Abstract: pBSSB1 is a linear plasmid which mediates the flagellar phase variation in H：z66 positive Salmonella enterica serovar Typhi（S. Typhi）. The gene named p17 is located on pBSSB1 and it encodes the protein P17 whose function is unknown. The p17 deleted mutant of S. Typhi was prepared through the λ-Red recombination system. The growth curves of wild type and p17 mutant strain were detected to compare their growth ability. The motility of wild type and p17 mutant strains was compared through the experiments on the semi-solid LB plates. The specific primers were designed to amplify the gene p17 by PCR. The amplicon was inserted into the expression vector pET28a（+）to construct recombinant vector pET28a（+）-p17, which was then transferred to E. coli BL21（DE3）to be expressed. The recombinant protein P17-His₆ was purified with Ni-TED packed column and was used as immunogen to prepare the rabbit anti-P17 polyclonal antibody. The results showed that p17 deleted mutant of S. Typhi was constructed successfully. It was showed that the growth of p17 mutant strain was significantly slower compared with the wild type strain（P<0.05）. The motility of p17 mutant strain was decreased obviously compared to the wild type strain. The gene p17 of S. Typhi was inserted into the vector pET-28a（+）and was expressed in E. coli BL21（DE3）. The rabbit anti-P17 polyclonal antibody was prepared.

Key words: Salmonella enterica serovar, Typhi Linear plasmid, pBSSB1, p17