Stability and integrity of self-assembled bovine parvovirus virus‑like particles (BPV‑VLPs) of VP2 and combination of VP1VP2 assisted by baculovirus-insect cell expression: a potential logistical platform for vaccine deployment

BACKGROUND

Bovine parvovirus (BPV) is an autonomous DNA virus with a smaller molecular size and subtle differences in its structural proteins, unlike other animal parvoviruses. More importantly, this virus has the potential to produce visible to silent economic catastrophes in the livestock business, despite receiving very little attention. Parvoviral virus-like particles (VLPs) as vaccines and as logistical platforms for vaccine deployment are well studied. However, no single experimental report on the role of VP1 in the assembly and stability of BPV-VLPs is available. Furthermore, the self-assembly, integrity and stability of the VLPs of recombinant BPV VP2 in comparison to VP1 VP2 Cap proteins using any expression method has not been studied previously. In this study, we experimentally evaluated the self-assembling ability with which BPV virus-like particles (VLPs) could be synthesized from a single structural protein (VP2) and by integrating both VP2 and VP1 amino acid sequences.

METHODS

In silico and experimental cloning methods were carried out. His-tagged and without-His-tag VP2 and V1VP2-encoding amino acid sequences were cloned and inserted into pFastbacdual, and insect cell-generated recombinant protein was evaluated by SDS‒PAGE and western blot. Period of infectivity and expression level were determined by IFA. The integrity and stability of the BPV VLPs were evaluated by transmission electron microscopy. The secondary structure of the BPV VLPs from both VP2 and V1VP2 was analyzed by circular dichroism.

RESULTS

Our findings show that VP2 alone was equally expressed and purified into detectable proteins, and the stability at different temperatures and pH values was not appreciably different between the two kinds of VLPs. Furthermore, BPV-VP2 VLPs were praised for their greater purity and integrity than BPV-VP1VP2 VLPs, as indicated by SDS‒PAGE. Therefore, our research demonstrates that the function of VP1 has no bearing on the stability or integrity of BPV-VLPs.

CONCLUSIONS

In summary, incredible physiochemically stable BPV VP2-derived VLPs have been found to be promising candidates for the development of multivalent vaccines and immunodiagnostic kits against enteric viruses and to carry heterogeneous epitopes for various economically important livestock diseases.

Structural Characterization of Canine Minute Virus, Rat and Porcine Bocavirus

Bocaparvovirus is an expansive genus of the Parvovirinae, with a wide range of vertebrate hosts. This study investigates Canine minute virus (CnMV), Rat bocavirus (RBoV), and Porcine bocavirus 1 (PBoV1). Both CnMV and PBoV1 have been found in gastrointestinal infections in their respective hosts, with CnMV responsible for spontaneous abortions in dogs, while PBoV has been associated with encephalomyelitis in piglets. The pathogenicity of the recently identified RBoV is currently unknown. To initiate the characterization of these viruses, their capsids structures were determined by cryo-electron microscopy at resolutions ranging from 2.3 to 2.7 Å. Compared to other parvoviruses, the CnMV, PBoV1, and RBoV capsids showed conserved features, such as the channel at the fivefold symmetry axis. However, major differences were observed at the two- and threefold axes. While CnMV displays prominent threefold protrusions, the same region is more recessed in PBoV1 and RBoV. Furthermore, the typical twofold axis depression of parvoviral capsids is absent in CnMV or very small in PBoV and RBoV. These capsid structures extend the structural portfolio for the Bocaparvovirus genus and will allow future characterization of these pathogens on a molecular level. This is important, as no antivirals or vaccines exist for these viruses.

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

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

Case Report: Bocavirus Infection Radiologically Resembling a Congestive Heart Failure in a Patient with Metastatic Castration-Resistant Prostate Cancer Case-Report

Background: Human bocavirus (HBoV) is a viral pathogen from the genus Bocaparvovirus (family Parvoviridae, subfamily Parvovirinae) discovered in 2005. Most of available literature is about HBoV in children and adults with hematological malignancies and in otherwise healthy children with respiratory infections. Information regarding infection in the adult population with solid tumors is scarce. Case Report: We report the case of a 51-year-old male with metastatic castration resistant prostate cancer undergoing chemotherapy treatment who presented with fever, dyspnea, dry cough, and pleuritic pain. Imaging techniques showed signs of congestive heart failure. Symptoms, laboratory tests and echocardiography revealed a more probable infectious etiology. Antibiotic therapy was started. A polymerase chain reaction (PCR) test of nasopharyngeal exudate for respiratory viruses was positive for HBoV. The rest of the microbiological tests were negative. Bronchoalveolar lavage (BAL) was performed. Bacterial culture of BAL was negative while respiratory virus PCR confirmed positivity for HBoV. Antibiotic therapy was discontinued. The patient gradually recovered. Conclusions: Emerging infectious diseases are a notorious threat for immunocompromised populations such as solid tumor patients. This case is unique because to our knowledge this is the first case report article of HBoV in a solid tumor patient and because imaging techniques exhibited signs of congestive heart failure that did not correlate with the rest of the tests. It shows that unusual pathogens should be considered when managing serious clinical complications with uncommon presentations in cancer patients. Notable diagnostic efforts should be made to reach a diagnosis in these cases.

[Clinical prospective study on maternal-fetal transmission of human bocavirus]

OBJECTIVE

To investigate maternal-fetal transmission at human bocavirus (HBoV).

METHODS

IgG antibody to HBoV in serum samples of 316 mothers were determined with ELISA and HBoV DNA was determined with real time PCR in the sera of the mothers and their infants.

RESULTS

HBoV-IgG was positive in 40.20 percent (127/316) of the mothers, while it was positive in 29.43 percent (93/316) of the cord blood specimens of the infants. The difference between the two groups was significant (X2=8.12, P less than 0.005); 93 samples of both the mothers and the infants were positive for HBoV-IgG.

CONCLUSION

HBoV-IgG can cross the placenta to the fetuses through placenta. Further study is needed to answer the question whether vertical maternal-fetal transmission occurs.

[Human bocavirus infections in Spanish 0-14 year-old: clinical and epidemiological characteristics of an emerging respiratory virus]

INTRODUCTION

In 2005 a new respiratory virus, called human bocavirus (HBoV), was cloned from respiratory samples from Swedish infants and children with lower respiratory tract infections.

OBJECTIVES

To determine whether HBoV has circulated in Spain, estimate the frequency of HBoV infections in patients hospitalized for respiratory infection and describe the clinical and epidemiological characteristics of these patients.

PATIENTS AND METHODS

We performed a descriptive prospective study of confirmed HBoV infections in patients aged < 14 years old, hospitalized for respiratory infections between October 2004 and June 2005. Virologic diagnosis was based on multiple RT-PCR for respiratory syncytial virus (RSV) A and B, influenza A,B, and C, parainfluenza 1-4, adenovirus and rhinovirus; PCR was used for human metapneumovirus (hMPV) and PCR in nasopharyngeal aspirates was used for HBoV. The clinical and epidemiological characteristics of patients were analyzed.

RESULTS

Fifty-two cases of HBoV infection were detected, representing 17.1% (95% CI: 13% a 21%) of patients hospitalized for respiratory infections. HBoV was the third most frequent viral agent after RSV (30%) and rhinovirus (25%). In 39 patients (71.1%) coinfection with another respiratory virus was detected. Fifty percent of the patients were aged less than 13.6 months and 75% were aged less than 2 years. The most frequent diagnoses were recurrent wheezing (55.8%), bronchiolitis (21.2%) and pneumonia (15.4%). Clinical sepsis with petechial exanthema was found in two patients. Fever > 38 degrees C was found in 72.1% and radiological infiltrate in 44%. Hypoxia was present in 55.8 % of the patients. HBoV was isolated in distinct episodes in two patients. Coinfections were similar to simple infections except that hypoxia was more frequent in the former (p = 0.038).

CONCLUSIONS

HBoV is one of the most frequent viruses in severe respiratory infections in patients aged less than 14 years old. Only RSV and rhinovirus are more frequent. Coinfections are highly frequent. Most patients are infants with recurrent wheezing and bronchiolitis.

Newly discovered respiratory viruses: significance and implications

With the recent advances in molecular biology and the ability to amplify viral genomes in a non-sequence-dependent manner, several previously unidentified human respiratory viruses have been discovered. There are accumulating data that some of these new pathogens are responsible for a substantial proportion of respiratory tract diseases, particularly in children. This review will focus on several of these newly identified pathogens for which there are clinical data implicating a role of these viruses in respiratory tract disease specifically, human metapneumovirus, human coronaviruses NL63 and HKU1, and the human bocavirus. Antivirals and effective vaccines for these new agents may decrease the burden of respiratory tract diseases.

Das humane Bocavirus: Erreger von Atemwegsinfektionen?

The human Bocavirus (HBoV), the second member of the parvovirus family, which displays pathogenicity in humans, has been described in 2005 by Allander et al.. It seems to be distributed worldwide and has been isolated mainly in infants and children with respiratory tract infection. This review covers all studies published on HBoV to February 2007 and discusses this emerging viral pathogen from the perspective of inpatient medical treatment centers.