Construction of an epitope vector utilising the diphtheria toxin B-subunit

An immunogenic loop within the diphtheria toxin has been deleted from the B-subunit by a modification of the inverse polymerase chain reaction (IPCR) and replaced by a unique restriction endonuclease site. An oligonucleotide encoding an identified epitope sequence from the major outer membrane protein of Neisseria meningitidis of similar size and structure to that deleted has been introduced into the restriction site. Expression of the resulting chimeric B-subunit from Escherichia coli yielded a protein that was recognised by a panel of antibodies specific for the meningococcal epitope. Initial immunisation data suggest that this protein could elicit an antibody response against both diphtheria toxin and meningococcal proteins.