The VirScan test gives doctors insight into a patient’s lifetime exposure to viruses and thus may be developed into a useful medical laboratory test

Scientists and pathologists are learning that blood is like a time capsule, holding precious information about exposure to viruses over the years—chickenpox at five, mononucleosis at 18, flu at 40. You get the idea.

Now, researchers at Howard Hughes Medical Institute (HHMI)  have found a way to tap that entire data stream, so to speak. An inexpensive blood test, they say, reveals every virus that has passed through the body over time.

New Discoveries Could Lead to a Useful Clinical Laboratory Test

The testing method, called VirScan by researchers, is an efficient alternative to current medical laboratory tests that test for specific viruses one at a time, according to an HHMI news statement about the new technology.

“We’ve developed a screening methodology to basically look back in time in peoples’ blood and see what viruses they have experienced. Instead of testing for one individual virus at a time, which is labor intensive, we can assay all of these at once. It’s one-stop shopping,” stated HHMI investigator Stephen Elledge, PhD, in the statement. Elledge is a Professor of Genetics at Harvard Medical School and at Brigham and Women’s Hospital, and led VirScan’s development.

For medical laboratory leaders and pathologists, the blood test may have profound implications:

1. It could help clinical labs manage costs associated with over-test utilization by reducing the guesswork of providers regarding specific lab tests that may or may not be the right ones for patients; and,

2. VirScan may possibly become an important source of data on individuals and populations. It may inform healthcare Big Data and longitudinal reports in unexpected ways by offering up complete viral history of an individual, aggregated across large populations.

Looking for a Way to Understand a Patient’s Viral History

Researchers were motivated to create a viral infection test that would go beyond testing one pathogen at a time based on a specific clinical hypothesis. They aimed their study on viruses, which leave footprints in the form of antibodies in the blood.

“A method that could simultaneously detect response to all human viruses would allow hypothesis-free analysis to detect associations between past viral infections and particular diseases or population structures,” they wrote in a paper about the study in the journal Science.

“Our preliminary studies have revealed intriguing general properties of the human immune system, both at the individual and population scale,” they concluded.

One Test Can Identify Many Viruses

The research team tested VirScan on 569 people from four countries (Peru, South Africa, Thailand, and the U.S.). Findings suggest that each person, on average, had antibodies in their blood for about 10 different viral species. Two people had antibodies for 84 different viruses.

The cost per blood sample is about $25. The VirScan approach to testing is “unbiased,” the researchers say. That’s because it has propensity to uncover diseases when it is unclear to doctors what to test for or what to suspect. For example, VirScan may discover undiagnosed and under-the-radar viruses such as hepatitis C and HIV.

“Ideally, this [VirScan test] will be a standard thing where you go to the doctor once a year for a checkup. There are literally millions of people walking around with unnoticed hepatitis C or HIV infections. Unless the doctor suspects you have HIV, they won’t even do a test for it,” said Elledge in an article about VirScan in Newsweek.

Dr. Stephen J. Elledge poses for photo in his office at Harvard Medical School on Wednesday , Nov. 14, 2012, in Boston. (Bizuayehu Tesfaye/AP Images for HHMI)

Dr. Stephen J. Elledge poses for photo in his office at Harvard Medical School on Wednesday , Nov. 14, 2012, in Boston. (Bizuayehu Tesfaye/AP Images for HHMI)

How Does It Work?

VirScan works by searching the blood for antibodies to any of the 206 virus species that are known to infect people, the researchers explained. But how does it do that?

In an article about VirScan, New Scientist reported the details of the methodology:

1) An international database of viruses known to infect humans (about 1,000 strains from 206 viral species) was initially compiled by researchers;

2) The gathered information helped researchers to recreate DNA in each virus responsible for making proteins;

3) The DNA segments were put into individual bacteriophages (bacteria-eating material);

4) Each bacteriophage makes a viral protein on its surface;

5) Antibodies in the blood grab the proteins on the bacteriophages; and,

6) Bacteriophage sequencing reveals viral history.

VirScan

VirScan at work according to the HHMI study: antiviral antibodies in the blood find and bind to their target epitopes within displayed peptides. Scientists retrieve the antibodies and wash away everything except for the few clinging bacteriophage. Sequencing the DNA of those bacteriophage, the researchers identify which viral protein pieces were grabbed onto by antibodies in the blood sample. And that reveals the viruses the test subject previously encountered—via infection or vaccination. (Photo copyright: HHMI.)

Could This Approach Be Used for Other Diagnostic Purposes?

VirScan has potential to do more than uncover viral history, the researchers pointed out. It also could suggest the role viruses play in diseases such as multiple sclerosis, diabetes, and others.

“We can look comprehensively for viral exposures that correlate with these kinds of diseases in a way that would be infeasible if you had to test for each virus separately,” stated Elledge Lab Researcher Tomasz Kula in an article about VirScan in Discover magazine.

During disease outbreaks, VirScan may provide public health officials with clues, experts concluded.

“It’s a really exciting technique. If we’d have had the test during the HIV outbreak in the 1980s, it would have given us a clue for where to be looking to find out more about the virus,” stated Pamela Vallely, PhD, Professor, Medical Virologist, the University of Manchester, UK, in the New Scientist article.

Screening for Pathogens, Antibodies in Cancer Patients, and Viral Infections

The blood test is reportedly being refined by researchers. Elledge said his lab is using VirScan to look for antibodies that attack a body’s tissues in certain autoimmune diseases that are associated with cancer. Researchers believe VirScan also could be applied to screening for pathogens such as bacteria, fungi, and parasites.

Still other research has focused on broad screening for viral infections. A genetic testing method could be a fast and efficient way to screen for viral infections, according to a news statement from Columbia University’s Mailman School of Public Health. Called VirCapSeq-VERT, the method was developed by scientists at the university’s Center for Infection and Immunity.

Pathologists and clinical laboratory leaders are no doubt intrigued by these developments. VirScan can help providers better understand patient and population health as well as reveal more about the immune system. It could be a treasure trove of diagnostic data for medical labs that will need to somehow corral it all.

—Donna Marie Pocius

Related Information:

Your Viral Infection History in a Single Drop of Blood

Comprehensive Serological Profiling of Human Populations Using a Synthetic Human Virome

VirScan Can Identify Your Past Viruses from a Drop of Blood

Cheap Blood Test Reveals Every Virus You’ve Ever Been Exposed To

Blood Test Can Detect Every Virus You Ever Had

Diagnostics Breakthrough Brings Viral Sequencing to Doctors’ Toolkit