Cellular and Humoral Immunogenicity of a Candidate DNA Vaccine Expressing SARS-CoV-2 Spike Subunit 1

• Published in: Vaccines (Basel) Vol. 9; no. 8; p. 852
• Main Authors: Alluhaybi, Khalid A, Alharbi, Rahaf H, Alhabbab, Rowa Y, Aljehani, Najwa D, Alamri, Sawsan S, Basabrain, Mohammad, Alharbi, Rehaf, Abdulaal, Wesam H, Alfaleh, Mohamed A, Tamming, Levi, Zhang, Wanyue, Hassanain, Mazen, Algaissi, Abdullah, Abuzenadah, Adel M, Li, Xuguang, Hashem, Anwar M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 04.08.2021; MDPI
• Subjects: Antibodies; CD4 antigen; CD8 antigen; cellular and humoral immunogenicity; Coronaviruses; COVID-19; COVID-19 vaccines; Deoxyribonucleic acid; DNA; DNA vaccine; DNA vaccines; Evaluation; Fatalities; Gene expression; Immune response; Immune response (cell-mediated); Immune response (humoral); Immune system; Immunization; Immunogenicity; Immunoglobulin G; Immunological memory; Lymphocytes; Lymphocytes T; Memory cells; Polyclonal antibodies; Protein expression; Proteins; SARS-CoV-2 vaccine; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Spike protein; Vaccine development; Vaccines; Beijing China; United States > US; China; Germany; DNA vaccine; SARS-CoV-2 vaccine; cellular and humoral immunogenicity
• ISSN: 2076-393X; 2076-393X
• DOI: 10.3390/vaccines9080852

The urgent need for effective, safe and equitably accessible vaccines to tackle the ongoing spread of COVID-19 led researchers to generate vaccine candidates targeting varieties of immunogens of SARS-CoV-2. Because of its crucial role in mediating binding and entry to host cell and its proven safety profile, the subunit 1 (S1) of the spike protein represents an attractive immunogen for vaccine development. Here, we developed and assessed the immunogenicity of a DNA vaccine encoding the SARS-CoV-2 S1. Following in vitro confirmation and characterization, the humoral and cellular immune responses of our vaccine candidate (pVAX-S1) was evaluated in BALB/c mice using two different doses, 25 µg and 50 µg. Our data showed high levels of SARS-CoV-2 specific IgG and neutralizing antibodies in mice immunized with three doses of pVAX-S1. Analysis of the induced IgG subclasses showed a Th1-polarized immune response, as demonstrated by the significant elevation of spike-specific IgG2a and IgG2b, compared to IgG1. Furthermore, we found that the immunization of mice with three doses of 50 µg of pVAX-S1 could elicit significant memory CD4 and CD8 T cell responses. Taken together, our data indicate that pVAX-S1 is immunogenic and safe in mice and is worthy of further preclinical and clinical evaluation.