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Characterization of BPSS1521 (bprD), a regulator of Burkholderia pseudomallei virulence gene expression in the mouse model.

Chirakul S, Bartpho T, Wongsurawat T, Taweechaisupapong S, Karoonutaisiri N, Talaat AM, Wongratanacheewin S, Ernst RK, Sermswan RW - PLoS ONE (2014)

Bottom Line: Severity of the disease is thought to be dependent on both the health status of the host, including diabetes mellitus and kidney disease, and bacterial-derived factors.One striking observation was the increased expression of BPSS1520 (bprC), located downstream of bprD, in the bprD mutant.BprC is a regulator of T6SS-1 that is required for the virulence of B. pseudomallei in murine infection models.

View Article: PubMed Central - PubMed

Affiliation: Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand; Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.

ABSTRACT
The Gram-negative saprophytic bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a severe infectious disease of both humans and animals. Severity of the disease is thought to be dependent on both the health status of the host, including diabetes mellitus and kidney disease, and bacterial-derived factors. To identify the bacterial factors important during an acute infection, gene expression profiles in the spleen, lung, and liver of BALB/c (Th2 prototype) and C57BL/6 mice (Th1 prototype) were determined using DNA microarrays. This analysis identified BPSS1521 (bprD), a predicted transcriptional regulator located in the type III secretion system (T3SS-3) operon, to be up regulated, specifically in C57BL/6 mice. BALB/c mice infected with a bprD mutant showed a shorter time to death and increased inflammation, as determined by histopathological analysis and enumeration of bacteria in the spleen. Elevated numbers of multinucleated giant cells (MNGCs), which is the hallmark of melioidosis, were detected in both the wild-type and the bprD mutants; a similar elevation occurs in melioidosis patients. One striking observation was the increased expression of BPSS1520 (bprC), located downstream of bprD, in the bprD mutant. BprC is a regulator of T6SS-1 that is required for the virulence of B. pseudomallei in murine infection models. Deletion of bprD led to the overexpression of bprC and a decreased time to death. bprD expression was elevated in C57BL/6--as compared to BALB/c--mice, suggesting a role for BprD in the natural resistance of C57BL/6 mice to B. pseudomallei. Ultimately, this analysis using mice with different immune backgrounds may enhance our understanding of the outcomes of infection in a variety of models.

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Fold changes in gene expression in the B. pseudomallei K96243 wild-type and bprD-mutant strains.The fold changes in expression in the B. pseudomallei K96243 wild-type (▪) and bprD-mutant (□) strains of the BPSS1520 (bprC) (A), BPSS1496 (tssA) (B), BPSS1497 (tssB) (C), and BPSS1498 (hcp1) (D) genes at mid-logarithmic phase in LB medium were measured by qRT-PCR. The bars indicate means ± standard error of two experiments; * significant difference.
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pone-0104313-g003: Fold changes in gene expression in the B. pseudomallei K96243 wild-type and bprD-mutant strains.The fold changes in expression in the B. pseudomallei K96243 wild-type (▪) and bprD-mutant (□) strains of the BPSS1520 (bprC) (A), BPSS1496 (tssA) (B), BPSS1497 (tssB) (C), and BPSS1498 (hcp1) (D) genes at mid-logarithmic phase in LB medium were measured by qRT-PCR. The bars indicate means ± standard error of two experiments; * significant difference.

Mentions: As BPSS1521 is the second gene in the T3SS-3 operon, whether deletion of this gene altered the expression of the flanking genes, BPSS1520 and BPSS1522, was determined (Figure 2A). Expression levels of the individual genes were assessed using RT-PCR (Figure 2B) and qRT-PCR (data not shown). The results showed that bprD mutation did not affect the expression level of the upstream gene (BPSS1522 - bprB), but altered the expression of the downstream gene (BPSS1520 - bprC) (Figure 2B). BPSS1520 (bprC), an AraC regulator that is required for the expression of T6SS-1, was upregulated in the bprD mutant. To confirm upregulation of BPSS1520 in the bprD mutant strain, the T6SS genes, BPSS1496 (tssA), BPSS1497 (tssB), and BPSS1498 (hcp1), under the control of bprC in vitro[20] were analyzed using qRT-PCR. All T6SS genes were found to be expressed at higher levels in the bprD mutant (Figure 3).


Characterization of BPSS1521 (bprD), a regulator of Burkholderia pseudomallei virulence gene expression in the mouse model.

Chirakul S, Bartpho T, Wongsurawat T, Taweechaisupapong S, Karoonutaisiri N, Talaat AM, Wongratanacheewin S, Ernst RK, Sermswan RW - PLoS ONE (2014)

Fold changes in gene expression in the B. pseudomallei K96243 wild-type and bprD-mutant strains.The fold changes in expression in the B. pseudomallei K96243 wild-type (▪) and bprD-mutant (□) strains of the BPSS1520 (bprC) (A), BPSS1496 (tssA) (B), BPSS1497 (tssB) (C), and BPSS1498 (hcp1) (D) genes at mid-logarithmic phase in LB medium were measured by qRT-PCR. The bars indicate means ± standard error of two experiments; * significant difference.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128674&req=5

pone-0104313-g003: Fold changes in gene expression in the B. pseudomallei K96243 wild-type and bprD-mutant strains.The fold changes in expression in the B. pseudomallei K96243 wild-type (▪) and bprD-mutant (□) strains of the BPSS1520 (bprC) (A), BPSS1496 (tssA) (B), BPSS1497 (tssB) (C), and BPSS1498 (hcp1) (D) genes at mid-logarithmic phase in LB medium were measured by qRT-PCR. The bars indicate means ± standard error of two experiments; * significant difference.
Mentions: As BPSS1521 is the second gene in the T3SS-3 operon, whether deletion of this gene altered the expression of the flanking genes, BPSS1520 and BPSS1522, was determined (Figure 2A). Expression levels of the individual genes were assessed using RT-PCR (Figure 2B) and qRT-PCR (data not shown). The results showed that bprD mutation did not affect the expression level of the upstream gene (BPSS1522 - bprB), but altered the expression of the downstream gene (BPSS1520 - bprC) (Figure 2B). BPSS1520 (bprC), an AraC regulator that is required for the expression of T6SS-1, was upregulated in the bprD mutant. To confirm upregulation of BPSS1520 in the bprD mutant strain, the T6SS genes, BPSS1496 (tssA), BPSS1497 (tssB), and BPSS1498 (hcp1), under the control of bprC in vitro[20] were analyzed using qRT-PCR. All T6SS genes were found to be expressed at higher levels in the bprD mutant (Figure 3).

Bottom Line: Severity of the disease is thought to be dependent on both the health status of the host, including diabetes mellitus and kidney disease, and bacterial-derived factors.One striking observation was the increased expression of BPSS1520 (bprC), located downstream of bprD, in the bprD mutant.BprC is a regulator of T6SS-1 that is required for the virulence of B. pseudomallei in murine infection models.

View Article: PubMed Central - PubMed

Affiliation: Melioidosis Research Center, Khon Kaen University, Khon Kaen, Thailand; Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.

ABSTRACT
The Gram-negative saprophytic bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a severe infectious disease of both humans and animals. Severity of the disease is thought to be dependent on both the health status of the host, including diabetes mellitus and kidney disease, and bacterial-derived factors. To identify the bacterial factors important during an acute infection, gene expression profiles in the spleen, lung, and liver of BALB/c (Th2 prototype) and C57BL/6 mice (Th1 prototype) were determined using DNA microarrays. This analysis identified BPSS1521 (bprD), a predicted transcriptional regulator located in the type III secretion system (T3SS-3) operon, to be up regulated, specifically in C57BL/6 mice. BALB/c mice infected with a bprD mutant showed a shorter time to death and increased inflammation, as determined by histopathological analysis and enumeration of bacteria in the spleen. Elevated numbers of multinucleated giant cells (MNGCs), which is the hallmark of melioidosis, were detected in both the wild-type and the bprD mutants; a similar elevation occurs in melioidosis patients. One striking observation was the increased expression of BPSS1520 (bprC), located downstream of bprD, in the bprD mutant. BprC is a regulator of T6SS-1 that is required for the virulence of B. pseudomallei in murine infection models. Deletion of bprD led to the overexpression of bprC and a decreased time to death. bprD expression was elevated in C57BL/6--as compared to BALB/c--mice, suggesting a role for BprD in the natural resistance of C57BL/6 mice to B. pseudomallei. Ultimately, this analysis using mice with different immune backgrounds may enhance our understanding of the outcomes of infection in a variety of models.

Show MeSH
Related in: MedlinePlus