Role of extracellular vesicles in viral and bacterial infections

Extracellular vesicles (EVs), or exosomes, are nanovesicles of endocytic origin that carry host and pathogen-derived protein, nucleic acid, and lipid cargos. They are secreted by most cell types and play important roles in normal cell-to-cell communications but can also spread pathogen- and host-derived molecules during infections to alter immune responses and pathophysiological processes. New research is beginning to decipher how EVs influence viral and bacterial pathogenesis. Researchers from Arizona State University describe how EVs influence viral and bacterial pathogenesis by spreading pathogen-derived factors and how they can promote and inhibit the immune response to these pathogens. They also discuss the emerging potential of EVs as diagnostic and therapeutic tools.

Overview of the EV incorporation of pathogen-derived factors by the EVs of their host cells, including pathogen receptors and regulatory factors, to promote infection and pathogenesis

(A) EVs of HIV-infected cells express the HIV receptor target proteins CCR5 and CXCR4 and regulatory factors, including the HIV protein Nef and TAR RNA, among others. (B) EVs of HCV-infected cells express E2 and CD81, which promote HCV uptake, as well as viral RNA and host proteins (e.g., CD63) that promote HCV infections. (C) EVs of HBV-infected cells contain EBV RNA and proteins (e.g., LMP1) and host proteins (e.g., EGFR and FGF2) that promote EBV infectivity and pathogenesis. (D) EVs of Mtb-infected cells contain Mtb-derived glycolipids (LAM) and lipoproteins (LpqH) that regulate innate and acquired immune responses to promote infection.