Limits...
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.

Show MeSH

Related in: MedlinePlus

Photomicrographs of hematoxylin-and-eosin-stained spleens from BALB/c mice infected with B. pseudomallei.The spleens were collected on day 3 from non-infected BALB/c mice (A; ×100) and mice infected with B. pseudomallei (B–F). The spleen of mice infected with the B. pseudomallei K96243 wild-type strain showed multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (arrows in B; ×100). The neutrophils (arrow) and necrotic cells (arrow head) are shown at high magnification (C; ×400). Numerous multinucleated giant cells are observed (arrows in D; ×400). Mice infected with the B. pseudomallei bprD mutant showed multifocal to coalescent pyogranulomatous splenitis (E; ×100). Necrotic areas with neutrophils (arrow) are shown at high magnification (F; ×400).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4128674&req=5

pone-0104313-g005: Photomicrographs of hematoxylin-and-eosin-stained spleens from BALB/c mice infected with B. pseudomallei.The spleens were collected on day 3 from non-infected BALB/c mice (A; ×100) and mice infected with B. pseudomallei (B–F). The spleen of mice infected with the B. pseudomallei K96243 wild-type strain showed multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (arrows in B; ×100). The neutrophils (arrow) and necrotic cells (arrow head) are shown at high magnification (C; ×400). Numerous multinucleated giant cells are observed (arrows in D; ×400). Mice infected with the B. pseudomallei bprD mutant showed multifocal to coalescent pyogranulomatous splenitis (E; ×100). Necrotic areas with neutrophils (arrow) are shown at high magnification (F; ×400).

Mentions: As the number of bacteria in the spleen at 3 days post infection differed significantly between the bprD mutant and the wild-type, a histological analysis of the spleens of infected mice was performed. The results indicated multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (Figure 5B–C). Pathological scores were as follows: 1–4: 0  =  within normal limits; 1 = <25%; 2 = 25–50%; 3 = 50–75%; and 4 = >75% inflammatory cell infiltration and neutrophil abscess formation. The pathological score of spleens collected from mice infected with B. pseudomallei K96243 wild-type was 1.5, whereas that of mice infected with the bprD mutant was 3.0. Normal histology of spleens from non-infected BALB/c mice is shown in Figure 5A. Spleens from mice infected with either the wild-type (Figure 5D) or the bprD mutant displayed multinucleated giant cells. Spleens from mice infected with the bprD mutant showed multifocal areas of granulomatous reactions with necrotic centers (Figure 5E–F). These lesions contained a mixture of macrophages and neutrophils surrounding the central areas, which comprised necrotic cells and nuclear debris. Larger abscesses were found in mice infected with the bprD mutant (Figure 5E) as compared to the wild type (Figure 5B).


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)

Photomicrographs of hematoxylin-and-eosin-stained spleens from BALB/c mice infected with B. pseudomallei.The spleens were collected on day 3 from non-infected BALB/c mice (A; ×100) and mice infected with B. pseudomallei (B–F). The spleen of mice infected with the B. pseudomallei K96243 wild-type strain showed multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (arrows in B; ×100). The neutrophils (arrow) and necrotic cells (arrow head) are shown at high magnification (C; ×400). Numerous multinucleated giant cells are observed (arrows in D; ×400). Mice infected with the B. pseudomallei bprD mutant showed multifocal to coalescent pyogranulomatous splenitis (E; ×100). Necrotic areas with neutrophils (arrow) are shown at high magnification (F; ×400).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0104313-g005: Photomicrographs of hematoxylin-and-eosin-stained spleens from BALB/c mice infected with B. pseudomallei.The spleens were collected on day 3 from non-infected BALB/c mice (A; ×100) and mice infected with B. pseudomallei (B–F). The spleen of mice infected with the B. pseudomallei K96243 wild-type strain showed multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (arrows in B; ×100). The neutrophils (arrow) and necrotic cells (arrow head) are shown at high magnification (C; ×400). Numerous multinucleated giant cells are observed (arrows in D; ×400). Mice infected with the B. pseudomallei bprD mutant showed multifocal to coalescent pyogranulomatous splenitis (E; ×100). Necrotic areas with neutrophils (arrow) are shown at high magnification (F; ×400).
Mentions: As the number of bacteria in the spleen at 3 days post infection differed significantly between the bprD mutant and the wild-type, a histological analysis of the spleens of infected mice was performed. The results indicated multifocal areas of inflammatory cell infiltration and neutrophil abscess formation (Figure 5B–C). Pathological scores were as follows: 1–4: 0  =  within normal limits; 1 = <25%; 2 = 25–50%; 3 = 50–75%; and 4 = >75% inflammatory cell infiltration and neutrophil abscess formation. The pathological score of spleens collected from mice infected with B. pseudomallei K96243 wild-type was 1.5, whereas that of mice infected with the bprD mutant was 3.0. Normal histology of spleens from non-infected BALB/c mice is shown in Figure 5A. Spleens from mice infected with either the wild-type (Figure 5D) or the bprD mutant displayed multinucleated giant cells. Spleens from mice infected with the bprD mutant showed multifocal areas of granulomatous reactions with necrotic centers (Figure 5E–F). These lesions contained a mixture of macrophages and neutrophils surrounding the central areas, which comprised necrotic cells and nuclear debris. Larger abscesses were found in mice infected with the bprD mutant (Figure 5E) as compared to the wild type (Figure 5B).

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