Human bocavirus: prevalence and clinical spectrum at a children's hospital

Prevalence and significance of a canine bocavirus-2 outbreak in a cohort of military dogs in Austria

Introduction

Bocaviruses are single-stranded DNA viruses from the Parvoviridae family, which have been minimally discussed in veterinary literature and are considered potentially pathogenic. Due to the recurring illness among young dogs in a closed cohort of military dogs in Austria, we assessed the prevalence, possible disease manifestation and outcome of CBoV-2 infection in this cohort.

Materials and methods

This led to a comprehensive study that not only analyzed past cases but also performed prospective screening PCR tests to identify CBoV-2 positive dogs within this specific dog population. Pharyngeal and rectal swabs were taken. In addition, a control group (n = 20) of clinically healthy client-owned dogs was sampled. A total of 190 samples were taken and tested for the presence of CBoV-2 specific nucleic acid using screening PCR. In addition to the primers used for routine diagnostics, two other primer pairs were used to verify questionable results. The retrospective part of the study includes a total of 13 military dogs that had previously shown suspected clinical signs.

Results

At the time of the first examination within the prospective part of the study, CBoV-2 was detected in 31% (12/39) of the dogs. During the second examination, 2% (1/47) tested positive, while all PCR testing in the control group (n = 20) was negative in all cases. The retrospective evaluation of the 13 cases revealed a total of six animals tested positive for CBoV-2 via screening PCR. All puppies suffered from skin lesions (papules, vesicles, or pustules). Other clinical signs included diarrhea (83%), vomiting (77%), respiratory (15%), and neurological (8%) signs.

Discussion

According to the study there are certain indications that CBoV-2 shares similarities with CPV-2 infection but also exhibits critical differences, making their differentiation essential for patient management, outcomes, and prevention strategies.

Clinical Course and Molecular Characterization of Human Bocavirus Associated with Acute Lower Respiratory Tract Infections in a Tertiary Care Hospital in Northern India

Respiratory samples from 139 hospitalized children were screened for the human bocavirus (HBoV) genome. Positive samples were sequenced for the partial VP1/VP2 gene followed by molecular and phylogenetic analyses. HBoV positivity was noted in 7.2% (10/139) of patients. All HBoV-positive children presented with fever, cough, and respiratory distress (90%, 9/10). Three children developed multisystemic viral illness, with one fatality. Eight children required intensive care management and five required mechanical ventilation. The nucleotide percent identity of the partial VP1/VP2 gene in the HBoV study strains ranged from 97.52% to 99.67%. Non-synonymous mutations in the VP1 protein were T591S (n = 8) and Y517S (n = 1) in the HBoV St1 strain and N475S (n = 8) and S591T (n = 2) in the HBoV St2 strain. One strain showed A556P, H556P, I561S, and M562R non-synonymous mutations. All the study strains belonged to the HBoV1 type. Seven HBoV strains belonged to the same lineage, and three belonged to another lineage. For evolutionary dynamics, GTR+I substitution model with uncorrelated relaxed lognormal clock and Bayesian Skyline tree prior showed 9.0 × 10-4 (95% highest probability density interval: 3.1 × 10-6, 2.1 × 10-3) nucleotide substitutions per site per year. Clinical suspicion and virological screening are necessary to identify HBoV infections in children.

Prevalence and Clinical Characterization of Bocavirus Infection in a Specialized Children's Hospital in Saudi Arabia

Aim

The aim of this study was to assess the prevalence and clinical characterization of bocavirus infection in patients admitted with respiratory symptoms to a specialized children’s hospital in Riyadh, Saudi Arabia.

Methods

This is a retrospective cross-sectional study that included children aged 0-14 years and was conducted over a two-year period (2017-2019). All data were gathered from an electronic information recording system, which included patients’ demographics, comorbidities, clinical presentation, complication, and duration of hospitalization.

Results

Among all patients (11,709) admitted to King Abdullah Specialized Children’s Hospital with predominant respiratory symptoms during the study period, 193 (1.6%) patients had bocavirus infections. Most of the patients were diagnosed in winter months. Cough was the primary presenting symptom (91.7%) followed by fever (83.4%). Gastrointestinal symptoms were also common (anorexia in 62% and vomiting in 39%). In 80% (n=154/193) of cases, bocavirus co-existed with other viruses, namely, human rhinovirus (45.8%), human adenovirus (31.2%), and respiratory syncytial virus type A (17.5%). Moreover, those who required oxygen supply stayed longer in the hospital (p<0.001) and were more likely to receive multiple medications such as bronchodilators (p<0.001), corticosteroids (p<0.001), and nebulized racemic epinephrine (p>0.05). Children infected with bocavirus and co-existing viruses were less likely to require oxygen supply (p<0.050).

Conclusion

Bocavirus infection is more common during winter months and predominantly affects respiratory and gastrointestinal systems in children. More studies are needed to evaluate the global impact of this recently recognized infection.

Interplay between hypoxia and inflammation contributes to the progression and severity of respiratory viral diseases

History of pandemics is dominated by viral infections and specifically respiratory viral diseases like influenza and COVID-19. Lower respiratory tract infection is the fourth leading cause of death worldwide. Crosstalk between resultant inflammation and hypoxic microenvironment may impair ventilatory response of lungs. This reduces arterial partial pressure of oxygen, termed as hypoxemia, which is observed in a section of patients with respiratory virus infections including SARS-CoV-2 (COVID-19). In this review, we describe the interplay between inflammation and hypoxic microenvironment in respiratory viral infection and its contribution to disease pathogenesis.

Human Bocavirus 1 Infection of Well-Differentiated Human Airway Epithelium

Human bocavirus 1 (HBoV1) is a small DNA virus that belongs to the Bocaparvovirus genus of the Parvoviridae family. HBoV1 is a common respiratory pathogen that causes mild to life-threatening acute respiratory tract infections in children and immunocompromised individuals, infecting both the upper and lower respiratory tracts. HBoV1 infection causes death of airway epithelial cells, resulting in airway injury and inflammation. In vitro, HBoV1 only infects well-differentiated (polarized) human airway epithelium cultured at an air-liquid interface (HAE-ALI), but not any dividing human cells. A full-length HBoV1 genome of 5543 nucleotides has been cloned from DNA extracted from a human nasopharyngeal swab into a plasmid called HBoV1 infectious clone pIHBoV1. Transfection of pIHBoV1 replicates efficiently in human embryonic kidney 293 (HEK293) cells and produces virions that are highly infectious. This article describes protocols for production of HBoV1 in HEK293 cells, generation of HAE-ALI cultures, and infection with HBoV1 in HAE-ALI. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Human bocavirus 1 production in HEK293 cells Support Protocol 1: HEK293 cell culture and transfection Support Protocol 2: Quantification of human bocavirus 1 using real-time quantitative PCR Basic Protocol 2: Differentiation of human airway cells at an air-liquid interface Support Protocol 3: Expansion of human airway epithelial cell line CuFi-8 Support Protocol 4: Expansion of human airway basal cells Support Protocol 5: Coating of plastic dishes and permeable membranes of inserts Support Protocol 6: Transepithelial electrical resistance measurement Basic Protocol 3: Human bocavirus 1 infection in human airway epithelium cultured at an air-liquid interface Support Protocol 7: Isolation of infected human airway epithelium cells from inserts Basic Protocol 4: Transduction of airway basal cells with lentiviral vector.

Cutaneous Manifestations of COVID-19: A Systematic Review

Objective: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently a pandemic. Although pulmonary health has been the primary focus of studies during the early days of COVID-19, development of a comprehensive understanding of this emergent disease requires knowledge of all possible disease manifestations in affected patients. This Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant review focuses on cutaneous manifestations reported in COVID-19 patients. Approach: Literature review was conducted using the PubMed database to examine various cutaneous manifestations related to the SARS-CoV-2 infection. Published articles (n = 56) related to search criteria from the onset of the COVID-19 pandemic to June 30, 2020, were included. The primary literature articles included in this study were mainly from France, Spain, Italy, and the United Kingdom. Results: Unique to many other symptoms of COVID-19, its cutaneous manifestations have been found in people of all age groups, including children. The cutaneous manifestations of COVID-19 are varied and include maculopapular, chilblain-like, urticarial, vesicular, livedoid, and petechial lesions. In addition, rashes are common in multisystem inflammatory syndrome in children, a new and serious health condition that shares symptoms with Kawasaki disease and is likely related to COVID-19. In addition, personal protective equipment-related skin wounds are of serious concern since broken cutaneous barriers can create an opening for potential COVID-19 infections. Innovation and Conclusion: As this virus continues to spread silently, mainly through asymptomatic carriers, an accurate and rapid identification of these cutaneous manifestations may be vital to early diagnosis and lead to possible better prognosis in COVID-19 patients. This systematic review and photo atlas provide a detailed analysis of the skin pathologies related to COVID-19. Study of these cutaneous manifestations and their pathogenesis, as well their significance in human health will help define COVID-19 in its entirety, which is a prerequisite to its effective management.

Bocavirus Infection in a Young Pregnant Woman: A Case Report and Literature Review

BACKGROUND Human bocavirus (HBoV) is a parvovirus found primarily in children and was first identified in 2005. It usually causes mild upper- and lower-respiratory tract infections. HBoV infection seems to be rare during adulthood, probably due to high antibody titers resulting from childhood infection and seroconversion. The clinical significance, possible complications, and consequences of an adulthood infection are still unclear. Furthermore, the consequences of HBoV infection during pregnancy are seldom reported in the literature. CASE REPORT We report the case of a 22-year-old pregnant woman in her third trimester who presented with a 1-week history of fever and cough followed by progressive shortness of breath. She was treated initially as a case of severe pneumonia; however, her condition deteriorated rapidly, resulting in hypoxic respiratory failure that required intensive care support. The patient was found to have dilated cardiomyopathy on echocardiography, and her fetal ultrasound showed no fetal heart activity; subsequently, labor induction for stillbirth was performed. An extensive workup for an underlying cause was unrevealing apart from positive respiratory viral PCR assay for human bocavirus, performed twice. A provisional diagnosis of HBoV pneumonia complicated by dilated cardiomyopathy, stillbirth, and multiorgan failure was made. Fortunately, the patient had a good recovery and was discharged home in good clinical condition. CONCLUSIONS In addition to severe pneumonia, HBoV infection may result in other life-threatening complications. Although the infection is rare during adulthood, infection in a pregnant woman should be taken seriously and close monitoring of such patients is advised.

Detection and phylogenetic analysis of Human bocavirus in children diagnosed with acute respiratory tract infection

Introduction. Human bocavirus (HBoV) is a recently discovered parvovirus; it has been shown to be a common cause of respiratory infections and gastroenteritis in children. Since its identification, HBoV has been detected worldwide in nasopharyngeal swabs, serum and stool samples particularly those obtained from young children suffering from respiratory or gastrointestinal tract infections.Aim. The aim of this work was to determine HBoV prevalence among children with acute respiratory tract infection in Egypt, to detect the most prevalent HBoV genotype and to compare PCR and ELISA as diagnostic techniques for HBoV infection.Methods. Nasopharyngeal swabs and blood samples were obtained within the first day of admission from 75 children diagnosed with acute respiratory tract infection in El-Shatby University Hospital for Children in Alexandria, Egypt from October 2018 to March 2019. Conventional PCR was used to detect HBoV DNA, ELISA was used to detect HBoV IgM antibodies and sequencing of the VP1/2 genes was used for genotyping.Results. Seven (9.3%) of the 75 nasopharyngeal swabs obtained from patients with acute respiratory tract infection were positive for HBoV by PCR, while 5 (6.7 %) of the 75 serum samples were positive for HBoV IgM antibodies using ELISA. The correlation between PCR and ELISA results showed a highly significant association between PCR and ELISA techniques (X ²=52.041, P<0.01) and a highly significant agreement between the two methods (Kappa=81.9 %, P<0.01). Phylogenetic analysis showed that all positive samples were related to the HBoV-1 genotype.Conclusion. Human bocavirus was detected at 9.3 % prevalence in nasopharyngeal swabs obtained from children with acute respiratory tract infection. The HBoV-1 genotype was the only genotype detected, suggesting that a single genetic lineage of HBoV is circulating in Egypt. PCR and ELISA are two reliable methods for detection and diagnosis of HBoV.

Role of Human Bocavirus Respiratory Tract Infection in Hematopoietic Cell Transplant Recipients

BACKGROUND

Limited data exist regarding the impact of human bocavirus (BoV) in hematopoietic cell transplant (HCT) recipients.

METHODS

In a longitudinal surveillance study among allogeneic HCT recipients, pre-HCT and weekly post-HCT nasal washes and symptom surveys were collected through day 100, then at least every 3 months through 1 year post-HCT at the Fred Hutch (2005-2010). Samples were tested by multiplex semi-quantitative PCR for 12 viruses. Plasma samples from BoV+ subjects were analyzed by PCR. Separately, we conducted a retrospective review of HCT recipients with BoV detected in lower respiratory tract specimens.

RESULTS

Among 51 children and 420 adults in the prospective cohort, 21 distinct BoV respiratory tract infections (RTIs) were observed by 1 year post-HCT in 19 patients. Younger age and exposure to children were risk factors for BoV acquisition. Univariable models among patients with BoV RTI showed higher peak viral load in nasal samples (p=0.04) and presence of respiratory copathogens (p=0.03) were associated with presence of respiratory symptoms but BoV plasma detection was not. Only watery eyes and rhinorrhea were associated with BoV RTI in adjusted models. With additional chart review, we identified 6 HCT recipients with BoV detected in lower respiratory tract specimens [incidence rate of 0.4% (9/2509) per sample tested]. Although all cases presented with hypoxemia, 4 had respiratory copathogens or concomitant conditions that contributed to respiratory compromise.

CONCLUSIONS

BoV RTI is infrequent in transplant recipients and associated with mild symptoms. Our studies did not demonstrate convincing evidence that BoV is a serious respiratory pathogen.

Rare and Emerging Viral Infections in the Transplant Population

Viral infections account for a large proportion of emerging infectious diseases, and the agents included in this group consist of recently identified viruses as well as previously identified viruses with an apparent increase in disease incidence. In transplant recipients, this group can include viruses with no recognized pathogenicity in immunocompetent patients and those that result in atypical or more severe disease presentations in the immunocompromised host. In this chapter, we begin by discussing viral diagnostics and techniques used for viral discovery, specifically as they apply to emerging and rare infections in this patient population. Focus then shifts to specific emerging and re-emerging viruses in the transplant population, including human T-cell leukemia virus 1, rabies, lymphocytic choriomeningitis virus, human bocavirus, parvovirus 4, measles, mumps, orf, and dengue. We have also included a brief discussion on emerging viruses and virus families with few or no reported cases in transplant recipients: monkeypox, nipah and hendra, chikungunya and other alphaviruses, hantavirus and the Bunyaviridae, and filoviruses. Finally, concerns regarding infectious disease complications in xenotransplantation and the reporting of rare viral infections are addressed. With the marked increase in the number of solid organ and hematopoietic stem cell transplants performed worldwide, we expect a corresponding rise in the reports of emerging viral infections in transplant hosts, both from known viruses and those yet to be identified.

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.

Nation-wide surveillance of human acute respiratory virus infections between 2013 and 2015 in Korea

The prevalence of eight respiratory viruses detected in patients with acute respiratory infections (ARIs) in Korea was investigated through analysis of data recorded by the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS) from 2013 to 2015. Nasal aspirate and throat swabs specimens were collected from 36 915 patients with ARIs, and viral nucleic acids were detected by real‐time (reverse‐transcription) polymerase chain reaction for eight respiratory viruses, including human respiratory syncytial viruses (HRSVs), influenza viruses (IFVs), human parainfluenza viruses (HPIVs), human coronaviruses (HCoVs), human rhinovirus (HRV), human adenovirus (HAdV), human bocavirus (HBoV), and human metapneumovirus (HMPV). The overall positive rate of patient specimens was 49.4% (18 236/36 915), 5% of which carried two or more viruses simultaneously. HRV (15.6%) was the most predominantly detected virus, followed by IFVs (14.6%), HAdV (7.5%), HPIVs (5.8%), HCoVs (4.2%), HRSVs (3.6%), HBoV (1.9%), and HMPV (1.6%). Most of the ARIs were significantly correlated with clinical symptoms of fever, cough, and runny nose. Although HRV and HAdV were frequently detected throughout the year in patients, other respiratory viruses showed apparent seasonality. HRSVs and IFVs were the major causative agents of acute respiratory diseases in infants and young children. Overall, this study demonstrates a meaningful relationship between viral infection and typical manifestations of known clinical features as well as seasonality, age distribution, and co‐infection among respiratory viruses. Therefore, these data could provide useful information for public health management and to enhance patient care for primary clinicians.

Whole-genome sequencing analysis of human bocavirus detected in South Korea

Human bocaviruses (HBoVs) have been detected in human gastrointestinal infections worldwide. In 2005, HBoV was also discovered in infants and children with infections of the lower respiratory tract. Recently, several genotypes of this parvovirus, including HBoV genotype 2 (HBoV2), genotype 3 (HBoV3) and genotype 4 (HBoV4), were discovered and found to be closely related to HBoV. HBoV2 was first detected in stool samples from children in Pakistan, followed by detection in other countries. HBoV3 was detected in Australia and HBoV4 was identified in stool samples from Nigeria, Tunisia and the USA. Recently, HBoV infection has been on the rise throughout the world, particularly in countries neighbouring South Korea; however, there have been very few studies on Korean strains. In this study, we characterised the whole genome and determined the phylogenetic position of CUK-BC20, a new clinical HBoV strain isolated in South Korea. The CUK-BC20 genome of 5184 nucleotides (nt) contains three open-reading frames (ORFs). The genotype of CUK-BC20 is HBoV2, and 98.77% of its nt sequence is identical with those of other HBoVs, namely Rus-Nsc10-N386. Especially, the ORF3 amino acid sequences from positions 212-213 and 454 corresponding to a variable region (VR)1 and VR5, respectively, showed genotype-specific substitutions that distinguished the four HBoV genotypes. As the first whole-genome sequence analysis of HBoV in South Korea, this information will provide a valuable reference for the detection of recombination, tracking of epidemics and development of diagnosis methods for HBoV.

Human Bocavirus: Can It Trigger Hemophagocytic Lymphohistiocytosis?

With improvements in molecular diagnostic methods, report of Human bocavirus (HBoV) as an etiologic agent in many studies on viral respiratory and gastrointestinal infections has been increasing. Two pediatric patients who presented with secondary hemophagocytic lymphohistiocytosis were examined for etiologic causes, including viruses. Whole bacterial and fungal cultures and viral serological studies were negative. Viral polymerase chain reaction of nasopharyngeal secretions showed HBoV. One was successfully treated with intravenous immunoglobulins, whereas the other died with multiorgan failure. Here we report 2 pediatric patients with secondary hemophagocytic lymphohistiocytosis and detection of HBoV as the sole agent, predicting an association.

Severe varicella-zoster virus pneumonia: a multicenter cohort study

BACKGROUND

Pneumonia is a dreaded complication of varicella-zoster virus (VZV) infection in adults; however, the data are limited. Our objective was to investigate the clinical features, management, and outcomes of critically ill patients with VZV-related community-acquired pneumonia (VZV-CAP).

METHODS

This was an observational study of patients with VZV-CAP admitted to 29 intensive care units (ICUs) from January 1996 to January 2015.

RESULTS

One hundred and two patients with VZV-CAP were included. Patients were young (age 39 years (interquartile range 32-51)) and 53 (52%) were immunocompromised. Time since respiratory symptom onset was 2 (1-3) days. There was a seasonal distribution of the disease, with more cases during spring and winter time. All but four patients presented with typical skin rash on ICU admission. Half the patients received mechanical ventilation within 1 (1-2) day following ICU admission (the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO₂/FiO₂) = 150 (80-284), 80% with acute respiratory distress syndrome (ARDS)). Sequential Organ Failure Assessment (SOFA) score on day 1 (odds ratio (OR) 1.90 (1.33-2.70); p < 0.001), oxygen flow at ICU admission (OR 1.25 (1.08-1.45); p = 0.004), and early bacterial co-infection (OR 14.94 (2.00-111.8); p = 0.009) were independently associated with the need for mechanical ventilation. Duration of mechanical ventilation was 14 (7-21) days. ICU and hospital mortality rates were 17% and 24%, respectively. All patients were treated with aciclovir and 10 received adjunctive therapy with steroids. Compared to 60 matched steroid-free controls, patients treated with steroids had a longer mechanical ventilation duration, ICU length of stay, and a similar hospital mortality, but experienced more ICU-acquired infections.

CONCLUSIONS

Severe VZV-CAP is responsible for an acute pulmonary involvement associated with a significant morbidity and mortality. Steroid therapy did not influence mortality, but increased the risk of superinfection.

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.

Human Bocavirus in Korean Children with Gastroenteritis and Respiratory Tract Infections

Human bocaviruses (HBoVs) are suggested to be etiologic agents of childhood respiratory and gastrointestinal infections. There are four main recognized genotypes of HBoVs (HBoV1–4); the HBoV-1 genotype is considered to be the primary etiologic agent in respiratory infections, whereas the HBoV2–4 genotypes have been mainly associated with gastrointestinal infections. The aim of the present study was to determine the distribution of HBoV genotypes in children with respiratory or gastrointestinal infections in a hospital in Korea. A total of 662 nasopharyngeal swabs (NPSs) and 155 fecal specimens were collected from children aged 5 years or less. Polymerase chain reaction (PCR) was conducted to detect the NS1 HBoV gene. The VP1 gene of HBoV was further amplified in samples that were positive for the NS1 gene. The PCR products of VP1 gene amplification were genotyped by sequence analysis. HBoV was detected in 69 (14.5%) of 662 NPSs and in 10 (6.5%) of 155 fecal specimens. Thirty-three isolates from NPSs and five isolates from fecal specimens were genotyped, and all 38 sequenced isolates were identified as the HBoV-1 genotype. HBoV-1 is the most prevalent genotype in children with respiratory or gastrointestinal HBoV infections in a hospital in Korea.

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.

Genetic characterization of human bocavirus among children with severe acute respiratory infection in China

OBJECTIVES

To investigate the genetic character of Human bocavirus (HBoV) among children with severe acute respiratory infection (SARI) in China.

METHODS

We screened 993 respiratory samples for HBoV by PCR among hospitalized children with SARI between September 2007 and March 2014. Four of HBoV1 samples were selected for complete genomes analysis by next-generation sequencing.

RESULTS

The results show that 200 (20.1%) out of 993 samples were HBoV-positive, most of these HBoV belong to HBoV1 subtype (n = 197), HBoV2 (n = 1) and HBoV3 (n = 2) were also detected. Fifty (5.04%) of 993 SARI patient were detected as HBoV-positive only. Four HBoV1 genomes in this study were conserved and showed no significant difference among the nucleotide diversity from different regions. Analyses of evolutionary rates showed that NS1 exhibited the highest degree of conservation while the VP1 gene exhibited the fastest rate of evolution at 4.20 × 10(-4) substitutions/site/year. The nucleotide deletions and substitutions occurred in NP1 and VP1 represented novel molecular signatures enabling subtype differentiation between HBoVs.

CONCLUSIONS

We described some new characteristics in the epidemiology of HBoV among children with SARI, these data will significantly expand the current knowledge of HBoV epidemic and genomic characterization among children with SARI.

Parvovirus B19

Primary parvovirus B19 infection is an infrequent, but serious and treatable, cause of chronic anemia in immunocompromised hosts. Many compromised hosts have preexisting antibody to B19 and are not at risk. However, upon primary infection, some patients may be able to mount a sufficient immune response to terminate active parvovirus B19 infection of erythroid precursors. The most common consequence of B19 infection in the compromised host is pure red-cell aplasia, resulting in chronic or recurrent anemia with reticulocytopenia. Anemia persists until neutralizing antibody is either produced by the host or passively administered. Parvovirus B19 should be suspected in compromised hosts with unexplained or severe anemia and reticulocytopenia, or when bone-marrow examination shows either giant pronormoblasts or absence of red-cell precursors. Diagnosis is established by detection of B19 DNA in serum in the absence of IgG antibody to B19. In some cases, IgG antibody is detected but is not neutralizing. Anti-B19 IgM may or may not be present. Therapy includes any or all of the following: red-cell transfusion, adjustment in medications to restore or improve the patient’s immune system, and administration of intravenous immunoglobulin (IVIG). Following treatment, patients should be closely monitored, especially if immunosuppression is unchanged or increased. Should hematocrit trend downward and parvovirus DNA trend upward, the therapeutic options above should be revisited. In a few instances, monthly maintenance IVIG may be indicated. Caregivers should be aware that B19 variants, though rarely encountered, can be missed or under-quantitated by some real-time polymerase-chain reaction methods.

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.

Evaluation of a PCR/ESI-MS platform to identify respiratory viruses from nasopharyngeal aspirates

Acute respiratory tract infection is a major cause of morbidity and mortality worldwide, particularly in infants and young children. High‐throughput, accurate, broad‐range tools for etiologic diagnosis are critical for effective epidemic control. In this study, the diagnostic capacities of an Ibis platform based on the PCR/ESI‐MS assay were evaluated using clinical samples. Nasopharyngeal aspirates (NPAs) were collected from 120 children (<5 years old) who were hospitalized with lower respiratory tract infections between November 2010 and October 2011. The respiratory virus detection assay was performed using the PCR/ESI‐MS assay and the DFA. The discordant PCR/ESI‐MS and DFA results were resolved with RT‐PCR plus sequencing. The overall agreement for PCR/ESI‐MS and DFA was 98.3% (118/120). Compared with the results from DFA, the sensitivity and specificity of the PCR/ESI‐MS assay were 100% and 97.5%, respectively. The PCR/ESI‐MS assay also detected more multiple virus infections and revealed more detailed subtype information than DFA. Among the 12 original specimens with discordant results between PCR/ESI‐MS and DFA, 11 had confirmed PCR/ESI‐MS results. Thus, the PCR/ESI‐MS assay is a high‐throughput, sensitive, specific and promising method to detect and subtype conventional viruses in respiratory tract infections and allows rapid identification of mixed pathogens. J. Med. Virol. 87:1867–1871, 2015. © 2015 Wiley Periodicals, Inc.

Identification of new respiratory viruses in the new millennium

The rapid advancement of molecular tools in the past 15 years has allowed for the retrospective discovery of several new respiratory viruses as well as the characterization of novel emergent strains. The inability to characterize the etiological origins of respiratory conditions, particularly in children, led several researchers to pursue the discovery of the underlying etiology of disease. In 2001, this led to the discovery of human metapneumovirus (hMPV) and soon following that the outbreak of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) promoted an increased interest in coronavirology and the latter discovery of human coronavirus (HCoV) NL63 and HCoV-HKU1. Human bocavirus, with its four separate lineages, discovered in 2005, has been linked to acute respiratory tract infections and gastrointestinal complications. Middle East Respiratory Syndrome coronavirus (MERS-CoV) represents the most recent outbreak of a completely novel respiratory virus, which occurred in Saudi Arabia in 2012 and presents a significant threat to human health. This review will detail the most current clinical and epidemiological findings to all respiratory viruses discovered since 2001.

'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.

Acute nonbacterial gastroenteritis in hospitalized children: a cross sectional study

Background:

Viral acute gastroenteritis (AGE) is a major cause of morbidity in childhood and leads to hospitalization in developed countries, such as Iran.

Objectives:

The aim of this study was to determine the prevalence and viral types (rotavirus, adenovirus, human parechoviruses-1, and human bocavirus) of acute nonbacterial gastroenteritis in hospitalized children.

Patients and Materials:

This was a across-sectional prospective study performed at the Pediatric Department of Rasoul Hospital, Tehran, Iran (2009-2011) on 80 hospitalized children with viral AGE. All Stool samples were collected on viral transport media. Human bocavirus (HBoV) was detected using the Real-time PCR TaqMan method. Molecular detection of human parechovirus type 1 (HPeV-1) RNA in stool samples was done using a specific nested reverse transcription PCR (RT-PCR). Rota and adeno virus antigens were sought by rapid chromatographic tests. P values less than 0.05 were considered statistically significant.

Results:

Fever was determined in 47.5% of cases (38), nausea and vomiting in 42.5% (34), respiratory symptoms in 16.3% (13), abdominal pain in 76%. Duration of diarrhea was 1-30 days (mean = 6.3 + 4.3 days). No dehydration was observed in 43.5% of subjects, mild dehydration in 33.8%, moderate dehydration in 17.5% and severe dehydration in 5% of cases. Positive rotavirus was found in 48.8% of cases (39), adenovirus in 20% (16), HBoV in 8% (6) and HPeV-1 in 23.2% (19), and adeno and rotaviruses co-infection in 6% (4). The frequency of positive HBoV was significantly lower than adeno and rotaviruses infection (P value = 0.0001). Rotavirus was more frequent in males (P value = 0.003) and in young children (17.49 months vs. 21.44 months) [P value = 0.03, CI = -13.4, 5.5]. Rotavirus infection was related to the degree of dehydration (P value = 0.001) but was not related to the presence of vomiting or fever (P value > 0.5).

Conclusions:

This study indicates that viral agents, especially rotavirus (48.8%), HPeV-1 (23.2%) and adenovirus (20%) are the most important causes for viral AGE in children while HBoV (8%) is infrequent during childhood. Determination of various viral pathogens of AGE is very important in planning diarrhea disease control strategies in our country where rotavirus vaccination in not routinely used.

Spontaneous pneumomediastinum as a complication in human bocavirus infection

The most common causes of spontaneous pneumomediastinum (SPM) in children are asthma attack and respiratory tract infection. Here, we describe a case of SPM in a human bocavirus-infected 2-year-old boy with bronchiolitis.

Human bocaviruses are commonly found in stools of hospitalized children without causal association to acute gastroenteritis

Human bocaviruses (HBoVs) may be grouped into respiratory (HBoV1) and enteric (HBoV2-4) types. We examined this association of HBoV types and clinical symptoms in 955 children who had acute gastroenteritis (AGE, n = 172), acute respiratory tract infection (ARTI, n = 545) or symptoms of both (n = 238). Both nasal swab and stool specimens were studied for such patients. HBoV1 DNA was detected in 6.2 % of patients with ARTI and 9.2 % of patients with symptoms of both ARTI and AGE, but in only 1.7 % of patients with AGE alone. In about one half of the cases, HBoV1 was detected concomitantly in nasal swab and stool samples. HBoV2 was found in stool samples of patients with AGE (5.8 %), ARTI (5.1 %) and symptoms of both (5.5 %) but only rarely in nasal swabs. HBoV3 was found in the stools, but not in nasal swabs, in 0.6, 1.1 and 0.8 % of patients with, respectively, AGE, ARTI and both. HBoV4 was not found. All but one HBoV-positive stool sample of AGE patients contained a known gastroenteritis virus (rotavirus, norovirus, sapovirus, astrovirus or enteric adenovirus) that was probably responsible for the symptoms of the respective case. Sera of 30 HBoV-positive patients were available, and IgM antibodies for HBoVs were found in ten cases and HBoV DNA in eight of these.

CONCLUSIONS

HBoV2 and HBoV3 were more commonly found in stool than in nasal swab samples, but the findings could not be causally linked with AGE. HBoV1 was commonly found in stool samples during ARTI, with or without gastrointestinal symptoms.

Epidemic and molecular evolution of human bocavirus in hospitalized children with acute respiratory tract infection

Human bocavirus (HBoV) is a novel parvovirus, often associated with respiratory tract diseases in children. This study explored the epidemiological characteristics and molecular evolution of HBoV-1 in southeastern China. Nasopharyngeal aspirates were collected from children admitted to hospital with acute respiratory tract infections. HBoV-1 was detected using real-time reverse transcription polymerase chain reaction and further characterized by complete genome sequences analysis. Among the 3,022 recruited children, 386 (12.77 %) were HBoV-1-positive and 300 (77.72 %) had co-detection with other respiratory viruses. Seasonal prevalence peaked in summer. HBoV-1 presence was significantly associated with asthma attack [odds ratio = 1.74; 95 % confidence interval: 1.30, 2.31; p < 0.001]. Similar results were obtained when either single detection or co-detection of HBoV-1 was considered, demonstrating the minor impact of co-detection on the clinical characteristics or epidemic pattern. Phylogenetic analysis based on the complete genome sequences showed that all the HBoV-1 sequences clustered together and no branch was formed that was supported by bootstrap value ≥750. The overall evolutionary rate of the complete genome of HBoV-1 was estimated at 1.08 × 10⁻⁴ nucleotide substitutions per site per year (s/s/y) [95 % highest probability density: (0.40–1.86) × 10⁻⁴ s/s/y]. Selective pressure analysis showed that all the ω-values were less than 1, suggesting that HBoV-1 was under negative selective pressure. Site-by-site analysis identified the codon site 40 of the VP1 gene under positive selection. In conclusion, our study disclosed the epidemiological and genetic dynamics of HBoV-1 epidemics in southeastern China in the most recent 3 years, the information of which might help to further improve our understanding of HBoV-1 infection and guide better surveillance and control strategies in the future.

Clinical and epidemiologic profile of lower respiratory tract infections associated with human bocavirus

BACKGROUND

Acute viral bronchiolitis (AVB) remains the leading cause of lower respiratory tract infection (LRTI) in infants under 2 years of age. Advances in molecular methods for virus detection have led to the identification of new infectious agents implicated in the development of AVB, such as human bocavirus (HBoV).

OBJECTIVES

To ascertain the frequency, seasonality, and clinical behavior of HBoV detection in a series of episodes of LRTI.

STUDY DESIGN

The frequency of HBoV was assessed in children with LRTI episodes, aged 1-24 months, seen at the emergency department of Hospital da Criança Santo Antônio, Porto Alegre, Brazil, between May 2007 and July 2008. Virus-specific polymerase chain reaction was used for detection.

RESULTS

A total of 455 nasal secretion samples were collected from 433 patients over a 14-month period. Of these, 60 were positive for HBoV (13.2%). Mean age was 7.9 months and 55% of patients were male. Just over half of patients were under 6 months of age (53.3%). Wheezing was the presenting respiratory complaint in 51.7%. Of the 60 patients, 80% were admitted to a pediatric ward. Diarrhea was present in nine patients (18%). Co-detection was a frequent finding in our sample, occurring in 95% of cases. In our series, the distribution of HBoV was clearly seasonal and was influenced by temperature, relative humidity, and precipitation.

CONCLUSIONS

We conclude that HBoV detection in infants with AVB and recurrent wheezing of viral etiology in Brazil is similar to that reported in other countries. The clinical course of HBoV detection is no different from that of other respiratory viruses commonly found in this age range.

Human Bocavirus in Iranian children with acute gastroenteritis

BACKGROUND

Human Bocavirus (HBoV) infection is of worldwide distribution. There is increasing evidencethat HBoV is pathogenic for the human gastroenteric tract. However, less data are available on the role of HBoVin gastroenteritis. The present study was aimed to determine the prevalence of HBoV in children with gastroenteritis.

METHODS

Real-time PCR TaqMan was used to screen 200 stool specimens that had been referred to the virologylaboratory for HBoV evaluation. All of samples were collected on viral transport media.

RESULTS

Of the 200 stool samples analyzed, 16 (8%) were positive for HBoV. Human Bocavirus positive samplesfrom patients aged between 1 to 5 years with acute gastroenteritis infection suggest a minor role of HBoVin gastroenteritis (p=0.0001).

CONCLUSION

The study showed a high prevalence of human Bocavirus in young children with acute gastroenteritisdiseases in Iran, suggesting that HBoV play a role in the pathogenesis of gastroenteritis.

Elucidation and clinical role of emerging viral respiratory tract infections in children

Acute respiratory viral infections (ARVI's) are the most common infectious disease in humans. With the appearance of molecular techniques the recovery of viruses has dramatically increased. Nowadays virologists can quickly discriminate virological families and related viruses from emerging viruses and consequently identify novel viruses. Many new respiratory viruses have been identified in children in the past 15 years. In this review we shortly discuss novel respiratory viruses and their pathogenic role in pediatric respiratory disease. Advantages and drawbacks of the technique and our current knowledge will be discussed. We will conclude this review with a general discussion on the future role of molecular diagnostic virology in the clinic.

Surveillance and genome analysis of human bocavirus in patients with respiratory infection in Guangzhou, China

Human bocavirus (HBoV) is a novel parvovirus associated with respiratory tract diseases and gastrointestinal illness in adult and pediatric patients throughout the world. To investigate the epidemiological and genetic variation of HBoV in Guangzhou, South China, we screened 3460 throat swab samples from 1686 children and 1774 adults with acute respiratory infection symptoms for HBoV between March 2010 and February 2011, and analyzed the complete genome sequence of 2 HBoV strains. Specimens were screened for HBoV by real-time PCR and other 6 common respiratory viruses by RT-PCR or PCR. HBoV was detected in 58 (1.68%) out of 3460 samples, mostly from pediatric patients (52/58) and inpatient children (47/58). Six adult patients were detected as HBoV positive and 5 were emergency cases. Of these HBoV positive cases, 19 (32.76%) had co-pathogens including influenza virus (n = 5), RSV (n = 5), parainfluenza (n = 4), adenovirus (n = 1), coronavirus (n = 7). The complete genome sequences of 2 HBoVs strains (Genbank no. JN794565 and JN794566) were analyzed. Phylogenetic analysis showed that the 2 HBoV strains were HBoV1, and were most genetically close to ST2 (GenBank accession number DQ0000496). Recombination analysis confirmed that HBoV strain GZ9081 was an intra–genotype recombinant strain among HBoV1 variants.

Comparison of three multiplex PCR assays for the detection of respiratory viral infections: evaluation of xTAG respiratory virus panel fast assay, RespiFinder 19 assay and RespiFinder SMART 22 assay

BACKGROUND

A broad spectrum of pathogens is causative for respiratory tract infections, but symptoms are mostly similar. Therefore, the identification of the causative viruses and bacteria is only feasible using multiplex PCR or several monoplex PCR tests in parallel.

METHODS

The analytical sensitivity of three multiplex PCR assays, RespiFinder-19, RespiFinder-SMART-22 and xTAG-Respiratory-Virus-Panel-Fast-Assay (RVP), were compared to monoplex real-time PCR with quantified standardized control material. All assays include the most common respiratory pathogens.

RESULTS

To compare the analytical sensitivity of the multiplex assays, samples were inoculated with 13 different quantified viruses in the range of 10(1) to 10(5) copies/ml. Concordant results were received for rhinovirus, whereas the RVP detected influenzavirus, RSV and hMPV more frequently in low concentrations. The RespiFinder-19 and the RespiFinder-SMART-22 showed a higher analytical sensitivity for adenoviruses and coronaviruses, whereas the RVP was incapable to detect adenovirus and coronavirus in concentrations of 10(4) copies/ml. The RespiFinder-19 and RespiFinder-SMART-22A did not detect influenzaviruses (104 copies/ml) and RSV (10(3) copies/ml). The detection of all 13 viruses in one sample was only achieved using monoplex PCR. To analyze possible competitive amplification reactions between the different viruses, samples were further inoculated with only 4 different viruses in one sample. Compared to the detection of 13 viruses in parallel, only a few differences were found.The incidence of respiratory viruses was compared in tracheal secretion (TS) samples (n = 100) of mechanically ventilated patients in winter (n = 50) and summer (n = 50). In winter, respiratory viruses were detected in 32 TS samples (64%) by RespiFinder-19, whereas the detection rate with RVP was only 22%. The most frequent viruses were adenovirus (32%) and PIV-2 (20%). Multiple infections were detected in 16 TS samples (32%) by RespiFinder-19. Fewer infections were found in summer (RespiFinder-19: 20%; RVP: 6%). All positive results were verified using monoplex PCR.

CONCLUSIONS

Multiplex PCR tests have a broad spectrum of pathogens to test at a time. Analysis of multiple inoculated samples revealed a different focus of the detected virus types by the three assays. Analysis of clinical samples showed a high concordance of detected viruses by the RespiFinder-19 compared to monoplex tests.

Human bocaviruses are not significantly associated with gastroenteritis: results of retesting archive DNA from a case control study in the UK

Gastroenteritis is a common illness causing considerable morbidity and mortality worldwide. Despite improvements in detection methods, a significant diagnostic gap still remains. Human bocavirus (HBoV)s, which are associated with respiratory infections, have also frequently been detected in stool samples in cases of gastroenteritis, and a tentative association between HBoVs, and in particular type-2 HBoVs, and gastroenteritis has previously been made. The aim of this study was to determine the role of HBoVs in gastroenteritis, using archived DNA samples from the case-control Infectious Intestinal Disease Study (IID). DNA extracted from stool samples from 2,256 cases and 2,124 controls were tested for the presence of HBoV DNA. All samples were screened in a real time PCR pan-HBoV assay, and positive samples were then tested in genotype 1 to 3-specific assays. HBoV was detected in 7.4% but no significantly different prevalence was observed between cases and controls. In the genotype-specific assays 106 of the 324 HBoV-positive samples were genotyped, with HBoV-1 predominantly found in controls whilst HBoV-2 was more frequently associated with cases of gastroenteritis (p<0.01). A significant proportion of HBoV positives could not be typed using the type specific assays, 67% of the total positives, and this was most likely due to low viral loads being present in the samples. However, the distribution of the untyped HBoV strains was no different between cases and controls. In conclusion, HBoVs, including HBoV-2 do not appear to be a significant cause of gastroenteritis in the UK population.

Human bocavirus NP1 inhibits IFN-β production by blocking association of IFN regulatory factor 3 with IFNB promoter

Human bocavirus (HBoV) mainly infects young children. Although many infected children suffer from respiratory or gastroenteric tract diseases, an association between HBoV and these diseases is not definite. Because modulation of type I IFN is crucial for viruses to establish efficient replication, in this study, we tested whether HBoV modulates type I IFN production. We observed that a nearly full-length HBoV clone significantly reduced both Sendai virus (SeV)- and poly(deoxyadenylic-thymidylic) acid-induced IFN-β production. Further study showed that NP1 blocked IFN-β activation in response to SeV, poly(deoxyadenylic-thymidylic) acid, and IFN-β pathway inducers, including retinoic acid-inducible protein I, mitochondrial antiviral signaling protein, inhibitor of κB kinase ε, and TANK-binding kinase 1. In addition, NP1 interfered with IRF-3-responsive PRD(III-I) promoter activated by SeV and a constitutively active mutant of IRF-3 (IRF-3/5D). Although NP1 suppressed the IRF-3 pathway, it did not affect IRF-3 activation processes, including phosphorylation, dimerization, and nuclear translocation. Coimmunoprecipitation assays confirmed the interaction between NP1 and IRF-3. Additional deletion mutagenesis and coimmunoprecipitation assays revealed that NP1 bound to the DNA-binding domain of IRF-3, resulting in the interruption of an association between IRF-3 and IFNB promoter. Altogether, our results indicate that HBoV NP1 blocks IFN production through a unique mechanism. To our knowledge, this is the first study to investigate the modulation of innate immunity by HBoV. Our findings suggest a potential immune-evasion mechanism used by HBoV and provide a basis for better understanding HBoV pathogenesis.

Human bocavirus amongst an all-ages population hospitalised with acute lower respiratory infections in Cambodia

BACKGROUND

Human bocavirus (HBoV) is a novel parvovirus that is associated with respiratory and gastrointestinal tract disease.

OBJECTIVES

To investigate the prevalence and genetic diversity of HBoV amongst hospitalized patients with acute lower respiratory infection (ALRI) in Cambodia.

STUDY DESIGN

  Samples were collected from 2773 patients of all ages hospitalised with symptoms of ALRI between 2007 and 2009. All samples were screened by multiplex RT-PCR/PCR for 18 respiratory viruses. All samples positive for HBoV were sequenced and included in this study.

RESULTS

Of the samples tested, 43 (1·5%) were positive for HBoV. The incidence of HBoV did not vary between the consecutive seasons investigated, and HBoV infections were detected year-round. The incidence of HBoV infection was highest in patients aged < 2 years, with pneumonia or bronchopneumonia the most common clinical diagnosis, regardless of age. A total of 19 patients (44%) were co-infected with HBoV and an additional respiratory pathogen. All isolates were classified as HBoV type 1 (HBoV-1). High conservation between Cambodian NP1 and V1V2 gene sequences was observed.

CONCLUSIONS

Human bocavirus infection can result in serious illness, however is frequently detected in the context of viral co-infection. Specific studies are required to further understand the true pathogenesis of HBoV in the context of severe respiratory illness.

Molecular diagnosis of respiratory virus infections

The appearance of eight new respiratory viruses, including the SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009, in the human population in the past nine years has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid based amplification tests (NATs) for respiratory viruses were first introduced two decades ago and today are utilized for the detection of both conventional and emerging viruses. These tests are more sensitive than other diagnostic approaches, including virus isolation in cell culture, shell vial culture (SVC), antigen detection by direct fluorescent antibody (DFA) staining, and rapid enzyme immunoassay (EIA), and now form the backbone of clinical virology laboratory testing around the world. NATs not only provide fast, accurate and sensitive detection of respiratory viruses in clinical specimens but also have increased our understanding of the epidemiology of both new emerging viruses such as the pandemic H1N1 influenza virus of 2009, and conventional viruses such as the common cold viruses, including rhinovirus and coronavirus. Multiplex polymerase chain reaction (PCR) assays introduced in the last five years detect up to 19 different viruses in a single test. Several multiplex PCR tests are now commercially available and tests are working their way into clinical laboratories. The final chapter in the evolution of respiratory virus diagnostics has been the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance. These assays are now being multiplexed with primary detection and subtyping assays, especially in the case of influenza virus. These resistance assays, together with viral load assays, will enable clinical laboratories to provide physicians with new and important information for optimal treatment of respiratory virus infections.

High viral load of human bocavirus correlates with duration of wheezing in children with severe lower respiratory tract infection

Background

Human bocavirus (HBoV) is a newly discovered parvovirus and increasing evidences are available to support its role as an etiologic agent in lower respiratory tract infection (LRTI). The objective of this study is to assess the impact of HBoV viral load on clinical characteristics in children who were HBoV positive and suffered severe LRTI.

Methods

Lower respiratory tract aspirates from 186 hospitalized children with severe LRTI were obtained by bronchoscopy. HBoVs were detected by real-time PCR and other 10 infectious agents were examined using PCR and/or direct fluorescent assay.

Results

Thirty-one patients (24.6%) were tested positive for HBoV in the respiratory tract aspirates. Fifteen samples had a high viral load (>10⁴ copies/mL) and the other sixteen samples had a low viral load (<10⁴ copies/mL). The duration of presented wheezing and hospitalization was longer in children with high viral load of HBoV than that in children with low viral load. The days of wheezing showed a correlation with viral load of HBoV.

Conclusion

We confirmed that HBoV was frequently detected in patients with severe LRTI. Wheezing was one of the most common symptoms presented by patients with positive HBoV. A high HBoV viral load could be an etiologic agent for LRTI, which led to more severe lower respiratory tract symptom, longer duration of wheezing and hospitalization.

Respiratory viruses involved in influenza-like illness in a Greek pediatric population during the winter period of the years 2005-2008

Viruses are the major cause of pediatric respiratory tract infection and yet many suspected cases of illness remain uncharacterized. This study aimed to determine the distribution of several respiratory viruses in children diagnosed as having influenza‐like illness, over the winter period of 2005–2008. Molecular assays including conventional and real time PCR protocols, were employed to screen respiratory specimens, collected by clinicians of the Influenza sentinel system and of outpatient pediatric clinics, for identification of several respiratory viruses. Of 1,272 specimens tested, 814 (64%) were positive for at least one virus and included 387 influenza viruses, 160 rhinoviruses, 155 respiratory syncytial viruses, 95 adenoviruses, 81 bocaviruses, 47 parainfluenza viruses, 44 metapneumoviruses, and 30 coronaviruses. Simultaneous presence of two or three viruses was observed in 173 of the above positive cases, 21% of which included influenza virus and rhinovirus. The majority of positive cases occurred during January and February. Influenza virus predominated in children older than 1 year old, with type B being the dominant type for the first season and subtypes A/H3N2 and A/H1N1 the following two winter seasons, respectively. Respiratory syncytial virus prevailed in children younger than 2 years old, with subtypes A and B alternating from year to year. This is the most comprehensive study of the epidemiology of respiratory viruses in Greece, indicating influenza, rhinovirus and respiratory syncytial virus as major contributors to influenza‐like illness in children. J. Med. Virol. 83:1841–1848, 2011. © 2011 Wiley‐Liss, Inc.

Human bocavirus in the nasopharynx of otitis-prone children

OBJECTIVES

Human bocavirus (HBoV) is frequently identified in children with respiratory tract infections, and its role in acute otitis media (AOM) has been suggested. The disease associations for the closely related bocaviruses HBoV2-4 remain unknown. Increasing evidence shows that probiotics may reduce the risk of AOM of viral origin. Objectives of the study was to examine the prevalence and persistence of bocaviruses in consecutive nasopharyngeal samples (NPS) of otitis-prone children, and whether an association exists between HBoV and the child's characteristics, respiratory symptoms, and AOM pathogens, and whether probiotics reduce the occurrence of HBoV.

METHODS

In a double-blind, placebo-controlled, randomized, 6-month intervention study, 269 otitis-prone children (aged 9 months to 5.6 years), consumed daily either one capsule of probiotics (Lactobacillus rhamnosus GG, L. rhamnosus Lc705, Bifidobacterium breve 99 and Propionibacterium freudenreichii JS) or placebo. After a clinical examination and NPS collected at three-time points, the presence and persistence of HBoV1-4 DNA in NPS was determined by RT-qPCR at the baseline, after 3, and 6 months.

RESULTS

A high load (>10,000 copies/ml) of HBoV DNA was detected in 26 (17.1%) of 152 children, and 16 (10.5%) showed a prolonged presence of HBoV for at least 3 months. None had DNA of HBoV2-4. Higher number of siblings associated with increased HBoV prevalence (p=0.029). Prevalence or persistence of HBoV was not significantly associated with other characteristics, respiratory symptoms, or AOM pathogens. Probiotic intervention significantly reduced the number of HBoV DNA-positive samples (probiotic vs. placebo: 6.4% vs. 19.0%, OR=0.25, CI 95%=0.07-0.94, p=0.039).

CONCLUSIONS

HBoV, but not HBoV2-4, DNA occurs often in the nasopharynx of otitis-prone children, and may persist for 3-6 months. Probiotic treatment possibly reduced the presence of HBoV.

Detection of human bocavirus from children and adults with acute respiratory tract illness in Guangzhou, southern China

BACKGROUND

Human bocavirus (HBoV) is a newly discovered parvovirus associated with acute respiratory tract illness (ARTI) and gastrointestinal illness. Our study is the first to analyze the characteristics of HBoV-positive samples from ARTI patients with a wide age distribution from Guangzhou, southern China.

METHODS

Throat swabs (n=2811) were collected and analyzed from children and adults with ARTI over a 13-month period. The HBoV complete genome from a 60 year-old female patient isolate was also determined.

RESULTS

HBoV DNA was detected in 65/2811 (2.3%) samples, of which 61/1797 were from children (<18 years old) and 4/1014 from adults (≥18 years old). Seasonal peaks of 4.8% and 7.7% were detected in May and June, respectively. 28 of 65 (43.1%) HBoV-positive samples were co-detected with 11/16 other potential pathogens. Mycoplasma pneumoniae had the highest frequency of 16.9% (11/65). Upper and lower respiratory tract illness were common symptoms, with 19/65 (29.2%) patients diagnosed with pneumonia by chest radiography. All four adult patients had systemic influenza-like symptoms. Phylogenetic analysis of the complete genome revealed a close relationship with other HBoVs, and a more distant relationship with HBoV2 and HBoV3.

CONCLUSIONS

HBoV was detected from children and adults with ARTI from Guangzhou, southern China. Elderly people were also susceptive to HBoV. A single lineage of HBoV was detected among a wide age distribution of patients with ARTI.

[Aetiology of bronchiolitis in hospitalised children in South-East Spain]

Introducción

La bronquiolitis es una de las infecciones respiratorias más comunes en niños menores de 2 años y una de las principales causas de ingreso en niños pequeños, especialmente durante el invierno.

Objetivos

Determinar la prevalencia y etiología de bronquiolitis en el sureste de España.

Material y métodos

Se realizó un estudio prospectivo durante la temporada de bronquiolitis (diciembre-abril). En el estudio se incluyeron niños menores de 18 meses ingresados en el hospital con motivo del primer episodio de bronquiolitis. Se analizaron aspirados nasofaríngeos mediante una técnica de reacción en cadena de la polimerasa (múltiple), precedida de transcripción inversa del ARN viral (RT-PCR).

Resultados

Se incluyeron en el estudio 235 niños, de cada uno de los cuales se obtuvo una muestra de aspirado nasofaríngeo. Se detectaron virus respiratorios en muestras de 204 niños (en total 287 virus). El virus respiratorio sincitial se detectó con mayor frecuencia seguido del rinovirus. Se observaron infecciones virales mixtas en el 36% de los niños en los que se detectó algún virus respiratorio. La asociación más frecuente fue el virus respiratorio sincitial A con rinovirus.

Conclusiones

Se detectaron virus respiratorios en la mayoría de los niños menores de 18 meses hospitalizados por bronquiolitis, en forma de infección mixta en el 36% de aquellos con infección viral.

Human bocavirus-the first 5 years

Four species of human bocavirus (HBoV) have been recently discovered and classified in the Bocavirus genus (family Parvoviridae, subfamily Parvovirinae). Although detected both in respiratory and stool samples worldwide, HBoV1 is predominantly a respiratory pathogen, whereas HBoV2, HBoV3, and HBoV4 have been found mainly in stool. A variety of signs and symptoms have been described in patients with HBoV infection including rhinitis, pharyngitis, cough, dyspnea, wheezing, pneumonia, acute otitis media, fever, nausea, vomiting, and diarrhea. Many of these potential manifestations have not been systematically explored, and they have been questioned because of high HBoV co-infection rates in symptomatic subjects and high HBoV detection rates in asymptomatic subjects. However, evidence is mounting to show that HBoV1 is an important cause of lower respiratory tract illness. The best currently available diagnostic approaches are quantitative PCR and serology. This concise review summarizes the current clinical knowledge on HBoV species.

Newly identified respiratory viruses associated with acute lower respiratory tract infections in children in Lanzou, China, from 2006 to 2009

Nasopharyngeal aspirates were collected from 813 children ≤ 14 years old with acute lower respiratory tract infections in Lanzhou, China, from December 2006 to November 2009. PCR or RT-PCR was used to screen for the presence of 10 respiratory viruses. Viral agents were identified in 73.92% (601/813) of specimens, including RSV in 40.71%, hMPV in 6.15%, IFVA in 7.13%, IFVB in 0.98%, PIV1-3 in 7.87%, HCoV-HKU1 in 2.21%, HCoV-NL63 in 3.81%, HRV in 19.93%, AdV in 7.50% and HBoV in 11.56%. Two or more viruses were detected in 34.44% (280/813) of cases. The newly identified respiratory viruses, HBoV, hMPV, HCoV-HKU1 and HCoV-NL63, accounted for 22.01% of the detected viral pathogens. RSV and HRV were frequently detected in patients with bronchiolitis, and hMPV was frequently associated with pneumonia. HCoV-NL63 was found to be one of the causative agents of acute respiratory wheezing in young children. No seasonal variation was found in the incidence of detection of HCoV-HKU1, HCoV-NL63 or HBoV. This 3-year study demonstrated that viral pathogens play an important role in children with ALRTIs, and more attention should be paid to these newly identified viral agents.

Human bocavirus in patients with respiratory tract infection

BACKGROUND

Human bocavirus (HBoV) is a newly identified viral pathogen, and its clinical epidemiology and significance in respiratory infections have not yet been completely elucidated. We investigated the prevalence of HBoV infection and the association between viral (HBoV) load and clinical features of the infection in patients of all age-groups.

METHODS

Nasopharyngeal aspirates from patients with symptoms of respiratory infection were tested for presence of HBoV by using real-time polymerase chain reaction. HBoV-positive patients were categorized into low- and high-viral-load groups using 1.0×10(6) copies/mL as the threshold value of viral load.

RESULTS

Detection rate of HBoV was 4.8% (N=93) in a total of 1,926 samples with peak incidence of infection being observed in patients aged 6-12 months. HBoV infection was more frequently observed in young children, especially, in children aged less than 5 yr, and the HBoV load decreased with increase in age. HBoV was codetected with other respiratory viruses in 17 (18.3%) of the 93 HBoV-positive patients and 15 patients (88.2%) belonged to the low-viral-load group. Patients infected with HBoV alone showed a higher viral load than those patients in whom HBoV was codetected with other respiratory viruses (median load, 3.78×10(5) copies/mL vs. 1.94×10(4) copies/mL, P=0.014). Higher pulse rate (P=0.007) and respiratory rate (P=0.021) were observed in patients with a high-viral-load.

CONCLUSIONS

Our results suggest that HBoV may be the causative agent of respiratory infection in the high-viral-load group.

Human bocavirus (HBoV) in children with respiratory tract infection by enzyme linked immunosorbent assay (ELISA) and qualitative polymerase chain reaction (PCR)

BACKGROUND

Human bocavirus (HBoV) is a recently discovered parvovirus associated with mild to severe lower respiratory tract infections in children, the aim of the work was determination of human bocavirus in nasopharyngeal aspirate (NPA) of infants by qualitative PCR and determination of acute human bocavirus infection by estimation of immunoglobulin M (IgM) antibodies in serum by enzyme linked immunosorbent assay.

RESULTS

Twenty two (22%) out of the 100 NPA specimens of the patients with respiratory manifestations were positive for HBoV by qualitative PCR, while ELISA revealed positive HBoV IgM antibodies in 18 (18%) patients who were also positive by PCR. Non of the controls were positive by both techniques. The correlation study between ELISA and PCR revealed high significant association, (p < 0.001, X2 = 36 and agreement = 96%). Also PCR detected 4 (18.1%) NPA samples as HBoV positive cases among the patients that were not identified by ELISA. This could be due to high sensitivity and efficacy of PCR. ELISA being less sensitive than RT-PCR, sensitivity was (81.8% vs 100%), the efficacy was 97.7% in ELISA versus 99.7% for RT-PCR.

CONCLUSION

HBoV infections could be diagnosed in NPA of children by conventional PCR as a rapid and sensitive technique. While ELISA was a reliable serologic analysis for diagnosis of acute HBoV infection by estimation IgM antibodies in serum.

Nucleic acid amplification-based diagnosis of respiratory virus infections

The appearance of eight new respiratory viruses in the human population in the past 9 years, including two new pandemics (SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009), has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid amplification tests (NATs) that first appeared two decades ago have been developed for both conventional and emerging viruses and now form the backbone of the clinical laboratory. NATs provide fast, accurate and sensitive detection of respiratory viruses and have significantly increased our understanding of the epidemiology of these viruses. Multiplex PCR assays have been introduced recently and several commercial tests are now available. The final chapter in the evolution of respiratory virus diagnostics will be the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance to multiplex assays. These resistance assays together with new viral load tests will enable clinical laboratories to provide physicians with important information for optimal treatment of patients.

Impact of PCR for respiratory viruses on antibiotic use: theory and practice

RATIONALE FOR THE STUDY

Real-time polymerase chain reaction (PCR) for respiratory viruses is more sensitive, yet more expensive, than conventionally used direct immunofluorescence (DIF). We determined the impact of real-time PCR, additional to DIF, on antibiotic prescription in ventilated children with lower respiratory tract infection (LRTI) at admission to the pediatric intensive care unit (PICU).

METHODS

First, a multicenter survey study was performed. Subsequently, in a prospective study, children (≤ 5 years) with LRTI were tested at admission by DIF and PCR. Positive DIF results were reported at the end of the first working day. PICU physicians reported antibiotic treatment on the second working day. After informing them of the PCR result antibiotic treatment was reevaluated.

RESULTS

The multicenter survey study (94 respondents) showed that PCR decreased antibiotic use (P < 0.001). In the prospective study 38 children were included, of which 19 (50%) were DIF positive. Of the 19 DIF negative patients 12 (63%) were treated with antibiotics before revealing the PCR result; the PCR test was positive in 9 out of 12. Revealing PCR results did not alter antibiotic treatment. In 7 DIF negative patients antibiotics not given, the PCR test was positive.

CONCLUSION

In contrast to their responses to the survey study, in real-life PICU physicians did not let their antibiotic prescription be influenced by respiratory real-time PCR in children ventilated for LRTI.