Defensins are immune system proteins which work to defend the body by bonding with invaders to interfere with their functions. Cyclic theta defensins might sound something a science fiction writer would say after a blow to the head, but they're a particular form of these useful compounds, called "cyclic" because the peptide chain that forms their backbone is actually circular. (That's actually definition of "theta" defensins, so please excuse our polysyllabic tautology.)
These defensins bond to HIV retroviruses to prevent them from entering cells - and a virus which can't get into cells is just a scrap of amino acids waiting to be destroyed. This incredibly useful anti-AIDS immune equipment was first found in monkeys, but a joint team of scientists from the Universities of Central Florida, California, and the Center for Disease Control (who are kind of into this sort of thing) found the genetic code for their construction in humans.
So why do thirty-three million people suffer? Because vulnerability to HIV is a genetic disorder, and one we all have. Many genetic diseases are the result of "nonsense mutations" where a random piece of code is accidentally transcribed as a stop codon, terminating construction of whatever protein that piece of DNA was responsible for. Most of such stop mutations are rare because the victims don't breed but since HIV (or any comparable disease) wasn't a problem until recently this inability to produce theta-defensins wasn't naturally selected against.
But what Mother Nature messes up, mankind can fix: the team have experimentally reactivated the code in the lab and shown that the brand new human-made theta-defensins (back on tour after a few million years vacation!) are as effective against HIV as ever, preventing any entry into potential host cells. Even better, they say in the future the code could be reactivated in cervicovaginal tissues by the application of a cream.
That's right. Anti-AIDS cream. Thanks Science! (Or if you want, you can stick with waving ancient texts at people and screaming "Don't do anything because it's all evil!")
Reawakening Retrocyclins: Ancestral Human Defensins Active Against HIV-1
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