The nonstructural protein NP1 of human bocavirus 1 induces cell cycle arrest and apoptosis in Hela cells

For better or worse: crosstalk of parvovirus and host DNA damage response

Parvoviruses are a group of non-enveloped DNA viruses that have a broad spectrum of natural infections, making them important in public health. NS1 is the largest and most complex non-structural protein in the parvovirus genome, which is indispensable in the life cycle of parvovirus and is closely related to viral replication, induction of host cell apoptosis, cycle arrest, DNA damage response (DDR), and other processes. Parvovirus activates and utilizes the DDR pathway to promote viral replication through NS1, thereby increasing pathogenicity to the host cells. Here, we review the latest progress of parvovirus in regulating host cell DDR during the parvovirus lifecycle and discuss the potential of cellular consequences of regulating the DDR pathway, targeting to provide the theoretical basis for further elucidation of the pathogenesis of parvovirus and development of new antiviral drugs.

The Effect of 5-Aminolevulinic Acid Photodynamic Therapy in Promoting Pyroptosis of HPV-Infected Cells

5-aminolevulinic acid photodynamic therapy (ALA-PDT) is highly effective in the treatment of condyloma acuminata (CA). Previous research has indicated that ALA-PDT could induce cell death by different mechanisms, including apoptosis and autophagy, but the role of pyroptosis in ALA-PDT remains uncertain. Thus, this study aimed to explore whether pyroptosis is a potential mechanism of ALA-PDT killing human papillomavirus (HPV) infected cells. HPV-positive HeLa cells were exposed to ALA-PDT, then cell viability assay, lactate dehydrogenase release (LDH) assay, detection of reactive oxygen species (ROS), quantitative real-time PCR (qPCR), and western blot were used to evaluate pyroptosis induced by ALA-PDT. Results suggested that ALA-PDT enhanced the expression of NLRP3, caspase-1, GSDMD, and the production of inflammatory cytokines such as IL-1β and IL-18. In addition, ALA-PDT induced the production of ROS and led to the destruction of the cell membrane. The inhibition of pyroptosis reduced the killing of HeLa cells by ALA-PDT. This study demonstrates that ALA-PDT induces pyroptosis in HPV-positive cells, which provides some explanation for the mechanism of ALA-PDT to treat CA and HPV infection-related diseases.

Heliothis virescens ascovirus 3h blocks the cell cycle of Spodoptera exigua fat body cells at G2 /M phase by downregulating cyclin B1 and cyclin-dependent kinase 1

Ascoviruses are double-stranded DNA viruses that are pathogenic to noctuid larvae. In vitro infection causes the cells to fail to replicate and proliferate normally. However, the molecular mechanisms are unclear. In this study, the transmission electron microscopy data of infected-Spodoptera exigua (Hübner) fat body cells (SeFB, IOZCAS-SpexII-A cells) showed that virions were internalized in phagocytic vesicles, but not in the nucleus. FACS of cell-cycle progression was performed in SeFB cells infected with Heliothis virescens ascovirus 3h (HvAV-3h). The cell cycle phase distributions of the SeFB cells were G₁  = 29.52 ± 1.10%, S = 30.33 ± 1.19%, and G₂ /M = 40.06 ± 0.75%. The cell culture doubling time was approximately 24 h. The G₁ , S, and G₂ /M phases were each approximately 8 h. The unsynchronized or synchronized cells were arrested at G₂ /M phase after infection with HvAV-3h. Our data also showed that cells with more than 4N DNA content appeared in the HvAV-3h-treated group. While the mRNA levels of cyclin B₁ , cyclin H, and cyclin-dependent kinase 1 (CDK1) were downregulated after HvAV-3h infection, the mRNA expression levels of cyclin A, cyclin D, and cyclin B₂ were not significantly changed. Western blotting results showed that the expression of cyclin B₁ and CDK1 in infected SeFB cells within 24 h postinfection (hpi), and HvAV-3h infection inhibited the expression of cyclin B₁ and CDK1 at 12-24 hpi. Overall, these data implied that HvAV-3h infection leads to an accumulation of cells in the G₂ /M phases by downregulating the expression of cyclin B₁ and CDK1.

Simultaneous detection of feline parvovirus and feline bocavirus using SYBR Green I-based duplex real-time polymerase chain reaction

Since both feline parvovirus (FPV) and feline bocavirus (FBoV) can cause diarrhea in cats, it is difficult to distinguish them clinically. This study aimed to develop a SYBR Green I-based duplex real-time polymerase chain reaction (PCR) assay for distinguishing FPV and FBoV-1 on the basis of the melting temperature of the PCR product. A total of 132 fecal samples from different domestic and feral cats were collected, and the results of SYBR Green I-based duplex real-time PCR assay were compared with those of the traditional PCR assay for a comprehensive evaluation. The melting temperatures were found to be 86 °C and 77.5 °C for FBoV-1 and FPV, respectively, and no specific melting peaks for other non-targeted feline viruses were observed. The data obtained from this assay had a good linear relationship; the detection limits of FPV and FBoV-1 were 2.907 × 10¹ copies/μL and 3.836 × 10¹ copies/μL, respectively. In addition, the experiment exhibited high reproducibility. The positive detection rates of the SYBR Green I-based duplex real-time PCR assay for FPV and FBoV-1 were 16.67% (22/132) and 6.82% (9/132), respectively, and the positive detection rate for co-infection with FPV and FBoV-1 was 3.03% (4/132). This result was much more sensitive than that of the traditional PCR method. Thus, the developed SYBR Green I-based assay is a sensitive, rapid, specific, and reliable method for the clinical diagnosis of FPV and FBoV-1 and can provide technical support for the simultaneous detection of co-infection with these viruses in the future.

Studies on apoptosis induced by B-norcholesteryl benzimidazole compounds in HeLa cells

Certain B-norcholesteryl benzimidazole compounds were found to mediate marked anti-tumor proliferative effects in vitro in our earlier study. Here, the mechanism of action of these anti-tumor effects was evaluated using HeLa human cervical cancer cells. Methods for detecting cell invasion and migration, Annexin V-PI double staining, cell cycle status, and mitochondrial membrane potential Δψ_m were employed. These compounds were confirmed to significantly inhibit the proliferation of HeLa cells in vitro. Compound 1 induced apoptosis in S phase, compound 2induced apoptosis in the G₀/G₁ phase and compound 3 induced late apoptosis in the G₂/M phase. These compounds induced HeLa cell apoptosis through depolarization of mitochondrial membrane potential Δψ_m in a dose-dependent manner. B-norcholesteryl benzimidazole compounds induced morphological changes in HeLa cells and inhibited proliferation, invasion and metastasis. Apoptosis was promoted by mechanisms involving p21 and p53 in this cervical cancer cell line.

A detailed analysis of synonymous codon usage in human bocavirus

Human bocavirus (HBoV) is a recently discovered parvovirus associated with respiratory and gastroenteric infections in children. To date, four distinct subtypes have been identified worldwide. HBoV1 is the most frequently detected bocavirus in clinical samples derived from the respiratory tract. HBoV has a single-stranded DNA genome, which encodes two nonstructural proteins, NS1 and NP1, and two structural proteins, VP1 and VP2. Despite a large number of available HBoV sequences, the molecular evolution of this virus remains enigmatic. Here, we applied bioinformatic methods to measure the codon usage bias in 156 HBoV genomes and analyzed the factors responsible for preferential use of various synonymous codons. The effective number of codons (ENC) indicates a highly conserved, gene-specific codon usage bias in the HBoV genome. The structural genes exhibit a higher degree of codon usage bias than the non-structural genes. Natural selection emerged as dominant factor influencing the codon usage bias in the HBoV genome. Other factors that influence the codon usage include mutational pressure, gene length, protein properties, and the relative abundance of dinucleotides. The results presented in this study provide important insight into the molecular evolution of HBoV and may serve as a primer for HBoV gene expression studies and development of safe and effective vaccines to prevent infection.

Detection and genetic characterization of feline bocavirus in Northeast China

Background

Bocaviruses have been reported to cause respiratory tract infection and gastroenteritis in most animal species. In cats, different genotype bocaviruses have been identified in USA, Japan, Hong Kong and Portugal. However, the clear relationship between the clinical symptoms and FBoV infection is unknown, and the prevalence of FBoV and the distribution of FBoV genotypes in China are still unclear.

Results

In this study, 197 fecal samples from cats with diarrhea (n = 105) and normal cats (n = 92) were collected in different regions between January 2016 and November 2017 and investigated using PCR targeting different FBoV genotypes. Screening results showed that 51 of 197 samples (25.9%) were positive for FBoV, and a higher positive rate was observed in cats with diarrhea (33.3%, 35/105) than in normal cats (17.4%, 16/92). Of these FBoV-positive samples, 35 were identified as FBoV-1, 12 as FBoV-2 and 4 as coinfection of FBoV-1 and FBoV-2. A phylogenetic analysis based on partial NS1 gene indicated that 24 sequences from randomly selected FBoV-positive samples were divided into 2 different FBoV groups: FBoV-1 and FBoV-2. Furthermore, 6 strains were randomly selected, and the complete genome was sequenced and analyzed. These strains exhibited the typical genome organization of bocavirus and were closely related to FBoV. Two FBoV-2 identified strains shared high homologies with FBoV-2 reference strains based on the complete genome and entire encoding gene, but lower identities were exhibited in the NP1 and VP1 regions for the other 4 FBoV-1 identified strains compared with FBoV-1 reference strains.

Conclusion

These findings demonstrate that genetically diverse FBoV-1 and FBoV-2 widely circulate in cats in Northeast China and that FBoV-1 is more prevalent. The high prevalence of FBoV in cats with diarrhea symptoms suggests that FBoV infection may be associated with diarrhea in cats.

Electronic supplementary material

The online version of this article (10.1186/s12985-018-1034-3) contains supplementary material, which is available to authorized users.

Human bocavirus induces apoptosis and autophagy in human bronchial epithelial cells

Human bocavirus (HBoV) is classified in the Bocavirus genus within the Parvoviridae family, first identified from children with respiratory diseases. Previous studies have investigated the stimulating effect of HBoV on cell apoptosis and autophagy. In the present study, human bronchial epithelial cells (HBECs) were utilized to examine the mechanism of HBoV recombination expressing vector (pWHL-1) on the promotion of cell apoptosis and autophagy. The results from the present study indicated that pWHL-1 inhibited the proliferation of HBECs in a time-dependent manner. Additionally, pWHL-1induced apoptosis, as substantiated by an increased apoptotic rate and presence of autophagosomes. Following pWHL-1 transfection, proliferating cell nuclear antigen, caspase-3 and B cell lymphoma 2 (Bcl-2) protein expression levels were decreased, with the exception of Bcl-2 associated × (Bax) protein, which increased. mRNA and protein expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC3) II and autophagy protein 5 were increased in pWHL-1-transfected HBECs, whereas, the mRNA and protein levels of LC3I and sequestosome 1 were decreased. Notably, pWHL-1 also enhanced the activation of p53 and inhibited AKT activation in HBECs. Results from the present study suggest that pWHL-1 induces apoptosis and autophagy, thus providing a novel insight into the effect of HBoV and its uses in respiratory diseases.

Evolutionary and genetic analysis of human bocavirus genotype-1 strains reveals an evidence of intragenomic recombination

PURPOSE

Human bocavirus (HBoV) exsits in four genotypes: 1 to 4, with HBoV-1 being the most prevalent genotype. The aim of the current study was to genetically analyze the full-length genome of the HBoV-1 of recently detected Egyptian strains.

METHODOLOGY

Seven overlapping sets of primers were developed to amplify an almost complete HBoV-1 genome from the clinical samples. The primer sets were tested on three recently identified Egyptian HBoV-1 strains with viral loads ≥105 ml-1. Sequencing was conducted using the same sets of primers. HBoV-1 virus strains were genetically analyzed based on the sequences of their complete genomes and the individual ORFs.

RESULTS

The new sets of primers successfully amplified the three tested strains. Sequence analysis of the full-length genome of the HBoV-1 revealed a considerable level of genetic heterogenicity between different strains. Based on the full genome and VP1 ORF, HBoV-1 viruses were clustered into three main lineages, A to C, and lineage A was further subdivided into three sublineages, A1-A3. The Egyptian strains were clustered within two sublineages, A1 and A2. New amino acid substitutions were detected in NS1 and VP1/VP2 proteins. Both inter- and intragenomic recombination events were detected among the Egyptian strains.

CONCLUSION

The existence of both intragenomic recombination event and multiple amino acid substitutions in the examined Egyptian HBoV-1 strains elucidates considerable level of genetic alterations among bocaviruses. Their possible effects on the virus virulence and multiplication efficiency need to be investigated.

Transient Receptor Potential Melastatin 4 (TRPM4) Contributes to High Salt Diet-Mediated Early-Stage Endothelial Injury

Background/Aims: The present study investigated whether the transient receptor potential melastatin 4 (TRPM4) channel plays a role in high salt diet (HSD)-induced endothelial injuries. Methods: Western blotting and immunofluorescence were used to examine TRPM4 expression in the mesenteric endothelium of Dahl salt-sensitive (SS) rats fed a HSD. The MTT, TUNEL, and transwell assays were used to evaluate the cell viability, cell apoptosis, and cell migration, respectively, of human umbilical vein endothelial cells (HUVECs). Enzyme-linked immunosorbent assays were used to determine the concentrations of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), and E-selectin. Carboxy-H2DCFDA, a membrane-permeable reactive oxygen species (ROS)-sensitive fluorescent probe, was used to detect intracellular ROS levels. Results: TRPM4 was mainly expressed near the plasma membrane of mesenteric artery endothelial cells, and its expression level increased in SS hypertensive rats fed a HSD. Its protein expression was significantly upregulated upon treatment with exogenous hydrogen peroxide (H2O2) and aldosterone in cultured HUVECs. Cell viability decreased upon treatment with both agents in a concentration-dependent manner, which could be partially reversed by 9-phenanthrol, a specific TRPM4 inhibitor. Exogenous H2O2 induced apoptosis, enhanced cell migration, and increased the release of adhesion molecules, including ICAM-1, VCAM-1, and E-selectin, all of which were significantly attenuated upon treatment with 9-phenanthrol. Aldosterone and H2O2 induced the accumulation of intracellular ROS, which was significantly inhibited by 9-phenanthrol, suggesting that oxidative stress is one of the mechanisms underlying aldosterone-induced endothelial injury. Conclusions: Given the fact that oxidative stress and high levels of circulating aldosterone are present in hypertensive patients, we suggest that the upregulation of TRPM4 in the vascular endothelium may be involved in endothelial injuries caused by these stimuli.

Identification and interspecies transmission of a novel bocaparvovirus among different bat species in China

We report the discovery of a novel bocaparvovirus, bat bocaparvovirus (BtBoV), in one spleen, four respiratory and 61 alimentary samples from bats of six different species belonging to three families, Hipposideridae, Rhinolophidae and Vespertilionidae. BtBoV showed a higher detection rate in alimentary samples of Rhinolophus sinicus (5.7 %) than those of other bat species (0.43-1.59 %), supporting R. sinicus as the primary reservoir and virus spillover to accidental bat species. BtBoV peaked during the lactating season of R. sinicus, and it was more frequently detected among female than male adult bats (P<0.05), and among lactating than non-lactating female bats (P<0.0001). Positive BtBoV detection was associated with lower body weight in lactating bats (P<0.05). Ten nearly complete BtBoV genomes from three bat species revealed a unique large ORF1 spanning NS1 and NP1 in eight genomes and conserved splicing signals leading to multiple proteins, as well as a unique substitution in the conserved replication initiator motif within NS1. BtBoV was phylogenetically distantly related to known bocaparvoviruses with ≤57.3 % genome identities, supporting BtBoV as a novel species. Ms-BtBoV from Miniopterus schreibersii and Hp-BtBoV from Hipposideros pomona demonstrated 97.2-99.9 % genome identities with Rs-BtBoVs from R. sinicus, supporting infection of different bat species by a single BtBoV species. Rs-BtBoV_str15 represents the first bat parvovirus genome with non-coding regions sequenced, which suggested the presence of head-to-tail genomic concatamers or episomal forms of the genome. This study represents the first to describe interspecies transmission in BoVs. The high detection rates in lactating female and juvenile bats suggest possible vertical transmission of BtBoV.

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.

Trehalose, sucrose and raffinose are novel activators of autophagy in human keratinocytes through an mTOR-independent pathway

Trehalose is a natural disaccharide that is found in a diverse range of organisms but not in mammals. Autophagy is a process which mediates the sequestration, lysosomal delivery and degradation of proteins and organelles. Studies have shown that trehalose exerts beneficial effects through inducing autophagy in mammalian cells. However, whether trehalose or other saccharides can activate autophagy in keratinocytes is unknown. Here, we found that trehalose treatment increased the LC3-I to LC3-II conversion, acridine orange-stained vacuoles and GFP-LC3B (LC3B protein tagged with green fluorescent protein) puncta in the HaCaT human keratinocyte cell line, indicating autophagy induction. Trehalose-induced autophagy was also observed in primary keratinocytes and the A431 epidermal cancer cell line. mTOR signalling was not affected by trehalose treatment, suggesting that trehalose induced autophagy through an mTOR-independent pathway. mTOR-independent autophagy induction was also observed in HaCaT and HeLa cells treated with sucrose or raffinose but not in glucose, maltose or sorbitol treated HaCaT cells, indicating that autophagy induction was not a general property of saccharides. Finally, although trehalose treatment had an inhibitory effect on cell proliferation, it had a cytoprotective effect on cells exposed to UVB radiation. Our study provides new insight into the saccharide-mediated regulation of autophagy in keratinocytes.

Ganoderma lucidum polysaccharides target a Fas/caspase dependent pathway to induce apoptosis in human colon cancer cells

Ganoderma lucidum polysaccharides (GLP) extracted from Ganoderma lucidum have been shown to induce cell death in some kinds of cancer cells. This study investigated the cytotoxic and apoptotic effect of GLP on HCT-116 human colon cancer cells and the molecular mechanisms involved. Cell proliferation, cell migration, lactate dehydrogenase (LDH) levels and intracellular free calcium levels ([Ca(2+)]i) were determined by MTT, wound-healing, LDH release and fluorescence assays, respectively. Cell apoptosis was observed by scanning and transmission electron microscopy. For the mechanism studies, caspase-8 activation, and Fas and caspase-3 expression were evaluated. Treatment of HCT-116 cells with various concentrations of GLP (0.625-5 mg/mL) resulted in a significant decrease in cell viability (P< 0.01). This study showed that the antitumor activity of GLP was related to cell migration inhibition, cell morphology changes, intracellular Ca(2+) elevation and LDH release. Also, increase in the levels of caspase-8 activity was involved in GLP-induced apoptosis. Western blotting indicated that Fas and caspase-3 protein expression was up-regulated after exposure to GLP. This investigation demonstrated for the first time that GLP shows prominent anticancer activities against the HCT-116 human colon cancer cell line through triggering intracellular calcium release and the death receptor pathway.

Triptolide attenuated injury via inhibiting oxidative stress in Amyloid-Beta25-35-treated differentiated PC12 cells

BACKGROUND

Recently, an abnormal deposition of Amyloid-Beta (Aβ) was considered the primary cause of the pathogenesis of Alzheimer's disease (AD). And how to inhibit the cytotoxicity is considered an important target for the treatment of AD. Triptolide (TP), a purified diterpenoid from the herb Tripterygium wilfordii Hook.f. (TWHF), has potential neuroprotective effects pertinent to disease of the nervous system. However, whether triptolide and its specific mechanisms have protective functions in differentiated PC12 cells treated with Aβ25-35 remain unclear.

AIMS

The purpose is to investigate the protective functions of triptolide in Aβ25-35-stimulated differentiated PC12 cells.

MAIN METHODS

In the study, we use 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, lactate dehydrogenase (LDH) assay, flow cytometry assay, immunohistochemical staining and Western blot to observe the effects of triptolide on cytotoxicity induced by Aβ25-35 and its mechanism of oxidative stress.

KEY FINDINGS

The result of MTT and LDH assay indicates that triptolide protected PC12 cells against Aβ25-35-induced cytotoxicity. The flow cytometry assay shows that triptolide attenuated Aβ25-35-induced apoptosis in differentiated PC12 cells. Meanwhile, the results give a clear indication that triptolide could downregulate generation of reactive oxygen species (ROS), hydrogen peroxide (H2O2) and malondialdehyde (MDA) induced by Aβ25-35. The apoptotic process triggered by triptolide involved the up-regulation of the activity of superoxide dismutase (SOD).

SIGNIFICANCE

The results suggest that triptolide may serve as an important role in the inhibition of the cell apoptosis induced by Aβ and the decreased oxidative stress is a key mechanism in the protective effect of triptolide in AD.

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.

Inhibition of migration and induction of apoptosis in LoVo human colon cancer cells by polysaccharides from Ganoderma lucidum

Ganoderma lucidum polysaccharides (GLPs), which were purified from the medicinal herb G. lucidum followed by ethanol precipitation, protein depletion using the Sevage assay, purification using DEAE‑cellulose (DE-52), dialysis and the use of ultrafiltration membranes, are used as an ingredient in traditional anticancer treatments in China. The aim of the current study was to evaluate the anticancer effects and investigate the underlying molecular mechanisms of GLPs on LoVo human colon cancer cells. The results demonstrated that the GLP‑mediated anticancer effect in LoVo cells was characterized by cytotoxicity, migration inhibition, enhanced DNA fragmentation, morphological alterations and increased lactate dehydrogenase release. Furthermore, the activation of caspases‑3, ‑8 and ‑9 was involved in GLP‑stimulated apoptosis. Additionally, treatment with GLPs promoted the expression of Fas and caspase‑3 proteins, whilst reducing the expression of cleaved poly(ADP‑ribose) polymerase. These data indicate that GLPs demonstrate potential antitumor activity in human colon cancer cells, predominantly through the inhibition of migration and induction of apoptosis. Furthermore, activation of the Fas/caspase-dependent apoptosis pathway is involved in the cytotoxicity of GLPs.

Detection and characterisation of novel bocavirus (genus Bocaparvovirus) and gastroenteritis viruses from asymptomatic pigs in Ireland

Background

Livestock animals have been the assumed source of several human epidemics in recent years, for example, influenza H1N1, rotavirus G8/G9, and MERS-CoV. Surveillance of novel viruses in animals is essential to evaluate the risk to human and animal health and to determine any economic impact, for example, failure to thrive. There is a paucity of data regarding detection and characterisation of gastroenteritis viruses, particularly novel viruses, in porcines in Ireland. Recently, a number of small novel porcine DNA viruses have emerged globally, for example, torque teno sus virus, porcine bocavirus, and parvoviruses 2 & 4, and little is known about the biology and potential pathogenicity of these viruses. Bocaparvovirus is a genetically distinct group of viruses which has been recently detected in humans and animals.

Methods

In this study, the presence of gastroenteritis viruses (rotavirus A, porcine circovirus, adenovirus, and porcine bocavirus) was investigated in a selection of archived faecal samples from asymptomatic piglets from a commercial farm in Ireland. A total of 104 specimens were pooled and screened using conventional molecular techniques (PCR and RT-PCR), a subset of specimens (n=44) were then examined individually. Viral diversity was then investigated using statistical and phylogenetic techniques.

Results

Initial screening showed a high prevalence of PBoV in this farm, with the formation of three distinct groups in phylogenetic analysis. Other viruses were also investigated in this study with the first report of PCV, PAdV and lineage I G5 RVA in Ireland. Some specimens contained >1 virus, with statistical analysis indicating a strong correlation for mixed infections of PBoV and PAdV on this farm.

Conclusion

Investigating the diversity of circulating enteric viruses on Irish porcine farms is important to improve the prophylactic tools available and to facilitate the early detection of changes in circulating viruses.

Mechanisms of cancer cell killing by the adenovirus E4orf4 protein

During adenovirus (Ad) replication the Ad E4orf4 protein regulates progression from the early to the late phase of infection. However, when E4orf4 is expressed alone outside the context of the virus it induces a non-canonical mode of programmed cell death, which feeds into known cell death pathways such as apoptosis or necrosis, depending on the cell line tested. E4orf4-induced cell death has many interesting and unique features including a higher susceptibility of cancer cells to E4orf4-induced cell killing compared with normal cells, caspase-independence, a high degree of evolutionary conservation of the signaling pathways, a link to perturbations of the cell cycle, and involvement of two distinct cell death programs, in the nucleus and in the cytoplasm. Several E4orf4-interacting proteins including its major partners, protein phosphatase 2A (PP2A) and Src family kinases, contribute to induction of cell death. The various features of E4orf4-induced cell killing as well as studies to decipher the underlying mechanisms are described here. Many explanations for the cancer specificity of E4orf4-induced cell death have been proposed, but a full understanding of the reasons for the different susceptibility of cancer and normal cells to killing by E4orf4 will require a more detailed analysis of the complex E4orf4 signaling network. An improved understanding of the mechanisms involved in this unique mode of programmed cell death may aid in design of novel E4orf4-based cancer therapeutics.

Sodium houttuyfonate inhibits inflammation by blocking the MAPKs/NF-κB signaling pathways in bovine endometrial epithelial cells

Sodium houttuyfonate (SH) has traditionally been used for the therapy of inflammatory diseases. In this research, we tried to assess the anti-inflammatory effects of SH on LPS-induced bovine endometrial epithelial cell (bEEC) inflammation. SH cell toxicity was measured using the MTT and LDH assays, and inflammatory cytokine expression was assessed by ELISA, qRT-PCR and Western blotting. We demonstrated that SH was not cytotoxic to bEECs, and that it significantly decreased the LPS-induced mRNA and protein expression of tumor necrosis factor (TNF) α, interleukin (IL)-1β, IL-6 and IL-8. Furthermore, in LPS-induced bEECs, SH inhibited IκBα degradation and NF-κB p65 phosphorylation, and suppressed the phosphorylation of the mitogen-activated protein kinases (MAPKs), p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). In conclusion, we found that SH could effectively block the NF-κB-mediated signaling pathway and reduce the inflammatory process, thereby exerting a protective effect on bEECs.

A study of the human bocavirus replicative genome structures

The complete genomes of two human bocavirus 4 (HBoV4) isolates recovered in 2011 in Novosibirsk, Russia have been determined. A set of primers was designed based on the determined and previously published HBoV sequences; this primer pair was able to detect all possible HBoV replicative intermediates. This primer set was used to assay all HBoV genotypes and detected only those structures that correspond to an episomal form of this viral genome. Also, for the first time, head-to-tail nucleotide sequences have been determined for HBoV4. Secondary structures of the terminal noncoding regions (NCRs) of episomal forms have been computed for all HBoV genotypes, as well as for the canine bocavirus. Conserved secondary structures in episomal NCRs, which are likely to play an important part in the replication of bocaviruses, were found. NCR heterogeneity in the genomes of individual HBoV isolates has been shown for the first time.

Complementation for an essential ancillary non-structural protein function across parvovirus genera

Parvoviruses encode a small number of ancillary proteins that differ substantially between genera. Within the genus Protoparvovirus, minute virus of mice (MVM) encodes three isoforms of its ancillary protein NS2, while human bocavirus 1 (HBoV1), in the genus Bocaparvovirus, encodes an NP1 protein that is unrelated in primary sequence to MVM NS2. To search for functional overlap between NS2 and NP1, we generated murine A9 cell populations that inducibly express HBoV1 NP1. These were used to test whether NP1 expression could complement specific defects resulting from depletion of MVM NS2 isoforms. NP1 induction had little impact on cell viability or cell cycle progression in uninfected cells, and was unable to complement late defects in MVM virion production associated with low NS2 levels. However, NP1 did relocate to MVM replication centers, and supports both the normal expansion of these foci and overcomes the early paralysis of DNA replication in NS2-null infections.

Human Bocavirus

Human bocavirus 1 (HBoV1), family Parvoviridae, subfamily Parvovirinae, genus Bocavirus, is a recently described respiratory virus with a worldwide distribution. It is recognized as one of the most frequently detected respiratory viruses in hospitalized children below 5 years of age and mainly detected in children between 6 and 24 months of age. The severe clinical course of HBoV1 infection can be seen in prematurely born children or children, but rarely adults, with other underlying medical conditions. The seroepidemiological studies show that most of the children are infected with HBoV1 by the age of 6 and that the IgG antibodies remain for life. The routine laboratory diagnostics of HBoV1 infections is almost exclusively based on detection of HBoV1 DNA in respiratory samples by PCR. Due to frequent coinfections with other respiratory viruses, PCR of plasma samples and detection of specific IgM might aid in determining the etiology of infection.

Structure of the NS1 protein N-terminal origin recognition/nickase domain from the emerging human bocavirus

Human bocavirus is a newly identified, globally prevalent, parvovirus that is associated with respiratory infection in infants and young children. Parvoviruses encode a large nonstructural protein 1 (NS1) that is essential for replication of the viral single-stranded DNA genome and DNA packaging and may play versatile roles in virus-host interactions. Here, we report the structure of the human bocavirus NS1 N-terminal domain, the first for any autonomous parvovirus. The structure shows an overall fold that is canonical to the histidine-hydrophobic-histidine superfamily of nucleases, which integrates two distinct DNA-binding sites: (i) a positively charged region mediated by a surface hairpin (residues 190 to 198) that is responsible for recognition of the viral origin of replication of the double-stranded DNA nature and (ii) the nickase active site that binds to the single-stranded DNA substrate for site-specific cleavage. The structure reveals an acidic-residue-rich subdomain that is present in bocavirus NS1 proteins but not in the NS1 orthologs in erythrovirus or dependovirus, which may mediate bocavirus-specific interaction with DNA or potential host factors. These results provide insights into recognition of the origin of replication and nicking of DNA during bocavirus genome replication. Mapping of variable amino acid residues of NS1s from four human bocavirus species onto the structure shows a scattered pattern, but the origin recognition site and the nuclease active site are invariable, suggesting potential targets for antivirals against this clade of highly diverse human viruses.