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Atomic structure of a nudivirus occlusion body protein determined from a 70-year-old crystal sample.Nature Communications Jul 2023Infectious protein crystals are an essential part of the viral lifecycle for double-stranded DNA Baculoviridae and double-stranded RNA cypoviruses. These viral protein...
Infectious protein crystals are an essential part of the viral lifecycle for double-stranded DNA Baculoviridae and double-stranded RNA cypoviruses. These viral protein crystals, termed occlusion bodies or polyhedra, are dense protein assemblies that form a crystalline array, encasing newly formed virions. Here, using X-ray crystallography we determine the structure of a polyhedrin from Nudiviridae. This double-stranded DNA virus family is a sister-group to the baculoviruses, whose members were thought to lack occlusion bodies. The 70-year-old sample contains a well-ordered lattice formed by a predominantly α-helical building block that assembles into a dense, highly interconnected protein crystal. The lattice is maintained by extensive hydrophobic and electrostatic interactions, disulfide bonds, and domain switching. The resulting lattice is resistant to most environmental stresses. Comparison of this structure to baculovirus or cypovirus polyhedra shows a distinct protein structure, crystal space group, and unit cell dimensions, however, all polyhedra utilise common principles of occlusion body assembly.
Topics: Nudiviridae; Baculoviridae; Viral Proteins
PubMed: 37443157
DOI: 10.1038/s41467-023-39819-1 -
Archives of Virology Jun 2023Viruses of four families of arthropod-specific, large dsDNA viruses (the nuclear arthropod large DNA viruses, or NALDVs) possess homologs of genes encoding conserved...
Viruses of four families of arthropod-specific, large dsDNA viruses (the nuclear arthropod large DNA viruses, or NALDVs) possess homologs of genes encoding conserved components involved in the baculovirus primary infection mechanism. The presence of such homologs encoding per os infectivity factors (pif genes), along with their absence from other viruses and the occurrence of other shared characteristics, suggests a common origin for the viruses of these families. Therefore, the class Naldaviricetes was recently established, accommodating these four families. In addition, within this class, the ICTV approved the creation of the order Lefavirales for three of these families, whose members carry homologs of the baculovirus genes that code for components of the viral RNA polymerase, which is responsible for late gene expression. We further established a system for the binomial naming of all virus species in the order Lefavirales, in accordance with a decision by the ICTV in 2019 to move towards a standardized nomenclature for all virus species. The binomial species names for members of the order Lefavirales consist of the name of the genus to which the species belongs (e.g., Alphabaculovirus), followed by a single epithet that refers to the host species from which the virus was originally isolated. The common names of viruses and the abbreviations thereof will not change, as the format of virus names lies outside the remit of the ICTV.
Topics: Animals; Arthropods; DNA Viruses; Viruses; Baculoviridae; Host Specificity; Granulovirus
PubMed: 37322175
DOI: 10.1007/s00705-023-05793-8 -
The International Journal of Biological... Dec 2023Many types of cancer exhibit high nuclear factor erythroid 2-related factor 2 (NRF2), which is effective in resisting drugs and radiation. However, the role of NRF2 gene...
BACKGROUND
Many types of cancer exhibit high nuclear factor erythroid 2-related factor 2 (NRF2), which is effective in resisting drugs and radiation. However, the role of NRF2 gene expression in predicting the prognosis of esophageal squamous cell carcinoma (ESCC) remains unclear.
METHODS
The association between NRF2, heme oxygenase-1 (HO-1), baculovirus IAP repeat 5 (BIRC5), P53 gene expression levels and their relationship to immune-infiltrating cells were assessed using the Cancer Genome Atlas dataset, the Human Protein Atlas and the TISDB database. The expression of NRF2, HO-1, BIRC5, and TP53 in 118 ESCC patients was detected by immunohistochemistry, and the relationship between their expression level and clinicopathological parameters and prognosis was analyzed.
RESULTS
In ESCC, NRF2 overexpression was significantly associated with Han ethnicity, lymph node metastasis, and distant metastasis. HO-1 overexpression was significantly associated with differentiation, advanced clinical staging, lymph node metastasis, nerve invasion, and distant metastasis. BIRC5 overexpression was significantly associated with Han ethnicity and lymph node metastasis. TP53 overexpression was significantly associated with Han ethnicity and T staging. The NRF2/HO-1 axis expression was positively correlated with BIRC5 and TP53. Kaplan-Meier and multivariate Cox regression analysis showed that NRF2, BIRC5, and TP53 genes co-expression was an independent prognostic risk factor. TISIDB dataset analysis showed that immune-infiltrating cells were significantly negatively correlated with NRF2 and BIRC5.
CONCLUSION
NRF2, BIRC5, and TP53 axis gene expressions are predictors of poor prognosis for ESCC. The overexpression of the NRF2/HO-1/BIRC5 axis may not be related to immune-infiltrating cells.
Topics: Humans; Esophageal Squamous Cell Carcinoma; Carcinoma, Squamous Cell; NF-E2-Related Factor 2; Esophageal Neoplasms; Lymphatic Metastasis; Heme Oxygenase-1; Baculoviridae; Prognosis; Biomarkers, Tumor; Tumor Suppressor Protein p53; Survivin
PubMed: 37312528
DOI: 10.1177/03936155231176571 -
Viruses Apr 2023Porcine deltacoronavirus (PDCoV) causes diarrhea and vomiting in neonatal piglets worldwide and has the potential for cross-species transmission. Therefore, virus-like...
Porcine deltacoronavirus (PDCoV) causes diarrhea and vomiting in neonatal piglets worldwide and has the potential for cross-species transmission. Therefore, virus-like particles (VLPs) are promising vaccine candidates because of their safety and strong immunogenicity. To the best of our knowledge, the present study reported for the first time the generation of PDCoV VLPs using a baculovirus expression vector system, and electron micrograph analyses revealed that PDCoV VLPs appeared as spherical particles with a diameter similar to that of the native virions. Furthermore, PDCoV VLPs effectively induced mice to produce PDCoV-specific IgG and neutralizing antibodies. In addition, VLPs could stimulate mouse splenocytes to produce high levels of cytokines IL-4 and IFN-γ. Moreover, the combination of PDCoV VLPs and Freund's adjuvant could improve the level of the immune response. Together, these data showed that PDCoV VLPs could effectively elicit humoral and cellular immunity in mice, laying a solid foundation for developing VLP-based vaccines to prevent PDCoV infections.
Topics: Animals; Mice; Swine; Baculoviridae; Antibodies, Neutralizing; Coronavirus; Immunity; Swine Diseases; Coronavirus Infections
PubMed: 37243181
DOI: 10.3390/v15051095 -
Viruses Apr 2023Baculoviruses are entomopathogens that carry large, double-stranded circular DNA genomes and infect insect larvae of Lepidoptera, Hymenoptera and Diptera, with...
Baculoviruses are entomopathogens that carry large, double-stranded circular DNA genomes and infect insect larvae of Lepidoptera, Hymenoptera and Diptera, with applications in the biological control of agricultural pests, in the production of recombinant proteins and as viral vectors for various purposes in mammals. These viruses have a variable genetic composition that differs between species, with some sequences shared by all known members, and others that are lineage-specific or unique to isolates. Based on the analysis of nearly 300 sequenced genomes, a thorough bioinformatic investigation was conducted on all the baculoviral protein coding sequences, characterizing their orthology and phylogeny. This analysis confirmed the 38 protein coding sequences currently considered as core genes, while also identifying novel coding sequences as candidates to join this set. Accordingly, homology was found among all the major occlusion body proteins, thus proposing that the polyhedrin, granulin and CUN085 genes be considered as the 39th core gene of .
Topics: Animals; Baculoviridae; Viral Proteins; Viral Structural Proteins; Insecta; Lepidoptera; Mammals
PubMed: 37243176
DOI: 10.3390/v15051091 -
Data in Brief Jun 2023The pine processionary moth is a Lepidopteran pest species occurring in the Western Mediterranean. It causes heavy pine defoliations and it is a public and animal...
Sequence, assembly and count datasets of viruses associated to the pine processionary moth (Denis & Schiffermüller) (Lepidoptera, Notodontidae) identified from transcriptomic high-throughput sequencing.
The pine processionary moth is a Lepidopteran pest species occurring in the Western Mediterranean. It causes heavy pine defoliations and it is a public and animal health concern because of its urticating caterpillars. Very little is known about the viruses associated to this species, as only two viruses were described so far. We here present a dataset corresponding to 34 viral transcripts, among which 27 could be confidently assigned to 9 RNA and DNA viral families ( and ). These transcripts were identified from an original transcriptome assembled for the insect host, using both blast search and phylogenetic approaches. The data were acquired from 2 populations in Portugal and 2 populations in Italy. The transcripts were de novo assembled and used to identify viral sequences by homology searches. We also provide information about the populations and life stages in which each virus was identified. The data produced will allow to enrich the virus taxonomy in Lepidopteran hosts, and to develop PCR-based diagnostic tools to screen colonies across the range and determine the distribution and prevalence of the identified viral species.
PubMed: 37213549
DOI: 10.1016/j.dib.2023.109180 -
Viruses Apr 2023Accurate and rapid quantification of (infectious) virus titers is of paramount importance in the manufacture of viral vectors and vaccines. Reliable quantification data...
Accurate and rapid quantification of (infectious) virus titers is of paramount importance in the manufacture of viral vectors and vaccines. Reliable quantification data allow efficient process development at a laboratory scale and thorough process monitoring in later production. However, current gold standard applications, such as endpoint dilution assays, are cumbersome and do not provide true process analytical monitoring. Accordingly, flow cytometry and quantitative polymerase chain reaction have attracted increasing interest in recent years, offering various advantages for rapid quantification. Here, we compared different approaches for the assessment of infectious viruses, using a model baculovirus. Firstly, infectivity was estimated by the quantification of viral nucleic acids in infected cells, and secondly, different flow cytometric approaches were investigated regarding analysis times and calibration ranges. The flow cytometry technique included a quantification based on post-infection fluorophore expression and labeling of a viral surface protein using fluorescent antibodies. Additionally, the possibility of viral (m)RNA labeling in infected cells was investigated as a proof of concept. The results confirmed that infectivity assessment based on qPCR is not trivial and requires sophisticated method optimization, whereas staining of viral surface proteins is a fast and feasible approach for enveloped viruses. Finally, labeling of viral (m)RNA in infected cells appears to be a promising opportunity but will require further research.
Topics: Baculoviridae; Genetic Vectors; RNA
PubMed: 37112978
DOI: 10.3390/v15040998 -
Pathogens (Basel, Switzerland) Apr 2023Cryptophlebia leucotreta granulovirus (CrleGV), a double-stranded DNA virus (genus , family ), is highly infective to the citrus insect pest . The South African isolate...
Cryptophlebia leucotreta granulovirus (CrleGV), a double-stranded DNA virus (genus , family ), is highly infective to the citrus insect pest . The South African isolate CrleGV-SA is formulated into a commercial biopesticide and registered for use in several countries. In South Africa, it is used as a biopesticide in a multi-faceted integrated pest management approach for citrus crops involving chemical and biological control methods. The virus nucleocapsid is surrounded and protected by an occlusion body (OB) composed of granulin protein in a crystalline matrix. Like all other baculoviruses, CrleGV is susceptible to ultraviolet (UV) radiation from sunlight. This reduces its efficacy as a biopesticide in the field and necessitates frequent respraying. UV damage to baculovirus biopesticides is detected by means of functional bioassays. However, bioassays do not give an indication of whether any structural damage has occurred that may contribute to functional loss. In this study, transmission electron microscopy (TEM) was used to observe damage to the OB and nucleocapsid (NC) of CrleGV-SA, following controlled UV irradiation in the laboratory to mimic field conditions. The resultant images were compared with images of non-irradiated CrleGV-SA virus. TEM images of irradiated CrleGV-SA samples revealed changes to the OB crystalline faceting, a reduction in the size of the OBs, and damage to the NC following UV exposure for 72 h.
PubMed: 37111476
DOI: 10.3390/pathogens12040590 -
Open Veterinary Journal Mar 2023African Swine Fever (ASF) is an infectious disease that affects domestic pig and wild boar populations. The ASF Virus (ASFV) has a genome characterized by a very complex...
BACKGROUND
African Swine Fever (ASF) is an infectious disease that affects domestic pig and wild boar populations. The ASF Virus (ASFV) has a genome characterized by a very complex DNA (170-193 kb) that encodes for more than 200 different proteins. Among these, the highly immunogenic phosphoprotein p30 plays a fundamental role in the induction of specific antibodies. To date, the lack of a vaccine against the disease requires continuous studies to improve knowledge about the virus and the development of new tests in addition to virological ones.
AIM
The aim of this work was to produce specific monoclonal antibodies (mAbs) against the p30 protein of ASFV, which could find useful applications in routine diagnostics and the implementation of new diagnostic tools.
METHODS
ASFV p30 encoding gene was amplified and used for the generation of the recombinant baculovirus by transfection of the Sf21 insect cells. The recombinant protein was analyzed by immunofluorescence assay, purified, and used for mice Balb-c immunization. The hybridomas obtained were cultured and screened, using an indirect Enzyme-linked Immunosorbent Assay (iELISA), in order to select clones that secrete the mAbs of interest.
RESULTS
The expression of recombinant p30 protein was assessed using direct immunofluorescence. The purified p30 protein fractions were analyzed by Coomassie gels staining confirming the presence of bands with a molecular weight of 30 kDa and used for the immunization of Balb-c mice. Six clones of pure hybridomas secreting the specific mAbs against recombinant p30 were obtained and tested in iELISA. The mAbs were also characterized by Western blot and immunofluorescence assay. The best results were obtained with the anti-p30 mAb 2B8E10 clone which showed high reactivity with both recombinant and viral p30 protein, respectively.
CONCLUSION
In this work, a recombinant p30 protein produced in an insect cell system was purified and used to immunize Balb-c mice. Six anti-p30 mAbs-secreting hybridomas clone cells were obtained. These mAbs displayed high reactivity against the recombinant protein, but only 2B8E10 mAb showed excellent functionality against the p30 protein produced by ASFV. These results open the possibility to develop different diagnostic assays.
Topics: Antibodies, Monoclonal; Recombinant Proteins; African Swine Fever; Mice, Inbred BALB C; Mice; Animals; Phosphoproteins; Viral Proteins; Baculoviridae; Sf9 Cells; Spodoptera; Female
PubMed: 37026062
DOI: 10.5455/OVJ.2023.v13.i3.13 -
Viruses Feb 2023We aimed to assess the potential of baculoviral vectors (BV) for brain cancer gene therapy. We compared them with adenoviral vectors (AdV), which are used in...
We aimed to assess the potential of baculoviral vectors (BV) for brain cancer gene therapy. We compared them with adenoviral vectors (AdV), which are used in neuro-oncology, but for which there is pre-existing immunity. We constructed BVs and AdVs encoding fluorescent reporter proteins and evaluated their transduction efficiency in glioma cells and astrocytes. Naïve and glioma-bearing mice were intracranially injected with BVs to assess transduction and neuropathology. Transgene expression was also assessed in the brain of BV-preimmunized mice. While the expression of BVs was weaker than AdVs in murine and human glioma cell lines, BV-mediated transgene expression in patient-derived glioma cells was similar to AdV-mediated transduction and showed strong correlation with clathrin expression, a protein that interacts with the baculovirus glycoprotein GP64, mediating BV endocytosis. BVs efficiently transduced normal and neoplastic astrocytes in vivo, without apparent neurotoxicity. BV-mediated transgene expression was stable for at least 21 days in the brain of naïve mice, but it was significantly reduced after 7 days in mice systemically preimmunized with BVs. Our findings indicate that BVs efficiently transduce glioma cells and astrocytes without apparent neurotoxicity. Since humans do not present pre-existing immunity against BVs, these vectors may constitute a valuable tool for the delivery of therapeutic genes into the brain.
Topics: Genetic Therapy; Baculoviridae; Genetic Vectors; Brain Neoplasms; Glioma; Animals; Mice; Cell Line, Tumor; Humans; Rats; Mice, Inbred C57BL; Male; Transduction, Genetic; Astrocytes; Transgenes
PubMed: 36992317
DOI: 10.3390/v15030608