Generation and evaluation of a recombinant myxomavirus expressing the VP60 protein of rabbit haemorrhagic disease virus / 生物工程学报

Rabbit haemorrhagic disease virus (RHDV) and myxoma virus (MYXV), are two pathogens that have harmful effect on rabbit breeding and population decline of European rabbits in their native range, causing rabbit haemorrhagic disease (rabbit fever) and myxomatosis, respectively. The capsid protein VP60 of the RHDV represents the major antigenic protein. To develop a recombinant bivalent vaccine candidate that can simultaneously prevent these two diseases, we used the nonessential gene TK (thymidine kinase) of MYXV as the insertion site to construct a recombinant shuttle vector p7.5-VP60-GFP expressing the RHDV major capsid protein (VP60) and the selectable marker GFP. Then the shuttle vector p7.5-VP60-GFP was transfected into rabbit kidney cell line RK13 which was previously infected with MYXV. After homologous recombination, the recombinant virus expressing GFP was screened under a fluorescence microscope and named as rMV-VP60-GFP. Finally, the specific gene-knock in and expression verification of the vp60 and gfp genes of the recombinant virus was confirmed by PCR and Western blotting. The results showed that these two genes were readily knocked into the MYXV genome and also successfully expressed, indicating that the recombinant MYXV expressing the vp60 of RHDV was generated. Protection against MYXV challenge showed that the recombinant virus induced detectable antibodies against MYXV which would shed light on development of the effective vaccine.

Co-expression, purification and bioassay of three avian viral antigens / 生物工程学报

To achieve uniform soluble expression of multiple proteins in the same Escherichia coli strain, and simplify the process steps of antigen production in genetic engineering subunit multivalent vaccine, we co-expressed three avian virus proteins including the fowl adenovirus serotype 4 (FAdV-4) Fiber-2 protein, infectious bursal disease virus (IBDV) VP2 protein and egg-drop syndrome virus (EDSV) Fiber protein in E. coli BL21(DE3) cells after optimization of gene codon, promoter, and tandem expression order. The purified proteins were analyzed by Western blotting and agar gel precipitation (AGP). The content of the three proteins were well-proportioned after co-expression and the purity of the purified proteins were more than 80%. Western blotting analysis and AGP experiment results show that all the three co-expression proteins had immunoreactivity and antigenicity. It is the first time to achieve the three different avian virus antigens co-expression and co-purification, which simplified the process of antigen production and laid a foundation for the development of genetic engineering subunit multivalent vaccine.

Protein expression profile of mast cells in response to recombinant VP1-VP4 of foot-and-mouth disease virus / 生物工程学报

To reveal the innate immunity of mast cells against recombinant VP1-VP4 protein of foot-and-mouth disease virus (FMDV), mouse peritoneal mast cells (PMCs) were pulsed with recombinant VP1-VP4 protein. The supernatants harvested from PMCs cultures were applied to the high throughput ELISA array. Our results show that the expression levels of CCL19, L-selectin, CCL17, and TNF alpha released from PMCs pulsed with recombinant VP1-VP4 were significantly down-regulated compared with PMCs alone (P<0.001). Surprisingly, in comparison with PMCs alone, the expression levels of CCL19, IL-15, IL-9, G-CSF, and Galectin-1 in PMCs with the mannose receptor (MR) inhibitor were significantly up-regulated (Plt;0.01), and the expression level of IL-10 was also remarkably up-regulated (Plt;0.05). Importantly, the protein expression levels in PMCs treated with MR inhibitor were higher than PMCs pulsed with VP1-VP4, including IL-10, IL-17, CCL20, IL-15, IL-9, L-selectin, CCL17, TNF alpha, and CCL19 (Plt;0.01) as well as CCL21, and G-CSF (Plt;0.05). Differential expression analysis in bioinformatics shows that both L-selectin and CCL17 were recognized as differentially expressed protein molecules (Log2(ratio)≤-1) when compared with PMCs alone. Furthermore, the up-regulation of the expression levels of CCL20, CCL19, L-selectin, and IL-15 in PMCs treated with MR inhibitor was defined as differential expression (Log2(ratio)≥1). These data indicate that PMCs are capable of secreting CCL19, L-selectin, CCL17, and TNF alpha spontaneously and the recombinant VP1-VP4 has an inhibitive potential to PMCs during their performance of innate immune response. Given the protein expression levels from PMCs pre-treated with MR inhibitor were significantly increased, it can be deduced that immunosuppression of FMDV is presumably initiated by the VP1 recognition of MR on mast cells.

Production of Brazilian human norovirus VLPs and comparison of purification methods

Abstract Noroviruses (NVs) are responsible for most cases of human nonbacterial gastroenteritis worldwide. Some parameters for the purification of NV virus-like particles (VLPs) such as ease of production and yield were studied for future development of vaccines and diagnostic tools. In this study, VLPs were produced by the expression of the VP1 and VP2 gene cassette of the Brazilian NV isolate, and two purification methods were compared: cesium chloride (CsCl) gradient centrifugation and ion-exchange chromatography (IEC). IEC produced more and purer VLPs of NV compared to CsCl gradient centrifugation.

Preparation and functional analysis of the monoclonal antibodies against severe fever with thrombocytopenia syndrome bunyavirus structural proteins / 病毒学报

To prepare monoclonal antibodies (mAbs) against structural proteins of severe fever with thrombocytopenia syndrome bunyavirus (SFTSV), BALB/c mice were immunized using purified inactivated SFTSV virions as the antigens. Subsequently, hybridoma cell lines that secreted monoclonal antibodies against nucleoprotein (NP) and glycoproteins (GP) were obtained using a hybridoma technique. The antigen specificities of prepared mAbs were examined by indirect immunofluorescence and immunoprecipitation assays. Functional analyses were then performed,including the detection of IFA antibody titers,the levels of neutralizing activity and antibody affinities. After cell fusion and cloning,13 hybridoma cell lines secreted mAbs specifically against SFTSV-GP and 7 hybridoma cell lines secreted mAbs specifically against SFTSV-NP. Immunofluorescence and immunoprecipitation assays showed that the mAbs had high levels of antigen specificity. Among the 13 anti-SFTSV-GP mAbs,6 recognized Gn,whereas the others reacted with Gc. IFA titers of most anti-SFTSV-GP mAbs were between 1,280 and 20,480, and four anti-SFTSV-Gn mAbs showed neutralizing activity. Seven of the obtained anti-SFTSV-NP mAbs reacted specifically with NP,of which the IFA titers ranged from 5,120 to 20,480 with no observed neutralizing activity. Furthermore, two anti-SFTSV-GP mAbs, 1C8 and 1G8, showed high levels of affinity via a non-competitive ELISA. Our study lays the foundation for the development of further diagnostic assays and basic research into SFTSV.

Development and Identification of the Recombinant Lentivirus Co-expressing HCV Structural Protein and Secreted Gaussia Luciferase (Gluc) / 病毒学报

To develop a recombinant lentivirus co-expressing structural protein of hepatitis C virus (HCV) and secreted Gaussia Luciferase (Gluc), we first constructed an expression vector that encoded HCV structural protein (C, E1, E2) and GLuc named pCSGluc2aCE1E2. The expression of HCV proteins and Gluc was confirmed by an immunofluorescence assay (IFA) and the detection of luciferase activity. Recombinant lentivirus (VSVpp-HCV) was developed by the co-transfection of pCSGluc2aCE1E2 into 293T cells with pHR'CMVA8.2 and pVSVG. The infectivity of VSVpp-HCV was confirmed by luciferase activity detection, IFA and western blotting. Virus-like particles were identified using electron microscopy after concentration. The results showed that the level of luciferase activity correlated with the expression of HCV protein after the infection of cells with lentivirus VSVpp-HCV. Therefore, the expression level of HCV proteins could be evaluated by detecting the luciferase activity of Gluc. In conclusion, this research pave a way for the development of transgenic mice that express HCV proteins and Gluc, which enable the evaluation of anti-HCV therapy and vaccine in vivo.

Preparation and identification of monoclonal antibodies against infectious bursal disease virus (IBDV) VP4 / 生物工程学报

Infectious bursal disease virus (IBDV) VP4 plays an important role in immunosuppression of host. In order to develop monoclonal antibodies (McAbs) against VP4, we vaccinated BALB/c mice with His-VP4, screened and subcloned positive clones. We established 4 hybridoma cell lines that stably secreted McAbs against VP4 and named these cell lines 3B3, 3H11, 4C8 and 4G6, respectively. We tested the dissociation constant (Kd) of these McAbs, and found that their K(d)s were 4.61 x 10(-11), 1.71 x 10(-10), 4.26 x 10(-11), 5.02 x 10(-11), respectively. The isotypes of these McAbs were determined to be IgG1, IgG1, IgG2b and IgG1. These McAbs specifically bound to VP4 in IBDV infected DF-1 cells as demonstrated by Western blotting analysis and fluorescence antibody assay. These McAbs would help to detect IBDV infection and to analyze the biological activities of IBDV VP4.

Immunogenicity of recombinant Lactobacillus casei expressing VP2 protein of infectious bursal disease virus in chickens / 生物工程学报

In order to determine immunogenicity and protective effect in chickens, we used the IBDV (Infectious bursal disease virus)-Vp2/Lactobacillus casei as antigen transfer system. First, the immunized and control chickens were challenged by IBDV/DQ at lethal dose to determine the protective ratio. Second, chickens were orallyand intranasally vaccinated twice with 10(9) CFU/mL pLA-VP2/L. casei, pLA/L. casei and PBS as negativecontrol and commercial vaccine as positive control. The bursa injury and the lesion score wererecorded post challenge. The level of specific IgG and sIgA in pLA-VP2/L. casei and positive control groups was significantly higher than that in negativecontrol groups. The protection efficacy in pLA-VP2/L. casei oral group was higher than that inintranasal group. The SI. of pLA-VP2/L. casei oral group was significant higher than other groups. The lesion score indicated the pLA-VP2/L. casei was safer than commercial vaccine for bursa. Collectively, the pLA-VP2/L. casei could be a vaccine candidate for IBDV.

Identification of nuclear localization signals of pseudorabies virus gene UL49 / 病毒学报

Tegument protein VP22 is encoded by Pseudorabies Virus (PRV) UL49. To identify the nuclear localization signals of UL49, it is necessary to determine the transport mechanism and biological functions of the VP22 protein. In this study, we identified two nuclear localization signals from UL49, NLS1 (5RKTRVA ADETASGARRR21) and NLS2 (241PGRKGKV247). The functional nuclear localization signal (NLS) of UL49 was identified by constructing truncated or site-specific UL49 mutants. The deletion of both NLS1 and NLS2 abrogated UL49 nuclear accumulation, whereas the deletion of NLS1 or NLS2 did not. Therefore, both NLS1 and NLS2 are critical for the nuclear localization of UL49. And our resuts showed that NLS2 is more important in this regard.

VP22 herpes simplex virus protein can transduce proteins into stem cells

The type I herpes simplex virus VP22 tegument protein is abundant and well known for its ability to translocate proteins from one cell to the other. In spite of some reports questioning its ability to translocate proteins by attributing the results observed to fixation artifacts or simple attachment to the cell membrane, VP22 has been used to deliver several proteins into different cell types, triggering the expected cell response. However, the question of the ability of VP22 to enter stem cells has not been addressed. We investigated whether VP22 could be used as a tool to be applied in stem cell research and differentiation due to its capacity to internalize other proteins without altering the cell genome. We generated a VP22.eGFP construct to evaluate whether VP22 could be internalized and carry another protein with it into two different types of stem cells, namely adult human dental pulp stem cells and mouse embryonic stem cells. We generated a VP22.eGFP fusion protein and demonstrated that, in fact, it enters stem cells. Therefore, this system may be used as a tool to deliver various proteins into stem cells, allowing stem cell research, differentiation and the generation of induced pluripotent stem cells in the absence of genome alterations.

The structural and accessory proteins M, ORF 4a, ORF 4b, and ORF 5 of Middle East respiratory syndrome coronavirus (MERS-CoV) are potent interferon antagonists

The newly emerged Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic respiratory virus with pathogenic mechanisms that may be driven by innate immune pathways. The goal of this study is to characterize the expression of the structural (S, E, M, N) and accessory (ORF 3, ORF 4a, ORF 4b, ORF 5) proteins of MERS-CoV and to determine whether any of these proteins acts as an interferon antagonist. Individual structural and accessory protein-coding plasmids with an N-terminal HA tag were constructed and transiently transfected into cells, and their native expression and subcellular localization were assessed using Wes tern blotting and indirect immunofluorescence. While ORF 4b demonstrated majorly nuclear localization, all of the other proteins demonstrated cytoplasmic localization. In addition, for the first time, our experiments revealed that the M, ORF 4a, ORF 4b, and ORF 5 proteins are potent interferon antagonists. Further examination revealed that the ORF 4a protein of MERS-CoV has the most potential to counteract the antiviral effects of IFN via the inhibition of both the interferon production (IFN-β promoter activity, IRF-3/7 and NF-κB activation) and ISRE promoter element signaling pathways. Together, our results provide new insights into the function and pathogenic role of the structural and accessory proteins of MERS-CoV.

Genotype features of norovirus associated with acute gastroenteritis through sentinel surveillance in Guizhou Province, 2011 / 病毒学报

To study the genotype of Norovirus associated with acute gastroenteritis in Guizhou Province 2011, the patients' fecal specimens were collected from the Guizhou Province People's Hospital in the period of May to December 2011. Noroviruses in specimens were detected by a real-time reverse transcription polymerase chain reaction (Real-time RT-PCR). VP1 genes of norovirus-positive strains were then cloned and sequenced. Out of 70 clinical samples, the positive rates for norovirus G I (1 strain) and G II (34 strains) were 1.43% and 48.57, respectively. The VP1 sequencing results of seven norovirus G II showed thatthree strains were genotype G II . 4 and four strains were genotype G II . 3 Those genotype GIL . 4 strains were new variants (GII . 4 2011),closest to GII . 4 2006b variant. One amino acid appeared back mutation. Those genotype G II . 3 strains were divided into 2 gene clusters. One cluster was closest to Korean strain (HM635118) and Shanghai strain(GU991355). One cluster was closest to Japaness strain (AB629943) and 2007 Indian strain (EU921389), Four amino acids appeared back mutations.

Expression, purification and glycosylation analysis of chicken infectious bursal disease virus VP2 in yeast

Infectious bursal disease [IBD], a highly contagious and devastating disease in young chicken, is caused by infectious bursal disease virus [IBDV]. To improve the immunogenicity of recombinant IBDV subunit vaccine, an attempt was made to find a new way to prepare IBD vaccine containing glycosylated mVP[2] antigen. Firstly, IBDV mVP[2] gene [with a nucleic acid sequence encoding B cell epitope of IBDV [KFDQML] in the 5'-end of the VP[2], with a nucleic acid sequence encoding B cell epitope of IBDV [LASP] and [His] 6-tag in the 3'-end of the VP[2]] was cloned. Secondly, IBDV mVP[2] protein was expressed in the methylotrophic yeast Pichia pastoris which can secret glycosylated protein. The recombinant mVP[2] protein could be stained pink with periodic acid-schiff reagents [PAS], which showed that mVP[2] was glycosylated. Finally, IBDV mVP[2] protein was purified with His-Trap [1 mL] affinity chromatography. These results indicate that glycosylated IBDV VP[2] protein modified with epitope peptides can be expressed in Pichia pastoris, which lay the groundwork for the development of a recombinant infectious bursal disease vaccine with high immunogenicity

Codon optimization of the rabbit hemorrhagic disease virus (RHDV) capsid gene leads to increased gene expression in Spodoptera frugiperda 9 (Sf9) cells

Rabbit hemorrhagic disease (RHD) is contagious and highly lethal. Commercial vaccines against RHD are produced from the livers of experimentally infected rabbits. Although several groups have reported that recombinant subunit vaccines against rabbit hemorrhagic disease virus (RHDV) are promising, application of the vaccines has been restricted due to high production costs or low yield. In the present study, we performed codon optimization of the capsid gene to increase the number of preference codons and eliminate rare codons in Spodoptera frugiperda 9 (Sf9) cells. The capsid gene was then subcloned into the pFastBac plasmid, and the recombinant baculoviruses were identified with a plaque assay. As expected, expression of the optimized capsid protein was markedly increased in the Sf9 cells, and the recombinant capsid proteins self-assembled into virus-like particles (VLPs) that were released into the cell supernatant. Rabbits inoculated with the supernatant and the purified VLPs were protected against RHDV challenge. A rapid, specific antibody response against RHDV was detected by an ELISA in all of the experimental groups. In conclusion, this strategy of producing a recombinant subunit vaccine antigen can be used to develop a low-cost, insect cell-derived recombinant subunit vaccine against RHDV.

Preparation of a monoclonal antibody against polyhedrin of Ectropis obliqua nucleopolyhedrovirus / 生物工程学报

To develop a method based on immunoreactions for detection of Ectropis obliqua Nucleopolyhedrovirus (EoNPV), the polyhedra of the virus were purified and used to immunize the mouse BALB/c. The spleen cells from the immunized mice were then fused with the myeloma cell line Sp2/0. A hybridoma cell line which can stably secrete the monoclonal antibody against EoNPV was achieved by using indirect ELISA screening and cloning methods, and was named as 7D3. Meanwhile, the polyhedrin gene was cloned from EoNPV and expressed in E. coli. Western blotting analysis showed that the monoclonal antibody prepared from 7D3 could specifically react with the recombinant polyhedrin. An indirect ELISA method based on this monoclonal antibody for detecting EoNPV in infected tea looper was developed.

Evaluation of modified vaccinia virus Ankara expressing VP2 protein of infectious bursal disease virus as an immunogen in chickens

A recombinant modified vaccinia Ankara (MVA) virus expressing mature viral protein 2 (VP2) of the infectious bursal disease virus (IBDV) was constructed to develop MVA-based vaccines for poultry. We demonstrated that this recombinant virus was able to induce a specific immune response by observing the production of anti-IBDV-seroneutralizing antibodies in specific pathogen-free chickens. Besides, as the epitopes of VP2 responsible to induce IBDV-neutralizing antibodies are discontinuous, our results suggest that VP2 protein expressed from MVA-VP2 maintained the correct conformational structure. To our knowledge, this is the first report on the usefulness of MVA-based vectors for developing recombinant vaccines for poultry.

Expression of structural and non-structural proteins of severe fever with thrombocytopenia syndrome bunyavirus / 病毒学报

Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) is a novel phlebovirus, causing a life-threatening illness associated with the symptoms of severe fever and thrombocytopenia syndrome. The sequence and structure of the genome have already been illustrated in previous study. However, the characteristics and function of the structure and non-structure proteins is still unclear. In this study, we identified the density of the purified SFTSV virions as 1.135 g/mL in sucrose solution. Using RT-PCR method, we amplified the full coding sequence of RNA dependent RNA polymerase(RdRp), glycoprotein precursor (M), glycoprotein n (Gn), glycoprotein c (Gc), nuclear protein (NP) and non structural protein (NSs) of SFTSV (strain HB29). Respectively inserted the target genes into eukaryotic expression vector pcDNA5/FRT or VR1012, the target protein in 293T cell were successfully expressed. By analyzing the SFTSV virions in SDS-PAGE and using recombinant viral proteins with SFTS patients sera in Western blotting and Immunofluorescent assay, the molecule weight of structure and non-structure proteins of SFTSV were defined. The study provides the first step to understand the molecular characteristics of SFTSV.

Screening proteins interacting with infectious bursa disease virus Gt VP2 from cDNA library of B lymphoid cells of the bursa of Fabricius / 生物工程学报

To screen the interactive proteins with IBDV Gt VP2 protein from cDNA library of B Lymphoid cells of the bursa of Fabricius. The expression cDNA library plasmids was transformed to the yeast competent cells, which have the bait plasmid-Gt VP2. After testing for growth in synthetic complete medium lacking histidine and uracil and for production of beta-galactosidase (X-gal), we obtained 16 positive clones. We searched the gene sequences of positive clones in the NCBI website. The blast results showed that five positive clones were the gallus sequences. They were Gallus gallus breed mitochondrial DNA, O_G1cNAc transferase, Tumor protein p53 binding protein, Stathmin and Chondroitin sulfate Ga1NAcT-2, respectively. This study is helpful for the further identifying the receptors of IBDV in B Lymphoid cells of the bursa of Fabricius.

Co-occlusion of foreign protein into polyhedra with BmNPV polyhedrin / 病毒学报

In order to make clear the packing mechanism of the BmNPV polyhedra, a polyhedrin gene negative recombinant baculovirus, vBmBac(polh-)-5B-EGFP, expressing EGFP was constructed, and used to infect BmN cells jointly with wild-type BmNPV. Fluorescent microscopic observation demonstrated that EGFP and polyhedrin were expressed simultaneously, and the EGFP expression and polyhedra formation occurred in most of the jointly infected cells. Analysis of the purified polyhedra from jointly infected BmN cells showed that the foreign proteins were present in the polyhedra. The results indicated that BmNPV polyhedrin could incorporate proteins other than viral proteins into the polyhedra. It implies that a nonspecific recognition mechanism exists in the embedment of BmNPV polyhedra.

Genetic evolution of VP1 of enterovirus type 71 in Shenzhen / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Genetic evolution of VP1 of enterovirus type 71 in Shenzhen were analyzed.</p><p><b>METHODS</b>All samples were tested by RT-PCR using EV71 specific primer. The VP1 of EV71 were amplified and sequenced. A phylogenetic tree was constructed by comparison of the sequences with subgenotype A, B and C using DNAStar, BioEdit and Mega 3.1 software.</p><p><b>RESULTS</b>Among 35 strains, the homogeneity of the VP1 nucleotide sequence was between 92.1%-100%. The homogeneity of the VP1 nucleotide sequence with subgenotype A and B was between 81.4% -91.1%. The VP1 nucleotide sequence of 35 strains of Shenzhen shared between 93% -97.4% identity with cluster C4. The prevalence strains of EV71 were cluster C4b from 1998 to 2004, and gradually moved to C4a since 2003. All of EV71 were C4b from 2006 to 2008. Also, the homogeneity of the VP1 nucleotide sequence with Anhui FY23 EV71 strain were 94.5% -94.7%, 95.7% -95.8%, 96.2%, 95.4% -97.5%, 96.3% -99.2% from 2003 to 2008. It shows that the homogeneity was increased year by year. There was a mutation (A --> C) at No. 66 nucleotide of VP1 of EV71 that two strains were isolated in 2003 and 8 strains in 2008, that caused amino acid mutation (Q --> H) at No. 22 of VP1.</p><p><b>CONCLUSION</b>EV71 C4b was gradually moved to C4a from 1998 to 2008. There was a missense mutation at No. 66 nucleotide of VP1.</p>