By Lori Solomon, Editor, Diagnostic Testing & Emerging Technologies
A new test can reveal a person’s entire viral exposure history from a single drop of blood, according to a study published June 5 in Science. The VirScan test allows for simultaneous, comprehensive analysis of antiviral antibodies in human serum by combining immunoprecipitation and DNA microarray technology.
“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 co-author Stephen Elledge, Ph.D., from Harvard Medical School, and Brigham and Women’s Hospital (both in Boston), 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.”
Tests detecting antiviral antibodies in blood can identify both ongoing and cleared infections, unlike nucleic acid tests which cannot identify cleared viruses. Scaling serological analyses to encompass the complete human virome could improve researchers’ understanding of the interactions between the virome and host. These virome-host interactions have been linked to the pathogenesis of complex diseases such as type 1 diabetes, inflammatory bowel disease, and asthma. Despite the growing appreciation for the importance of interactions between the virome and host, VirScan represents the first comprehensive method to systematically characterize these interactions.
The multi-institutional researchers screened sera from 569 human donors across four continents. The researchers assayed more than 100 million antibody-peptide interactions for reactivity to more than 1,000 strains of 206 human viral species. The researchers report that VirScan’s performance in detecting known infections and distinguishing between related virus species is comparable to that of classic serum antibody tests for single viruses. Antibodies to an average of 10 viral species were found per person. Cold and flu viruses, along with herpes viruses were most commonly detected. Antibody targets with 56–amino acid resolution are detectable.
"VirScan is a method that enables human virome-wide exploration, at the epitope level, of immune responses in large numbers of individuals," write the authors. "We have demonstrated its effectiveness for determining viral exposure and characterizing viral B cell epitopes in high throughput and at high resolution."
VirScan can be automated in a 96-well format to enable high-throughput sample processing. Barcoding of samples during polymerase chain reaction enables pooled analysis, the researchers say, that can dramatically reduce the per sample cost.
Elledge believes assay speed can be further improved, but currently estimates it would take about two to three days to process 100 samples. VirScan’s "unbiased" serological screen is expected initially to play a role in research—analyzing and comparing viral infections in large populations as well as aiding researchers in finding correlations between previous exposure to a particular virus and the development of a disease later in life. Other human pathogens, such as bacteria, fungi, and protozoa, could also be incorporated into the VirScan technology.