Vaccines (Aug 2021)

Recombinant Antigens Based on Non-Glycosylated Regions from RBD SARS-CoV-2 as Potential Vaccine Candidates against COVID-19

  • Leandro Núñez-Muñoz,
  • Gabriel Marcelino-Pérez,
  • Berenice Calderón-Pérez,
  • Miriam Pérez-Saldívar,
  • Karla Acosta-Virgen,
  • Hugo González-Conchillos,
  • Brenda Vargas-Hernández,
  • Ana Olivares-Martínez,
  • Roberto Ruiz-Medrano,
  • Daniela Roa-Velázquez,
  • Edgar Morales-Ríos,
  • Jorge Ramos-Flores,
  • Gustavo Torres-Franco,
  • Diana Peláez-González,
  • Jorge Fernández-Hernández,
  • Martha Espinosa-Cantellano,
  • Diana Tapia-Sidas,
  • José Abrahan Ramírez-Pool,
  • América Padilla-Viveros,
  • Beatriz Xoconostle-Cázares

DOI
https://doi.org/10.3390/vaccines9080928
Journal volume & issue
Vol. 9, no. 8
p. 928

Abstract

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The Receptor-Binding Domain (RBD) of the Spike (S) protein from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has glycosylation sites which can limit the production of reliable antigens expressed in prokaryotic platforms, due to glycan-mediated evasion of the host immune response. However, protein regions without glycosylated residues capable of inducing neutralizing antibodies could be useful for antigen production in systems that do not carry the glycosylation machinery. To test this hypothesis, the potential antigens NG06 and NG19, located within the non-glycosylated S-RBD region, were selected and expressed in Escherichia coli, purified by FPLC and employed to determine their immunogenic potential through detection of antibodies in serum from immunized rabbits, mice, and COVID-19 patients. IgG antibodies from sera of COVID-19-recovered patients detected the recombinant antigens NG06 and NG19 (A450 nm = 0.80 ± 0.33; 1.13 ± 0.33; and 0.11 ± 0.08 for and negatives controls, respectively). Also, the purified antigens were able to raise polyclonal antibodies in animal models evoking a strong immune response with neutralizing activity in mice model. This research highlights the usefulness of antigens based on the non-N-glycosylated region of RBD from SARS-CoV-2 for candidate vaccine development.

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