Harvard: From a single drop of blood, researchers can now simultaneously test for more than 1,000 different strains of viruses that may have currently or previously infected a person. Using a new method known as VirScan, researchers from Harvard Medical School and Brigham and Women’s Hospital tested for evidence of past viral infections. They detected 10 viral species per person on average. The new work sheds light on the interplay between a person’s immunity and the human virome—the vast array of viruses that can infect humans—with implications both for the clinic and for the field of immunology. The team reported its findings in Science on June 5.
Get more HMS news here.
“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,” said corresponding
author Stephen Elledge, Gregor Mendel Professor of Genetics and of Medicine at HMS and Brigham and Women’s.
“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
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. The team found the sensitivity and specificity of
VirScan to be very similar to that of ELISA assays. The tests cost a
comparable amount to run.
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.
Rates of viral exposure varied by age, geographic location and HIV
status, but the team found that a small number of peptides were
recognized by the vast majority of people’s immune systems. This
pattern, suggesting that the immune systems of many individuals are
hitting upon the same protein portion in a virus, could have important
implications for understanding immunity.
VirScan may also help researchers find correlations between previous
exposure to a particular virus and the development of a disease later in
life. A connection between Epstein-Barr virus— one of the most common
viruses seen in this study—and the risk of certain kinds of cancer is
already known. The new method may help reveal other as-yet-unknown
“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.”