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

MA104 cell line is permissive for human bocavirus 1 infection

Human bocavirus 1 (HBoV1) has appeared as an emerging pathogen, causing mild to life-threatening respiratory tract infections, acute otitis media, and encephalitis in young children and immunocompromised individuals. The lack of cell lines suitable for culturing replicative viruses hinders research on HBoV1. Here, we characterized the susceptibility to HBoV1 of 29 human and 7 animal cell lines, and identified a permissive cell line, MA104. The complete HBoV1 life cycle was achieved in MA104 cells, including viral entry, complete replication, and infectious progeny virion production. Additionally, the suppression of the interferon pathway facilitated the viral genome replication in MA104 cells. RNA-sequencing showed that innate immunity, inflammation, the PI3K-Akt and MAPK signaling pathways, and the cellular membrane system were mobilized in response to HBoV1 infection. Overall, our study is the first to identify a cell line, MA104, that supports the complete HBoV1 life cycle, which will promote research on HBoV1 virology and pathogenesis and benefit drug and vaccine development.IMPORTANCEHBoV1 is an emerging pathogen that mainly causes respiratory tract infections, while the lack of cell lines suitable for culture replicative viruses hindered research on HBoV1. Here, we identify a permissive cell line for HBoV1 infection, MA104, and reveal that the complete life cycle of HBoV1 was supported in MA104 cells. Our findings provide a suitable cell model for the study of HBoV1 and explore its application for antiviral drug evaluation, which is vital for research on HBoV1 virology and pathogenesis, as well as for drug and vaccine development.

Prevalence, Molecular Epidemiology, and Clinical Characteristics of Human Bocavirus Among Patients with Acute Gastroenteritis in Northern Brazil During 2017-2022

Acute gastroenteritis (AG) is a major illness in early childhood. Recent studies suggest a potential association between human bocavirus (HBoV) and AG. HBoV, a non-enveloped virus with a single-strand DNA genome, belongs to the Parvoviridae family. This study aimed to describe the frequency of HBoV in Northern Brazil using samples from patients with AG collected between 2017 and 2022. Fecal samples obtained from the viral gastroenteritis surveillance network at the Evandro Chagas Institute (IEC) were analyzed. Fecal suspensions (20%) were prepared, and the viral genome was extracted. PCR and nested-PCR were employed to detect HBoV, followed by nucleotide sequencing to identify viral types. Out of 692 samples, HBoV positivity was detected in 9.2% of cases (64/692). Genotypes HBoV-1, HBoV-2, HBoV-3, and HBoV-4 were found in 42.5% (17/40), 22.5% (9/40), 32.5% (13/40), and 2.5% (1/40) of the specimens, respectively. Co-infections with HBoV and other enteric viruses occurred in 48.3% (31/64) of cases, with RVA being the most frequent (31.2%, 20/64). The study results underscore the importance of continuous monitoring and further research to better understand the seasonality, coinfection patterns, and genetic variability of HBoV.

Prevalence and molecular characterization of human bocavirus-1 in children and adults with influenza-like illness from Kunming, Southwest China

Human bocavirus-1 (HBoV-1) has been associated with respiratory infections in both children and adults, often presenting symptoms similar to those of influenza. Understanding the prevalence and molecular characteristics of HBoV-1 in individuals with influenza-like illness (ILI) is essential for enhancing the diagnosis and treatment of respiratory infections in Kunming, Southwest China. Between December 2017 and December 2023, demographic and clinical data, along with respiratory tract specimens from individuals aged 0 to 97 years with ILI, were collected at three sentinel hospitals in Kunming. Each specimen was tested for 18 respiratory viruses, and the positive rates of HBoV-1 across different age groups were analyzed. Amplification of the near-complete HBoV genome was achieved through three overlapping fragments, followed by next-generation sequencing (NGS) and phylogenetic analysis. A total of 20,181 respiratory samples were collected from patients aged 1 month to 97 years presenting with ILI symptoms between December 2017 and December 2023, with HBoV detected in 0.8% of the samples. The prevalence was 1.0% (165/16,406) in children and 0.1% (3/3,775) in adults, with a significantly higher detection rate in pediatric patients (<18 years old) compared to adults (≥18 years old) (P < 0.001). Among the 168 HBoV-positive participants, 165 (98.2%) were children under 18 years, while 3 (1.8%) were adults. Genome-wide phylogenetic analyses indicated that HBoV-1 was the predominant genotype, showing that the HBoV-1 strains circulating in Kunming are closely related to strains from other regions of China and globally. Our findings confirm the prevalence of HBoV-1 in individuals with ILI in Kunming and provide valuable insights into the molecular characteristics of HBoV-1 in this region. Further studies are necessary to explore the clinical implications of HBoV-1 infection and its role in respiratory illnesses.IMPORTANCEViral respiratory infections are a leading cause of morbidity- and mortality-associated influenza-like illness (ILI) cases. It is estimated that there are several billion cases of ILI globally each year. Monitoring data from China in 2023 indicate that there are approximately 17 million cases of ILI nationwide. In the United States, the annual incidence of ILI ranges from 9 to 49 million cases. Human bocavirus-1 (HBoV-1) has been identified as a causative agent of ILI. The global prevalence of HBoV-1 respiratory infections varies from 1% to 56.8%, with the majority of studies focusing on pediatric populations; however, research including a broader age range is limited. Currently, the prevalence of HBoV-1 in the Kunming area is not well characterized, and its molecular features remain inadequately described. This study aims to analyze the prevalence of HBoV-1 among ILI cases in Kunming, encompassing both pediatric and adult patients. We present 107 complete genomic sequences of HBoV-1 strains obtained from three ILI sentinel hospitals in the region. Furthermore, we conducted phylogenetic analysis, homology comparisons, and assessments of nucleotide and amino acid substitution site variations. These findings provide important insights for further investigations into HBoV-1 and its epidemiological significance.

Assessment of crAssphage as a biological variable for SARS-CoV-2 data normalization in wastewater surveillance

AIMS

This study aimed to assess the use of cross-assembled phage (crAssphage) as an endogenous control employing a multivariate normalization analysis and its application as a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) data normalizer.

METHODS AND RESULTS

A total of 188 twelve-hour composite raw sewage samples were obtained from eight wastewater treatment plants (WWTP) during a 1-year monitoring period. Employing the N1 and N2 target regions, SARS-CoV-2 RNA was detected in 94% (177) and 90% (170) of the samples, respectively, with a global median of 5 log10 genomic copies per liter (GC l-1). CrAssphage was detected in 100% of the samples, ranging from 8.29 to 10.43 log10 GC l-1, with a median of 9.46 ± 0.40 log10 GC l-1, presenting both spatial and temporal variabilities.

CONCLUSIONS

Although SARS-CoV-2 data normalization employing crAssphage revealed a correlation with clinical cases occurring during the study period, crAssphage normalization by the flow per capita per day of each WWTP increased this correlation, corroborating the importance of normalizing wastewater surveillance data in disease trend monitoring.

Bocaparvovirus in infants hospitalized in a neonatal intensive care unit in Midwest Brazil during the COVID-19 pandemic (2021-2022)

Human bocaparvoviruses (HBoVs) belong to the Parvoviridae family, being currently classified into four species (HBoV1-4). These viruses have been found in association with respiratory and gastroenteric symptoms, as well as in asymptomatic individuals. This study aimed to investigate the occurrence of HBoVs in infants under 5 months old admitted to a Neonatal Intensive Care Unit (NICU) during the COVID-19 pandemic (between March 2021 and March 2022). Clinical samples (nasopharyngeal swab, serum, stool, and urine) were screened by qPCR TaqMan. The HBoV was detected in samples of 31.6% (12/38) of participants. The most frequent alteration among the HBoV-positive neonates was the chest X-ray with interstitial infiltrate, followed by tachycardia and vomiting. Viral DNA was detected in more than one type of clinical sample in three of the participants in association with respiratory symptoms. Two participants had positive stool samples with or without enteric symptoms. HBoV intermittent and continuous positivity patterns were observed. The present study stands out for the prospective evaluation of positivity for HBoV in different types of clinical samples from a population of hospitalized infants. Our data supports circulation of HBoV in nosocomial environment during the COVID-19 pandemic.

Impact of the COVID-19 pandemic on the prevalence of respiratory viral pathogens in patients with acute respiratory infection in Shanghai, China

Objective

This study aimed to evaluate the impact of nonpharmaceutical interventions (NPIs) taken to combat COVID-19 on the prevalence of respiratory viruses (RVs) of acute respiratory infections (ARIs) in Shanghai.

Methods

Samples from ARI patients were collected and screened for 17 respiratory viral pathogens using TagMan low density microfluidic chip technology in Shanghai from January 2019 to December 2020. Pathogen data were analyzed to assess changes in acute respiratory infections between 2019 and 2020.

Results

A total of 2,744 patients were enrolled, including 1,710 and 1,034 in 2019 and 2020, respectively. The total detection rate of RVs decreased by 149.74% in 2020. However, detection rates for human respiratory syncytial virus B (RSVB), human coronavirus 229E (HCoV229E), human coronavirus NL63 (HCoVNL63), and human parainfluenza virus 3 (HPIV3) increased by 91.89, 58.33, 44.68 and 24.29%, in 2020. The increased positive rates of RSVB, HPIV3, resulted in more outpatients in 2020 than in 2019. IFV detection rates declined dramatically across gender, age groups, and seasons in 2020.

Conclusion

NPIs taken to eliminate COVID-19 had an impact on the prevalence of respiratory viral pathogens, especially the IFVs in the early phases of the pandemic. Partial respiratory viruses resurged with the lifting of NPIs, leading to an increase in ARIs infection.

Genotypic diversity and long-term impact of human bocavirus on diarrheal disease: Insights from historical fecal samples in Brazil

This study aimed to investigate the frequency and genotypic diversity of human bocavirus (HBoV) in historical fecal samples collected before 2005 in Brazil and understand its natural history in patients with diarrhea. Between 1998 and 2005, 3347 samples were tested for HBoV by RT-PCR, with a detection rate of 5.8% (195/3347). Coinfection with norovirus (NoV) and human adenovirus (HAdV) was found in 34.9% (68/195), indicating HBoV's potential role as a causative agent of diarrheal disease. The detection rate varied over the years (p < 0.05), suggesting natural oscillatory fluctuations. HBoV was more prevalent in fall and winter, with higher positivity in children ≤5 years (p < 0.05), reinforcing that HBoV is an important pathogen in childhood diarrhea. Genotyping (32.8%; 64/195) revealed the circulation of HBoV-1 (79.7%, 51/64), HBoV-3 (12.5%, 8/64), HBoV-2 (6.2%, 4/64), and the rare HBoV-4 (1.6%, 1/64). Difference in HBoV-1 and HBoV-2/-3 mono-infections prevalence (p < 0.05), suggests a potential role of HBoV-1 in the pathogenicity of diarrheal disease. The study highlights HBoV's lasting impact on viral gastroenteritis in Brazil and emphasizes its genotypic diversity. Recommending screening for HBoV in public health laboratories is crucial for understanding its role in gastrointestinal diseases. The data also contribute to understanding the molecular characterization of enteric viruses in historical fecal samples.

Human bocavirus respiratory infection: Tracing the path from viral replication and virus-cell interactions to diagnostic methods

Human bocaviruses were first described between 2005 and 2010, identified in respiratory and enteric tract samples of children. Screening studies have shown worldwide distribution. Based on phylogenetic analysis, they were classified into four genotypes (HBoV1-4). From a clinical perspective, human bocavirus 1 (HBoV1) is considered the most relevant, since it can cause upper and lower acute respiratory tract infection, mainly in infants, including common cold, bronchiolitis, and pneumonia, as well as wheezing in susceptible patients. However, the specific processes leading to structural, biochemical, and functional changes resulting in the different clinical presentations have not been elucidated yet. This review surveys the interactions between the virus and target cells that can potentially explain disease-causing mechanisms. It also summarises the clinical phenotype of cases, stressing the role of HBoV1 as an aetiological agent of lower acute respiratory infection in infants, together with laboratory tests for detection and diagnosis. By exploring the current knowledge on the epidemiology of HBoV1, insights into the complex scenario of paediatric respiratory infections are presented, as well as the potential effects that changes in the circulation can have on the dynamics of respiratory agents, spotlighting the benefits of comprehensively increase insights into incidence, interrelationships with co-circulating agents and potential control of HBoV1.

HBoV-1: virus structure, genomic features, life cycle, pathogenesis, epidemiology, diagnosis and clinical manifestations

The single-stranded DNA virus known as human bocavirus 1 (HBoV-1) is an icosahedral, linear member of the Parvoviridae family. In 2005, it was discovered in nasopharyngeal samples taken from kids who had respiratory tract illnesses. The HBoV genome is 4.7-5.7 kb in total length. The HBoV genome comprises three open-reading frames (ORF1, ORF2, and ORF3) that express structural proteins (VP1, VP2, and VP3), viral non-coding RNA, and non-structural proteins (NS1, NS1-70, NS2, NS3, and NP1) (BocaSR). The NS1 and NP1 are crucial for viral DNA replication and are substantially conserved proteins. Replication of the HBoV-1 genome in non-dividing, polarized airway epithelial cells. In vitro, HBoV-1 infects human airway epithelial cells that are strongly differentiated or polarized. Young children who have HBoV-1 are at risk for developing a wide range of respiratory illnesses, such as the common cold, acute otitis media, pneumonia, and bronchiolitis. The most common clinical symptoms are wheezing, coughing, dyspnea, and rhinorrhea. After infection, HBoV-1 DNA can continue to be present in airway secretions for months. The prevalence of coinfections is considerable, and the clinical symptoms can be more severe than those linked to mono-infections. HBoV-1 is frequently detected in combination with other pathogens in various reports. The fecal-oral and respiratory pathways are more likely to be used for HBoV-1 transmission. HBoV-1 is endemic; it tends to peak in the winter and spring. This Review summarizes the knowledge on HBoV-1.

Epidemiologic and Clinical Characteristics of Human Bocavirus Infection in Children with or without Acute Gastroenteritis in Acre, Northern Brazil

Human bocavirus (HBoV) is an emerging virus detected around the world that may be associated with cases of acute gastroenteritis (AGE). However, its contribution to AGE has not been elucidated. This study aimed to describe the frequency, clinical features, and HBoV species circulation in children up to 5 years with or without AGE symptoms in Acre, Northern Brazil. A total of 480 stool samples were collected between January and December 2012. Fecal samples were used for extraction, nested PCR amplification, and sequencing for genotyping. Statistical analysis was applied to verify the association between epidemiological and clinical characteristics. Overall, HBoV-positivity was 10% (48/480), with HBoV-positive rates of 8.4% (19/226) and 11.4% (29/254) recorded in diarrheic and non-diarrheic children, respectively. The most affected children were in the age group ranging between 7 and 24 months (50%). HBoV infection was more frequent in children who live in urban areas (85.4%), use water from public networks (56.2%), and live with adequate sewage facilities (50%). Co-detection with other enteric viruses was 16.7% (8/48) and the most prevalent coinfection was RVA+ HBoV (50%, 4/8). HBoV-1 was the most frequent species detected in diarrheic and non-diarrheic children, responsible for 43.8% (21/48) of cases, followed by HBoV-3 (29.2%, 14/48) and HBoV-2 (25%, 12/48). In this study, HBoV infection was not always associated with AGE, as most HBoV cases belonged to the non-diarrheal group. Future studies are warranted in order to determine the role of HBoV in causing acute diarrhea disease.

Detection and Molecular Characterization of Enteric Viruses in Bivalve Mollusks Collected in Arraial do Cabo, Rio de Janeiro, Brazil

Viral bivalve contamination is a recognized food safety hazard. Therefore, this study investigated the detection rates, seasonality, quantification, and genetic diversity of enteric viruses in bivalve samples (mussels and oysters). We collected 97 shellfish samples between March 2018 and February 2020. The screening of samples by qPCR or RT-qPCR revealed the detection of norovirus (42.3%), rotavirus A (RVA; 16.5%), human adenovirus (HAdV; 24.7%), and human bocavirus (HBoV; 13.4%). There was no detection of hepatitis A virus. In total, 58.8% of shellfish samples tested positive for one or more viruses, with 42.1% of positive samples contaminated with two or more viruses. Norovirus showed the highest median viral load (3.3 × 106 GC/g), followed by HAdV (median of 3.5 × 104 GC/g), RVA (median of 1.5 × 103 GC/g), and HBoV (median of 1.3 × 103 GC/g). Phylogenetic analysis revealed that norovirus strains belonged to genotype GII.12[P16], RVA to genotype I2, HAdV to types -C2, -C5, and -F40, and HBoV to genotypes -1 and -2. Our results demonstrate the viral contamination of bivalves, emphasizing the need for virological monitoring programs to ensure the quality and safety of shellfish for human consumption and as a valuable surveillance tool to monitor emerging viruses and novel variants.

Molecular characterization of human bocavirus in recycled water and sewage sludge in Thailand

The study aimed to assess the presence and molecular characterization of human bocavirus (HBoV) in recycled water and sewage sludge samples in Thailand. One hundred and two recycled water and eighty-six sewage sludge samples collected from a wastewater treatment plant were tested for the presence of HBoV using nested PCR with broad-range primer pairs targeting the capsid proteins VP1 and VP2. HBoV DNA was detected in recycled water of 9/102 (8.8%) samples and sewage sludge of 27/86 (31.4%) samples. Based on DNA sequencing and phylogenetic analysis, the HBoV DNA sequences had 98.8-100.0% nucleotide identity to the sequences from HBoV reported globally. Thirty-five HBoV-positive samples were identified to genotypes as the predominant HBoV2; 26 followed by HBoV3; 8 and the rare HBoV4; 1 sample. Concerning recycled water, HBoV2 was detected in 3 (2.9%) and HBoV3 was detected in 5 (4.9%) of all samples. The sewage sludge samples were characterized as HBoV2 in 23 (26.7%), HBoV3 in 3 (3.5%) and HBoV4 in 1 (1.2%) of all samples. The frequency of HBoV detected in recycled water and sewage sludge samples significantly differed in sample type (p-value = 0.007). The findings of three HBoV genotypes in recycled water and sewage sludge emphasized the circulation of the virus in the environment and the potential source of transmission to the community.

Polymerase Chain Reaction Study of Human Bocavirus in Children with Acute Gastroenteritis

Aim:

The present study aimed to detect Human bocavirus (HBoV) in stool samples from young children below 5 years complaining of acute gastroenteritis (GE) in addition to detection of rotavirus, norovirus, and astrovirus.

Methods:

The study included 90 children below 5 years with acute GE with excluded bacterial pathogens. The determination of the presence of HBoV was performed by nested polymerase chain reaction (PCR) beside determination of astrovirus and norovirus by multiplex PCR and rotavirus antigen by enzyme-linked immunosorbent assay (ELISA).

Results:

The most prevalent virus among the studied viruses was rotavirus (33.3%) detected by ELISA for antigen in the stool. The other three viruses detected by molecular methods were bocavirus (14.4%), astrovirus (13.3%), and norovirus (10%). Mixed viral infection with two or more viruses was detected in 16 children (17.8%). The most common was bocavirus and rotavirus in 6 patients (37.5%). In the study of demographic and clinical presentations of the children with HBoV, the affected children were mainly females, i.e., 10 (76.9%), from rural residence i.e., 11 (84.6%) with the mild classification of GE in 7 children (53.8%) and moderate GE in 6 children (46.2%) and none of them had severe GE. Fever was the most common presenting sign in those children (53.8%) followed by vomiting (46.2%).

Conclusion:

The study highlights the existence of HBoV in children with acute GE under the age of five. The infection associated with this virus was either mild or moderate in severity. The combined viral infection was common especially associated with rotavirus. There is a need for further additional study to identify the type of the circulated strain of bocavirus and the confections with other pathogens.

Comparison of the clinical features of human bocavirus and metapneumovirus lower respiratory tract infections in hospitalized children in Suzhou, China

OBJECTIVE

We compared the clinical data of hospitalized children with lower respiratory tract infections caused by human bocavirus (HBoV) and human metapneumovirus (hMPV).

METHODS

In total, 8,430 children admitted to the Department of Respiration, Children's Hospital of Soochow University for lower respiratory tract infections from January 2017 to October 2021 were enrolled. Seven common respiratory viruses, including respiratory syncytial virus, influenza virus A, influenza virus B, parainfluenza virus (PIV) I, PIV II, PIV III, and adenovirus, were detected by direct immunofluorescence assay, whereas human rhinovirus and hMPV were detected by reverse transcription-polymerase chain reaction. Mycoplasma pneumoniae (MP) and HBoV were detected by real-time fluorescence quantitative polymerase chain reaction. Bacteria was detected in blood, nasopharyngeal secretion, bronchoalveolar lavage specimen or pleural fluid by culture. In parallel, MP was detected by enzyme-linked immunosorbent assay. In addition, we performed metagenomic testing of alveolar lavage fluid from some of the patients in our study.

RESULTS

The detection rate of HBoV was 6.62% (558/8430), whereas that of hMPV was 2.24% (189/ 8430). The detection rate of HBoV was significantly higher in children aged 1 to <3 years than in other age groups, but there were no significant differences in positivity rates for hMPV by age. Before 2020, the incidence of HBoV infection peaked in summer and autumn, whereas that of hMPV peaked in spring. The epidemiology of both HBoV and hMPV has changed because of the impact of the novel coronavirus. Among the positive cases, the HBoV mixed infection rate was 51.6%, which was similar to that for hMPV mixed infection (44.4%). Comparing clinical characteristics between HBoV and hMPV single infection, the median age of children was 17 months in the HBoV group and 11 months in the hMPV group. In the HBoV single infection group, 31 patients (11.5%) had pulse oxygen saturation of less than 92% on admission, 47 (17.4%) had shortness of breath, and 26 (9.6%) presented with dyspnea. Meanwhile, four patients (3.8%) in the hMPV single infection group had pulse oxygen saturation of less than 92% on admission, eight (7.6%) displayed shortness of breath, and three (2.9%) had dyspnea. The proportion of patients requiring mechanical ventilation and the rate of PICU admission were higher in the HBoV group than in the hMPV group.

CONCLUSION

The prevalence of HBoV infection is higher than that of hMPV infection in children with lower respiratory tract infection in Suzhou, and HBoV is more likely to cause severe infection than hMPV. Public health interventions for COVID-19 outbreaks have affected the prevalence of HBoV and hMPV.