Evaluation of Antigen Expression and Early Immune Response Following Cutaneous Suction‐Mediated DNA Delivery

ABSTRACT Suction‐based in vivo cutaneous DNA transfection is a newly developed, cost‐effective method that produces high transfection efficiency. This method has shown robust immunogenic responses following SARS‐CoV‐2 DNA vaccination in both pre‐clinical studies and clinical trials. The current work investigates suction‐based transfection and immune activation on a detailed, cellular level. The spatiotemporal patterns of antigen expression in rat skin following suction‐induced delivery of a pEGFP‐N1 plasmid and a SARS‐CoV‐2 DNA vaccine are evaluated via immunofluorescence staining, which demonstrates early and prolonged expression. The epidermis is identified as the primary location of transfection, and the transfected cells are primarily epidermal keratinocytes. Early immune response is assessed by detection of major histocompatibility complex class II‐positive (MHC‐II + ) cells following suction‐induced DNA vaccination.