When is a virus an exosome?

Exosomes can apparently be involved in disease transmission within a host, and their contents can be affected by EMF exposure.   Are they communicable between hosts?  This is all new to me and I haven’t had time to digest it yet, but I thought I’d throw this out there for anyone interested.

This image at https://www.sciencealert.com/this-is-what-the-covid-19-virus-looks-like-under-electron-microscopes is supposed to be  of covid-19 viruses emerging from an infected cell.   But are they viruses?

A bold new theory suggests that retroviruses have hijacked an inter-cellular communication system for both their biogenesis and spread. The concept, outlined by Stephen Gould, Amy Booth, and James Hildreth (Johns Hopkins University, Baltimore, MD) has implications for HIV treatment and immunization strategies, and may explain why tissue rejection occurs in humans.Hildreth was looking at human proteins that HIV acquires during its biogenesis, and noticed that lysosomal proteins were in the mix. This ties in with recent findings in this and other journals that HIV is packaged in late endosomes (for review see Amara and Littman, 2003).In uninfected cells, this endosomal compartment invaginates to form small, internal vesicles. The bag of vesicles, or multivesicular body, can fuse with the plasma membrane to disgorge these vesicles, named exosomes, which then travel to other cells to transmit messages. In the immune system, exosomes transfer peptide-laden MHC proteins to non-infected cells, and also act as miniature versions of antigen-presenting cells.  Hildreth now proposes that “the virus is fully an exosome in every sense of the word.” Others have found that HIV particles contain MHC, but by the exosome hypothesis they may also contain proteins that exosomes use to fuse with target cells and to avoid attack by complement. As Gould points out, an exosome makes a perfect vector for HIV, because an exosome “is not just proteins in a vesicle, it’s something that is meant to traffic.”…


Exosomes Communicate Protective Messages during Oxidative Stress; Possible Role of Exosomal Shuttle RNA


Background: Exosomes are small extracellular nanovesicles of endocytic origin that mediate different signals between cells,by surface interactions and by shuttling functional RNA from one cell to another. Exosomes are released by many cells including mast cells, dendritic cells, macrophages, epithelial cells and tumour cells. Exosomes differ compared to their donor cells, not only in size, but also in their RNA, protein and lipid composition.

Methodology/Principal Findings: In this study, we show that exosomes, released by mouse mast cells exposed to oxidative stress, differ in their mRNA content. Also, we show that these exosomes can influence the response of other cells to oxidative stress by providing recipient cells with a resistance against oxidative stress, observed as an attenuated loss of cell viability. Furthermore, Affymetrix microarray analysis revealed that the exosomal mRNA content not only differs between exosomes and donor cells, but also between exosomes derived from cells grown under different conditions; oxidative stress and normal conditions. Finally, we also show that exposure to UV-light affects the biological functions associated with exosomes released under oxidative stress.

Conclusions/Significance: These results argue that the exosomal shuttle of RNA is involved in cell-to-cell communication, by influencing the response of recipient cells to an external stress stimulus….


Exosomes: From Garbage Bins to Promising Therapeutic Targets.

Intercellular communication via cell-released vesicles is a very important process for both normal and tumor cells. Cell communication may involve exosomes, small vesicles of endocytic origin that are released by all types of cells and are found in abundance in body fluids, including blood, saliva, urine, and breast milk. Exosomes have been shown to carry lipids, proteins, mRNAs, non-coding RNAs, and even DNA out of cells. They are more than simply molecular garbage bins, however, in that the molecules they carry can be taken up by other cells. Thus, exosomes transfer biological information to neighboring cells and through this cell-to-cell communication are involved not only in physiological functions such as cell-to-cell communication, but also in the pathogenesis of some diseases, including tumors and neurodegenerative conditions. Our increasing understanding of why cells release exosomes and their role in intercellular communication has revealed the very complex and sophisticated contribution of exosomes to health and disease. The aim of this review is to reveal the emerging roles of exosomes in normal and pathological conditions and describe the controversial biological role of exosomes, as it is now understood, in carcinogenesis. We also summarize what is known about exosome biogenesis, composition, functions, and pathways and discuss the potential clinical applications of exosomes, especially as biomarkers and novel therapeutic agents.


Exosomes and Their Role in Viral Infections


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….


Visceral Adipose Tissue Derived Exosomes Exacerbate Colitis Severity via Pro-Inflammatory MiRNAs in High Fat Diet Fed Mice


Pioneering epidemic study has revealed a strong association between obesity and the risk of colitis. In this study, high fat diet was found significantly aggravated the colitis induced by dextran sulfate (DSS). Meanwhile, high fat diet changed the miRNA profile of the visceral adipose exosomes, switching the exosome from anti-inflammatory to pro-inflammatory phenotype.

Strikingly, these inflammatory exosomes efficiently circulated into the lamina propria of intestine, while these exosomes predisposed the intestine to inflammation via promoting macrophage M1 polarization. Mechanistically, the exosomes promoted M1 differentiation at least partially via transferring pro-inflammatory miRNAs, such as miR-155. Moreover, exosome mediated miR-155 inhibitor delivery significantly prevented the DSS induced colitis. Together, the study has revealed an exosomal pathway how obesity aggravates colitis and proposed an exosome-based intervention strategy for colitis management.


Oxidative mechanisms of biological activity of low-intensity radiofrequency radiation


This review aims to cover experimental data on oxidative effects of low-intensity radiofrequency radiation (RFR) in living cells. Analysis of the currently available peer-reviewed scientific literature reveals molecular effects induced by low-intensity RFR in living cells; this includes significant activation of key pathways generating reactive oxygen species (ROS), activation of peroxidation, oxidative damage of DNA and changes in the activity of antioxidant enzymes. It indicates that among 100 currently available peer-reviewed studies dealing with oxidative effects of low-intensity RFR, in general, 93 confirmed that RFR induces oxidative effects in biological systems.

A wide pathogenic potential of the induced ROS and their involvement in cell signaling pathways explains a range of biological/health effects of low-intensity RFR, which include both cancer and non-cancer pathologies. In conclusion, our analysis demonstrates that low-intensity RFR is an expressive oxidative agent for living cells with a high pathogenic potential and that the oxidative stress induced by RFR exposure should be recognized as one of the primary mechanisms of the biological activity of this kind of radiation.


Q&A: What are exosomes, exactly?


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