A review of vaccinology and <i>ex vivo</i> antigen-loaded dendritic cells: A different approach to infectious disease vaccines

Vaccinology originated with 18^th century efforts to prevent smallpox by injecting healthy individuals with the infectious contents of cutaneous lesions from smallpox patients (variolation) or from individuals afflicted with cowpox (vaccination). In the late 19^th century, vaccination was extended to other diseases after the development of chemical methods to kill pathogens (inactivation) and cell-culture passaging to decrease their virulence (attenuation). Since 1970, advances in immunology, cell subunit purification, and recombinant-DNA genetic engineering have enabled antigen-specific vaccines. During the SARS-CoV-2 pandemic, mRNA and DNA-based vaccines were introduced. Vaccinating with <i>ex vivo</i>-antigen-loaded autologous dendritic cells (DC) is appealing because DCs rapidly induce an adaptive immune response by circumventing the need for <i>in vivo</i> antigen-presenting cells to migrate to the injection site to load antigens. DC vaccines against HIV/AIDS, hepatitis B, and Herpes simplex have yielded encouraging results. During the SARS-CoV-2 COVID-19 pandemic, DC vaccines emerged as a viable vaccine platform against infectious diseases.