protective properties of nontoxic recombinant exotoxin a (domain i-ii) against pseudomonas aeruginosa infection

background: antibiotic resistance and the need for long-term treatments especially for chronic infections necessitate the developmentof a vaccine against pseudomonas aeruginosa infection.objectives: in this study, recombinant exotoxin a (domains i and ii), (exoa i-ii) protein was expressed, purifid and its immunologicalcharacteristics were evaluated in a mouse model.materials and methods: the genomic dna was extracted from p. aeruginosa strain pao1. the dna encoding for domains i and ii ofexotoxin a was amplifid by pcr and cloned into the pet22b expression vector. the construct was then transformed into e. coli bl21 andthe protein expression was evaluated by the sds-page method. the ni-nta affity chromatography was used for recombinant proteinpurifiation. mice were then immunized subcutaneously on day 0, 21, 42 and 72 with exotoxin a (domains i, ii). antibody production wasevaluated by the elisa method. the immunized and control group mice were exposed to an approximate 2 × ld50 (7.5 × 107 cfu) of clinicalstrain of mucoid p. aeruginosa.results: sequencing of the cloned gene showed that the sequence of exoa i-ii gene was in accordance with exoa i-ii from p. aeruginosapao1. sds-page analysis indicated the expression of recombinant protein with a molecular weight of 45 kda. vaccination with exoa i-iiproduced a signifiant amount of specifi igg antibodies in mice. also immunization of mice with exoa i-ii increased survival timesagainst intra-peritoneal challenge with an approximate 7.5 × 107 cfu (2 × ld50) of clinical strain of p. aeruginosa.conclusions: results of this study suggested that recombinant exoa i-ii is a highly immunogenic protein which can be used as a newvaccine candidate against p. aeruginosa.