Another example of ERV’s role in evolution


To end a royal dynasty, one has to eliminate its generals: this was the lesson of a Chinese movie I once watched in Netflix. Similar strategy is adopted by ERVs.
In a recent Plos Biology article (click here for a good summary for general audience) the authors identify MAVS, a protein produced by mitochondria (the general) that ignites immune response to protect the human cell (the Royalty) from Hepatitis-C virus (HCV). Three unrelated primates have the exact same non-synonymous mutation in the MAVS gene that  potentially alters the protein’s structure making it untouchable by the HCV particles. Unfortunately, humans, the primary host of HCV, do not have that mutation thus are relatively easily conquered by HCV. Sucks!
VERY INTERESTING is the presence of that same mutation in three different species: the authors apparently conclude it is a convergent evolution. However, this finding is in stark contrast with studies in yeast where convergence occurred at genic and network level but not at SNP level. Also, population genetics theories also find it very unlikely. Think about it, what is the probability that exactly same mutation would occur in three species branch AND SNP gets selected in all three branches? MINISCULE.
Could it be more plausible that the particular mutation existed in low frequencies in the common ancestor of all the primates and was readily available in all three branches at the time HCV like virus was active and quickly got fixed in the population? That particular virus probably did not infect humans (and other primates that do not have them) so they lost the mutaiton due to drift. Just a thought…

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Filed under Evolution, Human Evolution, My Life My Thoughts

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