To ensure maximum cross-strain recognition and reactivity, regions of proteins that are conserved between different Neisserial species, serogroups and strains can be used. The invention provides proteins which comprise stretches of amino acid sequence that are shared across the majority of Neisseria , particularly N. meningitidis and N. gonorrhoeae.
1. An isolated protein fragment comprising the amino acid sequence of NKPVILITNVAPGVKEGDVTNVAQLKGVAQNLNNRIDNVDGNARA GIAQAIATAGLVQAYLPGKSMMAIGGGTYRGEAGYAIGYSSISDGG NWIIKGTASGNSRGHFGASASVGYQW (SEQ ID NO:218), provided that said protein fragment is not full length N. meningitidis serogroup B ORF40.
2. The isolated protein fragment of claim 1 consisting of the amino acid sequence of SEQ ID NO:218.