Immunological Properties of Exotoxin A Toxoid — Detoxified Lipopolysaccharide — Gold Nanoparticles Conjugate Against Pseudomonas aeruginosa Infection

Pseudomonas aeruginosa is eudomonas aeruginosa is an important opportunistic pathogen, especially in patients with compromised host defense. Objective: To prepare the conjugate of detoxified lipopolysaccharide (D-LPS) and exotoxin A toxoid (T-ETA) from P. aeruginosa in gold nanoparticles (Au NPs) in a mice model. Methods: LPS and ETA were purified from P. aeruginosa PAO1. D-LPS was conjugated with T-ETA via the amidation method. Au NPs were bound to D-LPS-T-ETA conjugate via electrostatic interaction. Mice were immunized with D-LPS, D-LPS-Au NPs, T-ETA, T-ETA-Au NPs, D-LPS-T-ETA, D-LPS-T-ETA-Au NPs, D-LPS-Au NPs+T-ETA-Au NPs, Au NPs, and phosphate-buffered saline (PBS), and specific IgG titers were determined by the ELISA and the whole-cell ELISA methods. Mice in the vaccinated and control groups were exposed to a 2×LD50 of P. aeruginosa and mortality rates were recorded for one week. Results: The results showed that vaccination by D-LPS, D-LPSAu NPs, T-ETA, T-ETA-Au NPs, D-LPS-T-ETA, D-LPS-T-ETAAu NPs and D-LPS-Au NPs+T-ETA-Au NPs induced specific IgG. Mice received the D-LPS-T-ETA-Au NPs conjugate showed significant protection against bacterial challenge. Conclusion: These data indicate that D-LPS-T-ETA-Au NPs conjugate has a significant immunogenicity potential to be applied as a new vaccine against pseudomonas infections.