Thursday, July 26, 2012

A scientific breakthrough that will revolutionise archaeological epidemiology

My friend, Dr Angelique Corthals, has a new paper out. (Perhaps you recall her last one, which caused a stir by asserting that MS is a metabolic disorder.) This is another cracker: she and her team are the first to have detected an immune response in a mummy using proteomics. (Proteomics decodes proteins rather than DNA--which is an investigative method prone to contamination, especially when a sample is old and much-exposed to the vagaries of time.)

Here's the abstract of the paper, "Detecting the Immune System Response of a 500 Year-Old Inca Mummy," just published in in PLoS ONE:

Disease detection in historical samples currently relies on DNA extraction and amplification, or immunoassays. These techniques only establish pathogen presence rather than active disease. We report the first use of shotgun proteomics to detect the protein expression profile of buccal swabs and cloth samples from two 500-year-old Andean mummies. The profile of one of the mummies is consistent with immune system response to severe pulmonary bacterial infection at the time of death. Presence of a probably pathogenic Mycobacterium sp. in one buccal swab was confirmed by DNA amplification, sequencing, and phylogenetic analyses. Our study provides positive evidence of active pathogenic infection in an ancient sample for the first time. The protocol introduced here is less susceptible to contamination than DNA-based or immunoassay-based studies. In scarce forensic samples, shotgun proteomics narrows the range of pathogens to detect using DNA assays, reducing cost. This analytical technique can be broadly applied for detecting infection in ancient samples to answer questions on the historical ecology of specific pathogens, as well as in medico-legal cases when active pathogenic infection is suspected.
As the Stony Brook University Medical School press release notes, "Pathogen detection in human remains, including ancient ones, can help uncover mysteries of past diseases and epidemics and in determining cause of death. Techniques have been largely based on amplification of DNA from microbes. This process is effective for confirming the presence of a pathogen but not for determining if a person was ill with an infectious disease." Angelique explains why this is such an important breakthrough. "This approach opens a new door to ways in which scientists can more accurately solve some of history’s pressing medical mysteries, such as why the Influenza Epidemic of 1918 was so devastating, or what really caused such high mortality in Plague epidemics."

So now I just need some enterprising archaeologist to stumble over the body of Hild. We could learn so many things from her remains (yes, even 1,400 year-old remains): strontium levels in tooth enamel would tell us where she grew up. We could figure out what she ate. We could look at her skeleton and tell what kind of life she'd led: heavy labour, textile production, healthy leisure. And now we might also have a shot at identifying what she died of (my guess: malaria).

I love having smart friends. I love science.
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