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Protection and polyfunctional T cells induced by Ag85B-TB10.4/IC31 against Mycobacterium tuberculosis is highly dependent on the antigen dose.

Aagaard C, Hoang TT, Izzo A, Billeskov R, Troudt J, Arnett K, Keyser A, Elvang T, Andersen P, Dietrich J - PLoS ONE (2009)

Bottom Line: We found that vaccination with the combination of Ag85B-TB10.4 and IC31 resulted in high numbers of polyfunctional CD4 T cells co-expressing IL-2, IFN-gamma and TNF-alpha.Thus, whereas antigen doses of 5 and 15 microg did not induce significant protection against M.tb, reducing the dose to 0.5 microg selectively increased the number of polyfunctional T cells and induced a strong protection against infection with M.tb.In this model a 2.5 fold increase in the antigen dose reduced the protection against infection with M.tb to the level observed in non-vaccinated animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Disease Immunology, Statens Serum Institute, Copenhagen, Denmark.

ABSTRACT

Background: Previously we have shown that Ag85B-TB10.4 is a highly efficient vaccine against tuberculosis when delivered in a Th1 inducing adjuvant based on cationic liposomes. Another Th1 inducing adjuvant, which has shown a very promising profile in both preclinical and clinical trials, is IC31. In this study, we examined the potential of Ag85B-TB10.4 delivered in the adjuvant IC31 for the ability to induce protection against infection with Mycobacterium tuberculosis. In addition, we examined if the antigen dose could influence the phenotype of the induced T cells.

Methods and findings: We found that vaccination with the combination of Ag85B-TB10.4 and IC31 resulted in high numbers of polyfunctional CD4 T cells co-expressing IL-2, IFN-gamma and TNF-alpha. This correlated with protection against subsequent challenge with M.tb in the mouse TB model. Importantly, our results also showed that both the vaccine induced T cell response, and the protective efficacy, was highly dependent on the antigen dose. Thus, whereas antigen doses of 5 and 15 microg did not induce significant protection against M.tb, reducing the dose to 0.5 microg selectively increased the number of polyfunctional T cells and induced a strong protection against infection with M.tb. The influence of antigen dose was also observed in the guinea pig model of aerosol infection with M.tb. In this model a 2.5 fold increase in the antigen dose reduced the protection against infection with M.tb to the level observed in non-vaccinated animals.

Conclusions/significance: Small changes in the antigen dose can greatly influence the induction of specific T cell subpopulations and the dose is therefore a crucial factor when testing new vaccines. However, the adjuvant IC31 can, with the optimal dose of Ag85B-TB10.4, induce strong protection against Mycobacterium tuberculosis. This vaccine has now entered clinical trials.

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Protective efficacy of different doses of Ag85B-TB10.4 in IC31®.In two independent experiments (A and B) groups of mice were vaccinated with three different doses of H4 formulated in IC31® and compared to saline and BCG vaccinated controls. All groups were challenged by the aerosol route with virulent M.tb ten weeks after the first vaccination. Six weeks post-challenge, all mice were killed and the bacterial burden (CFU) was measured in the lung. In both experiments data are presented as mean values from six animals per group and standard errors of the means are indicated by bars. Statistical comparison among the vaccination groups were done by one-way ANOVA and Tukey's post test. Significant differences are shown. ***: p<0.001, *: p<0.05.
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pone-0005930-g004: Protective efficacy of different doses of Ag85B-TB10.4 in IC31®.In two independent experiments (A and B) groups of mice were vaccinated with three different doses of H4 formulated in IC31® and compared to saline and BCG vaccinated controls. All groups were challenged by the aerosol route with virulent M.tb ten weeks after the first vaccination. Six weeks post-challenge, all mice were killed and the bacterial burden (CFU) was measured in the lung. In both experiments data are presented as mean values from six animals per group and standard errors of the means are indicated by bars. Statistical comparison among the vaccination groups were done by one-way ANOVA and Tukey's post test. Significant differences are shown. ***: p<0.001, *: p<0.05.

Mentions: We next examined the protective efficacy of different doses of Ag85B-TB10.4/IC31®. Mice were vaccinated three times at two weeks interval with Ag85B-TB10.4/IC31® and as a positive control for protection, BCG vaccinated mice were included. Ten weeks after the first vaccination, the mice were challenged by the aerosol route with virulent M. tuberculosis and bacterial numbers were assessed in the lungs six weeks post challenge. As observed with the immunogenicity of the vaccine, the protective efficacy of the vaccine also decreased when vaccination dose was increased from 0.5 µg to 5 or 15 µg (Fig. 4, which show the result of two independent experiments). Thus, mice vaccinated with 0.5 µg Ag85B-TB10.4 in IC31® were found to have 5.0+/−0.2 Log10 CFU in the lungs, which was not significantly different from that observed in BCG vaccinated mice (4.90+/−0.35 Log10 CFU), but significantly reduced (p<0.001) compared to the bacterial numbers in non-vaccinated mice (5.83+/−0.12 Log10 CFU) (Fig. 4A). This was in contrast to mice vaccinated with 5 or 15 µg of Ag85B-TB10.4 in IC31®, in which the bacterial numbers were not significantly different from that found in the lungs of non-vaccinated mice (Fig. 4A). Repeating the experiment led to the same conclusion although the overall bacterial numbers were slightly lower in all the groups (Fig. 4B).


Protection and polyfunctional T cells induced by Ag85B-TB10.4/IC31 against Mycobacterium tuberculosis is highly dependent on the antigen dose.

Aagaard C, Hoang TT, Izzo A, Billeskov R, Troudt J, Arnett K, Keyser A, Elvang T, Andersen P, Dietrich J - PLoS ONE (2009)

Protective efficacy of different doses of Ag85B-TB10.4 in IC31®.In two independent experiments (A and B) groups of mice were vaccinated with three different doses of H4 formulated in IC31® and compared to saline and BCG vaccinated controls. All groups were challenged by the aerosol route with virulent M.tb ten weeks after the first vaccination. Six weeks post-challenge, all mice were killed and the bacterial burden (CFU) was measured in the lung. In both experiments data are presented as mean values from six animals per group and standard errors of the means are indicated by bars. Statistical comparison among the vaccination groups were done by one-way ANOVA and Tukey's post test. Significant differences are shown. ***: p<0.001, *: p<0.05.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2691953&req=5

pone-0005930-g004: Protective efficacy of different doses of Ag85B-TB10.4 in IC31®.In two independent experiments (A and B) groups of mice were vaccinated with three different doses of H4 formulated in IC31® and compared to saline and BCG vaccinated controls. All groups were challenged by the aerosol route with virulent M.tb ten weeks after the first vaccination. Six weeks post-challenge, all mice were killed and the bacterial burden (CFU) was measured in the lung. In both experiments data are presented as mean values from six animals per group and standard errors of the means are indicated by bars. Statistical comparison among the vaccination groups were done by one-way ANOVA and Tukey's post test. Significant differences are shown. ***: p<0.001, *: p<0.05.
Mentions: We next examined the protective efficacy of different doses of Ag85B-TB10.4/IC31®. Mice were vaccinated three times at two weeks interval with Ag85B-TB10.4/IC31® and as a positive control for protection, BCG vaccinated mice were included. Ten weeks after the first vaccination, the mice were challenged by the aerosol route with virulent M. tuberculosis and bacterial numbers were assessed in the lungs six weeks post challenge. As observed with the immunogenicity of the vaccine, the protective efficacy of the vaccine also decreased when vaccination dose was increased from 0.5 µg to 5 or 15 µg (Fig. 4, which show the result of two independent experiments). Thus, mice vaccinated with 0.5 µg Ag85B-TB10.4 in IC31® were found to have 5.0+/−0.2 Log10 CFU in the lungs, which was not significantly different from that observed in BCG vaccinated mice (4.90+/−0.35 Log10 CFU), but significantly reduced (p<0.001) compared to the bacterial numbers in non-vaccinated mice (5.83+/−0.12 Log10 CFU) (Fig. 4A). This was in contrast to mice vaccinated with 5 or 15 µg of Ag85B-TB10.4 in IC31®, in which the bacterial numbers were not significantly different from that found in the lungs of non-vaccinated mice (Fig. 4A). Repeating the experiment led to the same conclusion although the overall bacterial numbers were slightly lower in all the groups (Fig. 4B).

Bottom Line: We found that vaccination with the combination of Ag85B-TB10.4 and IC31 resulted in high numbers of polyfunctional CD4 T cells co-expressing IL-2, IFN-gamma and TNF-alpha.Thus, whereas antigen doses of 5 and 15 microg did not induce significant protection against M.tb, reducing the dose to 0.5 microg selectively increased the number of polyfunctional T cells and induced a strong protection against infection with M.tb.In this model a 2.5 fold increase in the antigen dose reduced the protection against infection with M.tb to the level observed in non-vaccinated animals.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Disease Immunology, Statens Serum Institute, Copenhagen, Denmark.

ABSTRACT

Background: Previously we have shown that Ag85B-TB10.4 is a highly efficient vaccine against tuberculosis when delivered in a Th1 inducing adjuvant based on cationic liposomes. Another Th1 inducing adjuvant, which has shown a very promising profile in both preclinical and clinical trials, is IC31. In this study, we examined the potential of Ag85B-TB10.4 delivered in the adjuvant IC31 for the ability to induce protection against infection with Mycobacterium tuberculosis. In addition, we examined if the antigen dose could influence the phenotype of the induced T cells.

Methods and findings: We found that vaccination with the combination of Ag85B-TB10.4 and IC31 resulted in high numbers of polyfunctional CD4 T cells co-expressing IL-2, IFN-gamma and TNF-alpha. This correlated with protection against subsequent challenge with M.tb in the mouse TB model. Importantly, our results also showed that both the vaccine induced T cell response, and the protective efficacy, was highly dependent on the antigen dose. Thus, whereas antigen doses of 5 and 15 microg did not induce significant protection against M.tb, reducing the dose to 0.5 microg selectively increased the number of polyfunctional T cells and induced a strong protection against infection with M.tb. The influence of antigen dose was also observed in the guinea pig model of aerosol infection with M.tb. In this model a 2.5 fold increase in the antigen dose reduced the protection against infection with M.tb to the level observed in non-vaccinated animals.

Conclusions/significance: Small changes in the antigen dose can greatly influence the induction of specific T cell subpopulations and the dose is therefore a crucial factor when testing new vaccines. However, the adjuvant IC31 can, with the optimal dose of Ag85B-TB10.4, induce strong protection against Mycobacterium tuberculosis. This vaccine has now entered clinical trials.

Show MeSH
Related in: MedlinePlus