Seroepidemiology of human bocavirus infection in Jamaica

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.

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.

Human Bocavirus in Brazil: Molecular Epidemiology, Viral Load and Co-Infections

Human bocavirus (HBoV) is an emerging virus and has been detected worldwide, especially in pediatric patients with respiratory and gastrointestinal infection. In this study, we describe HBoV prevalence, genotypes circulation and DNA shedding, in stool samples from children up to two years of age in Brazil. During 2016 and 2017, 886 acute gastroenteritis (AGE) stool samples from ten Brazilian states were analyzed by TaqMan^®-based qPCR, to detect and quantify HBoV. Positive samples were genotyped by sequencing the VP1/2 overlap region, followed by phylogenetic analysis and co-infections were accessed by screening other gastroenteric viruses. HBoV was detected in 12.4% (n = 110) of samples, with viral load ranging from 1.6 × 10² to 1.2 × 10⁹ genome copies per gram of stool. From these, co-infections were found in 79.1%, and a statistically lower HBoV viral load was found compared to viral loads of rotavirus, norovirus and adenovirus in double infected patients (p < 0.05). No significant differences were found between HBoV viral load in single or co-infections, age groups or genotypes. Phylogenetic analysis identified the circulation of HBoV-1 in 38%, HBoV-2 in 40% and HBoV-3 in 22%. Continuous HBoV monitoring is needed to clarify its role in diarrhea disease, especially in the absence of classic gastroenteric viruses.

Human Parvoviruses May Affect the Development and Clinical Course of Meningitis and Meningoencephalitis

Meningitis and meningoencephalitis are neurological inflammatory diseases, and although routine diagnostics include testing of a wide range of pathogens, still in many cases, no causative agent is detected. Human parvovirus B19 (B19V), human bocaviruses 1–4 (HBoV1–4), and human parvovirus 4 (hPARV4) are members of the Parvoviridae family and are associated with a wide range of clinical manifestations including neurological disorders. The main aim of this study was to determine whether human parvoviruses infection markers are present among patients with meningitis/meningoencephalitis in Latvia as well as to clarify the role of these viruses on the clinical course of the mentioned diseases. Our study revealed HBoV1–4 and B19V genomic sequences in 52.38% and 16.67% of patients, respectively. Furthermore, symptoms such as the presence of a headache and its severity, fatigue, disorientation, and difficulties to concentrate were significantly frequently present in patients with active parvovirus infection in comparison with parvoviruses negative patients, therefore we suggest that HBoV1–4 and B19V infection should be included in the diagnostics to reduce the number of meningitis/meningoencephalitis with unknown/unexplained etiology.

Co-detection of bocavirus and bacteria in a respiratory specimen from a pregnant woman using multiplex real time PCR; a pathogenic role, or a bystander?

A pregnant woman presented by cough and dyspenia. Employing a respiratory multiplex real-time PCR, Human bocavirus (HBoV), Haemophilus influenza and Staphylococcus aureus were positive at cycle thresholds (CTs) of 21, 35 and 33.5, respectively. The patient was diagnosed for bacterial respiratory infection superimposed by bocavirus due to a relative high CT value. Patient's condition improved using bronchodilators and corticosteroid without any further antibiotic treatment. HBoV is not exclusively a bystander pathogen in some patients.

Molecular epidemiology of human bocavirus infection in hospitalized children with acute gastroenteritis in South Africa, 2009-2015

Human bocavirus (HBoV) is known to be associated with a variety of clinical manifestation including acute gastroenteritis (AGE). Despite their global prevalence, no data is available on the epidemiology of HBoV associated with AGE in South Africa (SA). Between April 2009 and April 2015, 3765 stool specimens were collected from children less than 5 years of age hospitalized with diarrhea. Specimens were screened for selected enteric viruses by enzyme immunoassay and quantitative polymerase chain reaction, bacteria by culture and parasites by staining and microscopy. HBoV was detected in 5.63% (212 of 3765) of cases, the majority of which were children ≤2 years (92%, 195 of 212), and were common in the summer and autumn months (60%; 128 of 212). Further investigations of coinfections showed that bacteria (adjusted odds ratio [aOR] = 2.20; 95% confidence interval [CI], 1.41-3.45; P = .001) and sapovirus (aOR = 2.05; 95% CI, 1.08-3.86; P = .027) were significantly associated with HBoV in multivariate analysis. HBoV genotyping was successful in 191 of the 212 samples with HBoV-1 being the most prevalent genotype observed (79.6%; 152 of 191) followed by HBoV-3 (13.6%; 26 of 191), HBoV-2 (5.2%; 10 of 191), and HBoV-4 (1.6%; 3 of 191). The high prevalence of HBoV-1, a virus known to be associated with respiratory infections, and the association between HBoV-positive specimens and already established AGE agents, suggests that HBoV may play a limited role in the observed AGE cases in SA.

Prevalence of Human Bocavirus in Africa and Other Developing Countries between 2005 and 2016: A Potential Emerging Viral Pathogen for Diarrhea

BACKGROUND

Human Bocavirus (HBoV) is an emerging virus discovered in 2005 from individuals suffering gastroenteritis and respiratory tract infections. Numerous studies related to the epidemiology and pathogenesis of HBoV have been conducted worldwide. This review reports on HBoV studies in individuals with acute gastroenteritis, with and without respiratory tract infections in Africa between 2005 and 2016.

MATERIAL AND METHOD

The search engines of PubMed, Google Scholar, and Embase database for published articles of HBoV were used to obtain data between 2005 and 2016. The search words included were as follows: studies performed in Africa or/other developing countries or/worldwide; studies for the detection of HBoV in patients with/without diarrhea and respiratory tract infection; studies using standardized laboratory techniques for detection.

RESULTS

The search yielded a total of 756 publications with 70 studies meeting the inclusion criteria. Studies included children and individuals of all age groups. HBoV prevalence in Africa was 13% in individuals suffering gastroenteritis with/without respiratory tract infection.

CONCLUSION

Reports suggest that HBoV infections are increasingly being recognized worldwide. Therefore, surveillance of individuals suffering from infections in Africa is required to monitor the prevalence of HBoV and help understand the role of HBoV in individuals suffering from gastroenteritis with/without respiratory tract infection.

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.

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.

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.

Bocavirus Infection in Otherwise Healthy Children with Respiratory Disease

To evaluate the role of human bocavirus (hBoV) as a causative agent of respiratory disease, the importance of the viral load in respiratory disease type and severity and the pathogenicity of the different hBoV species, we studied all hBoV-positive nasopharyngeal samples collected from children who attended an emergency room for a respiratory tract infection during three winters (2009–2010, 2011–2012, and 2013–2014). Human bocavirus was detected using the respiratory virus panel fast assay and real-time PCR. Of the 1,823 nasopharyngeal samples, 104 (5.7%) were positive for hBoV; a similar prevalence was observed in all three periods studied. Among hBoV-infected children, 53.8% were between 1–2 years old, and hBoV was detected alone in 57/104 (54.8%) cases. All of the detected hBoV strains belonged to genotype 1. The median hBoV load was significantly higher in samples containing strains with both the N546H and T590S mutations compared to other samples (p<0.05). Children with a single hBoV-1 infection more frequently had upper respiratory tract infections (URTIs) than those who were co-infected (37.0% vs 17.8%, respectively, p = 0.04). The duration of hospitalization was longer among children with high viral loads than that observed among children with low viral loads (8.0 ±2.2 days vs 5.0 ±1.5 days, respectively, p = 0.03), and the use of aerosol therapy was more frequent among children with high viral loads than among those with low viral loads (77.1% vs 55.7%, respectively, p = 0.04). This study shows that hBoV is a relatively uncommon but stable infectious agent in children and that hBoV1 seems to be the only strain detected in Italy in respiratory samples. From a clinical point of view, hBoV1 seems to have in the majority of healthy children relatively low clinical relevance. Moreover, the viral load influences only the duration of hospitalization and the use of aerosol therapy without any association with the site of the respiratory disease.

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.

'Human bocavirus in Pakistani children with gastroenteritis'

Human Bocaviruses (HBoV) have been detected in human respiratory and gastrointestinal infections worldwide. Four genotypes of HBoV (HBoV1-4) have been described; HBoV-1 is associated with respiratory tract infections while HBoV-2, -3, and -4 genotypes are considered as entero-pathogenic although the exact role largely remains unclear. The global prevalence of HBoV has been reported, but the epidemiological data from Pakistan is largely unavailable to date. This study was conducted to understand the genetic diversity and disease prevalence of HBoV in hospitalized Pakistani children with acute diarrhea. During 2009, a total of 365 stool samples were collected from children hospitalized with gastrointestinal symptoms (as per WHO case definitions) at Rawalpindi General Hospital, Pakistan. Demographic and clinical data were recorded using a standardized questionnaire. The samples were tested for HBoV and rotavirus using real-time RT-PCR and ELISA, respectively. There were 47 (13%) samples positive for HBoV with 98% (n = 46) showing co-infection with rotavirus. HBoV-1 was the most frequently detected and was found in 94% samples followed by HBoV-2 and HBoV-3 genotypes. The mean age of infected children was 7.57 ± 5.4 months while detection was more frequent in males (n = 32, 68%). All cases recovered after 2.43 ± 1.0 mean days of treatment. On phylogenetic analysis, HBoV strains from Pakistan clustered closely with viruses from neighboring Bangladesh and China. These findings represent the first known epidemiological study in Pakistan to investigate the role of HBoV in acute gastroenteritis. The clinical data demonstrates that HBoV is not significantly associated with gastroenteritis alone and predominantly co-infections with rotavirus are found.

Conserved B-cell epitopes among human bocavirus species indicate potential diagnostic targets

BACKGROUND

Human bocavirus species 1-4 (HBoV1-4) have been associated with respiratory and enteric infections in children. However, the immunological mechanisms in response to HBoV infections are not fully understood. Though previous studies have shown cross-reactivities between HBoV species, the epitopes responsible for this phenomenon remain unknown. In this study, we used genomic and immunologic approaches to identify the reactive epitopes conserved across multiple HBoV species and explored their potential as the basis of a novel diagnostic test for HBoVs.

METHODOLOGY/PRINCIPAL FINDINGS

We generated HBoV1-3 VP2 gene fragment phage display libraries (GFPDLs) and used these libraries to analyze mouse antisera against VP2 protein of HBoV1, 2, and 3, and human sera positive for HBoVs. Using this approach, we mapped four epitope clusters of HBoVs and identified two immunodominant peptides--P1 (¹MSDTDIQDQQPDTVDAPQNT²⁰), and P2 (¹⁶²EHAYPNASHPWDEDVMPDL¹⁸⁰)--that are conserved among HBoV1-4. To confirm epitope immunogenicity, we immunized mice with the immunodominant P1 and P2 peptides identified in our screen and found that they elicited high titer antibodies in mice. These two antibodies could only recognize the VP2 of HBoV 1-4 in Western blot assays, rather than those of the two other parvoviruses human parvovirus B19 and human parvovirus 4 (PARV4). Based on our findings, we evaluated epitope-based peptide-IgM ELISAs as potential diagnostic tools for HBoVs IgM antibodies. We found that the P1+P2-IgM ELISA showed a higher sensitivity and specificity in HBoVs IgM detection than the assays using a single peptide.

CONCLUSIONS/SIGNIFICANCE

The identification of the conserved B-cell epitopes among human bocavirus species contributes to our understanding of immunological cross-reactivities of HBoVs, and provides important insights for the development of HBoV diagnostic tools.

Human bocavirus: lessons learned to date

Human bocavirus (HBoV) was identified as the second human parvovirus with pathogenic potential in 2005 in respiratory samples from children suffering from viral respiratory infections of unknown etiology. Since its first description, a large number of clinical studies have been performed that address the clinical significance of HBoV detection and the molecular biology of the virus. This review summarizes the most important steps taken in HBoV research to date and addresses open questions that need to be answered in the future to provide a better understanding of the role of a virus that is difficult to grow in cell culture and is suspected to be a pathogen, although it has not yet fulfilled Koch’s postulates.