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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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Kaplan-Meier plot of different doses of Ag85B-TB10.4 in the guinea pig TB model.(A and B). Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control). For antigen dose we used from 0.1 µg to 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and monitored for weight loss post infection. B. Selected groups from the same experiment.
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pone-0005930-g005: Kaplan-Meier plot of different doses of Ag85B-TB10.4 in the guinea pig TB model.(A and B). Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control). For antigen dose we used from 0.1 µg to 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and monitored for weight loss post infection. B. Selected groups from the same experiment.

Mentions: Having shown that the mouse model was very sensitive to the dose of antigen used for vaccination, we next examined the protective efficacy of Ag85B-TB10.4/IC31® in the guinea pig TB model, and whether a dose dependency would also be observed in this model. Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control) using an antigen dose of 0.1 ,1.0, 10, 20 and 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and survival was monitored (based on weight loss). The results showed that there was no significant difference in survival between adjuvant treated guinea pigs and those receiving 0.1 or 50 µg of vaccine (Fig. 5). However, significant differences (log rank analysis) in survival from that of adjuvant treated animals were observed with doses of 1, 10 (p<0.05) and 20 µg (p<0.005). Taken together, the data suggest that there is a range of doses of Ag85B-TB10.4 (in IC31®) that can be used to significantly prolong the survival of guinea pigs, outside of which, above and below, the vaccine becomes ineffective, and that the guinea pig model is sensitive enough to distinguish these differences. Thus, as observed in the mouse TB model, there was a strict dose dependency regarding the antigen Ag85B-TB10.4, but the optimal dose of Ag85B-TB10.4 also induced significant protection in the guinea pig TB model.


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)

Kaplan-Meier plot of different doses of Ag85B-TB10.4 in the guinea pig TB model.(A and B). Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control). For antigen dose we used from 0.1 µg to 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and monitored for weight loss post infection. B. Selected groups from the same experiment.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2691953&req=5

pone-0005930-g005: Kaplan-Meier plot of different doses of Ag85B-TB10.4 in the guinea pig TB model.(A and B). Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control). For antigen dose we used from 0.1 µg to 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and monitored for weight loss post infection. B. Selected groups from the same experiment.
Mentions: Having shown that the mouse model was very sensitive to the dose of antigen used for vaccination, we next examined the protective efficacy of Ag85B-TB10.4/IC31® in the guinea pig TB model, and whether a dose dependency would also be observed in this model. Groups of 15 animals per group were vaccinated three times with Ag85B-TB10.4 in IC31® or with IC31® alone (as a negative control) using an antigen dose of 0.1 ,1.0, 10, 20 and 50 µg. 10 weeks after the last vaccination the animals were infected via the aerosol route with virulent M. tuberculosis, and survival was monitored (based on weight loss). The results showed that there was no significant difference in survival between adjuvant treated guinea pigs and those receiving 0.1 or 50 µg of vaccine (Fig. 5). However, significant differences (log rank analysis) in survival from that of adjuvant treated animals were observed with doses of 1, 10 (p<0.05) and 20 µg (p<0.005). Taken together, the data suggest that there is a range of doses of Ag85B-TB10.4 (in IC31®) that can be used to significantly prolong the survival of guinea pigs, outside of which, above and below, the vaccine becomes ineffective, and that the guinea pig model is sensitive enough to distinguish these differences. Thus, as observed in the mouse TB model, there was a strict dose dependency regarding the antigen Ag85B-TB10.4, but the optimal dose of Ag85B-TB10.4 also induced significant protection in the guinea pig TB model.

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