The type II O-antigenic polysaccharide moiety of Burkholderia pseudomallei lipopolysaccharide is required for serum resistance and virulence

Mol Microbiol. 1998 Dec;30(5):1081-100. doi: 10.1046/j.1365-2958.1998.01139.x.


Melioidosis, an infection caused by the gram-negative bacterial pathogen Burkholderia pseudomallei, is endemic in south-east Asia and northern Australia. Acute septicaemic melioidosis is a major cause of morbidity and mortality, especially in north-east Thailand. B. pseudomallei is highly resistant to the bactericidal activity of normal human serum (NHS), and we have found that B. pseudomallei 1026b multiplies in 10-30% NHS. We developed a simple screen for the identification of serum-sensitive mutants based on this novel phenotype. Approximately 1200 Tn5-OT182 mutants were screened, and three serum-sensitive mutants were identified. The type II O-antigenic polysaccharide (O-PS) moiety of lipopolysaccharide was not present in the serum-sensitive mutants. A representative serum-sensitive mutant, SRM117, was killed by the alternative pathway of complement and was less virulent than 1026b in three animal models of melioidosis. The Tn5-OT182 integrations in the serum-sensitive mutants were physically linked on the B. pseudomallei chromosome, and further genetic analysis of this locus revealed a cluster of 15 genes required for type II O-PS production. The proteins encoded by these genes were similar to proteins involved in bacterial polysaccharide biosynthesis. The results presented here demonstrate that type II O-PS is essential for B. pseudomallei serum resistance and virulence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Acylglycerol-3-Phosphate O-Acyltransferase
  • Acyltransferases
  • Animals
  • Base Sequence
  • Blood Bactericidal Activity*
  • Burkholderia pseudomallei / genetics
  • Burkholderia pseudomallei / pathogenicity*
  • Burkholderia pseudomallei / physiology*
  • Carbohydrate Dehydrogenases
  • Complement System Proteins / immunology
  • Cricetinae
  • DNA, Bacterial
  • Disease Models, Animal
  • Female
  • Genes, Bacterial
  • Guinea Pigs
  • Humans
  • Melioidosis / microbiology
  • Mesocricetus
  • Molecular Sequence Data
  • Multigene Family
  • O Antigens*
  • Rats
  • Rats, Sprague-Dawley
  • Serum Albumin / immunology
  • Structure-Activity Relationship
  • Virulence


  • DNA, Bacterial
  • O Antigens
  • Serum Albumin
  • Complement System Proteins
  • Carbohydrate Dehydrogenases
  • dTDP-4-dehydrorhamnose reductase
  • Acyltransferases
  • 1-Acylglycerol-3-Phosphate O-Acyltransferase

Associated data

  • GENBANK/AF064070