Erschienen:
American Society for Microbiology, 2014
Erschienen in:
Infection and Immunity, 82 (2014) 5, Seite 2006-2015
Sprache:
Englisch
DOI:
10.1128/iai.01544-14
ISSN:
0019-9567;
1098-5522
Entstehung:
Anmerkungen:
Beschreibung:
ABSTRACT 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 ( Bp Δ BPSS1504 ) 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 Bp Δ BPSS1504 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.