Thursday, December 7, 2006 - 10:33
Five Bulgarian nurses and a Palestinian doctor (dubbed the Tripoli six) may be executed soon by the Libyan government for the crime of deliberately infecting over 400 children with HIV. If they did infect the children, this would be a horrendous crime. If they did not infect the children, it's the Libyan government that will be killing innocent people. The clock is ticking. Some of you might be wondering (I know I was): How exactly is molecular sequence data being used to solve the crime? Why are scientists and science bloggers claiming that the Tripoli six are innocent? Let's begin by summarizing what we know. What do we know about HIV? HIV evolves at a pretty quick rate. This rate can differ depending on the strain of the virus. This makes it possible for us to do the following:
- 1. Compare the sequences of different isolates. Because HIV changes quickly, we can conclude that if sequences are very similar, then they probably came from the same source.
- 2. Generate possible histories of HIV sequence evolution and use these to calculate the rate of evolutionary change. We can use the estimated rate of change to determine the date when strains diverged.