Recent Advances in Nanovaccines Using Biomimetic Immunomodulatory Materials

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

Liposomes are biomimetic products that are formed by dispersing phospholipids in water [58, 62, 63] . They occur as either unilamellar vesicles with a single phospholipid bilayer, or as multilamellar vesicles with several concentric phospholipid shells separated by different layers of water. Liposomes can be modified to incorporate both hydrophobic and hydrophilic molecules into the phospholipid bilayer and aqueous core [64] . Liposomes can be used to encapsulate antigens within their core for delivery. They form virosomes when viral envelope glycoproteins are incorporated into their base [65, 66] . Influenza virus was the primary focus for virosome studies which has been established for industrial application as human vaccine [67] . Five vaccines based on virosome are under clinical trials, and four virosome vaccines are approved for commercial application in various diseases [67] . One of the commonly used NPs for adjuvant delivery in DNA vaccines is liposome-polycation-DNA NPs; they are formed by the combination of cationic liposomes and cationic polymer-condensed DNA. Liposome-polycation-DNA assembles to form a nanostructure, with the condensed DNA located inside the liposome with a size of 150 nm [24, 68] . Moon et al. [21] reported the development of a malaria vaccine, which could be used for the delivery of polymeric PLGA NPs enveloped with lipid antigens. In their work, Moon and coworkers developed a pathogen-mimicking nanovaccine, in which the candidate malarial antigen was conjugated to the lipid membrane and incorporated with an immunostimulatory molecule, monophosphoryl lipid A-MPLA, and further used to elicit immune responses against P. vivax sporozoites [21] . Yang et al. [52] used cancer cell membranes which were modified with lipids using the lipid-anchoring method, and then further coated them over polymeric NPs with a toll-like receptor 7 (TLR 7). This biomimetic membrane nanocarrier was reported for use as an anticancer vaccine, as well as for the delivery of TLR 7 as an adjuvant [52] .