Abstract:To explore the immunoprotection function of Pseudomonas aeruginosa (P. aeruginosa) exotoxin A (ETA) protein, its strain was obtained by approach of molecular clone; ETA was purified by the way of gel slices, and immunized mice was employed to prepare the polyclonal antibody. Antibody titer was 1∶8 000 detected by enzyme-linked immuno sorbent assay(ELISA), and results of western blotting proved that the antiserum had a good specificity; mice specific immune was activated by ETA, and immune protection ratio for mice against P. aeruginosa infection was significant higher than the control group, reached to 50%. Results from ETA homology analysis showed that the homology of gram-negative bacteria was higher than gram-positive bacteria, and P. aeruginosa homology was higher than that of other species analyzed from software of DNAman. Results of phylogenetic analysis showed that the genetic relationship among various P. aeruginosa were higher than that of other bacteria. The specific antibodies produced by ETA immune animals might provide cross protection from the infection of different kinds of P. aeruginosa.