Recent Advances in Nanovaccines Using Biomimetic Immunomodulatory Materials

Vijayan, Veena; Mohapatra, Adityanarayan; Uthaman, Saji; Park, In-Kyu

For VLP to be used as a delivery vehicle, the target antigen from a virus different from the one used in the VLP is attached to the VLP surface; and this surface-modified VLP paves the way for its use in targeting various diseases. VLPs could be engineered to attach additional proteins on its surface, either through the fusion of proteins on the particle, or by expressing multiple antigens, which in turn protects against its source virus and other antigens present on its surface [75] . Polysaccharides and small organic molecules are non-protein antigens that can be chemically attached to the VLP surface to form bioconjugate particles [76] . The baculovirus expression system is mostly used to generate VLPs with an excellent safety profile, as baculovirus does not naturally infect human [77] . In another study, a safe and efficient VLP system based on avian retrovirus was designed such that the system was considered safe, as it could not replicate itself in human cells. This system was considered as safe because the VLP constitutes only Gag fusion protein; a single VLP could deliver about (2000-5000) copies of the Gag fusion protein into the transduced cell. In another study, VLPs were created for delivery with two different approaches: the intracellular distribution of Gag fusion proteins, or by modifying the surface of VLPs for receptor/ligand-mediated delivery ( Figure 2 ) [57] . 2.1.3. Self-assembling Protein nanoparticles (NPs) Many naturally occurring proteins can self-assemble to form NPs with high symmetry and stability, and these NPs are structurally organized to form particles that range in size (10-150) nm 2.1.3. Self-assembling Protein Nanoparticles (NPs) Many naturally occurring proteins can self-assemble to form NPs with high symmetry and stability, and these NPs are structurally organized to form particles that range in size nm [53, 54] . These NPs with diverse physiological roles are selected as vaccine carriers, owing to their ability to self-assemble and deploy into a definite structure that mimics a natural microbe architecture [55] .