Recombinant expression of SARS-CoV-2 Receptor Binding Domain (RBD) in Escherichia coli and its immunogenicity in mice

Document Type : Original Article


1 Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Department of Biology, Imam Hossein University, Tehran, Iran

3 Applied Virology Research Center, Baqiyatallah University of Medical Sciences, Iran

4 Applied Microbiology Research Center, System Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran



Objective(s): The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), giving rise to the coronavirus disease 2019 (COVID-19), has become a danger to wellbeing worldwide. Thus, finding efficient and safe vaccines for COVID-19 is of great importance. As a basic step amid contamination, SARS-CoV-2 employs the receptor-binding domain (RBD) of the spike protein to lock in with the receptor angiotensin-converting enzyme 2 (ACE2) on host cells. SARS-CoV-2 receptor-binding domain (RBD) is the main human antibody target for developing vaccines and virus inhibitors, as well as neutralizing antibodies. A bacterial procedure was developed for the expression and purification of the SARS-CoV-2 spike protein receptor-binding domain.
Materials and Methods: In this research study, RBD was expressed by Escherichia coli and purified with Ni-NTA chromatography. Then it was affirmed by the western blot test. The immunogenicity and protective efficacy of RBD recombinant protein were assessed on BALB/c mice. Additionally, RBD recombinant protein was tested by ELISA utilizing sera of COVID-19 healing patients contaminated with SARS-CoV-2 wild type and Delta variation. 
Results: Indirect ELISA was able to detect the protein RBD in serum of the immunized mouse expressed in E. coli. The inactive SARS-CoV2 was detected by antibodies within the serum of immunized mice. Serum antibodies from individuals recovered from Covid19 reacted to the expressed protein.
Conclusion: Our findings showed that RBD is of great importance in vaccine design and it can be used to develop recombinant vaccines through induction of antibodies against RBD.


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