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Vaccination with DNA encoding the immunodominant LACK parasite antigen confers protective immunity to mice infected with Leishmania major.

Gurunathan S, Sacks DL, Brown DR, Reiner SL, Charest H, Glaichenhaus N, Seder RA - J. Exp. Med. (1997)

Bottom Line: We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein.Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12.Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.

View Article: PubMed Central - PubMed

Affiliation: Lymphokine Regulation Unit, Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

ABSTRACT
To determine whether DNA immunization could elicit protective immunity to Leishmania major in susceptible BALB/c mice, cDNA for the cloned Leishmania antigen LACK was inserted into a euykaryotic expression vector downstream to the cytomegalovirus promoter. Susceptible BALB/c mice were then vaccinated subcutaneously with LACK DNA and challenged with L. major promastigotes. We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein. Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12. The immunity conferred by LACK DNA was durable insofar as mice challenged 5 wk after vaccination were still protected, and the infection was controlled for at least 20 wk after challenge. In addition, the ability of mice to control infection at sites distant to the site of vaccination suggests that systemic protection was achieved by LACK DNA vaccination. The control of disease progression and parasitic burden in mice vaccinated with LACK DNA was associated with enhancement of antigen-specific interferon-gamma (IFN-gamma) production. Moreover, both the enhancement of IFN-gamma production and the protective immune response induced by LACK DNA vaccination was IL-12 dependent. Unexpectedly, depletion of CD8(+) T cells at the time of vaccination or infection also abolished the protective response induced by LACK DNA vaccination, suggesting a role for CD8(+) T cells in DNA vaccine induced protection to L. major. Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.

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CD8+ T cells have an important role in mediating protection  induced by LACK DNA vaccination. Mice (n = 10/group) receiving  LACK or control DNA vaccination were treated with anti-CD8 antibody  intraperitoneally starting at the time of vaccination (V) or at the time of  infection (I) and then weekly until 4 wk after infection.
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Figure 9: CD8+ T cells have an important role in mediating protection induced by LACK DNA vaccination. Mice (n = 10/group) receiving LACK or control DNA vaccination were treated with anti-CD8 antibody intraperitoneally starting at the time of vaccination (V) or at the time of infection (I) and then weekly until 4 wk after infection.

Mentions: To assess the mechanism by which LACK DNA vaccination enhanced production of IFN-γ, mice were vaccinated with LACK DNA and treated weekly from the time of initial vaccination until 4 wk after infection with a neutralizing antibody against IL-12. As shown in Fig. 8 A, anti–IL-12 treatment completely abrogated protection. Furthermore, vaccinated mice treated with anti–IL-12 had a striking inhibition of in vitro production of IFN-γ (Fig. 8 B), suggesting that LACK DNA induced protective immunity through IL-12–dependent production of IFN-γ. In addition to the ability of DNA vaccination to enhance Th1 responses, it has also been shown to be a potent inducer of MHC class I–restricted CD8 responses (13–15). Furthermore, because CD8+ T cells typically secrete IFN-γ and have been previously shown to have a role in secondary infection to L. major (36–40), we evaluated the effect of CD8+ T cell depletion at both the time of vaccination and the time of infection. Depletion of CD8+ T cells at the time of vaccination would potentially eliminate an initial source of IFN-γ that may be important in generating a strong Th1 response. Alternatively, by delaying the depletion of CD8+ T cells until the time of infection, we could evaluate the requirement for these cells in the effector phase of the response while allowing for the potential production of IFN-γ from CD8+ T cells up to the time of infection. Surprisingly, anti-CD8 treatment at the time of infection completely abrogated the protective response elicited by immunization with LACK DNA (Fig. 9). These results suggest that CD8+ T cells have a role in mediating an effective immune response during a primary infection from mice vaccinated with LACK DNA.


Vaccination with DNA encoding the immunodominant LACK parasite antigen confers protective immunity to mice infected with Leishmania major.

Gurunathan S, Sacks DL, Brown DR, Reiner SL, Charest H, Glaichenhaus N, Seder RA - J. Exp. Med. (1997)

CD8+ T cells have an important role in mediating protection  induced by LACK DNA vaccination. Mice (n = 10/group) receiving  LACK or control DNA vaccination were treated with anti-CD8 antibody  intraperitoneally starting at the time of vaccination (V) or at the time of  infection (I) and then weekly until 4 wk after infection.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199076&req=5

Figure 9: CD8+ T cells have an important role in mediating protection induced by LACK DNA vaccination. Mice (n = 10/group) receiving LACK or control DNA vaccination were treated with anti-CD8 antibody intraperitoneally starting at the time of vaccination (V) or at the time of infection (I) and then weekly until 4 wk after infection.
Mentions: To assess the mechanism by which LACK DNA vaccination enhanced production of IFN-γ, mice were vaccinated with LACK DNA and treated weekly from the time of initial vaccination until 4 wk after infection with a neutralizing antibody against IL-12. As shown in Fig. 8 A, anti–IL-12 treatment completely abrogated protection. Furthermore, vaccinated mice treated with anti–IL-12 had a striking inhibition of in vitro production of IFN-γ (Fig. 8 B), suggesting that LACK DNA induced protective immunity through IL-12–dependent production of IFN-γ. In addition to the ability of DNA vaccination to enhance Th1 responses, it has also been shown to be a potent inducer of MHC class I–restricted CD8 responses (13–15). Furthermore, because CD8+ T cells typically secrete IFN-γ and have been previously shown to have a role in secondary infection to L. major (36–40), we evaluated the effect of CD8+ T cell depletion at both the time of vaccination and the time of infection. Depletion of CD8+ T cells at the time of vaccination would potentially eliminate an initial source of IFN-γ that may be important in generating a strong Th1 response. Alternatively, by delaying the depletion of CD8+ T cells until the time of infection, we could evaluate the requirement for these cells in the effector phase of the response while allowing for the potential production of IFN-γ from CD8+ T cells up to the time of infection. Surprisingly, anti-CD8 treatment at the time of infection completely abrogated the protective response elicited by immunization with LACK DNA (Fig. 9). These results suggest that CD8+ T cells have a role in mediating an effective immune response during a primary infection from mice vaccinated with LACK DNA.

Bottom Line: We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein.Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12.Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.

View Article: PubMed Central - PubMed

Affiliation: Lymphokine Regulation Unit, Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

ABSTRACT
To determine whether DNA immunization could elicit protective immunity to Leishmania major in susceptible BALB/c mice, cDNA for the cloned Leishmania antigen LACK was inserted into a euykaryotic expression vector downstream to the cytomegalovirus promoter. Susceptible BALB/c mice were then vaccinated subcutaneously with LACK DNA and challenged with L. major promastigotes. We compared the protective efficacy of LACK DNA vaccination with that of recombinant LACK protein in the presence or absence of recombinant interleukin (rIL)-12 protein. Protection induced by LACK DNA was similar to that achieved by LACK protein and rIL-12, but superior to LACK protein without rIL-12. The immunity conferred by LACK DNA was durable insofar as mice challenged 5 wk after vaccination were still protected, and the infection was controlled for at least 20 wk after challenge. In addition, the ability of mice to control infection at sites distant to the site of vaccination suggests that systemic protection was achieved by LACK DNA vaccination. The control of disease progression and parasitic burden in mice vaccinated with LACK DNA was associated with enhancement of antigen-specific interferon-gamma (IFN-gamma) production. Moreover, both the enhancement of IFN-gamma production and the protective immune response induced by LACK DNA vaccination was IL-12 dependent. Unexpectedly, depletion of CD8(+) T cells at the time of vaccination or infection also abolished the protective response induced by LACK DNA vaccination, suggesting a role for CD8(+) T cells in DNA vaccine induced protection to L. major. Thus, DNA immunization may offer an attractive alternative vaccination strategy against intracellular pathogens, as compared with conventional vaccination with antigens combined with adjuvants.

Show MeSH
Related in: MedlinePlus