Therapeutic efficacy of SipD/LptD-specific IgY entrapped in alginate nanoparticles against Salmonella Typhimurium infection

Abstract

Introduction: Salmonella, a zoonotic pathogen causing gastroenteritis, lacks a preventive vaccine. Passive immunization with IgY antibodies derived from immunized chickens has shown potential for treating bacterial infections. This study investigated the therapeutic efficacy of entrapped IgY targeting recombinant SipD and LptD proteins from Salmonella Typhimurium. Methods: The recombinant protein was expressed in E. coli BL21 (DE3) and purified using Ni-NTA affinity chromatography. Hens were immunized with the purified protein, and the resulting IgY was entrapped into alginate nanoparticles. The shape of spherical nanoparticles and their size in the nanometer range were determined by SEM and DLS analysis. The therapeutic efficacy of free and alginate-entrapped IgY against S. Typhimurium was evaluated in mice at 1, 50, and 100 LD50 bacterial doses. Results: The purified IgY concentration in each egg yolk was 6 mg/ml (35 mg/egg). Physicochemical and structural characterization revealed spherical nanoparticles with a diameter of 157.1 nm and a negatively charged surface (zeta potential of −35.6 mV). The loading efficiency of IgY into alginate nanoparticles was 95.5 %. In a challenge test with 100 LD50 of S. Typhimurium, all mice receiving alginate-entrapped IgY survived, whereas half of the mice receiving non-entrapped IgY died within 7 days. Conclusion: Our results indicate that IgY antibodies entrapped in alginate nanoparticles may offer therapeutic effect against S. Typhimurium infection.

Keywords

• Salmonella Typhimurium
• SipD protein
• LptD protein
• Immunoglobulin Y
• Nanoparticle
• Alginate