HIV: Why is the virus so ‘successful’?

HIV has repeatedly made the jump from animals to humans. But only once did it spread around the world. Jonathan Ball, professor of virology at the University of Nottingham, asks why. In Cameroon, about 100 years ago, an ill-fated human being, possibly a wildlife hunter or maybe a butcher, unwittingly became infected with a chimpanzee virus while handling a prized primate catch. At least that’s the consensus view on how the human immunodeficiency virus type 1 (HIV-1) pandemic started. But it wasn’t an isolated event. Scientists soon discovered that many different strains of HIV-1 existed. By studying their genetic relatedness, researchers were able to place all the known viral strains into one of four very clear groups, labelled Group M, N O and P, a tell-tale sign that these viruses successfully made the jump from their natural primate host into humans on at least four separate occasions. M for the win Groups M and N spilled...