OUTER-MEMBRANE VESICLE VACCINES MADE FROM SHORT-CHAIN LIPOPOLYSACCHARIDE MUTANTS OF SEROGROUP-B NEISSERIA-MENINGITIDIS - EFFECT OF THE CARBOHYDRATE CHAIN-LENGTH ON THE IMMUNE-RESPONSE

Outer membrane vesicle (OMV) vaccines were made from Neisseria meningi tidis strain 44/76 and its two short-chain lipopolysaccharide (LPS) mu tants, Mu-1 and Mu-4. Only the 44/76 vaccine contained LPS with the ho st antigen lacto-N-neotetraose, The protein composition of the vaccine s was similar The LPS carbohydrate chain length proved to influence dr astic changes in the LPS immunogenicity as well as the outer membrane proteins (OMPs) ability to elicit functional antibodies in mice, Only LPS in the Mu-1 and Mu-4 vaccines were immunogenic, and the 44/76 vacc ine differed also by not inducing antibodies to the class 4 OMP. The M u-1 vaccine, with a LPS carbohydrate chain comprising only two residue s of 2-keto-3-deoxy-octonic acid induced lower bactericidal activity a nd less antibodies to the class I OMP: compared to the two other vacci nes, This indicates that LPS of a certain carbohydrate chain length is required for adequate exposure of the class 1 OMP epitopes essential for inducing bactericidal antibodies. (C) 1997 Elsevier Science Ltd.