Construction and screening of antigen epitopes on Acinetobacter baumannii outer membrane protein 33×103-36×103 (OMP33-36) / 中华微生物学和免疫学杂志

ABSTRACT

Objective To screen B and T cell antigen epitopes on Acinetobacter baumannii outer membrane protein 33×103-36×103 (OMP33-36).Methods B and T cell epitopes on OMP33-36 of Acinetobacter baumannii were predicted by bioinformatics methods and synthesized.Recombinant expression plasmid pET-30a-OMP33-36 was cloned and used to express OMP33-36 in a prokaryotic expression system.The expressed OMP33-36 was used to immunize BALB/c mice after purification.Serum sample was collected from each mouse in immunization and negative control groups, and then analyzed by indirect ELISA with synthesized peptides to identify B cell epitopes.Splenocytes were separated from every mouse and then cultured with each of the synthesized peptides, respectively.Double sandwich ELISA was performed to detect IFN-γ secretion in the supernatant of cell cultures for screening of T cell epitopes.Results Candidates of B and T cell epitopes were constructed, which were PB1, PB2, PB3, PT1, PT2 and PT3.Results of the indirect ELISA showed that peptides PB1 and PB2 reacted with the serum samples collected from immunized mice and A450 values of the immunization group were significant higher than those of the negative control group.Compared with the negative control group, enhanced secretion of IFN-γ following peptide PT3 stimulation was observed in the immunization group as indicated by the double sandwich ELISA.Conclusion Two B cell epitopes PB1 and PB2, and one T cell epitope PT3 on the OMP33-36 of Acinetobacter baumannii were successfully constructed and screened out.