Professor of Biology, IU Bloomington
One of life's historical boogeyman carries The Black Death. When this IU microbiologist heard about the bacterium, she thought to herself: 'Wow, I have to study that.'
Eschewing the cute and furry, some biologists devote themselves to life's boogeyman -- the agents of predation and disease. Microbiologist Melanie Marketon studies Yersinia pestis, the bacterium known as plague or, to those of another era, The Black Death.
The strains Marketon studies are "attenuated," meaning they are altered in such a way that prevents the bacteria from becoming pathogenic, in part because what Marketon currently studies doesn't require she or her students handle a pathogenic version of Y. pestis.
"The moment I heard about what this bacterium does, I thought to myself, 'Wow, I have to study that," Marketon said.
Just before it attacks a healthy host cell, Y. pestis produces something microbiologists call the "type III secretion system," a sharp, needle-like protuberance from its side. The needle is driven through a host cell membrane, at which point the bacterium can inject horrible toxins that eventually kill the host cell. The resulting mess creates a nutrient rich environment that allows the bacteria to grow and spread to other organs.
"The bacteria are like living syringes," Marketon said. "They're even preloaded, in the sense that before it comes in contact with the host cell, the toxins are produced and ready to go."
Plague bacteria mainly exist in rodents. Infections of humans in the U.S. and Europe are rare, Marketon said, "because the contact between rodents and humans has gotten very low." But in some parts of the world, where rodent-human contact is more frequent, plague continues to be a public health problem. "India and Madagascar still see outbreaks," she said.
Marketon and colleagues from Purdue University and the University of Notre Dame are working on a new detection system that would help medical staff and rangers better detect the presence of Y. pestis in blood samples.
Medical staff makes sense, but why rangers? Marketon anticipates park service employees could extract blood from captured rodents to determine whether Y. pestis is endemic and, therefore, a risk to local species and hikers.
Y. pestis is susceptible to antibiotics, but successful treatment depends on quick diagnosis. "We want to help people know what's going on and also aid early detection," Marketon said. "If Y. pestis infections are caught early, survival rates are very high."
(Editor's note: Read more about Marketon's research at this web site: http://www.bio.indiana.edu/facultyresearch/faculty/Marketon.html.)