of helicobacter dna which was sequenced by the dideoxy chain termination method as known in the art sequenase 2 usb the deduced amino acid sequence seq id no 1 of the nickel binding protein encoded by the cloned dna seq id no 3 is shown in fig1 the cloned dna can be inserted into an expression vector which is then used to transform a host cell e g e coli to produce recombinant nickel binding protein expression techniques are well known to those skilled in the art the nickel binding protein or antigenic fragments thereof can be used to produce antibodies using conventional techniques if antigenic fragments are to be used they can be made using similar recombinant techniques as above by inserting only the portion of dna 24 or more nucleotides encoding the amino acids of interest into a vector e g prior to transformation of competent bacterial cells alternatively the entire protein whether recombinant or wild type can be digested with specific proteases to obtain antigenic fragments of 8 or more amino acids antisera can be generated by using either recombinant or wild type purified protein as an immunogen according to methods well known in the art antisera are collected and screened for specificity using known methods naturally occurring antisera have been collected from human patients infected with h pylori and antibodies to the nickel binding protein of the invention have been isolated following the methods of hall.