A Modified Recombinant DNA-Based SARS-CoV-2 Vaccine Expressing Stabilized Uncleavable Spike Protein Elicits Humoral and Cellular Immunity against Various SARS-CoV-2 Variants of Concern

Figure 1

Vaccine design and in vitro protein expression of SARS-CoV-2 S protein. (a) Schematic representation of the constructed SARS-CoV-2 DNA vaccine, VIU-1007, after modification. Orange indicates the spike gene of SARS-CoV-2. (b) The modified S protein expression from transfected HEK293 cells with VIU-1007 construct is shown by western blot at the predicted size as a single band due to the removal of furin cleavage. In contrast, cells transfected with a plasmid expressing S protein from the ancestral Wuhan strain (positive control) showed two bands. No SARS-CoV-2 S protein bands were seen upon transfecting the cells with controls, plasmid or cells only. (c) VIU-1007 or control plasmid transfected cells immunofluorescent staining. Red represents transfected cells stained with anti-SARS-CoV-2 S rabbit polyclonal antibodies, while blue displays the nuclei counterstained with DAPI.

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