Extracellular Vesicle Biomarkers for Infectious Diseases

Viral and bacterial infections are major causative agents of infectious diseases, resulting in public health challenges and economic losses in both developed and developing countries, as exemplified by the coronavirus disease 2019 pandemic. Many people worldwide are infected with infectious diseases. As signaling molecules that regulate many biological processes, extracellular vesicles (EVs) play important roles in infectious diseases and serve as promising diagnostic biomarkers for many diseases. EVs carry diverse molecules, such as proteins, DNAs, mRNAs, and lipids, through which they regulate their target cells. These cargoes have many different roles, particularly in host-pathogen interactions and immune regulation, and identification of novel biomarkers, including proteins and noncoding RNAs, has provided new opportunities for the diagnosis and prognosis of infectious diseases. This chapter focuses on infectious disease-derived EVs that have the potential for biomarker discovery, highlights challenges in this field, and identifies gaps that may impede the development of EV biomarkers in the diagnosis of infectious diseases. As intracellular parasites, viruses exhibit many biological processes similar to those of small EVs (sEVs) in modulating target cells and affecting target cell immune defense. Therefore, we discuss the sEV biology of viruses and parasites in this chapter to highlight their similarities and differences.