Infectious disease specialists on the medical staff at Children's have found a new method for identifying suspect viruses and bacteria that cause some of the most common acute infections in children.
   Traditionally, researchers have looked for clues to an infection by tracking down the virus or bacteria causing it. But that doesn't always work because the bacteria or virus may not be present in the blood or other easily accessible areas.  

A new approach
As the primary pediatric teaching facility for UT Southwestern, the medical staff at Children's conducts research that is instrumental in developing treatments, therapies, and greater understanding of pediatric diseases.
   In this case, researchers on the medical staff at Children's, UT Southwestern and the Baylor Institute for Immunology Research came up with a different approach - analyzing the telltale "fingerprints" a disease leaves behind on cells involved in the immune response, and using that information to get a composite sketch of the infectious agent.
   "We are genetically programmed to respond differently to different infections. We have developed the tools to understand that," said Dr. Octavio Ramilo, director of Infectious Disease Research at Children's, professor of Pediatrics at UT Southwestern and lead author of the study, which appears in the March edition of the journal Blood.
   "Infectious diseases are the No.1 cause of death in the world," Dr. Ramilo said.  "So we hope this eventually can be used not only to diagnose, but also to understand the prognosis and how the body is responding to therapy."

Finding the "fingerprint"
Different viruses and bacteria trigger the activation of very specific genes that code for proteins called receptors in leukocytes, the white blood cells that help the body fight infections. Researchers surmised that if they looked at the leukocytes, they could detect the specific pattern of receptors - similar to a disease "fingerprint" - and be able to identify which infection was present. The process to identify such bio-signatures, called gene expression profiling, is done using microarray analysis.
  
Looking ahead
The next step will be to study whether the microarray analysis can be applied in a more challenging clinical setting, such as an emergency room.
   "When a child comes in with a fever to the ER, we want to see if we can predict who just has a virus and can go home, and who has to be admitted and put into the intensive care unit and treated with antibiotics," said Dr. Ramilo. "That's our goal. This is just the first step, but it establishes a basis for us to do that."
   Further studies may eventually help doctors track the progression of disease and help assess risks of complications. It could also prove useful for identifying previously unknown illnesses or biological weapons.
   "Even if we don't know which pathogen it is, we still can tell which family or which group it's in, so if someone engineers a virus that has never been seen, we will have hints that it's close to something that is known," Dr. Ramilo said.
     
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