Structural basis of the Neisseria meningitidis immunotypes including the L4 and L7 immunotypes

The application of high-resolution 1H, 13C and 31P NMR and MS analyses to the oligosaccharide moieties of the L4 and L7 immunotypes of Neisseria meningitidis revealed that they had the following structures: [formula: see text] The fact that the L7 LPS is not sialylated at O-3 of its terminal beta-D-galactopyranosyl residue implies that it is a mutant strain unable to endogenously sialylate its lacto-N-neotetraose antenna. With the structural elucidation of the L4 and L7 LPS immunotypes, a more comprehensive structural profile of the LPS involved in disease isolates can now be assembled. This provides valuable insights into the structural basis of the N. meningitidis immunotyping system which could be of use in formulating an LPS-based vaccine against meningococcal meningitis.