Protective Effect Of DNA Vaccine Research Articles

Evaluation of immunogenicity and protective effect of DNA vaccine encoding surface antigen1 (SAG1) of Toxoplasma gondii and TLR-5 ligand as a genetic adjuvant against acute toxoplasmosis in BALB/c mice

AimsToxoplasma gondii is an obligate intracellular, protozoan that causes a high incidence of serious zoonotic parasitic disease in humans. In the present study the immune-protective efficacy of a DNA vaccine encoding SAG1 in combination with a gene sequence encoding FliC of Salmonella typhimurium (Toll-like receptor 5 agonist) was evaluated against acute T. gondii infection in mice. Methods and resultsNinety-nine female inbred BALB/c mice were divided into nine groups of 11 mice and were immunized intramuscularly three times at three-week intervals (days 0, 21 and 42) and challenged with virulent T. gondii RH strain 4 weeks later. The immunization of pVAX1-SAG1 administered with pVAX1-fliC in mice indicated specific humoral responses, with higher IgG antibody titers and a mixed IgG1/IgG2a response than in other groups (with a predominance of IgG2a over IgG2b and IgG1). Also, the cellular immune response elicited high levels of IFN-γ and IL-12 cytokines and low levels of IL-4 production compared to traditional adjuvants. Furthermore, the mice vaccinated with pVAX1-SAG1+pVAX1-fliC survived for slightly longer after the last immunization and challenge with the T. gondii. ConclusionThis investigation indicated that cocktail DNA vaccine encoded SAG1 gene of T. gondii and FliC can protect against acute toxoplasmosis.

Protective effect of DNA vaccine encoding pseudomonas exotoxin A and PcrV against acute pulmonary P. aeruginosa Infection.

Infections with Pseudomonas aeruginosa have been a long-standing challenge for clinical therapy because of complex pathogenesis and resistance to antibiotics, thus attaching importance to explore effective vaccines for prevention and treatment. In the present study, we constructed a novel DNA vaccine by inserting mutated gene toxAm encoding Pseudomonas Exotoxin A and gene pcrV encoding tip protein of the type III secretion system into respective sites of a eukaryotic plasmid pIRES, named pIRES-toxAm-pcrV, and next evaluated the efficacy of the vaccine in murine acute Pseudomonas pneumonia models. Compared to DNA vaccines encoding single antigen, mice vaccinated with pIRES-toxAm-pcrV elicited higher levels of antigen-specific serum immunoglobulin G (IgG), enhanced splenic cell proliferation and cytokine secretion in response to Pseudomonas aeruginosa antigens, additionally PAO1 challenge in mice airway resulted in reduced bacteria burden and milder pathologic changes in lungs. Besides, it was observed that immunogenicity and protection could be promoted by the CpG ODN 1826 adjuvant. Taken together, it’s revealed that recombinant DNA vaccine pIRES-toxAm-pcrV was a potential candidate for immunotherapy of Pseudomonas aeruginosa infection and the CpG ODN 1826 a potent stimulatory adjuvant for DNA vaccination.

Immunogenic and protective effects of a DNA vaccine containing flagellin flaC gene against Vibrio alginolyticus in red snapper(Lutjanus sanguineus)

In order to study the immunogenic and protective effects of DNA vaccine,plasmid DNA encoding flagellin flaC gene(designated as pcDNA-flaC)was used as a DNA vaccine to immunize red snapper(Lutjanus sanguineus).The distribution,expression and immunoprotection of the DNA vaccine were analyzed in tissues of the red snapper by PCR,RT-PCR and challenge test.PCR results indicated that pcDNA-flaC was distributed in liver,spleen,kidney,gill and injection site muscle at 7-28 days after vaccination.RT-PCR results indicated that the flaC gene was expressed in all above tissues of vaccinated fish at 7-28 days after vaccination.These results demonstrated that the DNA vaccine was distributed and flaC gene was expressed in various tissues of vaccinated fish.Red snapper immunized with DNA vaccine showed higher serum antibody levels at 7-28 days after vaccination,compared to fish vaccinated with the control eukaryotic expression vector pcDNA3.1 and PBS.In addition,fish immunized with DNA vaccine developed a protective response to live V.alginolyticus challenge 28 days post-inoculation,as demonstrated by increased survival of vaccinated fish over the control fish.This study indicates that pcDNA-flaC is an effective vaccine candidate against V.alginolyticus infection.

Cloning,expression and DNA vaccine analysis ofOmpWofVibrio harveyiZJ 0607

According to OmpW gene sequence published in GenBank,primers were designed and the DNA fragment of about 645 bp( encoding 214 amino acids) w as amplified by PCR from genomic DNA of Vibrio Harveyi ZJ0607. The full length product w as then cloned into the prokaryotic expression vector pET-32a( +) for protein expression in Escherichia coli strain BL21( DE3). The molecular weight of expression fusion protein OmpW w as about 43. 8 ku. The recombinant protein w as highly expressed under induction conditions of exposure at 37 ℃,in 0. 1 mmol / L of IPTG for 5 h. The recombinant protein w as purified by the best expression condition,purified and used as antigen to immunize the Kunming-mice,and the antibody titer reached 1 ∶ 30 000. The result of the Western-blot revealed that specific antigen-antibody reaction occurred betw een the antiserum and its corresponding recombinant fusion protein. In order to study the immunogenic and protective effects of DNA vaccine,plasmid DNA encoding outer membrane protein OmpW gene w as used as a DNA vaccine to immunize red snapper( Lutjanus sanguineus). PCR results indicated that pcDNA-OmpW w as distributed in muscle,head kidney,liver,spleen 7- 28 days after vaccination. RT-PCR results indicated that the OmpW gene w as expressed in all above tissues of vaccinated fish 7- 28 days after vaccination. Red snapper immunized w ith DNA vaccine show ed higher serum antibody and corresponding recombinant fusion protein by ELISA and Western-blot. In addition,fish immunized w ith DNA vaccine developed a protective response to live Vibrio harveyi challenged 35 days post-inoculation,as demonstrated by increased survival of vaccinated fish over the control fish. This study indicates that pcDNA-OmpW is an effective vaccine candidate against Vibrio harveyi infection.

Protective effect of DNA vaccine with the gene encoding 55kDa antigen fragment against Pneumocystis carinii in mice

Objective To evaluate the protective effect of DNA vaccine with the gene encoding 55kDa antigen fragment of Pneumocystis carinii ( P. carinii) against P. carinii in mice. Methods The fragment of the antigen within p55(p55-582) was cloned. Then recombinant plasmid was constructed based on the eukaryotic expression vector pcDNA3.1(+). BALB/c mice were used as experimental models to examine the immunogenicity of pcDNA3.1(+)−p55-582. ELISA and RT-PCR were used to evaluate the role of this kind of DNA vaccine. Results The results of western blot indicated that the recombinant DNA[pcDNA3.1(+)−p55-582] could be expressed correctly and had antigenicity in transfected COS-7 cells. ELISA and RT-PCR showed that pcDNA3.1(+)−p55-582 elicited antibody production, stimulated lymphocyte proliferation and provided partial protection by reducing the P. carinii burden. Conclusions The data demonstrate that pcDNA3.1(+)−p55-582 might be potent vaccination that can afford the partial protection for the immunized animals.

Protective efficacy of a new fusion anti-caries DNA vaccine encoding antigens of both Streptococcus mutans and Streptococcus sobrinus

To construct a new fusion anti-caries DNA vaccine pGJGAC/VAX encoding antigens of both S. mutans and S. sobrinus so as to enhance the protective effect of DNA vaccine against S. sobrinus infection. The CAT fragment of S. sobrinus OMZ176 gtf-I was amplified by semi-nest PCR and then inserted into the plasmid pGJA-P/VAX to construct the recombinant plasmid pGJGAC/VAX. The CHO cell was transfected and the expression of fusion protein detected using cellular immunohistochemistry and Western blot. Mice were immunized with pGJGAC/VAX and control plasmids via the intramuscular (i.m) or intranasal (i.n) routes. During the experiment, blood and saliva samples were collected at a 2-week interval for antibody assay by ELISA. Rats were orally challenged with S. mutans Ingbritt or S. sobrinus 6715 and then immunized i.n with pGJGAC/VAX, pGJA-P/VAX or pVAX1. The Keyes method was used to determine the caries activity. (1) CAT sequence was identical to the related sequence of gtf-I (OMZ176) in GenBank. The recombinant plasmid pGJGAC/VAX encoded the genes of antigens of both S. mutans and S. sobrinus. The expressed protein could respond to specific anti-PAc, anti-GLU and anti-CAT antibodies respectively. (2) As for antibody reactions, mice in the experiment group had significantly higher levels of anti-PAc, anti-GLU and anti-CAT IgG antibodies than those in the pVAX1 group (P < 0.01). The peak responses of specific anti-CAT antibodies were observed at 8 weeks (GAC/i.m) and 10 weeks (GAC/i.n) and were approximately 62.13 microg/ml and 11.43 microg/ml respectively. The peak responses of specific anti-CAT IgA antibodies were seen at 8 weeks (GAC/i.m) and 10 weeks (GAC/i.n) and were approximately 0.67% and 0.80% respectively. (3) In the group infected with S. mutans or S. sobrinus, the pGJGAC/VAX-immunized rats showed significantly fewer E, Ds and Dm lesions than pVAX1-immunized rats (P < 0.05) and decreased Ds and Dm levels than pGJA-P/VAX-immunized rats (P < 0.05) while there was no obvious difference in E lesions between the two groups (P > 0.05). A new fusion anti-caries DNA vaccine pGJGAC/VAX encoding antigens of both S. mutans and S. sobrinus is constructed successfully and expressed correctly in eukaryotic cells. It induces effective mucosal and systematic humoral responses so as to provide a better protection against S. sobrinus.

Protective effect of DNA vaccine during chemotherapy on reactivation and reinfection of Mycobacterium tuberculosis

Active disease of tuberculosis (TB) can be developed decades later by either a relapse of the initial infection (endogenous reactivation) or by an entrance of the secondary infection (exogenous reinfection), since the current chemotherapy cannot lead to complete elimination of tuberculosis. Although the immunotherapeutic approaches in conjunction with conventional chemotherapy were tried to prevent TB growth via boosting the immune system, their therapeutic effects are still controversial. Here, we found that TB DNA vaccination completely blocked tuberculosis reactivation and significantly prevented from the secondary infection when chemotherapy was combined simultaneously. In particular, double-gene DNA vaccine composed of Ag85A and PstS-3 genes could reduce bacteria growth better than single-gene DNA vaccine after a secondary reinfection, indicating a correlation between the breadth of Th1 IFN-gamma response and the efficacy of the protection from reinfection. Thus, we propose that multigene TB DNA immunotherapy including Ag85A and PstS-3 genes during the period of chemotherapy could benefit patients undergoing TB chemotherapy in prevention from exogenous reinfection as well as endogenous reactivation.