title: Expression of foreign LpxA acyltransferases in Neisseria meningitidis results in modified lipid A with reduced toxicity and retained adjuvant activity.
abstract: A major problem in the development of vaccines against Gram-negative bacteria is the endotoxic -activity of lipopolysaccharide (LPS), which is determined by its lipid A moiety. Nevertheless, LPS would be an interesting vaccine component because of its immune-stimulating properties. In the present study, we have changed the fatty acid composition of Neisseria meningitidis LPS by replacing the lpxA gene of strain H44/76 with the Escherichia coli or Pseudomonas aeruginosa homologue. The majority of the O-linked 3-OH C12 in N. meningitidis lipid A was replaced by 3-OH C14 (strain HA01E) and 3-OH C10 (strain HA25P) respectively. Both strains, but most notably strain HA01E, had reduced amounts of LPS compared with the wild-type strain. In addition, growth was severely impaired for HA01E. The major outer membrane proteins were expressed normally. Outer membrane complexes of both strains normalized on their LPS content showed a 10-fold reduction in their ability to induce tumour necrosis factor (TNF)-alpha. Immunogenicity studies in BALB/c mice revealed that the adjuvant activity of the LPS was not affected. Thus, the replacement of the O-linked fatty acids in meningococcal lipid A results in immunogenic outer membranes with reduced endotoxic activity, more suitable for use in outer membrane vesicle vaccines.
authors.affiliation: Laboratory of Vaccine Research, National Institute of Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, PO Box 1, 3720 BA Bilthoven, The Netherlands. liana.steeghs@rivm.nl
authors.forename: Liana
authors.initials: L
authors.lastname: Steeghs
authors.forename: Mariska
authors.initials: M
authors.lastname: Berns
authors.forename: Jan
authors.initials: J
authors.lastname: ten Hove
authors.forename: Ad
authors.initials: A
authors.lastname: de Jong
authors.forename: Paul
authors.initials: P
authors.lastname: Roholl
authors.forename: Loek
authors.initials: L
authors.lastname: van Alphen
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
authors.forename: Peter
authors.initials: P
authors.lastname: van der Ley
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism*; D000276:Adjuvants, Immunologic / Q000378:metabolism*; D001414:Bacitracin / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D018014:Gene Transfer Techniques; D008050:Lipid A / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D022401:Meningococcal Vaccines / Q000276:immunology; D009345:Neisseria meningitidis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D009675:Novobiocin / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism*; D012293:Rifampin / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D000276:Adjuvants, Immunologic; D005227:Fatty Acids; D008050:Lipid A; D022401:Meningococcal Vaccines; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D001414:Bacitracin; D009675:Novobiocin; D000217:Acyltransferases; C050304:acyl-(acyl-carrier-protein)-UDP-N-acetylglucosamine acyltransferase; D013752:Tetracycline; D012293:Rifampin