New blood test may reveal complete viral infection history: study

By analyzing a single drop of blood, a new technology called VirScan may identify almost all of the viruses that one has been exposed to over the course of their life, researchers said Thursday.

The test, described in the U.S. journal Science, costs only 25 U.S. dollars to run and was believed to be an efficient alternative to existing diagnostics that test for specific viruses one at a time.

"VirScan is a little like looking back in time: using this method, we can take a tiny drop of blood and determine what viruses a person has been infected with over the course of many years," Stephen Elledge of the Brigham and Women's Hospital, who led the development of VirScan, said in a statement.

"What makes this so unique is the scale: right now, a physician needs to guess what virus might be at play and individually test for it. With VirScan, we can look for virtually all viruses, even rare ones, with a single test."

Classic blood tests, known as ELISA assays, can only detect one pathogen at a time. Additionally, ELISA assays have not been developed against all viruses, further limiting their usefulness.

In the new study, Elledge and his colleagues tested blood samples from almost 600 people from Peru, the United States, South Africa and Thailand.

The team developed and used a library of peptides -- short protein fragments derived from viruses -- representing more than 1, 000 viral strains to find evidence of previous viral exposure.

They found most people had been exposed to about 10 viruses, but at least a couple volunteers had experienced 84 viral species.

As expected, certain antibodies, which were produced by the immune system when it encounters corresponding viruses, were common among adults but not in children, suggesting that children had not yet been exposed to those viruses.

Individuals residing South Africa, Peru and Thailand, tended to have antibodies against more viruses than people in the United States.

The researchers also found that people infected with HIV had antibodies against many more viruses than did people without HIV.

In addition, they were surprised to find that antibody responses against specific viruses were surprisingly similar between individuals.

"A viral infection can leave behind an indelible footprint on the immune system," said Elledge. "Having a simple, reproducible method like VirScan may help us generate new hypotheses and understand the interplay between the virome and the host's immune system, with implications for a variety of diseases."

The team suggested that VirScan's accuracy could be improved with more blood samples and that it might also be adapted for bacteria, fungi or protozoa in the future. Endite