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Age at Mycobacterium bovis BCG Priming Has Limited Impact on Anti-Tuberculosis Immunity Boosted by Respiratory Mucosal AdHu5Ag85A Immunization in a Murine Model.

Damjanovic D, Khera A, Afkhami S, Lai R, Zganiacz A, Jeyanathan M, Xing Z - PLoS ONE (2015)

Bottom Line: Tuberculosis (TB) remains a global pandemic despite the use of Bacillus Calmette-Guérin (BCG) vaccine, partly because BCG fails to effectively control adult pulmonary TB.Our results showed that age at parenteral BCG priming has limited impact on the efficacy of BCG prime-AdHu5Ag85A respiratory mucosal boost immunization-enhanced protection.However, when BCG immunization was delayed until the maturity of the immune system, longer sustained memory T cells were generated and resulted in enhanced boosting effect on T cells of AdHu5Ag85A respiratory mucosal immunization.

View Article: PubMed Central - PubMed

Affiliation: McMaster Immunology Research Centre and Department of Pathology & Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT
Tuberculosis (TB) remains a global pandemic despite the use of Bacillus Calmette-Guérin (BCG) vaccine, partly because BCG fails to effectively control adult pulmonary TB. The introduction of novel boost vaccines such as the human Adenovirus 5-vectored AdHu5Ag85A could improve and prolong the protective immunity of BCG immunization. Age at which BCG immunization is implemented varies greatly worldwide, and research is ongoing to discover the optimal stage during childhood to administer the vaccine, as well as when to boost the immune response with potential novel vaccines. Using a murine model of subcutaneous BCG immunization followed by intranasal AdHu5Ag85A boosting, we investigated the impact of age at BCG immunization on protective efficacy of BCG prime and AdHu5Ag85A boost immunization-mediated protection. Our results showed that age at parenteral BCG priming has limited impact on the efficacy of BCG prime-AdHu5Ag85A respiratory mucosal boost immunization-enhanced protection. However, when BCG immunization was delayed until the maturity of the immune system, longer sustained memory T cells were generated and resulted in enhanced boosting effect on T cells of AdHu5Ag85A respiratory mucosal immunization. Our findings hold implications for the design of new TB immunization protocols for humans.

No MeSH data available.


Related in: MedlinePlus

IFN-γ+CD4+ T cell kinetics in the lung and spleen of infant and adult mice following BCG immunization.Infant and adult mice were immunized s.c. with BCG and sacrificed at 4, 8, or 16 weeks following immunization. Cells from the lung (A) and spleen (B) were isolated and stimulated with mixed M.tb culture filtrate (CF) and crude BCG (cBCG) for 24h or with media only as a control (unstimulated). Cells were stained with extracellular cell markers, followed by intracellular staining for IFN-γ, and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ T cells in the tissues were calculated (unstimulated numbers were subtracted from stimulated), and representative dot plots are shown. Results are from one to two independent experiments per timepoint, n = 4-8/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ****, p < 0.0001.
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pone.0131175.g001: IFN-γ+CD4+ T cell kinetics in the lung and spleen of infant and adult mice following BCG immunization.Infant and adult mice were immunized s.c. with BCG and sacrificed at 4, 8, or 16 weeks following immunization. Cells from the lung (A) and spleen (B) were isolated and stimulated with mixed M.tb culture filtrate (CF) and crude BCG (cBCG) for 24h or with media only as a control (unstimulated). Cells were stained with extracellular cell markers, followed by intracellular staining for IFN-γ, and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ T cells in the tissues were calculated (unstimulated numbers were subtracted from stimulated), and representative dot plots are shown. Results are from one to two independent experiments per timepoint, n = 4-8/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ****, p < 0.0001.

Mentions: Parenteral BCG immunization in adult mice leads to induction of Th1 responses [26, 29]. To begin evaluating the impact of age at BCG immunization on BCG-induced immunity, BALB/c mice were either immunized at 3 weeks of age (infant) or 8 weeks of age (adult). At specified time points post-immunization Ag-specific IFN-γ+CD4+ T cell responses were enumerated by flow cytometry after in vitro stimulation of lung and spleen mononuclear cells with crude mycobacterial antigens (CF+cBCG). Analysis of longitudinal kinetics of Ag-specific responses in the lung revealed that the total number and frequency of Ag-specific IFN-γ+CD4+ T cell responses peaked at 8 weeks and contracted significantly by 16 weeks post-immunization in both groups of mice (Fig 1A). Although BCG immunization in infant and adult mice led to a comparable magnitude of Ag-specific responses at 8 and 16 weeks post-immunization, a significantly increased number of IFN-γ+CD4+ cells was found in the lung at 4 weeks in mice BCG immunized as infants compared to mice immunized as adults (Fig 1A). Unlike in the lung, longitudinal kinetics of Ag-specific responses in the spleen varied between the two groups. While Ag-specific responses in the spleens of mice immunized as infants peaked at 8 weeks post-immunization, responses in mice immunized as adults reached the highest magnitude by 4 weeks (Fig 1B). Of note, although over time in mice immunized as adults the Ag-specific responses significantly contracted by 16 weeks post-immunization, in mice immunized as infants these responses did not contract by 16 weeks (Fig 1B). Furthermore, in contrast to the lung a significantly increased number of IFN-γ+CD4+ cells was found in the spleen at 4 weeks post-immunization in mice BCG immunized as adults compared to those immunized as infants (Fig 1B). The above data suggest that regardless of age at BCG immunization a strong Th1 response is generated.


Age at Mycobacterium bovis BCG Priming Has Limited Impact on Anti-Tuberculosis Immunity Boosted by Respiratory Mucosal AdHu5Ag85A Immunization in a Murine Model.

Damjanovic D, Khera A, Afkhami S, Lai R, Zganiacz A, Jeyanathan M, Xing Z - PLoS ONE (2015)

IFN-γ+CD4+ T cell kinetics in the lung and spleen of infant and adult mice following BCG immunization.Infant and adult mice were immunized s.c. with BCG and sacrificed at 4, 8, or 16 weeks following immunization. Cells from the lung (A) and spleen (B) were isolated and stimulated with mixed M.tb culture filtrate (CF) and crude BCG (cBCG) for 24h or with media only as a control (unstimulated). Cells were stained with extracellular cell markers, followed by intracellular staining for IFN-γ, and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ T cells in the tissues were calculated (unstimulated numbers were subtracted from stimulated), and representative dot plots are shown. Results are from one to two independent experiments per timepoint, n = 4-8/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ****, p < 0.0001.
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Related In: Results  -  Collection

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pone.0131175.g001: IFN-γ+CD4+ T cell kinetics in the lung and spleen of infant and adult mice following BCG immunization.Infant and adult mice were immunized s.c. with BCG and sacrificed at 4, 8, or 16 weeks following immunization. Cells from the lung (A) and spleen (B) were isolated and stimulated with mixed M.tb culture filtrate (CF) and crude BCG (cBCG) for 24h or with media only as a control (unstimulated). Cells were stained with extracellular cell markers, followed by intracellular staining for IFN-γ, and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ T cells in the tissues were calculated (unstimulated numbers were subtracted from stimulated), and representative dot plots are shown. Results are from one to two independent experiments per timepoint, n = 4-8/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ****, p < 0.0001.
Mentions: Parenteral BCG immunization in adult mice leads to induction of Th1 responses [26, 29]. To begin evaluating the impact of age at BCG immunization on BCG-induced immunity, BALB/c mice were either immunized at 3 weeks of age (infant) or 8 weeks of age (adult). At specified time points post-immunization Ag-specific IFN-γ+CD4+ T cell responses were enumerated by flow cytometry after in vitro stimulation of lung and spleen mononuclear cells with crude mycobacterial antigens (CF+cBCG). Analysis of longitudinal kinetics of Ag-specific responses in the lung revealed that the total number and frequency of Ag-specific IFN-γ+CD4+ T cell responses peaked at 8 weeks and contracted significantly by 16 weeks post-immunization in both groups of mice (Fig 1A). Although BCG immunization in infant and adult mice led to a comparable magnitude of Ag-specific responses at 8 and 16 weeks post-immunization, a significantly increased number of IFN-γ+CD4+ cells was found in the lung at 4 weeks in mice BCG immunized as infants compared to mice immunized as adults (Fig 1A). Unlike in the lung, longitudinal kinetics of Ag-specific responses in the spleen varied between the two groups. While Ag-specific responses in the spleens of mice immunized as infants peaked at 8 weeks post-immunization, responses in mice immunized as adults reached the highest magnitude by 4 weeks (Fig 1B). Of note, although over time in mice immunized as adults the Ag-specific responses significantly contracted by 16 weeks post-immunization, in mice immunized as infants these responses did not contract by 16 weeks (Fig 1B). Furthermore, in contrast to the lung a significantly increased number of IFN-γ+CD4+ cells was found in the spleen at 4 weeks post-immunization in mice BCG immunized as adults compared to those immunized as infants (Fig 1B). The above data suggest that regardless of age at BCG immunization a strong Th1 response is generated.

Bottom Line: Tuberculosis (TB) remains a global pandemic despite the use of Bacillus Calmette-Guérin (BCG) vaccine, partly because BCG fails to effectively control adult pulmonary TB.Our results showed that age at parenteral BCG priming has limited impact on the efficacy of BCG prime-AdHu5Ag85A respiratory mucosal boost immunization-enhanced protection.However, when BCG immunization was delayed until the maturity of the immune system, longer sustained memory T cells were generated and resulted in enhanced boosting effect on T cells of AdHu5Ag85A respiratory mucosal immunization.

View Article: PubMed Central - PubMed

Affiliation: McMaster Immunology Research Centre and Department of Pathology & Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.

ABSTRACT
Tuberculosis (TB) remains a global pandemic despite the use of Bacillus Calmette-Guérin (BCG) vaccine, partly because BCG fails to effectively control adult pulmonary TB. The introduction of novel boost vaccines such as the human Adenovirus 5-vectored AdHu5Ag85A could improve and prolong the protective immunity of BCG immunization. Age at which BCG immunization is implemented varies greatly worldwide, and research is ongoing to discover the optimal stage during childhood to administer the vaccine, as well as when to boost the immune response with potential novel vaccines. Using a murine model of subcutaneous BCG immunization followed by intranasal AdHu5Ag85A boosting, we investigated the impact of age at BCG immunization on protective efficacy of BCG prime and AdHu5Ag85A boost immunization-mediated protection. Our results showed that age at parenteral BCG priming has limited impact on the efficacy of BCG prime-AdHu5Ag85A respiratory mucosal boost immunization-enhanced protection. However, when BCG immunization was delayed until the maturity of the immune system, longer sustained memory T cells were generated and resulted in enhanced boosting effect on T cells of AdHu5Ag85A respiratory mucosal immunization. Our findings hold implications for the design of new TB immunization protocols for humans.

No MeSH data available.


Related in: MedlinePlus