EXAMPLE 1
All DNA manipulations were performed under standard conditions as described by Sambrook et al. (Sambrook, et al., 1989). Briefly, the FliD gene was amplified by PCR using genomic DNA from H. pylori strain J99 as the template. Following oligonucleotides were used as primers: 5′-CAT ATG GCA ATA GGT TCA TTA A-3′ (SEQ ID NO: 19) and 5′-CTC GAG ATT CTT TTT AGC CGC TGC-3′ (SEQ ID NO: 20). Using this approach a NdeI site was introduced at the 5′-end of forward primers and a XhoI site at 5′-end of the reverse primers. After PCR amplification, the product (2058 bp) was ligated into the pTZ57R/T cloning vector (InsTAclone™ PCR Cloning Kit, MBI Fermentas, Lithuania). Subsequently, the insert was confirmed via PCR and sequencing, and was cloned into a PET-28a(+) expression vector (Qiagen, USA) using NdeI and XhoI restriction enzymes.