en 36504569 <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Background:</span><span style="font-size:10.0pt"> 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 <em>Escherichia coli</em> (EPEC and EHEC). This study aimed to evaluate the immunogenicity and cross-protective efficacy of rGroEL of <em><span style="background-color:white">Salmonella typhi</span></em> (<em>S. typhi</em>) encapsulated in poly lactic-co-glycolic acid (PLGA) nanoparticles against EPEC and EHEC.</span></span></p> <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Methods:</span> <span style="font-size:10.0pt">Recombinant GroEL was expressed in <em>Escherichia coli</em> (<em>E. coli</em>) 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. </span></span></p> <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Results:</span> <span style="font-size:10.0pt">Over-expression in <em>E. coli</em> led to corresponding 64.5 <em>kDa</em> 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&plusmn;3 <em>nm</em> and encapsulation efficiency of 89.5&plusmn;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. </span></span></p> <p><span style="font-size:11pt"><span style="font-size:9.5pt">Conclusion:</span><span style="font-size:10.0pt"> The findings indicated that immunization of the mice with recombinant GroEL of <em>S. typhi</em> elicited cross-protection against other bacterial infections. This represented the immense potential of GroEL to be developed as a single vaccine against multiple pathogens</span></span></p> Heat-shock proteins, Immunogenicity, Nanoparticles, Salmonella typhi, Vaccines 294 302 https://www.ajmb.org/En/Article.aspx?id=60517 https://www.ajmb.org/PDF/En/FullText/60517.pdf MiladParvane Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran91926ShahramNazarian11429EmadKordbachehBiology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran91903JavadFathiStudent Research Committee, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran91902Mohamad EbrahimMinae 91929Mohammad RezaRamezani Biology Research Center, Faculty of Basic Sciences, Imam Hossein University, Tehran, Iran91930