Use of Leishmania-Derived Extracellular Vesicles as a Vaccine Platform Against Emerging Viral Diseases

Abstract

Extracellular vesicles (EVs) are small membrane-bound “vehicles” responsible for transporting biological materials from source cells to target cells. EVs are thus indirectly capable of inducing changes in the physiological state and behavior of target cells once their contents are successfully released or received. Both prokaryotic and eukaryotic species utilize EVs for a variety of purposes. For example, Leishmania, a protozoan parasite, has demonstrated the ability to secrete immunomodulatory EVs. Various studies have shown that it is not these EVs in themselves, but rather the contents of these EVs that are directly involved in the parasite’s colonization and replication inside host cells. Although using Leishmania as an expression system for recombinant proteins has been explored (investigations have yielded successful and promising results), the use of Leishmania-derived EVs is a burgeoning field of research. In fact, considering extant research on EV-based vaccines, substantial potential lies in exploiting Leishmania-derived EVs as a novel vaccine platform. Hence, this study aims to discuss the immunomodulatory capabilities of Leishmania-derived EVs and their potential application in vaccine development. Lastly, in piecing together the nature of Leishmania-derived EVs and the general therapeutic potential of engineered EVs, it is further hypothesized that Leishmania may be an effective expression system for EVs that harbour desired viral antigens as a part of more efficient vaccine designs.