title: Smooth lipopolysaccharide is the major protective antigen for mice in the surface extract from IATS serotype 6 contributing to the polyvalent Pseudomonas aeruginosa vaccine PEV.
abstract: The nature of the protective antigen in one of the sixteen monovalent extracts (viz., extract-6) contributing to the pseudomonas polyvalent extract vaccine (PEV) was studied in a mouse challenge assay. Selective removal, by filtration through Sep-Pak C18 cartridges, of two major protein antigens with molecular weights of 16,200 and 21,000 had no effect on the protection afforded by extract-6. When analyzed on the basis of 2-keto-3-deoxyoctonate, lipopolysaccharide (LPS) purified by hot phenol extraction (LPS-A) from Pseudomonas aeruginosa (International Antigenic Typing System serotype 6) could account in full for the protective capacity of extract-6. Comparative analysis of LPS heterogeneity by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining indicated that both extract-6 and LPS-A possessed similar spectra of smooth LPS molecules, containing between 10 and approximately equal to 50 O-antigen repeating units. Differences in the profiles of heterogeneity displayed by LPS in LPS-A and extract-6 were restricted to molecular species with short O-antigen chains. Subfractionation of LPS molecules on the basis of number of O-antigen repeating units was achieved by gel filtration in the presence of deoxycholate. Protection experiments performed on the subfractionated species of LPS-A revealed a relationship between O-antigen chain length and protective capacity; molecules with over 18 O-antigen repeating units being 50 to 100 times more protective than those with zero-two repeating units. The results indicate that most of the protection afforded by LPS-A and extract-6 can be accounted for by LPS molecules possessing extended (10 or more) O-antigen repeating units.
authors.forename: S
authors.initials: S
authors.lastname: MacIntyre
authors.forename: R
authors.initials: R
authors.lastname: Lucken
authors.forename: P
authors.initials: P
authors.lastname: Owen
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology* / Q000302:isolation & purification; D001428:Bacterial Vaccines / Q000276:immunology*; D005260:Female; D008070:Lipopolysaccharides / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D011552:Pseudomonas Infections / Q000517:prevention & control; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D014611:Vaccination
chemical_list: D000942:Antigens, Bacterial; D001428:Bacterial Vaccines; D008070:Lipopolysaccharides