Testing for Proteins in Saliva Could Help Detect COVID-19 and Predict Severity

Researchers have identified a family of proteins that is significantly elevated in the saliva of patients hospitalized with COVID-19. The proteins, known as ephrin ligands, could potentially serve as a biomarker to help doctors identify patients who are at risk for serious illness.

For the study, researchers at the University of Utah Health (Salt Lake City, UT, USA) analyzed saliva samples collected from patients with respiratory symptoms. Out of these, 67 patients tested positive for COVID-19 while 64 patients did not. The researchers found that the presence of ephrin ligands in saliva was strongly associated with the diagnosis of severe COVID-19.

The study findings could help shed light on the biological processes involved in severe reactions to COVID-19 infection, according to the researchers. Previous studies suggest ephrins play a role in injury and inflammation. The scientists say more research is needed to determine whether ephrin concentrations are linked with a higher likelihood of hospitalization, critical illness or death. In addition, as new viral variants emerge, it can be difficult to tell whether existing COVID-19 tests are able to accurately detect infections involving new variants. Looking for ephrins in saliva could offer a simple, non-invasive way to provide corroborating evidence when there is inconsistency between test results and the clinical picture.

“Ephrins are detectable in saliva samples and could serve as adjunct markers to monitor COVID-19 disease progression,” said study author Erika Egal, DVM, PhD, a postdoctoral fellow at University of Utah Health. “We can collect saliva without harm or discomfort for most patients, which can reveal patient responses to COVID-19 and potentially guide care.”

“Saliva is packed with information beyond detecting the COVID-19 infection itself,” said Patrice Mimche, PhD, at University of Utah Health in Salt Lake City.. “We demonstrate that immune cells, cytokines and soluble proteins can be reliably measured from saliva samples. Our findings provide a starting point for investigations looking into causal pathways between infection and bad medical outcomes.”

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