6.1 DNA-based Vaccines
DNA vaccines provide a precise and flexible tactic to deliver antigens to the immune system and can contain additional sequences of coding molecules to manipulate the results (Rice et al., 2008). So far, a variety of DNA vaccine platforms have been exploited to enhance the vaccine efficacy through electroporation to deliver plasmids and addition of adjuvants, yielding improved the immune responses (Sardesai and Weiner, 2011). Inovio pharmaceuticals have begun pre-clinical trials of a DNA vaccine (named as INO-4800) against COVID-19 (INOVIO, 2020). This vaccine can induce T cell activation via transferring DNA plasmids that express the SARS-CoV-2 S proteins (INOVIO, 2020). This vaccine platform holds the preponderance of producing therapeutic antibodies and activating immune cells to deliver the vaccine to patients through the skin. With the support of CEPI, the corporation is making provision for the first phase of trials in the United States and China (INOVIO, 2020).