Sunday, 23 August 2015

Evolution of HIV Took 11-16 Million Years.

Model of a retrovirus capsid hexamer, showing the conserved beta-hairpin domains common to most kinds of retroviruses (circled) and a pocket containing additional sites thought to affect recognition of lentiviruses by the TRIM5 anti-viral defense proteins of old world monkeys (arrow).
Credit: Johnson et al, CC-BY
PLOS Pathogens: Evolutionary and Functional Analysis of Old World Primate TRIM5 Reveals the Ancient Emergence of Primate Lentiviruses and Convergent Evolution Targeting a Conserved Capsid Interface

If you sincerely want to be a sanctimonious religious bigot presenting yourself as the moral superior of other people, it helps to base it on real facts, not made up ones. Take, for example, those morally reprehensible evangelical Christian and Muslim bigots who like to condemn people suffering from AIDS by pointing the finger and telling them that the virus which causes it was made by God to punish sinners, especially homosexuals.

It ought to be something of a shock to these repugnant bigots then, to discover that the virus wasn't created at all but has been evolving slowly over at least 11 million years and maybe for 16 million years, just as everything else has been, and is an interesting example of the product of an ongoing arms race between pathogen and victim, with all the intelligence to be found in a fruitless arms race - i.e., none at all.

Recognising that these arms races exist, Welkin Johnson, from Boston College, USA, and colleagues decided to investigate the antiviral gene, TRIM5, to see what could be learned about its evolution and hence how species adapt to HIV-like viruses known as lentiviruses. Many primate species, unlike humans, have a version of TRIM5 which protects them against HIV by coding for a protein which attaches to HIV particles when they enter cells and prevents them replicating. It does this by having a special site which binds to a location on the coating protein on the virus- the capsid - like a key fits a lock.

By comparing the TRIM5 gene from 22 different African primates, the team believe they have shown that there have been several periods where the presence of the virus selected for variations of TRIM5 which rendered them harmless, then periods when the presence of protective TRIM5 genes selected for variations of viruses which could avoid the neutralising protein - in other words, the classical evolutionary arms race. Moreover, it proved possible to construct an evolutionary tree for this gene which gave protection for family-specific forms of virus. In other words, the evolutionary tree of this family of viruses maps closely to the evolutionary tree of the TRIM5 gene and to the evolutionary tree of these African primates.

Author Summary

Old World primates in Africa are reservoir hosts for more than 40 species of simian immunodeficiency viruses (SIVs), including the sources of the human immunodeficiency viruses, HIV-1 and HIV-2. To investigate the prehistoric origins of these lentiviruses, we looked for patterns of evolution in the antiviral host gene TRIM5 that would reflect selection by lentiviruses during evolution of African primates. We identified a pattern of adaptive changes unique to the TRIM5 proteins of a subset of African monkeys that suggests that the ancestors of these viruses emerged between 11–16 million years ago, and by reconstructing and comparing the function of ancestral TRIM5 proteins with extant TRIM5 proteins, we confirmed that these adaptations confer specificity for their modern descendants, the SIVs.*

Copyright: © 2015 McCarthy et al. Reproduced under the terms of Creative Commons Attribution License (CC-BY 4.0)

So, biologically and evolutionarily, it looks exactly like the current battle between humans and HIV is just another turn in the merry-go-round arms race.

Would any creationists like to try to justify their smug pretence of moral superiority by explaining why their magic invisible friend so closely mimicked a classic evolutionary process, taking maybe as long as 16 million years, to produce a virus to victimize a section of humanity, and especially Africans, adult, children, male gays and straights (but not lesbians), and began the process way back before there were not only no humans but none of the immediate ancestors of humans either?

Or haven't you thought it through in your rush to find something to condemn other people as your moral inferiors?

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