Evaluation of PLGA-Encapsulated Recombinant GroEL of S. typhi immune  Responses Against Enterohaemorrhagic and Enteropathogenic Escherichia coli

Milad  Parvane; Shahram  Nazarian; Emad  Kordbache; Javad  Fathi; Mohamad Ebrahim  Minae; Mohammad Reza  Ramezani

doi:10.18502/ajmb.v14i4.10484

Milad Parvane Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran
Shahram Nazarian Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran
Emad Kordbache Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran
Javad Fathi Department of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Mohamad Ebrahim Minae Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran
Mohammad Reza Ramezani Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran

DOI: https://doi.org/10.18502/ajmb.v14i4.10484

Keywords: Heat-Shock Proteins, Immunogenicity, Nanoparticles, Salmonella typhi, Vaccine

Abstract

Background: Heat Shock Proteins (HSPs) elicit humoral and cellular immune responses. Due to their high sequence homology, they can be developed as a new immunogen for cross prophylactic and vaccination effects against infectious agents such as Enteropathogenic and Enterohemorrhagic Escherichia coli (EPEC and EHEC). This study aimed to evaluate the immunogenicity and cross-protective efficacy of rGroEL of Salmonella typhi (S. typhi) encapsulated in poly lactic-co-glycolic acid (PLGA) nanoparticles against EPEC and EHEC.

Methods: Recombinant GroEL was expressed in Escherichia coli (E. coli) and purified using Ni-NTA affinity chromatography. The protein was encapsulated in PLGA by the double emulsion method, and the nanoparticles were characterized physicochemically. BALB/c mice were immunized, and the efficacy of the protein to elicit immune responses was assessed.

Results: Over-expression in E. coli led to corresponding 64.5 kDa protein bands in Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Non-ag-gregated nanoparticles had a spherical shape with a mean diameter of 194.3±3 nm and encapsulation efficiency of 89.5±2.5%. Antibody isotyping revealed that GroEL immunization induced both IgG1 and IgG2a antibodies. Moreover, immunization of the mice with recombinant GroEL protein conferred 80 and 60% protection against lethal infections by EPEC and EHEC, respectively. Furthermore, organ burden studies revealed a significant reduction in infection in the immunized mice compared to the non-immunized ones. Passive immunization with anti-GroEL sera also protected 50% of the mice against the lethal doses of EHEC and EPEC strains.

Conclusion: The findings indicated that immunization of the mice with recombinant GroEL of S. typhi elicited cross-protection against other bacterial infections. This represented the immense potential of GroEL to be developed as a single vaccine against multiple pathogens.