants of host and tissue tropism, pathogenicity, genome packaging, assembly, and antigenicity important for virus infection. This information is currently unavailable for the HBoVs and other bocaparvoviruses. This study identifies three strain-specific antigenic epitopes on the HBoV1 capsid and a cross-reactive epitope on the HBoV1, HBoV2, and HBoV4 capsids using structures of capsid-antibody complexes determined using cryo-electron microscopy and image reconstruction. This is the first study to report the highly conserved parvovirus DE loop at the 5-fold axis as a determinant of antigenicity. Additionally, knowledge of the strain-specific and conserved antigenic epitopes of the bocaviruses can be instrumental in characterization of the virus life cycle, development of peptide vaccines, and generation of gene delivery vectors for cystic fibrosis given the strict tropism of HBoV1 for human airway epithelial cells.

Detection and monitoring of human bocavirus 1 infection by a new rapid antigen test

Clinically relevant diagnosis of human bocavirus 1 (HBoV1) is challenging, as the virus is frequently detected in asymptomatic patients, and cofindings with other respiratory viruses are common. The clinical value of current diagnostic methods, such as PCR, is therefore low, and alternative diagnostic strategies are needed. We describe for the first time the use of an antigen detection assay for the rapid identification of HBoV1 in a paediatric patient with respiratory tract infection symptoms. We estimate the duration of active HBoV1 infection to be 6 days.

Respiratory infections of the human bocavirus

The human bocavirus is one of the most common respiratory viruses and occurs in all age groups. It is associated with upper and lower respiratory tract infections, and causes clinical symptoms from the mild common cold to life threatening respiratory diseases. Besides its ability to persist the virus appears to trigger chronic lung disease and increase the clinical symptoms, while being a putative trigger for fibrotic lung diseases.

Laboratory diagnostics should include serological diagnostics in order to rule out a viremia because due to prolonged viral shedding acute and chronic infections cannot be differentiated on the detection of viral nucleic acids in respiratory specimen alone.

Although Koch’s postulates cannot be formally fulfilled due to the lack of an animal model and the chance for clinical trials with volunteers are limited due to the long term effects of HBoV infections, there is no doubt that the virus is a serious pathogen and requires attention.

The aim of the chapter is to present an overview of our current knowledge on respiratory infections with the human bocavirus, and to provide basic and essential information on clinical features, molecular diagnostics, and epidemiologic challenges arising with this pathogen.

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.

High human bocavirus viral load is associated with disease severity in children under five years of age

Human bocavirus (HBoV) is a parvovirus and detected worldwide in lower respiratory tract infections (LRTIs), but its pathogenic role in respiratory illness is still debatable due to high incidence of co-infection with other respiratory viruses. To determine the prevalence of HBoV infection in patients with LRTI in Shanghai and its correlation with disease severity, we performed a 3-year prospective study of HBoV in healthy controls, outpatients and inpatients under five years of age with X-ray diagnosed LRTIs. Nasopharyngeal aspirates were tested by PCR for common respiratory viruses and by real time PCR for HBoV subtypes 1-4. Nasopharyngeal swabs from healthy controls and serum samples and stools from inpatients were also tested for HBoV1-4 by real time PCR. Viral loads were determined by quantitative real time PCR in all HBoV positive samples. HBoV1 was detected in 7.0% of inpatients, with annual rates of 5.1%, 8.0% and 4.8% in 2010, 2011 and 2012, respectively. Respiratory syncytial virus (RSV) subtype A was the most frequent co-infection detected; HBoV1 and RSVA appeared to co-circulate with similar seasonal variations. High HBoV viral loads (>10(6) copies/ml) were significantly more frequent in inpatients and outpatients than in healthy controls. There was a direct correlation of high viral load with increasing disease severity in patients co-infected with HBoV1 and at least one other respiratory virus. In summary, our data suggest that HBoV1 can cause LRTIs, but symptomatic HBoV infection is only observed in the context of high viral load.

Occurrence of human bocaviruses and parvovirus 4 in solid tissues

Human bocaviruses 1-4 (HBoV1-4) and parvovirus 4 (PARV4) are recently discovered human parvoviruses. HBoV1 is associated with respiratory infections of young children, while HBoV2-4 are enteric viruses. The clinical manifestations of PARV4 remain unknown. The objective of this study was to determine whether the DNAs of HBoV1-4 and PARV4 persist in human tissues long after primary infection. Biopsies of tonsillar tissue, skin, and synovia were examined for HBoV1-4 DNA and PARV4 DNA by PCR. Serum samples from the tissue donors were assayed for HBoV1 and PARV4 IgG and IgM antibodies. To obtain species-specific seroprevalences for HBoV1 and for HBoV2/3 combined, the sera were analyzed after virus-like particle (VLP) competition. While HBoV1 DNA was detected exclusively in the tonsillar tissues of 16/438 individuals (3.7%), all of them ≤8 years of age. HBoV2-4 and PARV4 DNAs were absent from all tissue types. HBoV1 IgG seroprevalence was 94.9%. No subject had HBoV1 or PARV4 IgM, nor did they have PARV4 IgG. The results indicate that HBoV1 DNA occurred in a small proportion of tonsils of young children after recent primary HBoV1 infection, but did not persist long in the other tissue types studied, unlike parvovirus B19 DNA. The results obtained by the PARV4 assays are in line with previous results on PARV4 epidemiology.