BPSS1504, a cluster 1 type VI secretion gene, is involved in intracellular survival and virulence of Burkholderia pseudomallei

Burkholderia pseudomallei is a Gram-negative rod and the causative agent of melioidosis, an emerging infectious disease of tropical and subtropical areas worldwide. B. pseudomallei harbors a remarkable number of virulence factors, including six type VI secretion systems (T6SS). Using our previously...

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Bibliographic Details
Published in:Infection and immunity 2014-05, Vol.82 (5), p.2006-2015
Main Authors: Hopf, Verena, Göhler, André, Eske-Pogodda, Kristin, Bast, Antje, Steinmetz, Ivo, Breitbach, Katrin
Format: Article
Language:English
Subjects:
Actins - metabolism
Animals
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Burkholderia pseudomallei
Burkholderia pseudomallei - genetics
Burkholderia pseudomallei - metabolism
Burkholderia pseudomallei - pathogenicity
Cellular Microbiology: Pathogen-Host Cell Molecular Interactions
Female
Gene Expression Regulation, Bacterial - physiology
Melioidosis - immunology
Melioidosis - microbiology
Mice
Mice, Inbred BALB C
Mutation
Specific Pathogen-Free Organisms
Virulence
Virulence Factors
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Summary:Burkholderia pseudomallei is a Gram-negative rod and the causative agent of melioidosis, an emerging infectious disease of tropical and subtropical areas worldwide. B. pseudomallei harbors a remarkable number of virulence factors, including six type VI secretion systems (T6SS). Using our previously described plaque assay screening system, we identified a B. pseudomallei transposon mutant defective in the BPSS1504 gene that showed reduced plaque formation. The BPSS1504 locus is encoded within T6SS cluster 1 (T6SS1), which is known to be involved in the pathogenesis of B. pseudomallei in mammalian hosts. For further analysis, a B. pseudomallei BPSS1504 deletion (BpΔBPSS1504) mutant and complemented mutant strain were constructed. B. pseudomallei lacking the BPSS1504 gene was highly attenuated in BALB/c mice, whereas the in vivo virulence of the complemented mutant strain was fully restored to the wild-type level. The BpΔBPSS1504 mutant showed impaired intracellular replication and formation of multinucleated giant cells in macrophages compared with wild-type bacteria, whereas the induction of actin tail formation within host cells was not affected. These observations resembled the phenotype of a mutant lacking hcp1, which is an integral component of the T6SS1 apparatus and is associated with full functionality of the T6SS1. Transcriptional expression of the T6SS components vgrG, tssA, and hcp1, as well as the T6SS regulators virAG, bprC, and bsaN, was not dependent on BPSS1504 expression. However, secretion of Hcp1 was not detectable in the absence of BPSS1504. Thus, BPSS1504 seems to serve as a T6SS component that affects Hcp1 secretion and is therefore involved in the integrity of the T6SS1 apparatus.
ISSN:0019-9567
1098-5522
DOI:10.1128/IAI.01544-14