Scientists have identified a group of proteins that, when detected in specific quantities in the mucous, are 86 percent accurate in confirming the infection is from a cold or flu virus, according to a small, proof-of-concept trialpublishedin the journalEBioMedicine.
The researchers hope their initial work identifying the protein signature could aid the development of a quick, noninvasive doctor's office test to determine the cause of upper respiratory illness and appropriate treatment.
Although upper respiratory infections are among the most common reasons people visit the doctor in the U.S., health care providers lack tools to distinguish between a bacterial infection that might warrant antibiotics and a viral infection that would instead call for symptom relief.
Widespread use of antibiotics for upper respiratory infections don't benefit patients with viral illness and can contribute to antibiotic-resistant superbugs, senior author said. More precise diagnoses of these infections could be another tool to curb the development of superbugs, he said.
For the trial, researchers infected 88 healthy adult volunteers with a common strain of cold or flu virus (influenza A/H3N2 or human rhinovirus).
Some participants didn't get sick. Among those who developed infections, researchers found a distinct set of 25 proteins in fluid samples they gathered by flushing about 2 teaspoons of saline through the participant's nasal passages.
Unbiased proteomic discovery analysis identified 3285 peptides corresponding to 438 unique proteins, and revealed that infection with H3N2 induces significant alterations in protein expression. These include proteins involved in acute inflammatory response, innate immune response, and the complement cascade. These data provide insights into the nature of the biological response to viral infection of the upper respiratory tract, and the proteins that are dysregulated by viral infection form the basis of signature that accurately classifies the infected state.
Verification of this signature using targeted mass spectrometry in independent cohorts of subjects challenged with influenza or rhinovirus demonstrates that it performs with high accuracy.
Analyzing proteins in mucous is a less invasive approach and requires less processing than blood samples. The researchers hope additional studies verify the initial results and lead to the development of a paper-based test that could be used in doctor's offices or even at home to determine whether a doctor's visit is necessary, said a senior author.
"The protein targets offer a faster, more cost-effective model for rapid screening and diagnoses of viral infections," senior author said. "If the data are verified, the model could be valuable in many circumstances, such as rural settings or developing countries with less convenient access to health care, or even as an airport screening tool during an outbreak of a particularly threatening strain of flu."