Evaluation of immunogenicity-induced DNA vaccines against different SARS-CoV-2 variants

PLoS One. 2023 Dec 7;18(12):e0295594. doi: 10.1371/journal.pone.0295594. eCollection 2023.

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in 2019 and caused the coronavirus disease 2019 (COVID-19) pandemic worldwide. As of September 2023, the number of confirmed coronavirus cases has reached over 770 million and caused nearly 7 million deaths. The World Health Organization assigned and informed the characterization of variants of concern (VOCs) to help control the COVID-19 pandemic through global monitoring of circulating viruses. Although many vaccines have been proposed, developing an effective vaccine against variants is still essential to reach the endemic stage of COVID-19. We designed five DNA vaccine candidates composed of the first isolated genotype and major SARS-CoV-2 strains from isolated Korean patients classified as VOCs, such as Alpha, Beta, Gamma, and Delta. To evaluate the immunogenicity of each genotype via homologous and heterologous vaccination, mice were immunized twice within a 3-week interval, and the blood and spleen were collected 1 week after the final vaccination to analyze the immune responses. The group vaccinated with DNA vaccine candidates based on the S genotype and the Alpha and Beta variants elicited both humoral and cellular immune responses, with higher total IgG levels and neutralizing antibody responses than the other groups. In particular, the vaccine candidate based on the Alpha variant induced a highly diverse cytokine response. Additionally, we found that the group subjected to homologous vaccination with the S genotype and heterologous vaccination with S/Alpha induced high total IgG levels and a neutralization antibody response. Homologous vaccination with the S genotype and heterologous vaccination with S/Alpha and S/Beta significantly induced IFN-γ immune responses. The immunogenicity after homologous vaccination with S and Alpha and heterologous vaccination with the S/Alpha candidate was better than that of the other groups, indicating the potential for developing novel DNA vaccines against different SARS-CoV-2 variants.

MeSH terms

  • Animals
  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19* / prevention & control
  • Humans
  • Immunoglobulin G
  • Mice
  • Pandemics
  • SARS-CoV-2 / genetics
  • Vaccination
  • Vaccines, DNA*

Substances

  • Vaccines, DNA
  • Antibodies, Neutralizing
  • Immunoglobulin G
  • Antibodies, Viral

Supplementary concepts

  • SARS-CoV-2 variants

Grants and funding

1.Initials of the authors who received the award: all authors Grant numbers awarded to each author: 4800-6634-313 The full name of funder: Korea National Institute of Health (KNIH) URL of funder website: www.nih.go.kr Did the sponsors or funders play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript?: The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. 2.Initials of the authors who received the award: all authors Grant numbers awarded to each author: Intramural Research number 2021-NI-002-01 The full name of funder: Korea National Institute of Health (KNIH) URL of funder website: www.nih.go.kr Did the sponsors or funders play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript?: The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.