Human evolution: virus DNA in our immune system (Introduction)

by David Turell , Saturday, October 29, 2022, 17:34 (754 days ago) @ David Turell

Protection from the past:

https://www.sciencedaily.com/releases/2022/10/221027154145.htm

"Viral DNA in human genomes, embedded there from ancient infections, serve as antivirals that protect human cells against certain present-day viruses, according to new research.

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"Previous studies have shown that fragments of ancient viral DNA -- called endogenous retroviruses -- in the genomes of mice, chickens, cats and sheep provide immunity against modern viruses that originate outside the body by blocking them from entering host cells. Though this study was conducted with human cells in culture in the lab, it shows that the antiviral effect of endogenous retroviruses likely also exists for humans.

"The research is important because further inquiry could uncover a pool of natural antiviral proteins that lead to treatments without autoimmune side effects. The work reveals the possibility of a genome defense system that has not been characterized, but could be quite extensive.

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"Endogenous retroviruses account for about 8% of the human genome -- at least four times the amount of DNA that make up the genes that code for proteins. Retroviruses introduce their RNA into a host cell, which is converted to DNA and integrated into the host's genome. The cell then follows the genetic instructions and makes more virus.

"In this way, the virus hijacks the cell's transcriptional machinery to replicate itself. Typically, retroviruses infect cells that don't pass from one generation to the next, but some infect germ cells, such as an egg or sperm, which opens the door for retroviral DNA to pass from parent to offspring and eventually become permanent fixtures in the host genome.

"In order for retroviruses to enter a cell, a viral envelope protein binds to a receptor on the cell's surface, much like a key into a lock. The envelope is also known as a spike protein for certain viruses, such as SARS-CoV-2.

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"The study shows how one human protein of retroviral origin blocks a cell receptor that allows viral entry and infection by a broad range of retroviruses circulating in many non-human species. In this way, Feschotte said, ancient retroviruses integrated into the human genome provide a mechanism for protecting the developing embryo against infection by related viruses.

"Future work will explore the antiviral activity of other envelope-derived proteins encoded in the human genome, he said."

Comment: in the past I proposed that God used viruses to advance evolution. This study supports the point.