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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

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.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