Enhanced Humoral and Cellular Immune Responses Elicited by Adenoviral Delivery of SARS-CoV-2 Receptor-Binding Motif Fused to Human Fc

• Published in: Vaccines (Basel) 2024-11, Vol.12 (11), p.1247
• Main Authors: Lee, Yea-Jin, Easwaran, Maheswaran, Jung, Yong-Sam, Qian, Yingjuan, Shin, Hyun-Jin
• Format: Article
• Language: English
• Subjects: Adenoviruses; Analysis; Animal models; Antibodies; Antigens; Assaying; Binding; COVID-19; Disease prevention; ELISPOT assay; enhance immune responses; Enzyme-linked immunosorbent assay; Enzymes; Expression vectors; Fc receptors; Fusion protein; Genetic engineering; Genomes; human Fc; Hydrofluorocarbons; IgG antibody; Immune response; Immune response (cell-mediated); Immune response (humoral); Immune system; Immunity (Disease); Immunization; Immunogenicity; Immunoglobulin G; Immunotherapy; Infections; Infectious diseases; Middle East respiratory syndrome; Mortality; Pandemics; Pathogens; Patient outcomes; Proteins; receptor binding motif; Receptors; Robust control; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Spike protein; Vaccines; Viruses; γ-Interferon
• ISSN: 2076-393X; 2076-393X
• DOI: 10.3390/vaccines12111247

: The receptor binding motif (RBM) of the SARS-CoV-2 spike protein is critical for viral entry into host cells. Development of a vaccine targeting this region is a promising strategy for COVID-19 prevention. To enhance the immunogenicity of SARS-CoV-2 vaccines, we developed an adenoviral vector expressing the RBM from the SARS-CoV-2 spike protein that fused to the human Fc (hFc) domain. : The recombinant RBM_hFc fusion protein was successfully cloned into the pacAd5CMV-N-pA (pAd5) vector and expressed in HEK293 cells as a ~40 kDa protein. A recombinant adenovirus encoding RBM_hFc was subsequently generated and confirmed by cytopathic effect assay. : Western blot analysis verified the expression of RBM_hFc in the adenovirus (AdV). ELISA assays, validated for IgG detection, demonstrated a twofold increase in IgG antibody levels (M-1.090 at 450 nm; SD-±0.326; and 95% CI-0.250 [0.839 to 1.340]) in sera from BALB/c mice immunized with Ad/RBM_hFc, compared to the negative control group. Result suggests a robust humoral immune response induced by the Ad/RBM_hFc vaccine. Moreover, ELISpot assays demonstrated a tenfold increase in IFN-γ -producing cells (M-440 spot-forming cells; SD-±124.976; and 95% CI-75.522 [364.478 to 515.522]) in mice immunized with AdV/RBM_hFc compared to the negative control group. Result proved that AdV/RBM_hFc-stimulated a robust cellular immune response in animal model. : Our findings indicate that the RBM_hFc fusion protein enhances both humoral and cellular immune responses. These results suggest the potential of adenoviral vectors carrying RBM_hFc as vaccine candidates. However, comprehensive evaluation of the protective efficacy of these adenoviral vectors will necessitate rigorous experimental studies.