1. Nanovaccines and the History of Vaccinology

Vaccines have been historically linked to prominent benefits for global health. The concept of vaccination was first recorded in Asia and subsequently consolidated by the better documented studies by Jenner and Pasteur during the eighteenth and nineteenth centuries. Later, mainly in the twentieth century, the design and production of vaccines were expanded to massively apply vaccines in the benefit of human and animal health, being prominently based on whole killed or attenuated bacteria or viruses. Next generation (subunit) vaccines based on few antigens and possibly some adjuvants have been proposed as the ideal vaccination approach since the risks (strain reversion to pathogenic forms, high reactogenicity, and expensive manufacture, among others) associated with the use of whole pathogens are avoided. The development of toxoids and the use of polysaccharide conjugates added an important piece to the vaccinology portfolio, leading to the first subunit vaccines; however, the application of these approaches in the clinic is only beginning and myriad efforts are ongoing to expand their use. Nanosized vaccines are a promise in this field since nanomaterials offer singular properties that may enhance the efficacy of subunit vaccines, thus resulting in innovative vaccines. Genetic engineering has made possible to introduce nanosized vaccines (based on virus-like particles) in the market, which target the hepatitis B virus and human papillomavirus and are produced in well-established platforms, namely recombinant yeasts and insect cells. Innovative recombinant platforms offering low cost and other advantages are under development; these include plant cells and algae, among others. Besides protein-based nanoparticles, the nanotechnology field offers a wide range of nanomaterials to be applied for vaccine nanotechnology that include metallic and polymeric nanoparticles, nanogels, carbon nanomaterials, and liposomes. A substantial progress in the vaccinology field is envisioned as a consequence of the application of such nanomaterials in the vaccinology field, especially on the development of mucosal vaccines.