Limits...
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

Colonization of target organs by TMM001 is partially rescued by iron supplementation.Bacterial burden in the lungs (A) and spleen (B) of mice infected with CSM001 and TMM001 grown ± 200 μM FeSO4 at 24, 48 and 72 h post infection. Bars plotted with their SD represent the mean of three independent experiments. Significant differences in colonization at 24 and 48 h were individually ascertained via one-way ANOVA followed by Tukey’s multiple comparisons test. Significant difference in colonization at 72 h was extrapolated by using an unpaired t test with equal SD. ★ p ≤ 0.05, ★★★p ≤ 0.001, ★★★★p ≤ 0.0001, ns = no significance.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4482651&req=5

pntd.0003863.g003: Colonization of target organs by TMM001 is partially rescued by iron supplementation.Bacterial burden in the lungs (A) and spleen (B) of mice infected with CSM001 and TMM001 grown ± 200 μM FeSO4 at 24, 48 and 72 h post infection. Bars plotted with their SD represent the mean of three independent experiments. Significant differences in colonization at 24 and 48 h were individually ascertained via one-way ANOVA followed by Tukey’s multiple comparisons test. Significant difference in colonization at 72 h was extrapolated by using an unpaired t test with equal SD. ★ p ≤ 0.05, ★★★p ≤ 0.001, ★★★★p ≤ 0.0001, ns = no significance.

Mentions: We next enumerated bacterial counts in infected organs to determine the role of TonB in B. mallei’s ability to disseminate and colonize target tissues. BALB/c mice challenged i.n. with 1.5 x 104 CFU of the wild-type CSM001 or TMM011 grown in LBG ± 200 μM FeSO4 were euthanized at 24, 48 and 72 h post challenge. At each time point, the lungs and spleen were processed and plated for CFU quantification. Compared to CSM001, the numbers of TMM001 recovered from the lungs were significantly reduced at 24 h (★ p ≤ .05) and 48 h (★★★★ p ≤ .0001), independent of growth conditions (Fig 3A). A similar trend was observed in the spleen with significantly reduced numbers of TMM001 compared to the CSM001 at 24 h (★ p ≤ .05) and 48 h (★★★ p ≤ .001) (Fig 3B). When grown in LBG + 200μM FeSO4 prior to challenge, TMM001 resembled CSM001, showing no statistical difference in the number of bacteria recovered from the lungs. However, a statistical difference was seen in the recovery of TMM001 grown in FeSO4 in the spleen at 72 h (★ p ≤ .05) (Fig 3A and 3B). BALB/c mice challenged with the CSM001 expired before the 72 h time point and data are not presented.


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)

Colonization of target organs by TMM001 is partially rescued by iron supplementation.Bacterial burden in the lungs (A) and spleen (B) of mice infected with CSM001 and TMM001 grown ± 200 μM FeSO4 at 24, 48 and 72 h post infection. Bars plotted with their SD represent the mean of three independent experiments. Significant differences in colonization at 24 and 48 h were individually ascertained via one-way ANOVA followed by Tukey’s multiple comparisons test. Significant difference in colonization at 72 h was extrapolated by using an unpaired t test with equal SD. ★ p ≤ 0.05, ★★★p ≤ 0.001, ★★★★p ≤ 0.0001, ns = no significance.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0003863.g003: Colonization of target organs by TMM001 is partially rescued by iron supplementation.Bacterial burden in the lungs (A) and spleen (B) of mice infected with CSM001 and TMM001 grown ± 200 μM FeSO4 at 24, 48 and 72 h post infection. Bars plotted with their SD represent the mean of three independent experiments. Significant differences in colonization at 24 and 48 h were individually ascertained via one-way ANOVA followed by Tukey’s multiple comparisons test. Significant difference in colonization at 72 h was extrapolated by using an unpaired t test with equal SD. ★ p ≤ 0.05, ★★★p ≤ 0.001, ★★★★p ≤ 0.0001, ns = no significance.
Mentions: We next enumerated bacterial counts in infected organs to determine the role of TonB in B. mallei’s ability to disseminate and colonize target tissues. BALB/c mice challenged i.n. with 1.5 x 104 CFU of the wild-type CSM001 or TMM011 grown in LBG ± 200 μM FeSO4 were euthanized at 24, 48 and 72 h post challenge. At each time point, the lungs and spleen were processed and plated for CFU quantification. Compared to CSM001, the numbers of TMM001 recovered from the lungs were significantly reduced at 24 h (★ p ≤ .05) and 48 h (★★★★ p ≤ .0001), independent of growth conditions (Fig 3A). A similar trend was observed in the spleen with significantly reduced numbers of TMM001 compared to the CSM001 at 24 h (★ p ≤ .05) and 48 h (★★★ p ≤ .001) (Fig 3B). When grown in LBG + 200μM FeSO4 prior to challenge, TMM001 resembled CSM001, showing no statistical difference in the number of bacteria recovered from the lungs. However, a statistical difference was seen in the recovery of TMM001 grown in FeSO4 in the spleen at 72 h (★ p ≤ .05) (Fig 3A and 3B). BALB/c mice challenged with the CSM001 expired before the 72 h time point and data are not presented.

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