Affiliation:
1. Department of Biochemistry, National University of Singapore, Faculty of Medicine, Singapore 119260
Abstract
ABSTRACT
Burkholderia pseudomallei
, a facultatively intracellular pathogen, is a flagellated and motile gram-negative bacterium and is the causative agent of melioidosis in humans. Flagella are commonly recognized as important virulence determinants expressed by bacterial pathogens since the motility phenotype imparted by these organelles often correlates with the ability of an organism to cause disease. We used a virulent isolate of
B. pseudomallei
, KHW, to construct an isogenic deletion mutant with a mutation in the flagellin gene (
fliC
) by gene replacement transposon mutagenesis. The KHWΔ
fliC
Km mutant was aflagellate and nonmotile in semisolid agar. The isogenic KHWΔ
fliC
Km mutant was not impaired in terms of the ability to invade and replicate in cultured human lung cells compared with the wild type. It was also equally virulent in slow-killing assays involving
Caenorhabditis elegans
, but it was avirulent during intranasal infection of BALB/c mice. Very few bacteria, if any, were isolated from the lungs and spleens of KHWΔ
fliC
Km
-
infected mice. In contrast, the bacterial loads in the lungs and spleens were similar in mice infected with KHW and in mice infected with the complemented mutant, KHWΔ
fliC
Km/pUCP28T
fliC.
Unlike the Syrian hamster or diabetic rat models of infection, the
B. pseudomallei
flagellin was also a virulence factor during intraperitoneal infection of BALB/c mice. In this study, all animals infected with KHWΔ
fliC
Km remained healthy and did not succumb to disease regardless of the route of infection. The flagellum is therefore an important and necessary virulence determinant of
B. pseudomallei
during intranasal and intraperitoneal infection of mice.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
117 articles.
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