ObjectiveTo obtain recombinant H.pylori adhesin A(rHpaA)by molecular cloning,protein expression and purification,immunize BALB/c mice to prepare anti-HpaA polyclonal antibody,and analyze its antibody specificity.MethodsThe three-dimensional structure and antigenic properties of rHpaA were analyzed by bioinformatics softwares such as Phyre2 and DNAstar;Adhesin HpaA gene was obtained by PAS(PCR-based accurate synthesis)and inserted into plasmid pCzn1.The prepared recombinant plasmid pCzn1-rHpaA was transformed to E.coli Artic Express(DE3),induced by IPTG and purified by Ni-IDA affinity chromatography to obtain rHpaA protein,which was identified for reactivity by Western blot.Six male BALB/c mice were immunized with rHpaA plus Freund's adjuvant to prepare anti-HpaA polyclonal anti-body,and the antibody specificity was identified by ELISA.ResultsrHpaA showed good three-dimensional structure and antigenic properties.Restriction analysis and gene sequencing showed that the recombinant plasmid pCzn1-rHpaA contained completely correct HpaA gene sequence.The recombinant strain pCzn1-rHpaA/Arctic Express expressed the soluble target protein rHpaA,which accounted for about 68.3% of total protein in the supernatant,with a purity of 98.1%.rHpaA bound to anti-His antibodies and anti-H.pylori antibodies;The anti-HpaA polyclonal antibody specifically recognized rHpaA and H.pylori lysates.ConclusionrHpaA protein with high purity can be obtained by induction at low temperature and purification.The prepared anti-HpaA polyclonal antibody had good specificity,which laid an experimental foundation of the development of H.pylori-related diagnostic reagents.