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A Modified Bacillus Calmette-Guérin (BCG) Vaccine with Reduced Activity of Antioxidants and Glutamine Synthetase Exhibits Enhanced Protection of Mice despite Diminished in Vivo Persistence.

Shoen CM, DeStefano MS, Hager CC, Tham KT, Braunstein M, Allen AD, Gates HO, Cynamon MH, Kernodle DS - Vaccines (Basel) (2013)

Bottom Line: The modifications included elimination of the oxidative stress sigma factor SigH, elimination of the SecA2 secretion channel, and reductions in the activity of iron co-factored superoxide dismutase and glutamine synthetase.In conclusion, despite reduced persistence in mice a modified BCG vaccine with diminished antioxidants and glutamine synthetase is superior to the parent vaccine in conferring protection against M. tuberculosis.The targeting of multiple immune suppressive factors produced by BCG is a promising strategy for simultaneously improving vaccine safety and effectiveness.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Medical Center, Syracuse, NY 13212, USA. shoenc@cnyrc.org.

ABSTRACT
Early attempts to improve BCG have focused on increasing the expression of prominent antigens and adding recombinant toxins or cytokines to influence antigen presentation. One such modified BCG vaccine candidate has been withdrawn from human clinical trials due to adverse effects. BCG was derived from virulent Mycobacterium bovis and retains much of its capacity for suppressing host immune responses. Accordingly, we have used a different strategy for improving BCG based on reducing its immune suppressive capacity. We made four modifications to BCG Tice to produce 4dBCG and compared it to the parent vaccine in C57Bl/6 mice. The modifications included elimination of the oxidative stress sigma factor SigH, elimination of the SecA2 secretion channel, and reductions in the activity of iron co-factored superoxide dismutase and glutamine synthetase. After IV inoculation of 4dBCG, 95% of vaccine bacilli were eradicated from the spleens of mice within 60 days whereas the titer of BCG Tice was not significantly reduced. Subcutaneous vaccination with 4dBCG produced greater protection than vaccination with BCG against dissemination of an aerosolized challenge of M. tuberculosis to the spleen at 8 weeks post-challenge. At this time, 4dBCG-vaccinated mice also exhibited altered lung histopathology compared to BCG-vaccinated mice and control mice with less well-developed lymphohistiocytic nodules in the lung parenchyma. At 26 weeks post-challenge, 4dBCG-vaccinated mice but not BCG-vaccinated mice had significantly fewer challenge bacilli in the lungs than control mice. In conclusion, despite reduced persistence in mice a modified BCG vaccine with diminished antioxidants and glutamine synthetase is superior to the parent vaccine in conferring protection against M. tuberculosis. The targeting of multiple immune suppressive factors produced by BCG is a promising strategy for simultaneously improving vaccine safety and effectiveness.

No MeSH data available.


Related in: MedlinePlus

Lymphohistiocytic nodules in the lung parenchyma. Mid-power (×10 microscope objective) photomicrographs of regions of lung consolidation within the tissue sections in Figure 4 are displayed at a greater magnification. Most of the areas that stain dark blue in the PBS and BCG groups represent dense collections of lymphocytes within the lung parenchyma that are accompanied by lymphohistiocytic infiltration and consolidation of the alveolar spaces. Examples of these regions are indicated with arrows (black arrowheads) and the white rectangles outline regions of lung tissue that are enlarged further in Figure 6. Lymphoid aggregates were also observed in the lung parenchyma in the 4dBCG group of mice however they were typically smaller with less dense alveolar infiltrate compared to the PBS and BCG groups. The arrows with white arrowheads indicate BALT, which is distinguished from lymphohistiocytic nodules in the lung parenchyma by their association with blood vessels and bronchi.
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vaccines-01-00034-f005: Lymphohistiocytic nodules in the lung parenchyma. Mid-power (×10 microscope objective) photomicrographs of regions of lung consolidation within the tissue sections in Figure 4 are displayed at a greater magnification. Most of the areas that stain dark blue in the PBS and BCG groups represent dense collections of lymphocytes within the lung parenchyma that are accompanied by lymphohistiocytic infiltration and consolidation of the alveolar spaces. Examples of these regions are indicated with arrows (black arrowheads) and the white rectangles outline regions of lung tissue that are enlarged further in Figure 6. Lymphoid aggregates were also observed in the lung parenchyma in the 4dBCG group of mice however they were typically smaller with less dense alveolar infiltrate compared to the PBS and BCG groups. The arrows with white arrowheads indicate BALT, which is distinguished from lymphohistiocytic nodules in the lung parenchyma by their association with blood vessels and bronchi.

Mentions: Titer of M. tuberculosis challenge bacilli in the spleens and left lungs of C57Bl/6 mice. Mice received aerosol challenge with 100 cfu of M. tuberculosis strain Erdman S-1. The whole spleens and left lungs were assessed for cfu titer while the right lungs were processed for histopathology as shown in Figure 4, Figure 5, Figure 6 and Figure 7. The individual data points (circles) and median (bar) for each vaccination arm are shown at 8 weeks (top, six mice per vaccination arm) and 26 weeks (bottom, eight or nine mice per vaccination arm) post-challenge. The dotted lines extend the bar representing the median value of the PBS-vaccinated and BCG-vaccinated groups and are marked P* and P**, respectively. Analysis of spleen and lung results at 8 weeks and lung results at 26 weeks by 1 way ANOVA demonstrated that the median values of the groups varied significantly by Kruskal-Wallis test. The groups were also compared using the Mann-Whitney test and values in the row labeled P* above the panel indicate the comparison of each vaccinated group against the phosphate-buffered saline (PBS) group. The values in the row labeled P** indicate the comparison of the 4dBCG and BCG groups.


A Modified Bacillus Calmette-Guérin (BCG) Vaccine with Reduced Activity of Antioxidants and Glutamine Synthetase Exhibits Enhanced Protection of Mice despite Diminished in Vivo Persistence.

Shoen CM, DeStefano MS, Hager CC, Tham KT, Braunstein M, Allen AD, Gates HO, Cynamon MH, Kernodle DS - Vaccines (Basel) (2013)

Lymphohistiocytic nodules in the lung parenchyma. Mid-power (×10 microscope objective) photomicrographs of regions of lung consolidation within the tissue sections in Figure 4 are displayed at a greater magnification. Most of the areas that stain dark blue in the PBS and BCG groups represent dense collections of lymphocytes within the lung parenchyma that are accompanied by lymphohistiocytic infiltration and consolidation of the alveolar spaces. Examples of these regions are indicated with arrows (black arrowheads) and the white rectangles outline regions of lung tissue that are enlarged further in Figure 6. Lymphoid aggregates were also observed in the lung parenchyma in the 4dBCG group of mice however they were typically smaller with less dense alveolar infiltrate compared to the PBS and BCG groups. The arrows with white arrowheads indicate BALT, which is distinguished from lymphohistiocytic nodules in the lung parenchyma by their association with blood vessels and bronchi.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4552197&req=5

vaccines-01-00034-f005: Lymphohistiocytic nodules in the lung parenchyma. Mid-power (×10 microscope objective) photomicrographs of regions of lung consolidation within the tissue sections in Figure 4 are displayed at a greater magnification. Most of the areas that stain dark blue in the PBS and BCG groups represent dense collections of lymphocytes within the lung parenchyma that are accompanied by lymphohistiocytic infiltration and consolidation of the alveolar spaces. Examples of these regions are indicated with arrows (black arrowheads) and the white rectangles outline regions of lung tissue that are enlarged further in Figure 6. Lymphoid aggregates were also observed in the lung parenchyma in the 4dBCG group of mice however they were typically smaller with less dense alveolar infiltrate compared to the PBS and BCG groups. The arrows with white arrowheads indicate BALT, which is distinguished from lymphohistiocytic nodules in the lung parenchyma by their association with blood vessels and bronchi.
Mentions: Titer of M. tuberculosis challenge bacilli in the spleens and left lungs of C57Bl/6 mice. Mice received aerosol challenge with 100 cfu of M. tuberculosis strain Erdman S-1. The whole spleens and left lungs were assessed for cfu titer while the right lungs were processed for histopathology as shown in Figure 4, Figure 5, Figure 6 and Figure 7. The individual data points (circles) and median (bar) for each vaccination arm are shown at 8 weeks (top, six mice per vaccination arm) and 26 weeks (bottom, eight or nine mice per vaccination arm) post-challenge. The dotted lines extend the bar representing the median value of the PBS-vaccinated and BCG-vaccinated groups and are marked P* and P**, respectively. Analysis of spleen and lung results at 8 weeks and lung results at 26 weeks by 1 way ANOVA demonstrated that the median values of the groups varied significantly by Kruskal-Wallis test. The groups were also compared using the Mann-Whitney test and values in the row labeled P* above the panel indicate the comparison of each vaccinated group against the phosphate-buffered saline (PBS) group. The values in the row labeled P** indicate the comparison of the 4dBCG and BCG groups.

Bottom Line: The modifications included elimination of the oxidative stress sigma factor SigH, elimination of the SecA2 secretion channel, and reductions in the activity of iron co-factored superoxide dismutase and glutamine synthetase.In conclusion, despite reduced persistence in mice a modified BCG vaccine with diminished antioxidants and glutamine synthetase is superior to the parent vaccine in conferring protection against M. tuberculosis.The targeting of multiple immune suppressive factors produced by BCG is a promising strategy for simultaneously improving vaccine safety and effectiveness.

View Article: PubMed Central - PubMed

Affiliation: Veterans Affairs Medical Center, Syracuse, NY 13212, USA. shoenc@cnyrc.org.

ABSTRACT
Early attempts to improve BCG have focused on increasing the expression of prominent antigens and adding recombinant toxins or cytokines to influence antigen presentation. One such modified BCG vaccine candidate has been withdrawn from human clinical trials due to adverse effects. BCG was derived from virulent Mycobacterium bovis and retains much of its capacity for suppressing host immune responses. Accordingly, we have used a different strategy for improving BCG based on reducing its immune suppressive capacity. We made four modifications to BCG Tice to produce 4dBCG and compared it to the parent vaccine in C57Bl/6 mice. The modifications included elimination of the oxidative stress sigma factor SigH, elimination of the SecA2 secretion channel, and reductions in the activity of iron co-factored superoxide dismutase and glutamine synthetase. After IV inoculation of 4dBCG, 95% of vaccine bacilli were eradicated from the spleens of mice within 60 days whereas the titer of BCG Tice was not significantly reduced. Subcutaneous vaccination with 4dBCG produced greater protection than vaccination with BCG against dissemination of an aerosolized challenge of M. tuberculosis to the spleen at 8 weeks post-challenge. At this time, 4dBCG-vaccinated mice also exhibited altered lung histopathology compared to BCG-vaccinated mice and control mice with less well-developed lymphohistiocytic nodules in the lung parenchyma. At 26 weeks post-challenge, 4dBCG-vaccinated mice but not BCG-vaccinated mice had significantly fewer challenge bacilli in the lungs than control mice. In conclusion, despite reduced persistence in mice a modified BCG vaccine with diminished antioxidants and glutamine synthetase is superior to the parent vaccine in conferring protection against M. tuberculosis. The targeting of multiple immune suppressive factors produced by BCG is a promising strategy for simultaneously improving vaccine safety and effectiveness.

No MeSH data available.


Related in: MedlinePlus