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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

Ag-specific T cell responses in the lung after boost AdHu5Ag85A immunization in BCG primed mice.Infant and adult mice were BCG immunized, and the AdHu5Ag85A booster vaccine was administered i.n. at 16 weeks post-BCG (A). The mice were sacrificed 4 weeks (B, C, D) or 8 weeks (E, F, G) after boosting. Lung cells were stimulated either with M.tb CF + crude BCG for 24h (open bar), or Ag85A-specific CD4 or CD8 T cell peptide for 6h (black bar), or left unstimulated (B, C, E, F). Cells were stained and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ (B, E) and IFN-γ+CD8+ (C, F) T cells were calculated (unstimulated subtracted from stimulated). Ag85A CD8 peptide tetramer staining was performed on lung cells, and analyzed by flow cytometry (D, G). Absolute numbers of tet+CD8+ T cells were calculated. Results are from one experiment per timepoint, n = 4-5/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ***, p < 0.0005. All other comparisons (not indicated) were not significant.
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pone.0131175.g004: Ag-specific T cell responses in the lung after boost AdHu5Ag85A immunization in BCG primed mice.Infant and adult mice were BCG immunized, and the AdHu5Ag85A booster vaccine was administered i.n. at 16 weeks post-BCG (A). The mice were sacrificed 4 weeks (B, C, D) or 8 weeks (E, F, G) after boosting. Lung cells were stimulated either with M.tb CF + crude BCG for 24h (open bar), or Ag85A-specific CD4 or CD8 T cell peptide for 6h (black bar), or left unstimulated (B, C, E, F). Cells were stained and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ (B, E) and IFN-γ+CD8+ (C, F) T cells were calculated (unstimulated subtracted from stimulated). Ag85A CD8 peptide tetramer staining was performed on lung cells, and analyzed by flow cytometry (D, G). Absolute numbers of tet+CD8+ T cells were calculated. Results are from one experiment per timepoint, n = 4-5/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ***, p < 0.0005. All other comparisons (not indicated) were not significant.

Mentions: Having systematically investigated the nature of immunogenicity following parenteral BCG immunization at different ages as described above, we next set out to examine the effect on AdHu5Ag85A boost immunization. To this end, a group of infant and a group of adult mice were immunized via the parenteral route with BCG (Fig 4A). At 16 weeks post-BCG a set of mice immunized as infants or adults were boosted with AdHu5Ag85A via the intranasal route (BCG/AdHu5Ag85A) (Fig 4A). Another set of mice was left without boosting as controls (BCG). At 4 or 8 weeks post-boost mice were sacrificed and antigen-specific responses in the bronchoalveolar lavage (BAL) and lung were enumerated (Fig 4A). BAL cells were in vitro stimulated with crude-mycobacterial antigens (CF+cBCG) and lung mononuclear cells were stimulated with either CF+cBCG or Ag85A CD4 or CD8 peptides and analyzed for Ag-specific IFN-γ+CD4+ and IFN-γ+CD8+ responses. In addition, lung mononuclear cells were stained for Ag85A CD8 tetramer. Consistent with our previous findings [26, 29] parenteral BCG priming alone did not elicit airway luminal CD4 or CD8 T cell responses in either group (data not shown). On the other hand, intranasal AdHu5Ag85A boosting markedly increased multi-mycobacterial antigen-specific CD4 and CD8 T cells in the airway lumen in both groups at 4 weeks post-boost (Table 1). Although Ag-specific responses contracted, they were sustained in the BAL in both groups at 8 weeks post-boost (Table 1). BCG priming alone induced comparable levels of multi-mycobacterial antigen (CF+cBCG) reactive CD4 (Fig 4B and 4E) and CD8 (Fig 4C and 4F) T cells in the lungs of both groups. In comparison, as expected intranasal AdHu5Ag85A boost significantly increased multi-mycobacterial antigen-specific and Ag85A-specific CD4 T cells (Fig 4B) and Ag85A-specific CD8 T cells (Fig 4C) in the lungs of both groups at 4 weeks post-boost. However, intranasal AdHu5Ag85A boosting in mice BCG immunized as adults resulted in significantly increased multi-mycobacterial antigen-specific CD4 T cells and Ag85A-specific CD4 T cells in the lung compared to mice BCG immunized as infants at 4 weeks post-boost (Fig 4B). Furthermore, at 4 weeks post-boost although boosting enhanced the Ag85A-specific tetramer+ CD8 T cells in both groups of mice, the extent of enhancement was greater in mice BCG immunized as adults compared to mice BCG immunized as infants (Fig 4D). At 8 weeks post-boost the differences in the immune responses found between mice BCG immunized as infants or as adults faded and became comparable (Fig 4E, 4F and 4G). Together these results indicate that respiratory mucosal AdHu5Ag85A boost immunization enhances CD4 and CD8 T cell responses in the lungs of mice BCG immunized as adults to a greater extent than mice immunized as infants.


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)

Ag-specific T cell responses in the lung after boost AdHu5Ag85A immunization in BCG primed mice.Infant and adult mice were BCG immunized, and the AdHu5Ag85A booster vaccine was administered i.n. at 16 weeks post-BCG (A). The mice were sacrificed 4 weeks (B, C, D) or 8 weeks (E, F, G) after boosting. Lung cells were stimulated either with M.tb CF + crude BCG for 24h (open bar), or Ag85A-specific CD4 or CD8 T cell peptide for 6h (black bar), or left unstimulated (B, C, E, F). Cells were stained and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ (B, E) and IFN-γ+CD8+ (C, F) T cells were calculated (unstimulated subtracted from stimulated). Ag85A CD8 peptide tetramer staining was performed on lung cells, and analyzed by flow cytometry (D, G). Absolute numbers of tet+CD8+ T cells were calculated. Results are from one experiment per timepoint, n = 4-5/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ***, p < 0.0005. All other comparisons (not indicated) were not significant.
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Related In: Results  -  Collection

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pone.0131175.g004: Ag-specific T cell responses in the lung after boost AdHu5Ag85A immunization in BCG primed mice.Infant and adult mice were BCG immunized, and the AdHu5Ag85A booster vaccine was administered i.n. at 16 weeks post-BCG (A). The mice were sacrificed 4 weeks (B, C, D) or 8 weeks (E, F, G) after boosting. Lung cells were stimulated either with M.tb CF + crude BCG for 24h (open bar), or Ag85A-specific CD4 or CD8 T cell peptide for 6h (black bar), or left unstimulated (B, C, E, F). Cells were stained and analyzed by flow cytometry. Absolute numbers of IFN-γ+CD4+ (B, E) and IFN-γ+CD8+ (C, F) T cells were calculated (unstimulated subtracted from stimulated). Ag85A CD8 peptide tetramer staining was performed on lung cells, and analyzed by flow cytometry (D, G). Absolute numbers of tet+CD8+ T cells were calculated. Results are from one experiment per timepoint, n = 4-5/group/timepoint. Data are expressed as Mean ± SEM. *, p < 0.05; **, p < 0.005; ***, p < 0.0005. All other comparisons (not indicated) were not significant.
Mentions: Having systematically investigated the nature of immunogenicity following parenteral BCG immunization at different ages as described above, we next set out to examine the effect on AdHu5Ag85A boost immunization. To this end, a group of infant and a group of adult mice were immunized via the parenteral route with BCG (Fig 4A). At 16 weeks post-BCG a set of mice immunized as infants or adults were boosted with AdHu5Ag85A via the intranasal route (BCG/AdHu5Ag85A) (Fig 4A). Another set of mice was left without boosting as controls (BCG). At 4 or 8 weeks post-boost mice were sacrificed and antigen-specific responses in the bronchoalveolar lavage (BAL) and lung were enumerated (Fig 4A). BAL cells were in vitro stimulated with crude-mycobacterial antigens (CF+cBCG) and lung mononuclear cells were stimulated with either CF+cBCG or Ag85A CD4 or CD8 peptides and analyzed for Ag-specific IFN-γ+CD4+ and IFN-γ+CD8+ responses. In addition, lung mononuclear cells were stained for Ag85A CD8 tetramer. Consistent with our previous findings [26, 29] parenteral BCG priming alone did not elicit airway luminal CD4 or CD8 T cell responses in either group (data not shown). On the other hand, intranasal AdHu5Ag85A boosting markedly increased multi-mycobacterial antigen-specific CD4 and CD8 T cells in the airway lumen in both groups at 4 weeks post-boost (Table 1). Although Ag-specific responses contracted, they were sustained in the BAL in both groups at 8 weeks post-boost (Table 1). BCG priming alone induced comparable levels of multi-mycobacterial antigen (CF+cBCG) reactive CD4 (Fig 4B and 4E) and CD8 (Fig 4C and 4F) T cells in the lungs of both groups. In comparison, as expected intranasal AdHu5Ag85A boost significantly increased multi-mycobacterial antigen-specific and Ag85A-specific CD4 T cells (Fig 4B) and Ag85A-specific CD8 T cells (Fig 4C) in the lungs of both groups at 4 weeks post-boost. However, intranasal AdHu5Ag85A boosting in mice BCG immunized as adults resulted in significantly increased multi-mycobacterial antigen-specific CD4 T cells and Ag85A-specific CD4 T cells in the lung compared to mice BCG immunized as infants at 4 weeks post-boost (Fig 4B). Furthermore, at 4 weeks post-boost although boosting enhanced the Ag85A-specific tetramer+ CD8 T cells in both groups of mice, the extent of enhancement was greater in mice BCG immunized as adults compared to mice BCG immunized as infants (Fig 4D). At 8 weeks post-boost the differences in the immune responses found between mice BCG immunized as infants or as adults faded and became comparable (Fig 4E, 4F and 4G). Together these results indicate that respiratory mucosal AdHu5Ag85A boost immunization enhances CD4 and CD8 T cell responses in the lungs of mice BCG immunized as adults to a greater extent than mice immunized as infants.

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