Genomic Signature in Blood Differentiates Among Colds, Flu, and Pneumonia

A genomic signature in blood revealed exposure to common upper respiratory viruses, such as the cold or flu, even before symptoms appeared.

The viral signature, determined from a single tube of blood, reflected a subtle but robust set of changes in genes that were activated as the body responded to infection. The signal from the signature was strong enough in symptomatic individuals to reveal whether the infection was viral or bacterial. It also discriminated between those who had a viral infection and those who did not.

In a study carried out at Duke University (Durham, NC, USA) 59 healthy volunteers were infected with a live cold virus, human respiratory syncytial virus (RSV), or influenza A virus. Scientists identified changes in 30 genes that were activated as the body responded to infection. The symptoms of a cold, flu, or pneumonia are frequently similar. Currently doctors are unable to tell what the patient is suffering from until laboratory tests are conducted, and that can take days.

The body's immune system responds quickly and in a specific manner when exposed to a virus as opposed to bacteria, explained Dr. Aimee Zaas, an infectious diseases specialist at Duke University and lead author of the study. However, the acute viral response signature might only be applicable to people who have healthy immune systems. It will be necessary to show that the approach works in patients with underlying immune deficiencies before it can be used as a diagnostic tool for everyone.

The study was published in the published in the August 6, 2009 edition of Cell Host & Microbe.

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