600 Microarray patch-based adenovirus vaccines enable effective skin immunization

Abstract

Recombinant live adenovirus (Ad) vectors represent a readily modular vaccine construct that can be engineered to include any antigen of interest, thereby enabling rapid vaccine development against a myriad of infectious pathogens, including coronaviruses. However, current approaches used for delivery, storage, and distribution of Ad vaccines hinder their full potential for effective global immunization campaigns. Here, we developed simple, effective, practical, and needle-free Ad vaccines based on microarray patches (MAPs) to enable sustainable mass vaccination against SARS-CoV-2. Rational formulation of live Ads with nonreducing sugars and mechanically strong carbohydrates into dissolvable MAPs enabled effective skin-targeted delivery of Ads and efficient cutaneous transduction as determined by in vivo live imaging of mice following skin application of MAPs integrating Ad vectors with a reporter gene. Immunogenicity assessment of dissolving MAP-based Ad vectors encoding SARS-CoV-2 proteins in mice demonstrated that skin immunization via MAP delivery of Ad-vectored COVID-19 vaccines elicited robust antigen-specific antibody responses, and these antibodies led to virus-specific neutralization activities, which were enhanced compared to those obtained with traditional intramuscular immunization. Furthermore, MAP delivery of Ad-vectored vaccines elicited potent cell-mediated immune responses, including polyfunctional virus-specific CD8+ and CD4+ T-cell responses in spleens and lungs of immunized mice, as determined by intracellular cytokine staining and flow cytometry, as well as antigen-specific cytotoxic T-cell responses in spleens of mice, as determined by lytic assay. Collectively, our results suggest that dissolvable MAPs could enable the development of skin-targeted Ad-based vaccines that may increase the effectiveness of global immunization programs for SARS-CoV-2 and other existing or future pathogens.