Immunological characterization of the Campylobacter jejuni 72Dz/92 cjaD gene product and its fusion with B subunit of E. coli LT toxin.

Campylobacter jejuni 72Dz/92 cjaD gene, orthologue of C. jejuni NCTC 11168 cj0113, C. jejuni M275 omp18 and C. jejuni ATCC 29428 omp18, has been cloned, sequenced and analysed from the viewpoint of its immunological attributes. Neither the 5' nor 3' fragment of the cjaD encodes protein capable of reacting with anti-Campylobacter antibodies. Several fusions of the cjaD with eltB, which encodes B subunit of the E. coli LT toxin, have been constructed. The hybrid proteins, which differ in respect to their cellular localization, retain the ability to react with GM1 and are recognized by the antibodies specific for both moieties of the proteins. The fusion protein equipped with signal sequence, reveals a stronger affinity to GM1 than its equivalent which is unable to cross the inner membrane. Two recombinant plasmids (pUWM405 expressing both LTB and CjaD proteins and pUWM299 containing cjaD gene fused into 3' end of Escherichia coli eltB gene lacking signal sequence) were introduced into avirulent Salmonella enterica serovar Typhimurium strain where they are stably maintained.