Re-engineering of bicistronic plasmid pGPD/IFN to construct fusion gene co-expressing Glyceraldehyde 3-phosphate dehydrogenase gene (GAPDH) of Edwardsiella tarda and Interferon-gamma (IFN-?) gene of Labeo rohita (Hamilton) and its in vitro functional analysis

Edwardsiella septicemia disease in the cultured Indian major carps is caused by the fish pathogen Edwardsiella tarda and it is preventable by DNA vaccination. Here, we tried to develop a bicistronic DNA vaccine pGPD/IFN expressing the Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene of Edwardsiella tarda and Interferon-gamma (IFN-?) gene of Labeo rohita. The vaccine showed high protective efficiency in our previous studies; however as a limitation of bicistronic construct the expression of gene cloned in second frame (B) is poor. To overcome this limitation we re-engineered the construct and designed a fusion gene co-expressing the GAPDH and IFN-? genes as one frame with an aim to get the optimum expression of both the genes. For this purpose, a fusion insert comprising GAPDH and IFN-? coding sequences was cloned in to pcDNA3.1(+) plasmid vector. The fusion genes' in vitro expression was confirmed in the striped snakehead fish cell line (SSN-1). Successful expression of the re-engineered fusion gene DNA vaccine in the cell line was achieved at 48h post-transfection, which was confirmed by amplifying the expression transcripts of GAPDH and IFN-? genes. Thus, the study concludes that the re-engineered fusion vaccine pcGPD/IFN (pcDNA3.1(+) plasmid having fusion GPD/IFN) is functional and can be effectively utilized to vaccinate rohu (Labeo rohita) as it contains the species-specific immune gene (IFN-?) as an adjuvant

Construction of a replicative expression vector based on the porcine circovirus 2 replicon / 生物工程学报

The antigen gene expression level of a DNA vaccine is the key factor influencing the efficacy of the DNA vaccine. Accordingly, one of the ways to improve the antigen gene expression level of a DNA vaccine is to utilize a plasmid vector that is replicable in eukaryotic cells. A replicative DNA vaccine vector pCMVori was constructed based on the non-replicative pcDNA3.1 and the replicon of porcine circovirus 2 (PCV2) in this study. An EGFP gene was cloned into pCMVori and the control plasmid pcDNA3.1. The two recombinant vectors were transfected into PK-15 cell, and the plasmid DNA and RNA were extracted from the transfected cells. Real-time PCR was used to determine the plasmid replication efficiency of the two plasmids using plasmid before and after Bcl Ⅰ digestion as templates, and the transcription level of the Rep gene in PCV2 replicon was detected by RT-PCR. The average fluorescence intensity of cells transfected with the two plasmids was analyzed with software Image J, and the transcription level of EGFP was determined by means of real-time RT-PCR. The results showed that the replication efficiency of pCMVori in PK-15 cells incubated for 48 h was 136%, and the transcriptions of Rep and Rep' were verified by RT-PCR. The average fluorescence intensity of the cells transfected with pCMVori-EGFP was 39.14% higher than that of pcDNA3.1-EGFP, and the transcription level of EGFP in the former was also 40% higher than that in the latter. In conclusion, the DNA vaccine vector pCMVori constructed in this study can independently replicate in eukaryotic cells. As a result, the expression level of cloned target gene was elevated, providing a basis for developing the pCMVori-based DNA vaccine.

Preparation and preliminary evaluation of SARS-CoV-2 DNA vaccine based on PLGA nanoparticles / 药学学报

We constructed and optimized the plasmid DNA (pDNA) Opt-S encoding the gene of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein, using poly (lactic-co-glycolic acid) copolymer (PLGA) as a delivery carrier for pDNA. PLGA-pDNA NPs were loaded by nanoprecipitation and its properties in vitro were preliminary evaluated. The results showed that the prepared PLGA-pDNA NPs were regular morphology, clear edges, with an average particle size of (184.2 ± 2.4) nm, polydisperse index (PDI) of 0.093 ± 0.013, zeta potential of (-68.10 ± 0.36) mV, and encapsulation rate of (98.92 ± 0.22)%. The PLGA-pDNA NPs were stable at -20 ℃ for 7 months and could protect pDNA against nuclease degradation. And they also exhibited sustained release of pDNA in vitro. The PLGA-pDNA NPs have low cytotoxicity and high safety. In addition, in vitro transfection experiments showed that the SARS-CoV-2 S gene could enter cells and be expressed. These results indicate that PLGA-pDNA NPs non-viral gene vector have simple preparation process and good performance, which are expected to provide a new idea for the research and development of SARS-CoV-2 vaccine.

Development and verification of high performance liquidchromatography for determination of ethylenediaminetetraacetic acid disodium salt residue in NMM tumor DNA vaccine / 中国生物制品学杂志

@#Objective To develop and verify a high performance liquid chromatography(HPLC) method for the determination of ethylenediaminetetraacetic acid disodium salt(EDTA-2Na) residues in the bulk of NMM tumor DNA vaccine for the quality control of DNA vaccine.Methods After NMM tumor DNA vaccine bulk was complexed with copper sulfate,a HPLC method for the determination of EDTA-2Na residues was developed with Agilent ZORBA XSB-C18(150 mm × 4.6 mm,5 μm) as the chromatographic column,water,tetrabutylammonium hydroxide 10% and acetonitrile solution(74.5:0.5:25)as the mobile phase.The detection method was as follows:the detection wavelength was 254 nm,the flow rate was 0.8 mL/min,the column temperature was 20 ℃ and the injection volume was 20 μL.The method was verified for the specificity,linear range,limit of detection(LOD),limit of quantification(LOQ),solution stability,durability,accuracy and precision,and used to detect the EDTA-2Na residues in several batches of DNA vaccine bulk.Results When EDTA-2Na control and DNA vaccine bulk with EDTA-2Na reacted with copper sulfate,the absorption peak appeared at around 5.3 min,while no absorption peak was observed when DNA vaccine bulk reacted with copper sulfate;In the range of 4～400 μg/mL,the control solution concentration showed a good linear relationship with the peak area,R~2=0.999 9;The LOD of the method was 10 ng/mL,and the LOQ was 40 ng/mL;The solution of control and sample was stable after placed for 12 h;When the detection conditions changed slightly(different mobile phase ratio,flow rate and column temperature),the influence on the detection results was within acceptable range;The average recovery rate of EDTA-2Na in low,medium and high concentration standard added samples was 101.38% with the RSD of 0.39%;0.1 mg/mL control solution was injected continuously for 6 times,and the peak area RSD was 0.04%.EDTA-2Na was not detected in 6 sample solution,and the peak area RSD of DNA vaccine bulk with EDTA-2Na solution was 0.02%,indicating a good intermediate precision.EDTA-2Na residue was not detected in these batches of DNA vaccine bulk.Conclusion The developed method is simple,accurate,reliable with good specificity,which can be used for the determi-nation of EDTA-2Na residues in DNA vaccine bulk.

Construction of a novel bivalent DNA vaccine against SARS-CoV-2 and influenza A virus H3N2 and evaluation of its immunogenicity in mice / 中华微生物学和免疫学杂志

Objective:To construct a bivalent DNA vaccine against SARS-CoV-2 and influenza A virus H3N2 and to evaluate its immunogenicity in mice.Methods:The coding sequences for spike 1 (S1) protein of SARS-CoV-2 Beta variant and hemagglutinin (HA) of influenza A virus Cambodia (H3N2) strain were codon-optimized and synthesized. The two coding genes were ligated by the self-cleaving 2A peptide using over-lapping PCR to construct S1-2A-HA fragment, which was inserted into pVRC vector to construct the bivalent DNA vaccine, named as pVRC-S1-2A-HA. Indirect immunofluorescence assay (IFA) and Western blot were performed to detect the expression of S1 and HA proteins. BALB/c mice were immunized with pVRC-S1-2A-HA by intramuscular injection and electroporation. The humoral immune responses induced in mice were detected by indirect ELISA, pseudovirus neutralization assay and hemagglutination inhibition assay. Cellular immune responses were detected by IFN-γ ELISPOT, intracellular cytokine staining (ICS) and cytometric bead array (CBA).Results:The bivalent DNA vaccine pVRC-S1-2A-HA could express S1 and HA proteins in vitro. Specific cellular immune responses against S1 protein and specific IgG antibody against HA protein were significantly induced in mice with single-dose immunization. The antigen-specific immunity was significantly enhanced after booster immunization. The geometric mean titer (GMT) of specific IgG antibody increased to 3 251 for S1 protein and 45 407 for HA protein after two-dose immunization. Moreover, the S1-specific T cells increased to 1 238 SFC/10 6 cells. ICS results indicated that the booster vaccination induced CD4 + T and CD8 + T cells to produce IL-2, IFN-γ and TNF-α in mice. The secretion of various cytokines including IL-2, IL- 4, IL-6, IL-10 and IFN-γ in mouse splenocytes was induced after single-dose immunization. Conclusions:A bivalent DNA vaccine against SARS-CoV-2 and influenza A virus H3N2 was constructed and could induce S1- and HA-specific humoral and cellular immune responses in mice, suggesting the great potential of it for further development and application.

Construction and in vivo evaluation of a thermosensitive hydrogel system loading with Pseudomonas aeruginosa DNA vaccine / 中国药科大学学报

@#A thermosensitive hydrogel system consisting of PLGA-PEG-PLGA hydrogel and Pseudomonas aeruginosa DNA vaccine was constructed and the immune efficacy of the system was evaluated. The PLGA-PEG-PLGA thermosensitive hydrogel containing Pseudomonas aeruginosa DNA vaccine was prepared by a simple physical mixing method. The gelation temperature, cytotoxicity, and release curve in vitro were tested.The degradability of hydrogel in vivo was evaluated. The mice were divided into control group (PBS), hydrogel group (Hydrogel), in vivo-jetPEI/plasmid DNA group (in vivo-jetPEI/pDNA), and hydrogel + in vivo-jetPEI/plasmid group (Gel+in vivo-jetPEI/pDNA). Mice were immunized three times with a ten-day interval. Two weeks after the last immunization, the mice were sacrificed. The proliferation of splenic lymphocytes, serum specific IgG antibodies and IFN-γ in supernatant of splenic lymphocytes were detected. The gelation temperature of PLGA-PEG-PLGA hydrogel was (32 ± 0.5) ℃. There was no obvious toxicity to cells in vitro, and about 80% of plasmid DNA was released after 7 days in vitro. PLGA-PEG-PLGA hydrogel was biodegradable, and degraded almost completely after 15 days in vivo. The spleen lymphocytes proliferated; the levels of specific IgG antibodies and IFN-γ of in vivo-jetPEI/pDNA and Gel+in vivo-jetPEI/pDNA groups increased. The hydrogel could enhance the immune response induced by DNA vaccine.Results suggest that the thermosensitive hydrogel system consisting of PLGA-PEG-PLGA hydrogel and Pseudomonas aeruginosa DNA vaccine is a promising new strategy for the development of PA vaccine.

Biopolymer Xanthan: A New Adjuvant for DNA Vaccines

Abstract DNA vaccines have been evaluated as an option to prevent several diseases. In this study, the capacity of the xanthan biopolymer to improve the DNA vaccines immune response, administered intramuscularly, was evaluated. The experimental vaccines consisted of genes encoding fragments of the proteins LigA and LigB of Leptospira interrogans serogroup Icterohaemorrhagiae serovar Copenhageni strain Fiocruz L1-130. The humoral immune response was evaluated by indirect ELISA. Cytokine expression levels were determined by RT-qPCR. Compared to the control group, the IgG antibody levels of animals immunized with pTARGET/ligAni and pTARGET/ligBrep plasmids associated with xanthan biopolymer were significantly higher than the control group. Additionally, there was a significant increase in IL-17 expression in animals vaccinated with pTARGET/ligBrep and xanthan.

Enhancing immune effects of a DNA vaccine against kidney cancer using CD40L as an adjuvant

The use of specific combinations of antigens and adjuvant represents a promising approach for increasing the immunogenicity of DNA vaccines. In the present study, we evaluated the immunity and antitumor effects of DNA vaccines with G250 as the target antigen in a mouse model of renal cell carcinoma. We constructed two recombinant plasmids, pVAX1-G250 and pVAX1-CD40L. The recombinant plasmids were injected into mice by intramuscular injection and electrical pulse stimulation. ELISA and ELISPOT experiments were performed to evaluate the corresponding humoral and cellular immune responses following immunization. To further investigate the antitumor potential of the DNA vaccines, we established a tumor-bearing mouse model expressing G250 target antigen. Our results showed that immunization with the combination of the two plasmids exerted the strongest anti-tumor effects. Therefore, our findings demonstrated the effectiveness of CD40L as an adjuvant for DNA vaccines and highlighted the promising use of these vaccines for the treatment of tumors.

Construction and in vitro evaluation of DC-targeted aptamer-modified Pseudomonas aeruginosa DNA vaccine delivery system / 中国药科大学学报

@#This study aimed to construct a DC-targeted aptamer-modified Pseudomonas aeruginosa(PA)DNA vaccine delivery system. The cationic liposome was prepared by ethanol injection method. The cationic liposome loading pVAX1-OprF-VP22(Lip-pOprF-VP22)was prepared by electrostatic adsorption method. The encapsulation efficiency of Lip-pOprF-VP22 with different mass ratios of DOTAP/pDNA on pVAX1-OprF-VP22, cytotoxicity and transfection rate to DC2. 4 in vitro were discussed. The particle size and zeta potential of Lip-pOprF-VP22 with best mass ratio were tested. Aptamer-modified cationic liposome loading pVAX1-OprF-VP22(Apt-Lip-pOprF-VP22)was prepared by post-insertion method. The expression of OprF protein after transfection of DC2. 4 and its effect on the maturation of bone marrow-derived dendritic cells(BMDCs)were detected. Data showed that as the mass ratio of DOTAP/pDNA increased, the encapsulation efficiency of Lip-pOprF-VP22 on pVAX1-OprF-VP22 was gradually increased. When the mass ratio was 5 ∶1, pVAX1-OprF-VP22 was encapsulated well. When Lip-pOprF-VP22 with different mass ratios was applied to DC2. 4 for 24 h or 48 h, the survival rates of DC2. 4 were all above 80%. When the mass ratio of DOTAP/pDNA increased from 2 ∶1 to 10 ∶1, the transfection rate increased first and then decreased. When the mass ratios of DOTAP/pDNA were 4 ∶1 and 5 ∶1, the transfection rates were relatively high. When the mass ratio of DOTAP/pDNA was 5 ∶1, the particle size of Lip-pOprF-VP22 was(171. 67±1. 27)nm, and the Zeta potential was(11. 30±0. 57)mV. Furthermore, Apt-Lip-pOprF-VP22 can express more OprF protein and significantly promote the maturation of BMDCs. In conclusion, Apt-Lip-pOprF-VP22 can target to DC and promote the maturation of DC.

Glycyrrhiza uralensis Fisch L. crude polysaccharides enhance mouse immunity and immune responses induced by HPV-DNA vaccine / 中华微生物学和免疫学杂志

Objective To investigate the effects of Glycyrrhiza uralensis Fisch L. crude polysac-charides (GUCP) as an adjuvant on the immunity of mice and the immune responses induced by human pap-illoma virus ( HPV)-DNA vaccine. Methods ICR mice were injected with different concentrations of GUCP by different ways to detect the influences of GUCP on body weight, organ indexes and the numbers of immune cells in spleen. C57BL/ 6 mice were co-immunized with HPV-DNA vaccine and GUCP to detect the adjuvant efficacy on antigen-specific cellular and humoral immune responses. Results GUCP in all injected groups had no side effect on mouse body weight and liver, heart, lung and kidney indexes, but intraperitone-al injection of GUCP significantly increased spleen and thymus indexes and the numbers of B cells, CD4+ T cells, macrophages and dendritic cells in spleen. Subcutaneous injection of GUCP significantly increased the numbers of B cells and macrophages in spleen and intragastric administration significantly increased the num-bers of CD4+ and CD8+ T cells in spleen. Furthermore, GUCP as an adjuvant enhanced the antigen-specific CD4+ and CD8+ T cell responses and the levels of IgG, IgG1 and IgG2a induced by HPV-DNA vaccine at a certain degree. Conclusion GUCP enhanced the immunity of mice and the antigen-specific cellular and hu-moral immune responses induced by HPV-DNA vaccine. These results suggested that GUCP might be used as an adjuvant for DNA vaccine.

Humoral immunity evaluation and virual challenge of lysosomal targeted hantavirus envelope glycoprotein DNA vaccine / 中国免疫学杂志

Objective:To build the DNA vaccine encoding hantavirus glycoprotein fused with lysosome-associated membrane protein (LAMP) and assess its immune response.Methods:BALB/c mice were immuned with the previous experimental expressing purified recombinant plasmids pVAX-Gn,pVAX-Gc,pVAX-LAMP/Gn,pVAX-LAMP/Gc,and inactivated vaccine.Indirect ELISA and neutralization test was used to detect specific antibody and neutralizing antibody in the serum of mice.The mice were tested to detect the protective effects in vivo.Results:Indirect ELISA results showed that the pVAX-LAMP/Gc group was the highest,followed by pVAX-Gc,pVAX-LAMP/Gn,and PVAX-Gn,and inactivated vaccine group.In neutralization test,there were significantly higher serum antibodies in LAMP group than those in conventional DNA group,which were higher than the inactivated vaccine group.The mice immuned had good protective effect in vivo without the specific antigen of hantavirus in vivo.Conclusion:Chimeric DNA vaccines induced higher levels of antibody in BALB/c mice and produced better protective efficacy,which illustrate the targeting strategy is expected to be an effective way to improve the DNA vaccine efficacy.

Secreted CTLA-4 fusion Plasmodium falciparum DNA vaccine combined with GM-CSF enhances immune response of mice / 基础医学与临床

Objective To study effects of secreted cytotoxic T-lymphocyte-associated protein-4(CTLA-4)fusion Plasmodium falciparum DNA vaccine combined with granulocyte-macrophage colony stimulating factor(GM-CSF) on humoral and cellular immune responses in mice.Methods The malaria antigen coding sequence fused with CTLA-4 extracellular region of mouse was constructed as eukaryotic secretory expression vector VR 1012-sES312-CTLA,recombinant protein in culture of transfected HEK 293 cells was detected by Western blot.Balb/c mice were co-administrated with VR1012-sES312-CTLA and GM-CSF expression vector.After immunization specific antibody IgG titers and cytokines IFN-γand IL-4 expression levels were evaluated by ELISA and ELISPOT respectively. Results The introduction of CTLA-4 into malaria DNA vaccine system and application of GM-CSF adjuvant signifi-cantly enhanced the specific immune response to the vaccine.Antibody titers in VR1012-sES312-CTLA and GM-CSF co-immunized mice showed a 190-fold increase compared with the simple designed VR1012-ES312 immunization(P<0.001).Conclusions Humoral and cellular immunity induced by malaria DNA vaccine are significantly en -hanced by both dendritic cell-targeting modification and the introduction of GM-CSF molecular adjuvant into the im-mune system.This result provides a new idea for effectively raising the immune response to malaria DNA vaccine.

Neutralizing Antibody Titer Test of Ebola Recombinant Protein Vaccine and Gene Vector Vaccine pVR-GP-FC / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>In previous studies, we immunized mice with Ebola recombinant protein vaccine and gene vector vaccine. Both stimulated high levels of humoral immunity. In this work, we constructed a pseudovirus containing Ebola membrane proteins to verify whether the two immunization strategies can induce neutralizing antibodies in mice.</p><p><b>METHODS</b>A pseudovirus containing an Ebola virus membrane protein based on the HIV-1 viral gene sequence was constructed and evaluated using a known neutralizing antibody. The titer of the neutralizing antibody in the sera of mice immunized with the recombinant protein and the gene vector vaccine was examined using a neutralization test.</p><p><b>RESULTS</b>Ebola pseudovirus was successfully prepared and applied for neutralizing antibody detection. Immunological experiments showed that recombinant protein GP-Fc and gene vaccine pVR-modGP-Fc had good immunogenicity. The titer of the bound antibody in the serum after 8 weeks of immunization in mice was more than 1:105, and the recombinant protein induced greater humoral immunity. The results of the neutralization test based on the Ebola pseudovirus system demonstrated that both vaccines induced production of protective antibodies, while the gene vaccine induced a higher titer of neutralizing antibodies.</p><p><b>CONCLUSION</b>An Ebola pseudovirus detection system was successfully established and used to evaluate two Ebola vaccines. Both produced good immunogenicity. The findings lay the foundation for the development of new Ebola vaccines and screening for neutralizing monoclonal antibodies.</p>

Evaluation of Protective Immune Response Induced by a DNA Vaccine Encoding GRA8 against Acute Toxoplasmosis in a Murine Model

Toxoplasma gondii is an apicomplexan zoonotic protozoan parasite that infects most species of warm-blooded animals, including humans. The heavy incidence and severe or lethal damage caused by T. gondii infection clearly indicate a need for the development of an effective vaccine. T. gondii GRA8 is a member of the dense granules protein family and is used as a marker of acute infection. In the present study, we evaluated the protective immunity induced by DNA vaccination based on a recombinant eukaryotic plasmid, pDsRed2-GRA8, against acute toxoplasmosis in mice. BALB/c mice were intramuscularly immunized with the pDsRed2-GRA8 plasmid and then challenged by infection with the highly virulent GFP-RH strain of T. gondii. The specific immune responses and protective efficacy against T. gondii of this vaccine were analyzed by measuring cytokine and serum antibody titers, splenocyte proliferation assays, and the survival times of mice after challenge. Our results showed that mice immunized with pDsRed2-GRA8 demonstrated specific humoral and cellular responses, induced higher IgG antibody titers with predominant IgG2a production; increased levels of IL-10, IL-12 (p70), IFN-γ, TNF-α, and splenocyte proliferation; and prolonged survival times compared to those of control mice. The present study showed that DNA immunization with pDsRed2-GRA8 induced humoral and cellular immune responses, and all immunized mice showed greater Th1-type immune responses and longer survival times than those of control mice. These results indicated that T. gondii GRA8 DNA immunization induces a partial protective effect against acute toxoplasmosis.

Tumor specific immune response induced by three tandem repeats of CEA mini gene DNA vaccine and safety evaluation / 中国免疫学杂志

Objective:To observe the specific killing effect on tumor cells of the spleen cells in mice immunized with three tandem repeats of CEA minigene DNA vaccine pcDNA-triCEA625-667 and to evaluate the safety of the vaccine. Methods: The BALB/c mice were randomly divided into blank vector group ( pcDNA3. 0 ) , haploid vaccine group ( pcDNA-CEA625-667 ) and tandem repeats vaccine group (pcDNA-triCEA625-667). The mice received a total of 4 intramuscular immunization every 10 days once. The changes of body weight,survival state were recorded and the levels of serum ALT and serum creatinine were detected. The specific CTL killing activity of spleen cells in accinated mice on mouse hepatoma cells(H22-CEA+),gastric cancer cells(MFC-CEA+),colorectal cancer cells ( CT26-CEA+) with high expression of CEA and mouse hepatoma cells ( H22-CEA-) without expression of CEA was detected. Results:The two vaccines had strong killing activity on CEA positive liver cancer,gastric cancer and colon cancer cells,and the difference was statistically significant ( P<0. 01 ) compared with the PcDNA3. 0 group. And they had almost no effect on CEA negative tumor cells (H22-CEA-). The killing activity on liver cancer cell(H22-CEA+) and gastric cancer cell(MFC-CEA+) induced by pcDNA-triCEA625-667 was stronger than that induced by pcDNA-triCEA625-667(P<0. 05). The survival status,change of body weight and function of liver and kidney of the mice were not affected by the vaccine. Conclusion:There was no adverse reaction in the course of vaccine immunization. The minigene DNA vaccine derived from CEA can induce tumor specific CTL effect and the immune response level elicited by three tandem repeats of minigene DNA vaccine was superior to that elicited by haploid vaccine.

Immune responses in mice induced by DNA vaccines containing different glycoprotein C (Gc) gene fragments of Xinjiang hemorrhagic fever virus / 中华微生物学和免疫学杂志

Objective To construct two DNA vaccines based on two glycoprotein antigen segments of Xinjiang hemorrhagic fever virus (XHFV) and to evaluate the immune responses in BALB/c mice following vaccination.Methods Two recombinant expression plasmids pVAX1-GcⅠand pVAX1-Gc Ⅱ were constructed by inserting XHFV YL04057 strain Gc Ⅰ (1 229-1 349 aa) and Gc Ⅱ (1 443-1 566 aa) fragments into the eukaryotic expression vector pVAX1 and then were identify by restriction enzyme digestion and sequencing analysis.The recombinant expression plasmids were transfected into mice by hydrodynamics-based transfection.Immune responses induced in mice were evaluated by testing the proliferation of T cells with MTT,measuring serum antibody level with ELISA and detecting cytokines in the supernatant of spleen cell culture with ELISA kit.Results The recombinant expression plasmids were successfully constructed as indicated by the results of restriction enzyme digestion and sequencing analysis.Expression of Gc Ⅰ and Gc Ⅱ genes in mice liver tissues was detected.Antibody titers in mice immunized with pVAX1-GcⅠor pVAX1-Gc Ⅱ were higher than those in mice immunized with pVAX1.Compared with pVAX1,pVAX1-Gc Ⅱ significantly enhanced the proliferation of splenic T lymphocytes and the expression of IFN-γ (P<0.01).Conclusion The constructed two DNA vaccines for XHFV can induce specific humoral and cellular immune responses in mice.pVAX1-Gc Ⅱ is better than pVAX1-GcⅠin immunogenicity and protective efficacy,suggesting that it can be used as a promising candidate for the development of DNA vaccine for XHFV.

Observation of anti tumor activity in vivo of three tandem repeats of minigene DNA vaccine derived from CEA gene / 中国免疫学杂志

Objective:To observe the inhibitory effect of haploid vaccine pcDNA-CEA625-667 and three tandem repeats of minigene DNA vaccine pcDNA-triCEA625-667 derived from CEA gene on tumor in mice bearing tumor and the changes of survival time. Methods:The experimental animal model of mouse liver cell carcinoma was established and the mice were immunized with pcDNA-CEA625-667 and three series of DNA vaccine. Some of the mice were treated with normal saline as control group. The growth curve of tumor growth curve was recorded and the effect of vaccine on the survival time of tumor bearing mice was observed. Results:Compared with the normal saline control group,the two vaccines were able to significantly inhibit the tumor size and growth rate ( P<0. 01 ) of CEA positive tumor bearing mice,the inhibition of pcDNA-triCEA625-667 vaccine group was significantly better than the pcDNA-CEA625-667 vaccine group (P<0. 01),while the two were not inhibited tumor growth in CEA negative tumor bearing mice. The average survival time of the pcDNA-CEA625-667 vaccine group was(48. 50±6. 73)d,and there was significant difference (P<0. 01) compared with the saline control group ( 39. 00 ± 6. 64 ) d. The survival time ( 48. 50 ± 6. 73 ) d of the pcDNA-triCEA625-667 vaccine group was significantly higher than that of the normal saline control group and the pcDNA-CEA625-667 vaccine group (P<0. 01). The survival time of CEA negative tumor bearing mice could not be prolonged in the two groups. Conclusion:Either the haploid or the three series of the DNA vaccine,were able to significantly inhibit tumor growth rate (P<0. 01) and significantly prolong the survival time (P<0. 01) of CEA positive tumor bearing mice,but they had no therapeutic effect on CEA negative tumor bearing mice.

Efficacy of CZP3 DNA vaccine immune infertility enhanced by electric pulse method / 中国免疫学杂志

Objective:To analyze the immunocontraceptive efficacy of CZP3 DNA vaccine by electric pulse stimulating and the correlation between antibody level and antifertility. Methods: The mice were immunized with 5, 10, 20 and 50 μg DNA vaccine pcDNA3. 0-CZP3 respectively and were stimulated at leg muscle by electric pulse. Detect the antibody level of each mice group and the highest antibody titer by ELISA. After mated with male mice for three weeks,calculated infertility rate of mice,the average litter size of each immune group and did statistical analysis. Results:Compared with the intramuscular injection alone,the electric pulse stimulation could increase serum antibody titers of mice significantly, the antibody titer of 50 μg group which was stimulated by electric pulse reached 1∶4 000. Moreover,the infertility of the mice increased and the mice average litter size reduced along with the increase of CZP3 antibody level significantly. Statistical analysis showed that the antibody level and the average litter size had a negative correlation. Conclusion:The electric pulse stimulation can improve the immune level and reduce the fertility efficiency of mice significantly,therefore establishes a foundation for further application of CZP3 DNA vaccine in stray dog contraception.

Effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the anti-fertility efficacy of canine zona pellucida glycoprotein 3 (CZP3) DNA vaccine / 中华微生物学和免疫学杂志

Objective To investigate the effects of GM-CSF (granulocyte-macrophage colony-stimulating factor) as an immune adjuvant on the anti-fertility efficacy of canine zona pellucida glycoprotein 3 (CZP3) DNA vaccine.Methods RT-PCR and quantitative real-time PCR were performed to analyze the effects of GM-CSF on the maturation of antigen presenting cells (APCs) and the enrichment of APCs at injection site.Female BALB/c mice were immunized with CZP3 DNA vaccine pcDNA3-CZP3 alone or in combination with genetic adjuvant pcDNA3-GM-CSF by using the method of electrical impulses.ELISA (enzyme-linked immunosorbent assay) was used to detect the levels of IgG and sIgA (secretory IgA) antibodies in serum samples and genital tracts and the levels of IL-4 and IFN-γ in serum samples.MTT method was used to analyze the proliferation of spleen T cells in mice.The binding ability of serum anti-CZP3 antibody to native mouse oocytes was analyzed by indirect immunofluorescence assay.All of the female BALB/c mice were coupled with male mice of the same age six weeks after the first-dose vaccination.Litter size at birth in each group was counted and the differences between different groups were comparatively analyzed.ResultsImmunizing the mice with pcDNA3-CZP3 and GM-CSF significantly promoted the expression of CD80, CD83 and CD86 (P<0.05) and increased the sIgA antibody level in genital tract and IgG level in serum (P<0.01).Moreover, the levels of IL-4 and IFN-γ in serum samples were significantly up-regulated (P<0.05) and the proliferation of spleen T cells was significantly enhanced (P<0.05).Results of the indirect immunofluorescence assay showed that the fluorescence intensity and density on mouse egg surface were positively correlated with the level of antibody in serum.Results of the anti-fertility test suggested that GM-CSF significantly reduced the litter size in mice immunized with pcDNA3-CZP3 vaccine (P<0.05).Conclusion GM-CSF could be used as an effective adjuvant to enhance the anti-fertility efficacy of CZP3 DNA vaccine.

Study on antitumor effect of minigene DNA vaccine derived from Carcinoembry-onic Antigen ( CEA) gene in mice / 中国免疫学杂志

Objective:To observe the immunological activity of haploid vaccine and three tandem repeats of minigene DNA vac -cine derived from Carcinoembryonic Antigen (CEA) gene.Methods:The immunoreaction was induced by intramuscular injection with pc-DNA3.0,pcDNA-CEA625-667 and pcDNA-triCEA625-667 in BALB/c.Four weeks after injection,the spleen cells and serum were separa-ted respectively from the mice for the in vitro assessment .Changes of the T lymphocytes subset was analyzed by flow cytometry .Lymph proliferation responses were tested by 3 H-TdR incorporation ,IFN-γ,IL-4 and GM-CSF in their cultural supernatants were detected with ELISA and seral IgG antibody against CEA were detected with Western blot and ELISA .Results:The difference of the ratio of CD 4+/CD8+of the mice immuned by pc-DNA3.0,pcDNA-CEA625-667 or pcDNA-triCEA625-667 was not significant.Lymph proliferation responses were more significant in the mice immuned by pcDNA-CEA625-667 and pcDNA-triCEA625-667 in a shorter time by contrast with na ?ve mice.Low tilter IgG antibody against CEA was detected in the antiserum of the mice immuned by repeats of minigene DNA vaccine , which suggested the activation of helper T-cell.ELISA showed that the level of IFNγin the 3 days culture of the splenocytes was rela-tively higher in the groups of minigene DNA vaccination than in the control groups ,while IL-4 expression was absent in all groups .The immune response level elicited by three tandem repeats of minigene DNA vaccine pcDNA -triCEA625-667 was superior to that elicited by pcDNA-CEA625-667 ,which showed that any immunogenic inadequacies in minigene presentation can be rectified by linking itself in a string-of-beads vaccine.Conclusion:The haploid vaccine and three tandem repeats of minigene DNA vaccine derived from CEA geneboth can not change the ratio of CD 4+/CD8+but can induce the activation of helper T-cell and skew T -cells toward Th -1 response.The immune response level elicited by three tandem repeats of minigene DNA vaccine was superior to thatelicited by haploid vaccine .