Exosomes and Their Role in Viral Infections

Abstract

Exosomes are excretory nano-vesicles that are formed by the cell's endocytic system and shed from the surface of almost all types of cells. These tiny extracellular vesicles, once thought to be "garbage bags for cells," carry a wide variety of molecules of cellular origin, including proteins, lipids, and RNAs, that are selectively incorporated during the formation of exosomes. Exosomes are now known to play a central role in several important biological processes such as cellular communication, intercellular transfer of bioactive molecules, and immune modulation. Recent advances in the field have shown that a number of animal viruses can exploit the exosomal pathway by incorporating specific cellular or viral factors within exosomes, in order to modulate the cellular microenvironment and influence downstream processes such as host immunity and virus spread. In this chapter, we provide an overview of our current understanding of exosome biogenesis and how this normal physiological process is hijacked by some pathogenic viruses. Viral components that appear to be selectively incorporated into exosomes and the potential role of these exosomes in viral pathogenesis are discussed. Identifying viral signatures in exosomes and their mode of action is fundamental for any future diagnostic and therapeutic strategies for viral infections.

SARS-CoV-2 Dissemination Through Peripheral Nerves Explains Multiple Organ Injury

“…Lateral transfections, i.e., cell-to-cell or axo-axonal spreading via exocytosis, could be also possible. Exosomal pathways are hypothesized to contribute to viral dissemination ( Khan et al, 2017 ), and it was demonstrated that ACE2 trafficking could involve exosome-mediated cell-to-cell transfer ( Wang et al, 2020a ). Arguably, this mechanism could allow the infection to spread from neurons to cerebrovascular endothelial cells, and vice versa .…”

Extracellular Vesicles as Delivery Vehicles of Specific Cellular Cargo

“…Furthermore, EVs can harbor viral miRNA [89] and non-coding RNA (Epstein-Barr Virus (EBV)) [90], as well as several proteins, like the latent membrane protein 1 (EBV) [91] or glycoprotein B (herpes simplex virus) [92]. A full list was compiled in the review of Khan et al [93]. For retroviruses, a trojan exosome hypothesis was published in 2003 and describes how these viruses use the endogenous exosome mechanism of the host cell to form infectious, but mimicked particles [94].…”

Extracellular vesicles and their cells of origin: Open issues in autoimmune diseases

“…Both cells and EVs can be contaminated with bioactive components, including but not limited to viruses, bacteria, and endotoxins, that should be checked before any administration. Considering similarities between viruses and exosomes ( 306 – 309 ), viral contaminations for EV preparations are one of the main concerns. Usually, the size of bacteria and fungi are larger than EVs; however, infections specifically by intracellular contaminations such as mycoplasma can change both cell and EVs properties ( 310 – 313 ).…”