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Development of an Optimized Process for Functional Recombinant SARS-CoV-2 Spike S1 Receptor-Binding Domain Protein
Mohamed Boumaiza1, Ameni Chaabene1, Ines Akrouti1
1Laboratory of Molecular Microbiology, Vaccinology and Biotechnology Development, Group of Biotechnology Development, Institut Pasteur de Tunis, Université Tunis El Manar, Tunis 1002, Tunisia.
Tropical Medicine and Infectious Disease
|November 24, 2023
Summary
Researchers developed an affordable method to produce SARS-CoV-2 antigens for local serological tests. This approach enhances COVID-19 surveillance capabilities, especially in lower-middle-income countries, using the S1RBD protein via baculovirus expression.
Area of Science:
- Virology
- Immunology
- Biotechnology
Background:
- Mapping Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spread and immune responses requires efficient local serological tests.
- High costs of SARS-CoV-2 immunogenic proteins limit accessibility in lower-middle-income countries (LMICs).
Purpose of the Study:
- To establish an affordable production method for the SARS-CoV-2 receptor-binding domain (RBD) of the spike S1 protein (S1RBD) using the baculovirus expression vector system (BEVS).
- To optimize conditions for high-yield S1RBD production and evaluate its antigenicity for developing diagnostic tools.
Main Methods:
- Production of S1RBD using the BEVS.
- Optimization of culture conditions including multiplicity of infection (MOI), cell density, and harvest time.
- Western blot analysis to monitor S1RBD expression and evaluate antigenicity against COVID-19 patient sera.
Main Results:
- Optimal production conditions identified: MOI 3, cell density 2-3 × 10^6 cells/mL, and harvest time of 72-96 hours post-infection.
- Achieved high S1RBD yields: 4 mg/L in shake flasks and up to 70 mg/L in a 7L bioreactor.
- Produced S1RBD demonstrated excellent antigenicity against sera from COVID-19 patients.
Conclusions:
- The study successfully established an efficient and scalable method for producing SARS-CoV-2 S1RBD.
- The developed S1RBD is a viable antigen for creating cost-effective serological assays like ELISA for COVID-19 surveillance.
- This method can support local diagnostic test development and seroprevalence studies, particularly in resource-limited settings.
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