Expression of the Recombinant Protein Containing CfaB, ST, CfaE, and LtB from Enterotoxigenic Escherichia coli and Loading It in Chitosan Nanoparticles

 Enterotoxigenic Escherichia coli (ETEC) is the most important bacteria causing traveler’s diarrhea. The bacterium has several virulence factors, including colonization factors (CFs) or Escherichia coli adhesins, heat-labile (LT), and heat-stable (ST) toxins. The design and production of vaccine against this disease is one of the goals of the World Health Organization due to increased antibiotic resistance and a reduction of healthy water sources. An effective subunit vaccine against ETEC could include a toxoid from both toxins and colonization factors. The aim of the current study was to express, purify, and encapsulate the recombinant protein in chitosan nanoparticles.

 In the present experimental study, the E. coli BL21DE3 harbring pET- 28a-cscl vector was used. The chimeric cscl gene is composed of cfab along with st toxin, cfae, and ltb. After the expression and purification of recombinant protein, using Ni-NTA column, Western blotting was performed with anti-His antibody. Then, the CSCl protein was encapsulated in chitosan nanoparticles and the particle size was measured.

 The recombinant CSCL protein was purified by Ni-NTA column and urea denaturation method. Then, this purified protein (~57kDa) was confirmed by Western blotting and the size of the nanoparticles was estimated as 112.0 nm with 98.8% of encapsulation efficiency.

 With some advantages, including the presence of surface and important antigens of ETEC and encapsulating in chitosan nanoparticles, the CSCL recombinant protein can be considered as a candidate for producing oral nanovaccine and stimulating of mucosal and systemic immune response.