Immunogenicity of recombinant L7/L12 ribosomal protein of Neisseria meningitidis--high prevalence of specific antibodies in humans but limited immunogenicity for T cells.

The rplL gene, coding for ribosomal protein L7/L12 of Neisseria meningitidis was cloned and expressed as a fusion protein. The recombinant protein was used in Western blots and lymphocyte proliferation assays to study the prevalence of specific antibodies in human sera and the immunogenicity for the cellular immune system. Most of the serum samples studied were found to be positive for L7/L12-specific antibodies. A number of peripheral blood mononuclear cell preparations tested displayed activation in lymphocyte proliferation assays. The magnitude of activation (stimulation index) was moderate, and there was no correlation with a history of meningococcal disease. The high prevalence of specific antibodies is explained by the high carriage rate of meningococci in the normal population or cross-reactivity to ribosomal proteins of other bacteria, thus indicating immunogenicity. However, meningococcal L7/L12 does not seem to be a potential T cell antigen.