This Single Test Could Identify Every Virus That's Ever Infected You
April 27, 2017•4 min
A story from Curiosity. Blood tests are no fun. Luckily, a group of researchers at Harvard Medical School and Brigham and Women's Hospital, along with others, have come up with what could become the king of all blood tests—and it needs just one drop of blood to work. Even better, it tests for more than 1,000 virus strains to determine whether a person has had a virus in the past, even if they're feeling just fine today. Turns out, the human body never forgets a virus. For their test, known as VirScan, the researchers encoded 93,000 pieces of synthetic DNA to create proteins produced by different viruses. Then they inserted those strings of DNA into bacteria-infecting viruses called bacteriophages so that each one produced a different type of viral protein. In all, that added up to every protein sequence you'd find in 1,000 different strains of human viruses. Finally, they let those bacteriophages mingle with a blood sample. Here's where the magic happens: every virus you've ever had leaves what the researchers describe as "an indelible footprint on the immune system"—that is, antibodies that are still ready to fight a virus, even years after an acute sickness. When the antibodies in the blood met up with the bacteriophage that matched the viral protein it was made to fight, the antibodies attacked and binded to that bacteriophage. All the researchers had to do then was retrieve those antibodies and check which bacteriophages were clinging to which antibodies, and then they knew what viruses had been in that blood sample before. The team published the results of their test in a 2015 study of nearly 600 people, which found each person had been exposed to an average of 10 viruses. Many study subjects' immune systems responded the same way to certain viruses, which the researchers said surprised them. Subjects with HIV had antibodies against many more viruses those who didn't have HIV, according to a Howard Hughes Medical Institute news release. Best of all, the VirScan method was found to be about as accurate and as costly as traditional methods. Right now, virus testing techniques focus on one virus at a time, rather than considering a person's full immune system. For example, if your doctor suspects you've got mononucleosis, or the "kissing disease," you'll get tested specifically for those antibodies today, and none other. The ability to evaluate a patient's virome, or the full complement of viruses within the human body, could potentially give a doctor more to work with when determining how to approach diagnosis or treatment. Researchers say some viruses actually change your immune system, and that alteration could affect type 1 diabetes, inflammatory bowel disease, asthma, and others. "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," said corresponding author Stephen Elledge of Harvard, in a news release. Elledge told the Howard Hughes Medical Institute his lab is "also using it to look for antibodies that attack a body's own tissue in certain autoimmune diseases that are associated with cancer." The VirScan test is still being researched, so for now you'll have to get tested for one virus at a time, only when your doctor suspects you've been infected.