Aim: To study immunogenicity of outer membrane protein F (OprF) fused with B subunit of LT (LTB), against Pseudomonas aeruginosa (P. aeruginosa).
Methods: The OprF, 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 OprF and OprF-LTB fusion gene was cloned, expressed and purified. BALB/c mice and rabbits were immunized using recombinant OprF and OprF-LTB and challenged at the burn site with P. aeruginosa lethal dose of 10(4) CFU. The protective efficacy of rabbit anti OprF IgG 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 OprF and anti OprF IgG titer in serum was increased. Experimental findings showed significantly higher average survival rate in burned mice immunized with OprF-LTB than immunized with OprF or the control group. Rabbits anti OprF IgG brought about 75% survival of mice following challenge with P. aeruginosa. Post challenge hepatic and splenic tissues of mice group immunized with OprF-LTB had significantly lower bacterial load than those immunized with OprF or the control groups.
Conclusion: These results demonstrate that LTB-fused OprF might be a potential candidate protein for a prophylactic measure against P. aeruginosa in burn infection.
Keywords: B subunit of LT; Burn; Immunization; Outer membrane protein F; Pseudomonas aeruginosa.