Evaluation of an RBD-nucleocapsid fusion protein as a booster candidate for COVID-19 vaccine

Bruno Vinicius Santos Valiate; Julia Teixeira de Castro; Tomás Gazzinelli Marçal; Luis Adan Flores Andrade; Livia Isabela de Oliveira; Gabriela Barbi Freire Maia; Lídia Paula Faustino; Natalia S Hojo-Souza; Marconi Augusto Aguiar Dos Reis; Flávia Fonseca Bagno; Natalia Salazar; Santuza R Teixeira; Gregório Guilherme Almeida; Ricardo Tostes Gazzinelli

doi:10.1016/j.isci.2024.110177

Evaluation of an RBD-nucleocapsid fusion protein as a booster candidate for COVID-19 vaccine

iScience. 2024 Jun 4;27(7):110177. doi: 10.1016/j.isci.2024.110177. eCollection 2024 Jul 19.

Authors

Bruno Vinicius Santos Valiate^{1

2}, Julia Teixeira de Castro^{1

2}, Tomás Gazzinelli Marçal¹, Luis Adan Flores Andrade², Livia Isabela de Oliveira^{1

3}, Gabriela Barbi Freire Maia⁴, Lídia Paula Faustino¹, Natalia S Hojo-Souza^{1

2}, Marconi Augusto Aguiar Dos Reis³, Flávia Fonseca Bagno², Natalia Salazar², Santuza R Teixeira², Gregório Guilherme Almeida^{1

2}, Ricardo Tostes Gazzinelli^{1

2}

Affiliations

¹ Fundação Oswaldo Cruz-Minas, Belo Horizonte 30.190-002, MG, Brazil.
² Centro de Tecnologia de Vacinas, Universidade Federal de Minas Gerais, Parque Tecnológico de Belo Horizonte, Belo Horizonte 31.310-260, MG, Brazil.
³ Fundação Hospitalar do Estado de Minas Gerais, Belo Horizonte 31.630-901, MG, Brazil.
⁴ Faculdade Ciências Médicas de Minas Gerais, Belo Horizonte 30.130-110, MG, Brazil.

Abstract

Despite successful vaccines and updates, constant mutations of SARS-CoV-2 makes necessary the search for new vaccines. We generated a chimeric protein that comprises the receptor-binding domain from spike and the nucleocapsid antigens (SpiN) from SARS-CoV-2. Once SpiN elicits a protective immune response in rodents, here we show that convalescent and previously vaccinated individuals respond to SpiN. CD4⁺ and CD8⁺ T cells from these individuals produced greater amounts of IFN-γ when stimulated with SpiN, compared to SARS-CoV-2 antigens. Also, B cells from these individuals were able to secrete antibodies that recognize SpiN. When administered as a boost dose in mice previously immunized with CoronaVac, ChAdOx1-S or BNT162b2, SpiN was able to induce a greater or equivalent immune response to homologous prime/boost. Our data reveal the ability of SpiN to induce cellular and humoral responses in vaccinated human donors, rendering it a promising candidate.

Keywords: Health sciences; Immunology; Public health; Virology.