Comparison of immune response in sheep immunized with DNA vaccine encoding Toxoplasma gondii GRA7 antigen in different adjuvant formulations

Lincoln University, P.O. Box 84, Lincoln 7647, Canterbury, New Zealand.
Experimental Parasitology (Impact Factor: 1.64). 12/2009; 124(4):365-72. DOI: 10.1016/j.exppara.2009.11.015
Source: PubMed


Immunization with plasmid DNA, a relatively novel technique, is a promising vaccination technique. To improve the immune response by DNA vaccination various methods have been used, such as chemical adjuvants or immunomodulatory molecules formulated into microparticles or liposomes. The aim of this research is to evaluate the immune responses of sheep immunized with DNA plasmids encoding Toxoplasma gondii dense granule antigen GRA7 formulated into three different adjuvant formulations. Sixty sheep were injected intramuscularly with the DNA plasmids. Twelve received the liposome-formulated plasmid pVAXIgGRA7, 12 Emulsigen P formulated plasmid pVAXIgGRA7 and 12 Emulsigen D formulated plasmid pVAXIgGRA7. Twelve animals were used as a control and received the vector alone. All the animals were inoculated at week 0, and week 4. Immunization of the sheep with plasmids encoding GRA7, with the different adjuvant formulations, effectively primed the immune response. After the first inoculation, moderate to high antibody responses were observed with the three different adjuvant formulations. A significantly elevated specific IgG2 response was observed in the sheep immunized with liposomes and Emulsigen D as adjuvants. In the group immunized with Emulsigen P as an adjuvant, lower IgG1 and IgG2 antibody levels were developed compared to the other treatment groups. In all the immunized groups, DNA immunization stimulated a IFN-gamma response. No antibody or IFN-gamma responses were detected in the control group immunized with an empty plasmid or not immunized. These results indicate that intramuscular immunization of sheep with a DNA vaccine with the adjuvants liposomes and Emulsigen D induce a significant immune response against T. gondii.

Download full-text


Available from: Józef Kur, Oct 13, 2014
38 Reads
  • Source
    • "In these areas, most adult cattle do not encounter A. marginale infection when immature and are vulnerable to outbreaks with a high mortality rate. This characterizes an area of enzootic instability (GUGLIELMONE, 1995). Even in a stable area, measures for vector control and for reducing contact between calves and vectors may be adopted, thereby fostering the development of an unstable situation with serious consequences. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The protective efficacy of an inactivated vaccine from Anaplasma marginale that was cultured in tick cells (IDE8) for use against bovine anaplasmosis was evaluated. Five calves (Group 1) were inoculated subcutaneously, at 21-day intervals, with three doses of vaccine containing 3 × 10(9) A. marginale initial bodies. Five control calves received saline solution alone (Group 2). Thirty-two days after the final inoculation, all the calves were challenged with approximately 3 × 10(5) erythrocytes infected with A. marginale high-virulence isolate (UFMG2). The Group 1 calves seroconverted 14 days after the second dose of vaccine. After the challenge, all the animals showed patent rickettsemia. There was no significant difference (p > 0.05) between the Group 1 and 2 calves during the incubation period, patency period or convalescence period. All the animals required treatment to prevent death. The results suggest that the inactivated vaccine from A. marginale produced in IDE8 induced seroconversion in calves, but was not effective for preventing anaplasmosis induced by the UFMG2 isolate under the conditions of this experiment.
    Revista brasileira de parasitologia veterinaria = Brazilian journal of veterinary parasitology: Orgao Oficial do Colegio Brasileiro de Parasitologia Veterinaria 06/2012; 21(2):112-7. DOI:10.1590/S1984-29612012000200008 · 0.87 Impact Factor
  • Source
    • "Thus, demonstrating that lipoplex delivery was able to increase the immunogenicity of the candidate vaccines and deliver a stronger or detectable response after a single immunisation. Similar improvements to antibody generation through use of liposomes to deliver DNA vaccines have been reported by Perrie [28] and more recently by Hiszczyńska-Sawicka [29]. The relevance of antibodies for clearance of Brucella remains undetermined at this point. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We have previously demonstrated protective efficacy against B. melitensis using formulations of naked DNA vaccines encoding genes ialB and omp25. The present study was undertaken to further understand the immune response generated by the protective vaccination regimens and to evaluate cationic liposome adsorption as a delivery method to improve vaccine utility. The protective efficacy and immunogenicity of vaccines delivered as four doses of naked DNA, a single dose of naked DNA or a single dose of DNA surface adsorbed to cationic liposomes were compared using the BALB/c murine infection model of B. melitensis. Antigen-specific T cells and antibody responses were compared between the various formulations. The four dose vaccination strategy was confirmed to be protective against B. melitensis challenge. The immune response elicited by the various vaccines was found to be dependent upon both the antigen and the delivery strategy, with the IalB antigen favouring CD4+ T cell priming and Omp25 antigen favouring CD8+. Delivery of the p-ialB construct as a lipoplex improved antibody generation in comparison to the equivalent quantity of naked DNA. Delivery of p-omp25 as a lipoplex altered the profile of responsive T cells from CD8+ to CD4+ dominated. Under these conditions neither candidate delivered by single dose naked DNA or lipoplex vaccination methods was able to produce a robust protective effect. Delivery of the p-omp25 and p-ialB DNA vaccine candidates as a lipoplex was able to enhance antibody production and effect CD4+ T cell priming, but was insufficient to promote protection from a single dose of either vaccine. The enhancement of immunogenicity by lipoplex delivery is a promising step toward improving the practicality of these two candidate vaccines, and suggests that this lipoplex formulation may be of value in situations where improvements to CD4+ responses are required. However, in the case of Brucella vaccine development it is suggested that further modifications to the candidate vaccines and delivery strategies will be required in order to deliver sustained protection.
    Genetic Vaccines and Therapy 07/2010; 8(1):5. DOI:10.1186/1479-0556-8-5 · 2.10 Impact Factor
  • Gastroenterology 04/1995; 108(4). DOI:10.1016/0016-5085(95)23338-5 · 16.72 Impact Factor
Show more