Measuring genomic response to infection leads to earlier, accurate diagnoses
[Via EurekAlert! – Infectious and Emerging Diseases]
(Duke University Medical Center) Duke researchers are looking to genomic technologies — not the isolation of bacteria or viruses — to quickly detect and diagnose infectious diseases such as the flu and staph.
Two studies appearing online Jan. 9, 2013, both in the journal PLOS ONE, show how a pattern of genomic information among infected individuals can be used to accurately pinpoint the cause of infection.
“Traditional diagnostic tests for infectious diseases rely on detecting the specific illness-causing pathogens. So you only find what you’re looking for,” said Geoffrey Ginsburg, M.D., PhD, a senior author on both studies and director of genomic medicine at the Duke Institute for Genome Sciences & Policy and professor of medicine.
Identifying the culprit pathogen guides the selection of treatment for sick patients; however, these traditional tests for infectious diseases can take several days and have varying levels of accuracy.
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Sequencing and expression tools will make identifying disease almost trivial in a few short years. And we will know we are sick days before wwe actually show symptoms.
The paper is quite interesting. They took volunteers and infected them with one of two strains of influenza. They they looked at different RNA expression patterns in the cells from their blood as time when on.
It turns out that we can now measure the responses of our bodies and how gene expression changes in order to respond to an infection. In this case, they could detect a set of gene expression changes that served as markers for infection, in many cases several days before any overt physical symptoms occurs.
The identification did not need the infectious agents to be isolated or cultured. And the predictive power was about 92%. They then went and looked at blood from people taken during the 2009 pandemic and were also able to identify those who were infected from those who were not.
Simply by looking at the changing expression levels of our own genes.
And another paper from Duke also showed that, at least at the bench, they could tell what type of infectious agent it was by the differing expression responses. They could identify Staphlycoccus infections, a major cause of septic shock, in mice and in humans. In as little as 2 hours after infection.
They were even able to differentiate between antibiotic-resistant strains of staph (MRSA) and antibiotic sensitive strains, a potentially huge benefit in the hospital. Another cool aspect was that the cohort of genes whose expression changes were seen in mice could also be translated to human gene expression patterns.
Even though not all the murine genes were found in humans (only about 69% were) it was still enough for the murine classifier to be used against human blood samples. This means that much of the work on disease identifiers can be done in mice and then checked in humans without having to do a lot of human experimentation.
I think an important aspect of this will be how speedy the entire operation is. In a real clinical setting, getting a result in a few hours is a must. I would imagine this is something they are working on.
But being able to diagnose disease from our body’s response is a great first step. The next is to run an array like this at home – yes we will need better tools but I think they will come. We prick our skin, provide a few drops of blood and get results in a shirt time. We would know we were sick even before we felt the physical symptoms.
This could change a lot of things.
A Man With A Ph.D. 