Antibodies recognizing a variety of different structural motifs on meningococcal Lip antigen fail to demonstrate bactericidal activity

Abstract

The neisserial Lip antigen is a conserved antigen associated with the pathogenic Neisseria species, and is composed of multiple repeats of a consensus pentapeptide. A series of monoclonal antibodies reacting with meningococcal Lip antigen were subjected to epitope mapping, using solid-phase synthetic peptides based on the consensus repeat sequence. The antibodies were found to recognize different continuous epitopes based on the consensus sequence. One monoclonal antibody was utilized in affinity chromatography to obtain purified Lip antigen and the antigen was used for immunization of mice. The resulting antisera did not recognize Lip antigen on Western blots but reacted specifically with Lip antigen in immune precipitation experiments, indicating that the predominant polyclonal immune response was directed against conformational epitopes. Despite the diversity of both continuous and conformational epitopes recognized by the antibodies produced, none of the antibodies demonstrated the ability to promote complement-mediated bactericidal activity. Thus despite its initial apparent promise as a potential vaccine candidate the case for the inclusion of Lip antigen in vaccine formulation cannot be supported at present.

Diversity in coding tandem repeats in related Neisseria spp.

“…No PCR products were generated from the commensal N. lactamica strains, which is consistent with restriction of this gene to the pathogenic species [28]. This protein has not been pursued recenty as a vaccine candidate, probably because antibodies directed against it were poorly bactericidal [29,30]. A second gene within the genomes (NMB1533/NMA1733) contains repeated copies of the AAEAP Lip consensus sequence [31].…”

Current status of meningococcal group B vaccine candidates: capsular or noncapsular?

“…This antigen, initially designated H.8 (25), is a lipoprotein with a molecular mass of 18 to 30 kDa. Antibodies to Lip recognize both continuous and conformational epitopes, but none have the capacity to promote complement-mediated bactericidal activity (26,203).…”

Applying Phage Antibodies to Proteomics: Selecting Single Chain Fv Antibodies to Antigens Blotted on Nitrocellulose

“…Like monoclonal antibodies produced by hybridoma technology, scFv isolated from phage antibody libraries may fail to recognize antigens blotted onto membranes (27). This limits their use as probes for screening cDNA expression libraries (e.g., gt 11) that requires the recognition of epitopes on denatured proteins blotted on membrane (28 -30).…”