Figure 3.

Differences in exosome content secretion from uninfected and gammaherpesvirus-infected cells. (A) Exosome biogenesis and secretion from uninfected cells. Multivesicular bodies (MVBs) are formed by fusion with early endosomes. Next, the MVBs fuse either with the lysosome for degradation, or with the plasma membrane, which releases the exosomal content into the extracellular space. The exosomal content contains proteins encoded by tumor susceptibility gene 101 (Tsg101), apoptosis-linked gene-2 interacting protein X (Alix), tetraspanins, and flotillins, which can all be used for exosome identification. Additionally, multiple RNA species such as cellular mRNA, microRNA (miRNA), and long non-coding RNA (lncRNA) can be found within exosomes. Finally, exosomes can also contain DNA and lipids. (B) Exosome biogenesis and secretion from gammaherpesvirus-infected cells. In addition to the above content found in exosomes secreted from uninfected cells, viral proteins and viral nucleic acids can also be found within exosomes from virus-infected cells. The content of these exosomes often influences the surrounding cellular environment to result in epithelial-to-mesenchymal transition (EMT), malignant transformation, oncogenic signaling, angiogenesis, and immune evasion.