Recombinant outer membrane protein F-B subunit of LT protein as a prophylactic measure against Pseudomonas aeruginosa burn infection in mice

AIM: To study immunogenicity of outer membrane protein F(Opr F) fused with B subunit of LT(LTB), against Pseudomonas aeruginosa(P. aeruginosa). METHODS: The Opr F, a major surface exposed outer membrane protein that is antigenically conserved in various strains of P. aeruginosa, is a promising immunogen against P. aeruginosa. In the present study recombinant Opr F and Opr F-LTB fusion gene was cloned, expressed and purified. BALB/c mice and rabbits were immunized using recombinant Opr F and Opr F-LTB and challenged at the burn site with P. aeruginosa lethal dose of 104 CFU. The protective efficacy of rabbit anti Opr F Ig G against P. aeruginosa burn infection was investigated by passive immunization. RESULTS: It has been well established that the LTB is a powerful immunomodulator with strong adjuvant activity. LTB as a bacterial adjuvant enhanced immunogenicity of Opr F and anti Opr F Ig G titer in serum was increased. Experimental findings showed significantly higher average survival rate in burned mice immunized with Opr F-LTB than immunized with Opr F or the control group. Rabbits anti Opr F Ig G brought about 75% survival of mice following challenge with P. aeruginosa. Post challenge hepatic and splenic tissues of mice group immunized with Opr F-LTB had significantly lower bacterial load than those immunized with Opr F or the control groups. CONCLUSION: These results demonstrate that LTBfused Opr F might be a potential candidate protein for a prophylactic measure against P. aeruginosa in burn infection.