Assessment of recombinant proteins representing the Receptor Binding Domain (RBD) as vaccine candidates against COVID-19.

• Grant number: 24/16244-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: March 01, 2025
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Immunology - Applied Immunology
• Principal Investigator: Daniela Santoro Rosa
• Grantee: João Pedro da Silva Nunes
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

The rapid development of several safe and effective vaccines against COVID-19 was the cornerstone of the pandemic control. However, inequality in vaccine distribution and the emergence of new variants of concern (VOCs) highlighted significant gaps in the global strategy for mitigating SARS-CoV-2 infection. Despite the use of different platforms, most approved vaccines use the Spike protein as the main antigen due to its crucial role in virus entry, mediated by the receptor-binding domain (RBD). In this context, the RBD stands out as a promising antigen for a subunit vaccine, as it is the primary target of neutralizing antibodies, has a well-established scalable production chain, and has proven safety. Various approaches can be used to enhance the immunogenicity of RBD, such as the addition of adjuvants and antigen multimerization. The objective of the present study is to compare the immunogenic properties of the monomeric and homodimeric RBD of the Wuhan strain with a heterotrimeric RBD formulation composed of Delta, Beta, and Gamma variants, in the presence of different adjuvants, aiming to optimize both humoral and cellular immunity. Additionally, we intend to map T-cell epitopes present within the RBD sequence, seeking to better characterize the immune response to RBD-based subunit vaccines.