While most people can’t remember every viral infection they've ever had their blood definitely can. A new test, developed by researchers in Boston, counts the antibodies present in a person’s blood to reveal the complete history of the viruses they've been infected with over the course of their life.
The method is not only useful for diagnosing current and past illnesses, but also for developing vaccines and studying interactions between viruses and chronic disease.
“This is really a technical tour de force,” claims immunologist Hidde Ploegh of the Massachusetts Institute of Technology in Cambridge, who wasn't involved with the work but sees the implications.
The test also has the potential to reduce the number of tests required to find a particular pathogen, as presently medical staff most test blood samples for one pathogen at a time. This means a variety of tests looking for a variety of things. While the process is getting better, as companies like Theranos labs shrink test size and improve speed and accuracy, one test is always better than many.
Researchers led by Stephen Elledge of Brigham and Women's Hospital in Boston and Harvard Medical School developed their test by first assembling a library of almost a hundred thousand synthetic protein fragments, each representing a piece of a virus that an antibody might recognize.
When the proteins are added to a drop of blood, antibodies attach to recognized fragments and from there researchers isolate the antibodies to determine which viruses someone has been infected with.
The creative new test, dubbed VirScan, “allows scientists to ask questions that just couldn't be asked before,” Elledge says. “You can compare groups of people—young and old or those with a disease and those without—and see whether there’s a difference in their viral histories.”
In their research, most of which was outside the United States, most people had 10 previous viral infections, with those having HIV or living outside the United States averaging more. The most common viruses included the herpes virus and rhinoviruses, which causes the common cold.
Surprisingly, most people generated the exact same antibodies, disproving earlier theories that each person's immune system is incredibly unique.
It remains to be seen if the test can substitute for more specific, disease by disease tests, says microbiologist Vincent Racaniello of Columbia University. “Before we view this as a definitive definition of what people have been infected with, we need to be sure it’s a comprehensive picture,” he says. “Right now, I don’t think it is.”
Racaniello points deficiencies in finding the antibodies linked to noroviruses and rotaviruses, which cause large numbers of intestinal infections. This could be because such anti-bodies don't linger in the body for as long or it could just mean the test needs further fine-tuning.
Yet the work stands out by its breadth and technological innovation. Never before has such a comprehensive set of results been available in one simple test.
VirScan is not yet a commercial product but Elledge thinks it won't cost much more than existing tests that only look at one pathogen at a time. “You could give a drop of blood every few years and they can run it to see if you have any new infections,” he says. This could be particularly useful in diagnosing viruses like hepatitis C, which people are often unaware they have.