title: Comparative in vivo and in vitro analyses of putative virulence factors of Burkholderia pseudomallei using lipopolysaccharide, capsule and flagellin mutants.
abstract: Burkholderia pseudomallei is a gram-negative bacillus that is the causative agent of melioidosis. We evaluated host-pathogen interaction at different levels using three separate B. pseudomallei mutants generated by insertional inactivation. One of these mutants is defective in the production of the polysaccharide side chains associated with lipopolysaccharide; one does not produce the capsular polysaccharide with the structure -3)-2-O-acetyl-6-deoxy-beta-d-manno-heptopyranose-(1-; and the third mutant does not produce flagellin. We compared the in vivo virulence in BALB/c mice, the in vitro fate of intracellular survival inside human polymorphonuclear cells (PMNs) and macrophages (Mphis) and the susceptibility to killing by 30% normal human serum, reactive nitrogen and oxygen intermediates and antimicrobial peptides with that of their wild-type counterpart. The lipopolysaccharide and capsule mutants demonstrated a marked reduction in virulence for BALB/c mice, but the flagellin mutant was only slightly less virulent than the parent strain. The results from the BALB/c mice experiments correlated with survival in Mphis. The lipopolysaccharide and capsule mutants were also more susceptible to killing by antimicrobial agents. All bacteria were equally susceptible to killing by PMNs. Altogether, the data suggest that lipopolysaccharide and capsule and, to a much lesser extent, flagella, are most likely associated with the virulence of this bacterium and highlight the importance of intracellular killing by PMNs and Mphis in disease pathogenesis.
authors: Department of Microbiology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors: Chanthiwa
authors: C
authors: Wikraiphat
authors: Jaruek
authors: J
authors: Charoensap
authors: Pongsak
authors: P
authors: Utaisincharoen
authors: Surasakdi
authors: S
authors: Wongratanacheewin
authors: Suwimol
authors: S
authors: Taweechaisupapong
authors: Donald E
authors: DE
authors: Woods
authors: Jan G M
authors: JG
authors: Bolscher
authors: Stitaya
authors: S
authors: Sirisinha
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology; D016667:Bacterial Capsules / Q000235:genetics; D001426:Bacterial Proteins / Q000502:physiology*; D001770:Blood Bactericidal Activity; D016957:Burkholderia pseudomallei / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity*; D005408:Flagellin / Q000235:genetics; D055786:Gene Knockout Techniques; D006801:Humans; D008070:Lipopolysaccharides / Q000235:genetics; D008264:Macrophages / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D050296:Microbial Viability; D016254:Mutagenesis, Insertional; D009504:Neutrophils / Q000382:microbiology; D026361:Reactive Nitrogen Species / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000494:pharmacology; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D037521:Virulence Factors; D005408:Flagellin