Extracellular vesicles as new-age vaccine carriers: a focused account on viral diseases

Extracellular vesicles are shifting the paradigm in vaccine development by virtue of their diverse benefits as carriers of immunogens to targeted hosts. These nano-sized naturally occurring biomolecules offer safety, transmissibility across membranes, excellent presentation of antigens and robust immune responses when engineered as vaccine delivery vehicles. Given the remarkable potential of these nanoscale biological carriers, the scientific community has witnessed substantial escalation in research activity highlighting their applications in vaccines and drug delivery. However, the research is still in its early stage and the scientists are actively striving to optimize the engineering of these molecules for effective therapeutic applications. As a research group working on similar lines, we sought to explore the diverse engineering strategies with the aim of understanding the potential of extracellular vesicles as potent vaccine delivery vehicles. We conducted a systematic search to critically screen original research studies investigating engineering of extracellular vesicles for production of vaccines against viral infections. Our analysis of the studies revealed that extracellular vesicles provide diverse engineering opportunities to enable efficient viral antigen presentation, and to elicit robust immune responses both in vitro and in vivo. A wide spectrum of viruses has been targeted driving development of versatile as well as pathogen-specific vaccine strategies. Advancing research in this domain could deepen mechanistic insight into viral infections, while opening novel pathways for translational application, drug delivery and vaccine design. We conclude that substantial opportunities remain to fully harness the potential of extracellular vesicles in biomedical research, particularly in context of viral infections.