The Tree of Life: Phylogenetics

STORY BY James Sullivan

Published: August 11, 2013

Some time ago there was the speculative question of what would be genetic science's equivalent to the Walkman – questioning the advances in genetic research that would be applicable to our own everyday lives, if for nothing else but to make them more convenient. All too often is the question asked, “What is the practical purpose of evolutionary biology, apart from being its own field?” Phylogenetics may be the answer to both – one of the very basic components of biology – in which the descent of various organisms is steadily mapped out and its relationships between the other forms of life diagrammed through computer algorithms just by entering in phenotypes to create a result. With just knowledge of phenotypes of a few related organisms, by computer they are able to construct a tree that features its line of descent.

This can mean not only breakthroughs in fighting viral epidemics by discovering where a specific strain of virus comes from and its potentially growing resistance to treatments, but also can represent a breakthrough in criminal forensics as well. This science has already been applied in Spain by researchers working at the University of Valencia. A local anesthesiologist Juan Maeso has been accused of spreading the Hepatitis C virus to his patients over the course of nine years through equipment that he failed to sterilize, a disease that he himself had been infected with and continued to practice. Collecting data from patients who had tested positive for the virus, the researchers isolated a specific genome of the E1-E2 region. Maeso tested positive for Hepatitis C himself, and further, the researchers isolated 322 cases of patients also testing positive – who carried a virus with the same phenotypes as the anesthesiologist. There were 47 additional cases that were quickly ruled out as not being related to Maeso's infection, and therefore these patients had acquired the virus from a different source.

Having gathered the phenotype, Valencia researchers were able to then establish at what point the victims had first become infected, a timing that coincided with the first reported cases of Hepatitis C being observed in Maeso's patients. Although the case may seem like a rare horror story that hasn't been seen in the States since the case of Kim Bergalis and her dentist Dr. David Acer back in 1987 (one year before Maeso had developed his infection), this seemed all too familiar for me to read about. At least this story has a somewhat more satisfying ending. Maeso was charged with criminal negligence and given a lifelong prison sentence, in addition to having to make reparations to his victims. In the case of Kim Bergalis, the connection that she contracted AIDS from her dentist (and thus making her a so-called 'innocent victim,') has never been firmly established. At the same time, over twenty years later, people are still reeling in horror from the case of Scott Harrington in Tulsa, Oklahoma, in which some 7,000 patients may have potentially been exposed to HIV as well as types of Hepatitis, many of which are awaiting results.

 

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