Doctors often don't have a complete picture of their patients' health histories — they only know about past illnesses that a patient remembers and tells them about, and patients may not know whether they've been exposed to certain diseases.
But now, researchers at Brigham and Women's Hospital in Boston say they have created a tool that could reveal many of the viruses that have infected a person in the past. Called VirScan, the test looks for hundreds of viruses at once, and does so at a fraction of the cost of traditional tests, and with smaller samples of blood, according to the researchers.
"We could use a lot less blood [than traditional tests]," said Tomasz Kula, one of the co-authors of the new research and a graduate student at Harvard Medical School. "It could be a pinprick."
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To make the test, the researchers used the DNA codes of 206 viruses whose genomes had previously been sequenced. The researchers focused on the part of the viral DNA that codes for the proteins that appear on the virus' surfaces, and engineered new viruses to have these surface proteins. [The 9 Deadliest Viruses on Earth]
The VirScan test uses these engineered viruses to look for antibodies to each of these viruses in a sample of a person's blood. Antibodies are immune system molecules that zero in on the proteins of a virus's coat and stick to it, flagging the virus as a foreign invader and alerting other parts of the immune system to kill or neutralize the virus.
In experiments, the researchers ran the test on nearly 600 people living on four continents. They found that the study participants had antibodies to an average of 10 virus species. In two people, they found antibodies to 84 virus species.
To see how well the scan could work as a test, the group ran the scan on people known to be infected with hepatitis C and HIV. VirScan detected the viruses 95 percent of the time.
The researchers were surprised to find that widely separated groups of people, more often than not, showed antibodies to the same or similar viruses. "We thought it would be a lot more individual than that," Kula said. "Maybe antibodies have more similarity than we've been thinking."
Kula said this finding showcased one of the big advantages of this method of testing for a person's viral infection history: The VirScan allows researchers to see similarities and differences in large populations.
This could be helpful in studying conditions — for example, chronic fatigue syndrome — that researchers suspect may be caused by a virus but haven't proven for sure to have a viral origin. Current methods of testing for hundreds of viruses at are time-consuming and expensive, but the new test could make such an analysis feasible, the researchers said.
"We could also see if individual viruses are correlated to other diseases, or try to figure out why only a fraction of patients" are helped by certain cancer treatments, Kula said.
Because the new test is relatively cheap — Kula noted the chemicals necessary are a few dollars per person, or perhaps even less — it could also help doctors and patients by detecting their exposure to a virus they weren't aware of. Hepatitis C, Kula said, is often not detected for months or years, because few people think to ask about it.
But there are limits to what VirScan can do. It won't work on newly discovered viruses, or any other virus that researchers have not yet sequenced. Also, viruses with small genomes may be harder for the test to find, Kula said.
The study was funded by the Howard Hughes Medical Institute, and appears today (June 4) in the journal Science.
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