Human bocavirus in patients with encephalitis, Sri Lanka, 2009-2010

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

Influenza and Viral Pneumonia

Influenza and other respiratory viruses are commonly identified in patients with community-acquired pneumonia, hospital-acquired pneumonia, and in immunocompromised patients with pneumonia. Clinically, it is difficult to differentiate viral from bacterial pneumonia. Similarly, the radiological findings of viral infection are in general nonspecific. The advent of polymerase chain reaction testing has enormously facilitated the identification of respiratory viruses, which has important implications for infection control measures and treatment. Currently, treatment options for patients with viral infection are limited but there is ongoing research on the development and clinical testing of new treatment regimens and strategies.

Molecular Surveillance for Bocaparvoviruses and Bufaviruses in the European Hedgehog (Erinaceus europaeus)

The presence of bocaparvoviruses (BoVs) and bufaviruses (BuVs) in the European hedgehog (Erinaceus europaeus) was investigated by screening duodenal and liver samples collected from 183 carcasses, delivered to wildlife rescue centers located in northwestern Italy. BoV DNA was detected in 15 animals (8.2%), with prevalences of 7.1% (13/183) and 2.7% (5/183) in intestine and liver samples, respectively. Upon the sequence analyses of the NS1 gene, two highly divergent BoVs (65.5-67.8% nt identities) were identified. Fourteen strains showed the highest identity (98.3-99.4% nt) to the hedgehog BoV strains recently detected in China in Amur hedgehogs (Erinaceus amurensis), whilst four strains were genetically related (98.9-99.4% nt identities) to the porcine BoVs identified in pigs and classified in the species Bocaparvovirus ungulate 4, which included related viruses also found in rats, minks, shrews, and mice. BuV DNA was detected in the duodenal samples of two hedgehogs, with a prevalence rate of 1.1%. The nearly full-length genome of two BuV strains, Hedgehog/331DU-2022/ITA and Hedgehog/1278DU/2019/ITA, was reconstructed. Upon phylogenetic analysis based on the NS and VP aa sequences, the Italian hedgehog BuVs tightly clustered with the BuVs recently identified in the Chinese Amur hedgehogs, within a potential novel candidate species of the genus Protoparvovirus.

Human Bocavirus in Childhood: A True Respiratory Pathogen or a "Passenger" Virus? A Comprehensive Review

Recently, human bocavirus (HBoV) has appeared as an emerging pathogen, with an increasing number of cases reported worldwide. HBoV is mainly associated with upper and lower respiratory tract infections in adults and children. However, its role as a respiratory pathogen is still not fully understood. It has been reported both as a co-infectious agent (predominantly with respiratory syncytial virus, rhinovirus, parainfluenza viruses, and adenovirus), and as an isolated viral pathogen during respiratory tract infections. It has also been found in asymptomatic subjects. The authors review the available literature on the epidemiology of HBoV, the underlying risk factors associated with infection, the virus's transmission, and its pathogenicity as a single pathogen and in co-infections, as well as the current hypothesis about the host's immune response. An update on different HBoV detection methods is provided, including the use of quantitative single or multiplex molecular methods (screening panels) on nasopharyngeal swabs or respiratory secretions, tissue biopsies, serum tests, and metagenomic next-generations sequencing in serum and respiratory secretions. The clinical features of infection, mainly regarding the respiratory tract but also, though rarely, the gastrointestinal one, are extensively described. Furthermore, a specific focus is dedicated to severe HBoV infections requiring hospitalization, oxygen therapy, and/or intensive care in the pediatric age; rare fatal cases have also been reported. Data on tissue viral persistence, reactivation, and reinfection are evaluated. A comparison of the clinical characteristics of single infection and viral or bacterial co-infections with high or low HBoV rates is carried out to establish the real burden of HBoV disease in the pediatric population.

Seasonal Trends in the Prevalence and Incidence of Viral Encephalitis in Korea (2015-2019)

Viral infections are a common cause of encephalitis. This study investigated the relationship between the incidence of encephalitis and that of respiratory and enteric viral infections in all age groups from 2015 to 2019, using the Health Insurance Review and Assessment (HIRA) Open Access Big Data Platform. We identified monthly incidence patterns and seasonal trends using the autoregressive integrated moving average (ARIMA). The Granger causality test was used to analyze correlations between encephalitis incidence and the positive detection rate (PDR) at 1-month intervals. A total of 42,775 patients were diagnosed with encephalitis during the study period. The incidence of encephalitis was highest in the winter (26.8%). The PDRs for respiratory syncytial virus (HRSV) and coronavirus (HCoV) were associated with the trend in encephalitis diagnosis in all age groups, with a 1-month lag period. In addition, an association with norovirus was observed in patients aged over 20 years, and with influenza virus (IFV) in patients aged over 60 years. This study found that HRSV, HCoV, IFV, and norovirus tended to precede encephalitis by 1 month. Further research is required to confirm the association between these viruses and encephalitis.

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.

Human bocavirus 1 respiratory tract reactivations or reinfections in two adults, contributing to neurological deficits and death

Human bocavirus 1 (HBoV1) of the family Parvoviridae causes mild to life-threatening respiratory tract infections in young children, but, due to widespread immunity, it is uncommon in adults. HBoV1 reinfections or reactivations leading to casualties are rare, but might be underdiagnosed. We report two young adults, one previously healthy and one immunosuppressed, with rare diagnostic patterns of HBoV1 respiratory tract infection. Both patients exhibited very high loads of HBoV1 DNA in respiratory samples. The immunosuppressed patient was also HBoV1 DNA-positive in blood, stool and a colon biopsy, but exhibited prior HBoV1-specific high-avidity IgG and weak IgM positivity 9 months before the respiratory symptoms. Likewise, the previously healthy patient exhibited HBoV1 IgG of high avidity and very weak IgM in serum, pointing to prior immunity, but with a seroconversion in cerebrospinal fluid. This patient also showed strong HBoV2 cross-reactivity. The molecular and serological results, together with their ages, suggest that both patients exhibited unusual reinfection or reactivation of HBoV1, contributing to neurological deficits and death.

Canine bocavirus-2 infection and its possible association with encephalopathy in domestic dogs

Canine bocaviruses (CBoVs) have been recognized as pathogens associated with intestinal diseases. Hematogenous spreading caused by CBoV has been documented and may potentiate the virus entry across the blood-brain barrier to initiate a brain infection. This study focused attention on CBoV detection in cases of encepahlopathy and attempted to determine its viral localization. A total of 107 dog brains that histologically exhibited encephalopathy (ED) were investigated for the presence of CBoVs using polymerase chain reaction (PCR). Thirty-three histologically normal brain samples from dogs were used as a control group (CD). CBoV-2 was detected in 15 ED dogs (14.02%) but not in CD dogs (p = 0.02), while no CBoV-1 and -3 were detected. Among the CBoV-2 positive dogs, brain histological changes were characterized by nonsuppurative encephalitis, with inclusion body-like materials in some brains. In situ hybridization (ISH) and transmission electron microscopy (TEM) confirmed the presence of CBoV-2 viral particles in glial cells, supporting neurotropism of this virus. ISH signals were also detected in the intestines, lymphoid organs, and the heart, suggesting both enteral and parenteral infections of this virus. Whole genome characterization and evolutionary analysis revealed genetic diversity of CBoV-2 sequences and it was varying among the different countries where the virus was detected. This study points to a possible association of CBoV-2 with encephalopathy in dogs. It also highlights the genetic diversity and cellular tropism of this virus.

Respiratory virus-related meningoencephalitis in adults

Purpose

Respiratory viruses (RVs) are pathogens that can cause central nervous system (CNS) infection, but previous research has been limited to a pediatric population. In recent years, several cases of adult RV meningoencephalitis have begun to be reported. We decided to research the CNS infection of RV in the entire neuroinfection registry.

Methods

We retrospectively reviewed the neurologic infection registry of Seoul National University (Seoul, Korea). Among a total of 661 patients in the registry, 10 adult patients were diagnosed with RV-related meningoencephalitis on RV multiplex polymerase chain reaction (PCR) screening test. We analyzed the clinical presentation, laboratory findings, and clinical course of the 10 patients.

Results

Three patients were definite RV meningoencephalitis who had positive PCR results from cerebrospinal fluid. The other seven patients were diagnosed with probable RV meningoencephalitis if they had positive PCR results in the sputum and negative results in other extensive workup.

Conclusion

RV-related meningoencephalitis should be considered a possible etiology in adult meningoencephalitis patients. To diagnose these viruses, screening test of RV PCR is recommended even in patients without upper respiratory infection symptoms.

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.

Identification of a novel bocaparvovirus in a wild squirrel in Kunming, Yunnan Province, China

In December 2017, a squirrel (Callosciurus phayrei) died 2 days after capture in Kunming, and its intestinal tract, heart, liver, spleen, lung, and kidney were subjected to metagenomics analysis. Reassembly and verification by reverse transcription PCR of contigs generated by next-generation sequencing yielded a 5176-nt sequence, which was designated "squirrel bocaparvovirus" (SQBOV). Phylogenetic trees based on the aa sequences of NS1, NP1, and VP1 showed that SQBOV formed an independent branch in the bocaparvovirus phylogenetic tree. The amino acid sequence identity of the NS1 of SQBOV to those of other bocaparvoviruses was below the threshold of 85% that is used to demarcate species within the genus, indicating that it should be considered a member of a new bocaparvovirus species. To our knowledge, this is the first report of a bocaparvovirus in squirrels. Our findings will enable further studies of viral diversity in rodents and of the genetic diversity and host range of bocaparvoviruses.

Genetic Diversity and Phylogenetic Analysis of Human Bocavirus 2 in Pediatric Patients with Acute Gastroenteritis in Taiwan

Human bocavirus (HBoV) is a causative agent of respiratory and gastrointestinal diseases worldwide. Four HBoV species (HBoV1-4) have been identified so far. Although a previous report has documented the HBoV association with acute gastroenteritis (AGE) in Taiwan, their epidemiology, genetic diversity, and phylogenetic relationships remain unclear. In this study, we focused on an investigation of these unsolved issues, which will help to reveal molecular epidemiology and phylogeny of the circulating HBoV2 in Taiwan. A total of 176 stool samples were collected from children with AGE for this study. PCR amplification and sequencing on the VP1 gene region were used to identify species. Phylogenetic analysis was conducted by maximum-likelihood and neighbor-joining methods. Selection pressure was also estimated to obtain HBoV evolutionary information. Our results showed the prevalence of HBoV in AGE children was 8.5%, of which HBoV1 was the predominant species (6.3%), followed by HBoV2 (2.3%). Phylogenetic analysis showed those Taiwanese HBoV2 strains have significant genetic variability and can be divided into two clusters. One belongs to HBoV2 genotype A and the other forms an independent unclassified cluster. The nucleotide distance between that independent cluster and the known HBoV2 genotypes was more than 5%, suggesting a new HBoV2 genotype. No positive selection site was found and the virus was under purifying selection. This is the first report to reveal HBoV2 genetic diversity and phylogenetic relationships among AGE children in Taiwan. We find that HBoV2 may have been introduced into the country by multiple origins, and a potential new HBoV2 genotype is proposed.

The Role of CRM Fog Computing on Innovation and Customer Service Quality: an Empirical Study

CRM fog computing and entrepreneurial, innovation, and service quality have been identified as an important driving force for job growth. The study aimed to identify the involvement of CRM fog computing on entrepreneurial, innovation, and service quality in the Jordanian telecom company. The authors employed a quantitative approach to identify the level of the Appling of CRM fog computing in the company. The study contained the findings of a questionnaire of 325 respondents (male and female employees). Multiple linear regression and One-Way ANOVA analyses were used to examine the data. The predictive model of CRM fog computing and entrepreneurial, innovation, and service quality was a significant impact. Implications for CRM fog computing and practice are entrepreneurial, innovation, and service quality are discussed. The researchers recommend building enthusiasm for creating fog CRM mist processing as a result of its job in client administrations improvement: to increase using the information provided by CRM system in decision making; to consider services quality more as it affects sales volume positively; to consider customer’s feedback, listen to their opinions about the services provided to enhance performance. Entrepreneurship and innovation are increasingly an indispensable portion of organizations nationally, regionally and globally, and considered as a powerful tool for revenue streams. The authors state that entrepreneurship uses innovation to expand the business scope and boost growth. Therefore, entrepreneurship and innovation are dynamic and holistic processes that are not confined to the initial stage of a new venture. The implementation of CRM Fog computing and entrepreneurial aids the organization's productivity because it enhances the product and services offered by several organizations that adopt its concept. It enhances services to customers due to its easy to access nature and as well. The authors conclude that CRM Fog computing improves the e-commerce of any organization or community that adopts its concept and applies it in all areas. Keywords: CRM fog computing, entrepreneurial, innovation, service quality, customer experience.

Human bocavirus infection in Belgian children with respiratory tract disease

Human bocavirus (HBoV) has been detected primarily in children with acute lower respiratory tract disease (LRTD), but its occurrence, clinical profile, and role as a causative agent of RTD are not clear. The aim of this study was to investigate the prevalence and the potential clinical relevance of HBoV. Using molecular tests, we tested 1352 nasopharyngeal samples obtained between October 1, 2017 and April 30, 2018 from children up to the age of 16 with RTD for the presence of HBoV DNA and 20 other respiratory pathogens at three different hospitals in Belgium. HBoV was detected in 77 children with a median age of 10.6 months. Consecutive samples were available for 15 HBoV-positive children and showed persistent HBoV positivity in four of them. Monoinfection was observed in six infants. Four of them were born prematurely and were infected during hospitalization at the neonatal intensive care unit (NICU). Only one of these six monoinfected children was diagnosed with recurrent wheezing due to HBoV. This child was carried to term and had a high viral load. Coinfections, most frequently with rhinovirus (52.1%) and adenovirus (49.3%), were observed in 72 patients. In seventeen of them in which HBoV was present at high viral load or higher viral load than its copathogens, bronchi(oli)tis (n = 8), recurrent wheezing (n = 8) or episodic wheezing (n = 1) were diagnosed. Our results suggest that HBoV infection at high viral load in infants is associated with wheezing (P = 0.013, Cramer's V = 0.613).

Novel Primate Bocaparvovirus Species 3 Identified in Wild Macaca Mulatta in China

Primate bocaparvovirus (BOV) is a possible cause of respiratory disorders and gastroenteritis in humans. However, the diversity and evolution of these viruses remain largely unknown, despite the identification of a growing number of BOVs in non-human primates (NHPs). Here, we report the identification of a novel BOV (provisionally named Macaca mulatta bocaparvovirus [MmBOV]) in the feces of wild Macaca mulatta in China by viral metagenomic analysis. Seven of 400 fecal samples from Macaca mulatta were positive for MmBOV. An almost complete genome sequence of 4,831 nucleotides was obtained, which had genomic organization and protein motifs similar to human bocaviruses (HOBVs), and shared characteristically low G/C content and weak codon usage bias. Sequence analyses of NS1, NP1, and VP1 revealed that MmBOV was most closely related to HBOV4 of Primate bocaparvovirus 2 (approximately 68.4%/70.6%, 73.3%/67.6%, and 70.4%/73.1% nucleotide/amino acid identities, respectively). Additionally, phylogenetic analysis revealed that MmBOV formed an independent peripheral branch, but clustered closely with those of the Primate bocaparvovirus species in the BOV genus (particularly HBOV4). These data strongly suggest that HBOV4 originated from NHP bocaparvoviruses around 200-300 years ago, and that NHPs may act as HBOV reservoirs. Following the International Committee of Taxonomy for Viruses guidelines, we propose MmBOV as a new species (tentatively named Primate bocaparvovirus 3) in the genus Bocaparvovirus, which is the first report of a novel species of primate BOV. Our data facilitate future research on the genetic diversity and evolution of primate bocaparvoviruses and highlight the importance of bocaparvovirus surveys in wild NHPs.

Emerging Human Parvoviruses: The Rocky Road to Fame

Parvoviruses are structurally simple viruses with linear single-stranded DNA genomes and nonenveloped icosahedral capsids. They infect a wide range of animals from insects to humans. Parvovirus B19 is a long-known human pathogen, whereas adeno-associated viruses are nonpathogenic. Since 2005, many parvoviruses have been discovered in human-derived samples: bocaviruses 1-4, parvovirus 4, bufavirus, tusavirus, and cutavirus. Some human parvoviruses have already been shown to cause disease during acute infection, some are associated with chronic diseases, and others still remain to be proven clinically relevant-or harmless commensals, a distinction not as apparent as it might seem. One initially human-labeled parvovirus might not even be a human virus, whereas another was originally overlooked due to inadequate diagnostics. The intention of this review is to follow the rocky road of emerging human parvoviruses from discovery of a DNA sequence to current and future clinical status, highlighting the perils along the way.

Human bocaviruses and paediatric infections

Human bocavirus 1 (HBoV1), belonging to the Parvoviridae family, was discovered in 2005, in nasopharyngeal samples from children with respiratory tract infections. Three additional bocaviruses, HBoV2-4, were discovered in 2009-10. These viruses have mainly been found in faecal samples and their role in human diseases is still uncertain. HBoV1 causes a wide spectrum of respiratory diseases in children, including common cold, acute otitis media, pneumonia, bronchiolitis, and asthma exacerbations. HBoV1 DNA can persist in airway secretions for months after an acute infection. Consequently, acute HBoV1 infection cannot be diagnosed with standard DNA PCR; quantitative PCR and serology are better diagnostic approaches. Because of their high clinical specificity, diagnostic developments such as HBoV1 mRNA and antigen detection have shown promising results. This Review summarises the knowledge on human bocaviruses, with a special focus on HBoV1.

Influenza and Viral Pneumonia

Influenza and other respiratory viruses are commonly identified in patients with community-acquired pneumonia, hospital-acquired pneumonia, and in immunocompromised patients with pneumonia. Clinically, it is difficult to differentiate viral from bacterial pneumonia. Similarly, the radiological findings of viral infection are nonspecific. The advent of polymerase chain reaction testing has enormously facilitated the identification of respiratory viruses, which has important implications for infection control measures and treatment. Currently, treatment options for patients with viral infection are limited, but there is ongoing research on the development and clinical testing of new treatment regimens and strategies.

Human bocavirus is detected in human placenta and aborted tissues

Background

To date, four human bocaviruses (HBoV) have been described. The most closely related viruses (bovine and canine parvoviruses) are associated with miscarriage in their hosts. The objective of this retrospective study was to determine the frequency of HBoV DNA in miscarriage.

Study Design

Tissue samples from 172 patients, in which miscarriage occurred, were included and tested with a published qPCR protocol. Positive PCRs were mutually confirmed by sequencing.

Results

43 patients (25%) were positive for HBoV DNA. Of those, the majority of HBoV‐positive samples were tissues from miscarriage (placenta: 6; aborted tissue products of conception: 37 specimens). The samples were not paired; either placental or aborted tissue was available.

Conclusions

The results show that, as long as no animal model is available, the role of HBoV in the occurrence of miscarriage requires additional prospective studies in order to investigate its significance and causal involvements of this pathogen.

Epidemiology of HBoV1 infection and relationship with meteorological conditions in hospitalized pediatric patients with acute respiratory illness: a 7-year study in a subtropical region

BACKGROUND

Human bocavirus 1 (HBoV1) is an important cause of acute respiratory illness (ARI), yet the epidemiology and effect of meteorological conditions on infection is not fully understood. To investigate the distribution of HBoV1 and determine the effect of meteorological conditions, hospitalized pediatric patients were studied in a subtropical region of China.

METHODS

Samples from 11,399 hospitalized pediatric patients (≤14 years old), with ARI were tested for HBoV1 and other common respiratory pathogens using real-time PCR, between July 2009 and June 2016. In addition, local meteorological data were collected.

RESULTS

Of the 11,399 patients tested, 5606 (49.2%) were positive for at least one respiratory pathogen. Two hundred forty-eight of 11,399 (2.2%) were positive for HBoV1 infection. Co-infection was common in HBoV1-positive patients (45.2%, 112/248). A significant difference in the prevalence of HBoV1 was found in patients in different age groups (p < 0.001), and the peak prevalence was found in patients aged 7-12 months (4.7%, 56/1203). Two HBoV1 prevalence peaks were found in summer (between June and September) and winter (between November and December). The prevalence of HBoV1 was significantly positively correlated with mean temperature and negatively correlated with mean relative humidity, and the mean temperature in the preceding month had better explanatory power than the current monthly temperature.

CONCLUSIONS

This study provides a better understanding of the characteristics of HBoV1 infection in children in subtropical regions. Data from this study provide useful information for the future control and prevention of HBoV1 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.

Two novel bocaparvovirus species identified in wild Himalayan marmots

Bocaparvovirus (BOV) is a genetically diverse group of DNA viruses and a possible cause of respiratory, enteric, and neurological diseases in humans and animals. Here, two highly divergent BOVs (tentatively named as Himalayan marmot BOV, HMBOV1 and HMBOV2) were identified in the livers and feces of wild Himalayan marmots in China, by viral metagenomic analysis. Five of 300 liver samples from Himalayan marmots were positive for HMBOV1 and five of 99 fecal samples from these animals for HMBOV2. Their nearly complete genome sequences are 4,672 and 4,887 nucleotides long, respectively, with a standard genomic organization and containing protein-coding motifs typical for BOVs. Based on their NS1, NP1, and VP1, HMBOV1 and HMBOV2 are most closely related to porcine BOV SX/1-2 (approximately 77.0%/50.0%, 50.0%/53.0%, and 79.0%/54.0% amino acid identity, respectively). Phylogenetic analysis of these three proteins showed that HMBOV1 and HMBOV2 formed two distinctly independent branches in BOVs. According to these results, HMBOV1 and HMBOV2 are two different novel species in the Bocaparvovirus genus. Their identification expands our knowledge of the genetic diversity and evolution of BOVs. Further studies are needed to investigate their potential pathogenicity and their impact on Himalayan marmots and humans.

Increased serum vascular endothelial growth factor is associated with acute viral encephalitis in Bangladeshi children

Encephalitis causes significant global morbidity and mortality. A large number of viruses cause encephalitis, and their geographic and temporal distributions vary. In many encephalitis cases, the virus cannot be detected, even after extensive testing. This is one challenge in management of the encephalitis patient. Since cytokines are pivotal in any form of inflammation and vary according to the nature of the inflammation, we hypothesized cytokine levels would allow us to discriminate between encephalitis caused by viruses and other aetiologies. This pilot study was conducted in a tertiary care hospital in Dhaka, Bangladesh. Viral detection was performed by polymerase chain reaction using patient cerebrospinal fluid. Acute phase reactants and cytokines were detected in patient serum. Of the 29 biomarkers assessed using the Wilcoxon rank-sum test, only vascular endothelial growth factor (VEGF) was significantly higher (P = 0.0015) in viral-positive compared with virus–negative encephalitis patients. The area under the curve (AUC) for VEGF was 0.82 (95% confidence interval: 0.66–0.98). Serum VEGF may discriminate between virus-positive and virus-negative encephalitis. Further study will be needed to confirm these findings.

Emerging Foodborne and Agriculture-Related Viruses

Viruses rapidly evolve and can emerge in unpredictable ways. Transmission pathways by which foodborne viruses may enter human populations and evolutionary mechanisms by which viruses can become virulent are discussed in this chapter. A majority of viruses emerge from zoonotic animal reservoirs, often by adapting and infecting intermediate hosts, such as domestic animals and livestock. Viruses that are known foodborne threats include hepatitis E virus, tick-borne encephalitis virus, enteroviruses, adenovirus, and astroviruses, among others. Viruses may potentially evolve and emerge as a result of modern agricultural practices which can concentrate livestock and bring them into contact with wild animals. Examples of viruses that have emerged in this manner are influenza, coronaviruses such as severe acute respiratory syndrome and Middle East respiratory syndrome, and the Nipah virus. The role of bats, bush meat, rodents, pigs, cattle, and poultry as reservoirs from which infectious pathogenic viruses emerge are discussed.

Acute necrotizing encephalopathy causing human bocavirus

Acute necrotizing encephalopathy is characterized by multiple, symmetrical lesions involving the thalamus, brainstem, cerebellum, and white matter and develops secondarily to viral infections. Influenza viruses are the most common etiological agents. Here, we present the first case of acute necrotizing encephalopathy to develop secondarily to human bocavirus. A 3-year-old girl presented with fever and altered mental status. She had had a fever, cough, and rhinorrhea for five days. The patient was admitted to the intensive care unit with an initial diagnosis of encephalitis when vomiting, convulsions, and loss of consciousness developed. Signs of meningeal irritation were detected upon physical examination. There was a mild increase in proteins, but no cells, in the cerebrospinal fluid (CSF). Brain magnetic resonance imaging showed symmetrical, heterogeneous hyperintensities bilaterally in the caudate nuclei and putamen. Ammonium, lactate, tandem mass spectroscopy, and urine organic acid were normal. No bacteria were detected in the CSF cultures. Human bocavirus was detected in a nasopharyngeal aspirate using real-time PCR, while no influenza was detected. Oseltamivir, acyclovir, 3% hypertonic saline solution, and supportive care were used to treat the patient, who was discharged after two weeks. She began to walk and talk after one month of physical therapy and complete recovery was observed after six months. Human bocavirus is a recently identified virus that is mainly reported as a causative agent in respiratory tract infections. Here, we present a case of influenza-like acute necrotizing encephalopathy secondary to human bocavirus infection.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Prevalence and Phylogenetic Analysis of Human Bocaviruses 1-4 in Pediatric Patients with Various Infectious Diseases

Objectives

Viral infections caused by human bocaviruses 1–4 (HBoV1-4) are more complicated than previously believed. A retrospective, large-scale study was undertaken to explore the prevalence of HBoV1-4 in pediatric patients with various infectious diseases and delineate their phylogenetic characteristics.

Methods

Clinical samples from four specimen types, including 4,941 respiratory, 2,239 cerebrospinal fluid (CSF), 2,619 serum, and 1,121 fecal specimens, collected from pediatric patients with various infectious diseases were screened for HBoV1-4. A 690-nt fragment in each specimen was then amplified and sequenced for phylogenetic analysis. Clinical characteristics of HBoV-positive patients with different specimen types available were evaluated.

Results

Approximately 1.2% of patients were confirmed as HBoV-positive, with the highest positive rate in patients with gastrointestinal infection (2.2%), followed by respiratory (1.65%), central nervous system (0.8%), and hematological infections (0.2%). A single genetic lineage of HBoV1 circulated among children over the 8-year period, while a new cluster of HBoV2, via intra-genotype recombination between HBoV2A and HBoV2B, was prevalent. Some patients had HBoV1-positive respiratory and serum specimens or fecal specimens. Several cases became HBoV1-positive following the appearance of respiratory infection, while several cases were positive for HBoV2 only in CSF and serum specimens, rather than respiratory specimens.

Conclusions

A single genetic lineage of HBoV1 is speculated as a viral pathogen of respiratory infection and causes both comorbid infection and acute gastroenteritis. Additionally, a new cluster of HBoV2 is prevalent in China, which may infect the host through sites other than the respiratory tract.

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.

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.

Case Report: Human Bocavirus Associated Pneumonia as Cause of Acute Injury, Cologne, Germany

Although the human bocavirus (HBoV) is known since a decade, limited information about its pathogenesis is available due to the lack of an animal model. Thus, clinical cases and studies are the major source of novel information about the course of infection and the related pathophysiology.In this context, a clinical case of an adult patient suffering from severe HBoV-pneumonia is described that was associated with loss of consciousness followed by acute rib fracture and subsequent neurological disorder.Following initial global respiratory dysfunction the clinical respiratory symptoms recovered but the neurological symptoms maintained after weaning and intensive care in the stroke unit. During the initial phase, an acute active HBoV infection was confirmed by positive polymerase chain reactions from bronchoalveolar lavage fluid and serum.The case further demonstrates that HBoV can cause severe pneumonia, induce secondary disease also in adults, and may be associated with neurological symptoms as previously assumed.

Human bocaviruses: Possible etiologic role in respiratory infection

Four species of human bocaviruses (HBoV) are currently included in the Bocavirus genus. There is satisfactory evidence demonstrating an association between HBoV1 and respiratory disease in children, and there is evidence that HBoV2 (and possibly the HBoV3 and HBoV4 species) are associated with gastroenteritis. In particular, HBoV1 has been associated with a prolonged period of persistence in the mucosa of the respiratory tract. Virus persistence does play a role in the high frequency of co-infections with proper pathogens of the upper and lower respiratory tracts. The high detection rate of multiple respiratory viruses in up to 83% of respiratory specimens and the presence of asymptomatic HBoV1 infections complicate the elucidation of the pathogenic role of the agent. Overall, a large amount of data are available concerning HBoV1, whereas little information is available about other bocavirus species. High viral loads are often associated with symptoms, and viremia may be associated with systemic manifestations such as encephalopathy. The effects and mechanisms of latency, persistence, reactivation, and reinfection are poorly understood. Thus, particularly in co-infections, the pathogenic contribution of the detected bocavirus species cannot be accurately stated. This review summarizes the current knowledge of HBoV species and provides perspectives for future clinical studies.

The Fecal Virome of Children with Hand, Foot, and Mouth Disease that Tested PCR Negative for Pathogenic Enteroviruses

Hand, foot, and mouth disease (HFMD) affects infant and young children. A viral metagenomic approach was used to identify the eukaryotic viruses in fecal samples from 29 Thai children with clinical diagnosis of HFMD collected during the 2012 outbreak. These children had previously tested negative by PCR for enterovirus 71 and coxsackievirus A16 and A6. Deep sequencing revealed nine virus families: Picornaviridae, Astroviridae, Parvoviridae, Caliciviridae, Paramyxoviridae, Adenoviridae, Reoviridae, Picobirnaviridae, and Polyomaviridae. The highest number of viral sequences belonged to human rhinovirus C, astrovirus-MLB2, and coxsackievirus A21. Our study provides an overview of virus community and highlights a broad diversity of viruses found in feces from children with HFMD.

Atypical presentation of human bocavirus: Severe respiratory tract infection complicated with encephalopathy

Human bocavirus (HBOV) has been reported as a worldwide distributed respiratory pathogen. It has also been associated with encephalitis recently by detection of the virus in cerebrospinal fluid (CSF) of patients presented with encephalitis. This retrospective study aimed to present clinical features of HBOV infections in children with respiratory symptoms and describe unexplained encephalopathy in a subgroup of these patients. Results of 1,143 pediatric nasal samples from mid-December 2013 to July 2014 were reviewed for detection of HBOV. A multiplex real time polymerase chain reaction assay was used for viral detection. Medical records of the patients were retrospectively analyzed. HBOV was detected in 30 patients (2.6%). Median age was 14 months (5-80). Clinical diagnoses were upper respiratory tract infection (n = 10), bronchopneumonia (n = 9), acute bronchiolitis (n = 5), pneumonia (n = 4), acute bronchitis (n = 1), and asthma execarbation (n = 1). Hospitalization was required in 16 (53.3%) patients and 10 (62.5%) of them admitted to pediatric intensive care unit (PICU). Noninvasive mechanical ventilation modalities was applied to four patients and mechanical ventilation to four patients. Intractable seizures developed in four patients while mechanically ventilated on the 2nd-3rd days of PICU admission. No specific reason for encephalopathy was found after a thorough investigation. No mortality was observed, but two patients were discharged with neurological sequela. HBOV may lead to respiratory infections in a wide spectrum of severity. This report indicates its potential to cause severe respiratory infections requiring PICU admission and highlights possible clinical association of HBOV and encephalopathy, which developed during severe respiratory infection.

Acute meningoencephalitis associated with echovirus 9 infection in Sri Lanka, 2009

The aetiology of acute meningoencephalitis in Sri Lankan children and adults is poorly understood. This study was carried out to determine pathogens responsible for meningoencephalitis in Sri Lanka. A hospital-based cross-sectional study was performed using cerebrospinal fluid samples (22 adult and 17 pediatric) collected from August to December 2009 from patients clinically diagnosed with acute meningoencephalitis at two tertiary care hospitals in Sri Lanka. Routine microbiology for bacterial pathogens together with in-house RT-PCR and PCR assays for the detection of dengue viruses, Japanese encephalitis virus, West Nile virus, chikungunya virus, enteroviruses, mumps virus, measles virus, herpes simplex viruses types 1 and 2, and varicella zoster virus were performed. Bacterial pathogens were not isolated from any patient specimens. However, from nine of the paediatric patients aged 1 month to 10 years (mean age 5.2 years) echovirus 9 (E-9; family Picornaviridae, genus Enterovirus,species Enterovirus B ) was detected by RT-PCR. All nine patients presented with fever, six had headache, and seven had vomiting. Neck stiffness indicating meningitis was present in six of the patients. Phylogenetic analysis of partial VP1 and VP4-VP2 genes showed these E-9 strains to be most closely related to E-9 strains detected in CSF from Korea and France in 2005 and 2006. The remaining patients were negative for all other viruses tested. E-9 was the most common cause of acute meningoencephalitis in the tested paediatric population from Sri Lanka in 2009, which likely reflects circulation of this E-9 strain between Europe and Asia over several years.

Small circular single stranded DNA viral genomes in unexplained cases of human encephalitis, diarrhea, and in untreated sewage

Viruses with small circular ssDNA genomes encoding a replication initiator protein can infect a wide range of eukaryotic organisms ranging from mammals to fungi. The genomes of two such viruses, a cyclovirus (CyCV-SL) and gemycircularvirus (GemyCV-SL) were detected by deep sequencing of the cerebrospinal fluids of Sri Lankan patients with unexplained encephalitis. One and three out of 201 CSF samples (1.5%) from unexplained encephalitis patients tested by PCR were CyCV-SL and GemyCV-SL DNA positive respectively. Nucleotide similarity searches of pre-existing metagenomics datasets revealed closely related genomes in feces from unexplained cases of diarrhea from Nicaragua and Brazil and in untreated sewage from Nepal. Whether the tropism of the cyclovirus and gemycircularvirus reported here include humans or other cellular sources in or on the human body remains to be determined.