The protein syncytin, which is essential for formation of the placenta, originally came to the genome of our ancestors, and those of other mammals, via a retrovirus infection. Placental structures have also developed in non-mammalian vertebrates. The Mabuya lizard (pictured: image credit), which emerged 25 million years ago, has a placenta very much like those in mammals, and its development was likely driven by capture of a retroviral gene.
Paul Bieniasz joins the TWiV team to talk about the co-option, millions of years ago, of an endogenous retrovirus envelope protein by hominid ancestors for host defense against viral infection.
You can find TWiV #439 at microbe.tv/twiv, or listen. below.
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