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Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development.

Mott TM, Vijayakumar S, Sbrana E, Endsley JJ, Torres AG - PLoS Negl Trop Dis (2015)

Bottom Line: At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls.At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001.Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America.

ABSTRACT

Background: In this study, a Burkholderia mallei tonB mutant (TMM001) deficient in iron acquisition was constructed, characterized, and evaluated for its protective properties in acute inhalational infection models of murine glanders and melioidosis.

Methodology/principal findings: Compared to the wild-type, TMM001 exhibits slower growth kinetics, siderophore hyper-secretion and the inability to utilize heme-containing proteins as iron sources. A series of animal challenge studies showed an inverse correlation between the percentage of survival in BALB/c mice and iron-dependent TMM001 growth. Upon evaluation of TMM001 as a potential protective strain against infection, we found 100% survival following B. mallei CSM001 challenge of mice previously receiving 1.5 x 10(4) CFU of TMM001. At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls. At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001. In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected. While wild type was cleared in all B. mallei challenge studies, mice failed to clear TMM001.

Conclusions/significance: Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

No MeSH data available.


Related in: MedlinePlus

TMM001 attenuated growth kinetics is partially rescued by iron supplementation.Overnight cultures of wild type (solid square) and TMM001 (solid circle) were diluted 1:100 in 50 mL of Luria broth with 4% glycerol (LBG). An additional overnight culture of TMM001 (solid triangle) was diluted 1:100 in 50 mL of LBG + 200 μM FeSO4. At the indicated time points, optical densities at 600 nm of all strains were measured. The average with their SD is representative of three independent experiments. Statistical significance was determined by Dunnett’s test of multiple comparisons relative to wild-type. ★★ p ≤ 0.001, ★★★ p ≤ 0.0001, ★★★★ p ≤ 0.0001.
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pntd.0003863.g001: TMM001 attenuated growth kinetics is partially rescued by iron supplementation.Overnight cultures of wild type (solid square) and TMM001 (solid circle) were diluted 1:100 in 50 mL of Luria broth with 4% glycerol (LBG). An additional overnight culture of TMM001 (solid triangle) was diluted 1:100 in 50 mL of LBG + 200 μM FeSO4. At the indicated time points, optical densities at 600 nm of all strains were measured. The average with their SD is representative of three independent experiments. Statistical significance was determined by Dunnett’s test of multiple comparisons relative to wild-type. ★★ p ≤ 0.001, ★★★ p ≤ 0.0001, ★★★★ p ≤ 0.0001.

Mentions: To determine the effect of the tonB deletion on growth rate and iron requirement, growth curves were performed with the following strains and broth conditions: wild type in LBG, TMM001 in LBG ± 200 μM FeSO4 (Fig 1). When grown in LBG, TMM001 exhibited a reduced growth rate, displaying a longer lag phase, compared to that of the wild type. When grown in LBG + 200 μM FeSO4, the growth rate of the TMM001 increased substantially approaching that of the wild type. Notably, TMM001 grown in iron-supplemented media maintained wild-type growth rates showing statistically significant differences only after 25h of growth.


Characterization of the Burkholderia mallei tonB Mutant and Its Potential as a Backbone Strain for Vaccine Development.

Mott TM, Vijayakumar S, Sbrana E, Endsley JJ, Torres AG - PLoS Negl Trop Dis (2015)

TMM001 attenuated growth kinetics is partially rescued by iron supplementation.Overnight cultures of wild type (solid square) and TMM001 (solid circle) were diluted 1:100 in 50 mL of Luria broth with 4% glycerol (LBG). An additional overnight culture of TMM001 (solid triangle) was diluted 1:100 in 50 mL of LBG + 200 μM FeSO4. At the indicated time points, optical densities at 600 nm of all strains were measured. The average with their SD is representative of three independent experiments. Statistical significance was determined by Dunnett’s test of multiple comparisons relative to wild-type. ★★ p ≤ 0.001, ★★★ p ≤ 0.0001, ★★★★ p ≤ 0.0001.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482651&req=5

pntd.0003863.g001: TMM001 attenuated growth kinetics is partially rescued by iron supplementation.Overnight cultures of wild type (solid square) and TMM001 (solid circle) were diluted 1:100 in 50 mL of Luria broth with 4% glycerol (LBG). An additional overnight culture of TMM001 (solid triangle) was diluted 1:100 in 50 mL of LBG + 200 μM FeSO4. At the indicated time points, optical densities at 600 nm of all strains were measured. The average with their SD is representative of three independent experiments. Statistical significance was determined by Dunnett’s test of multiple comparisons relative to wild-type. ★★ p ≤ 0.001, ★★★ p ≤ 0.0001, ★★★★ p ≤ 0.0001.
Mentions: To determine the effect of the tonB deletion on growth rate and iron requirement, growth curves were performed with the following strains and broth conditions: wild type in LBG, TMM001 in LBG ± 200 μM FeSO4 (Fig 1). When grown in LBG, TMM001 exhibited a reduced growth rate, displaying a longer lag phase, compared to that of the wild type. When grown in LBG + 200 μM FeSO4, the growth rate of the TMM001 increased substantially approaching that of the wild type. Notably, TMM001 grown in iron-supplemented media maintained wild-type growth rates showing statistically significant differences only after 25h of growth.

Bottom Line: At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls.At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001.Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America.

ABSTRACT

Background: In this study, a Burkholderia mallei tonB mutant (TMM001) deficient in iron acquisition was constructed, characterized, and evaluated for its protective properties in acute inhalational infection models of murine glanders and melioidosis.

Methodology/principal findings: Compared to the wild-type, TMM001 exhibits slower growth kinetics, siderophore hyper-secretion and the inability to utilize heme-containing proteins as iron sources. A series of animal challenge studies showed an inverse correlation between the percentage of survival in BALB/c mice and iron-dependent TMM001 growth. Upon evaluation of TMM001 as a potential protective strain against infection, we found 100% survival following B. mallei CSM001 challenge of mice previously receiving 1.5 x 10(4) CFU of TMM001. At 21 days post-immunization, TMM001-treated animals showed significantly higher levels of B. mallei-specific IgG1, IgG2a and IgM when compared to PBS-treated controls. At 48 h post-challenge, PBS-treated controls exhibited higher levels of serum inflammatory cytokines and more severe pathological damage to target organs compared to animals receiving TMM001. In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected. While wild type was cleared in all B. mallei challenge studies, mice failed to clear TMM001.

Conclusions/significance: Although further work is needed to prevent chronic infection by TMM001 while maintaining immunogenicity, our attenuated strain demonstrates great potential as a backbone strain for future vaccine development against both glanders and melioidosis.

No MeSH data available.


Related in: MedlinePlus