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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.In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected.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

Attenuated virulence of TMM001 is partially rescued by iron supplementation.Mice (n = 8) were challenged i.n. with 1.5 x 105 CFU (solid circle/open circle), 1.5 x 106 CFU (solid square/open square) or 1.5 x 107 CFU (solid triangle/open triangle) of TMM001 grown in LBG with (open) or without (closed) 200 μM FeSO4. The statistical significance of differences in survival times was determined by plotting Kaplan-Meier curves, followed by a log rank test. ★★★★ p ≤ 0.0001.
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pntd.0003863.g002: Attenuated virulence of TMM001 is partially rescued by iron supplementation.Mice (n = 8) were challenged i.n. with 1.5 x 105 CFU (solid circle/open circle), 1.5 x 106 CFU (solid square/open square) or 1.5 x 107 CFU (solid triangle/open triangle) of TMM001 grown in LBG with (open) or without (closed) 200 μM FeSO4. The statistical significance of differences in survival times was determined by plotting Kaplan-Meier curves, followed by a log rank test. ★★★★ p ≤ 0.0001.

Mentions: In previous characterization studies of our acute respiratory murine inhalational glanders model, we observed that the 50% lethal dose using B. mallei strain ATCC 23344 was 7.4 x 104 CFU/50 μL (Torres lab experimental data). To establish the role of tonB in B. mallei virulence, we challenged BALB/c mice intranasally (i.n.) with 1.5 x 105 CFU, 1.5 x 106 CFU and 1.5 x 107 CFU of TMM001 grown in LBG ± 200 μM FeSO4 and monitored them for survival up to day 14. The Kaplan-Meier curve shows an inverse correlation between the dose and/or iron concentration and the mouse survival rate (Fig 2). Despite growth conditions, all BALB/c mice challenged with 1.5 x 107 CFU of TMM001 succumbed to infection by 4 days post challenge. At lower doses, the effect of supplementing TMM001 with 200 μM FeSO4 on survival was still apparent. At day 14, survival increased from 62.5% to 100% and 0% to 12.5% when BALB/c mice received a challenge dose of 1.5 x 105 CFU and 1.5 x 106 CFU of the TMM001, respectively, which was grown in LBG alone.


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)

Attenuated virulence of TMM001 is partially rescued by iron supplementation.Mice (n = 8) were challenged i.n. with 1.5 x 105 CFU (solid circle/open circle), 1.5 x 106 CFU (solid square/open square) or 1.5 x 107 CFU (solid triangle/open triangle) of TMM001 grown in LBG with (open) or without (closed) 200 μM FeSO4. The statistical significance of differences in survival times was determined by plotting Kaplan-Meier curves, followed by a log rank test. ★★★★ p ≤ 0.0001.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0003863.g002: Attenuated virulence of TMM001 is partially rescued by iron supplementation.Mice (n = 8) were challenged i.n. with 1.5 x 105 CFU (solid circle/open circle), 1.5 x 106 CFU (solid square/open square) or 1.5 x 107 CFU (solid triangle/open triangle) of TMM001 grown in LBG with (open) or without (closed) 200 μM FeSO4. The statistical significance of differences in survival times was determined by plotting Kaplan-Meier curves, followed by a log rank test. ★★★★ p ≤ 0.0001.
Mentions: In previous characterization studies of our acute respiratory murine inhalational glanders model, we observed that the 50% lethal dose using B. mallei strain ATCC 23344 was 7.4 x 104 CFU/50 μL (Torres lab experimental data). To establish the role of tonB in B. mallei virulence, we challenged BALB/c mice intranasally (i.n.) with 1.5 x 105 CFU, 1.5 x 106 CFU and 1.5 x 107 CFU of TMM001 grown in LBG ± 200 μM FeSO4 and monitored them for survival up to day 14. The Kaplan-Meier curve shows an inverse correlation between the dose and/or iron concentration and the mouse survival rate (Fig 2). Despite growth conditions, all BALB/c mice challenged with 1.5 x 107 CFU of TMM001 succumbed to infection by 4 days post challenge. At lower doses, the effect of supplementing TMM001 with 200 μM FeSO4 on survival was still apparent. At day 14, survival increased from 62.5% to 100% and 0% to 12.5% when BALB/c mice received a challenge dose of 1.5 x 105 CFU and 1.5 x 106 CFU of the TMM001, respectively, which was grown in LBG alone.

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.In a cross-protection study of acute inhalational melioidosis with B. pseudomallei, TMM001-treated mice were significantly protected.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