Archive for Beatrice Hahn

King Leopold’s Pandemic

Posted in Ecological resilience, Evolution, HIV with tags , , , , , , , , , on March 2, 2010 by Rob Wallace

The origins of HIV offer a great example of the ways treating human impact as an afterthought—discussed in our previous post—locks the study of pathogens into limited and oftentimes downright drunken trajectories.

In 2006 Beatrice Hahn and her colleagues identified the likely source for the SIVcpz progenitor that seeded HIV-1 group M, the clade that produced the AIDS pandemic. The team identified two wild chimpanzee groups in the southeastern corner of Cameroon—50 km north of Ouesso—with SIVcpz phylogenetically closest to group M.

The team hypothesized the virus spread to humans there a hundred years or so ago before making its way south by the Sangha and Congo Rivers to Leopoldville (now Kinshasa), one of several new colonial administrative centers in the area. By a relaxed molecular clock permitting different rates of nucleotide substitution across phylogenetic branches, Worobey et al. (2008) dated the emergence of group M to 1908 (1884-1924). After circulating regionally for decades, diversifying into many of its present-day subtypes, the virus exploded in population size and made its way out onto the global travel network and to the rest of the world.

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