Abstract
Extracellular vesicles (EVs) subtype, exosome is an extracellular nano-vesicle that sheds from cells’ surface and originates as intraluminal vesicles during endocytosis. Firstly, it was thought to be a way for the cell to get rid of unwanted materials as it loaded selectively with a variety of cellular molecules, including RNAs, proteins, and lipids. However, it has been found to play a crucial role in several biological processes such as immune modulation, cellular communication, and their role as vehicles to transport biologically active molecules. The latest discoveries have revealed that many viruses export their viral elements within cellular factors using exosomes. Hijacking the exosomal pathway by viruses influences downstream processes such as viral propagation and cellular immunity and modulates the cellular microenvironment. In this manuscript, we reviewed exosomes biogenesis and their role in the immune response to viral infection. In addition, we provided a summary of how some pathogenic viruses hijacked this normal physiological process. Viral components are harbored in exosomes and the role of these exosomes in viral infection is discussed. Understanding the nature of exosomes and their role in viral infections is fundamental for future development for them to be used as a vaccine or as a non-classical therapeutic strategy to control several viral infections.
Highlights
Published: 4 September 2021Extracellular vesicles (EVs) are a heterogeneous group of lipid-bound vesicles, which are derived from the plasma membrane or endosomes and secreted by almost all cell types into the extracellular lumen [1,2]
EVs are considered as cell debris, but recently they have emerged as important mediators in intercellular communication and they are involved in numerous physiological and pathological processes [5,6] such as inflammation and immune response [7], neuron-glia communication and myelination [8,9], infection [10,11], and cancer [12,13]
EVs play a crucial role in viral infection influencing viral entry, transmission, and immune evasion [14,15,16,17], as they serve as an important intercellular communication tool between uninfected and infected cells [15,18]
Summary
Extracellular vesicles (EVs) are a heterogeneous group of lipid-bound vesicles, which are derived from the plasma membrane or endosomes and secreted by almost all cell types into the extracellular lumen [1,2]. EVs are categorized into three main subtypes: exosomes (30 to 100 nm), microvesicles (~100–1000 nm), and apoptotic bodies (~500–4000 nm) based on their size, content, biogenesis, and function. These EVs subtypes have been detected in different biological fluids such as cerebrospinal fluid, saliva, blood, breast milk, ascetic fluid, amniotic fluid, seminal fluid, and urine [3,4]. Society for Extracellular Vesicles (ISEV) recommended the term “extracellular vesicles” on the nomenclature of non-replicative, lipid bilayer naturally released vesicles from different cells as this term has a very clear meaning to non-specialists and specialists alike [26]. Regardless of the argument between scientists on the nomenclature and their bias to specific terms as we observed in different reviews in the literature, we will focus our discussion on the role of exosomes in viral infection
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