Viruses possess an ability to mutate into strains that can render vaccines useless and become deadlier than their predecessor. But for a team of Texan scientists, this biological danger became a forensic asset that helped prosecutors convict two men accused of infecting close to a dozen women with HIV.
In 2009, Philippe Padieu was sentenced in Texas to 45 years in prison for aggravated assault with a deadly weapon – the weapon, in this case, being HIV. After learning that he had contracted HIV, Padieu had sex with six women, all of whom later tested positive. Prosecutors needed to show that the women’s cases had a common source.
In a paper published this week in Proceedings of the National Academy of Sciences, researchers from the University of Texas at Austin and Baylor College of Medicine in Houston explained how they proved it.
The researchers took samples of the virus from Padieu and the victims. (The samples were labeled anonymously, so that the researchers did not know whether each sample belonged to a victim or to the accused.)
HIV mutates at a breathtaking rate. Once a virus infects a host it can make as many as 10 billion virus particles per day. Usually just one or two strains of the virus survive to reproduce and infect a new host. This “genetic bottleneck” that occurs when the virus is transmitted allows scientists to track which viruses from different infected hosts are related, and whether they had a common source.
After comparing DNA sequences on two gene regions of the virus, the researchers were able to show that the samples did appear to be related – and that one of them was the source for the rest. At trial, that source was revealed to be the defendant, Philippe Padieu.
The scientists had also done the same analysis for a case in Washington state involving Anthony Eugene Whitfield, who was accused of having unprotected sex with 17 women from 1999 to 2004 after finding out seven years earlier that he had been infected. Five of the women later found they had the virus. Whitfield was convicted in 2004 of first-degree assault with sexual motivation, and sentenced to 178 years.
Though the study lays out the groundwork for tracking such HIV-related cases, the authors wrap up on a cautionary note. “Some argue that criminalization of HIV is likely to have a negative impact on public health and human rights,” the researchers wrote. Having HIV (and perhaps unknowingly transmitting it) should not be a crime — but consciously using it as a weapon may be another matter.
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