Viral History in One Drop of Blood

The newspapers of course are blowing the research findings a bit out of proportion.  Baltimore Sun “Drop of blood may disclose person’s whole viral history”, New York Times “Every Virus a Person Has Had Can be Seen in a Drop of Blood, Researchers Find” or the Washington Post “This Blood Test can Tell You Every Virus You’ve Ever Had”

Wow, sounds impressive right? But is you read carefully, it is still impressive, just not as impressive as the headlines make it sound. So here is the deal:

The June 5, 2015 issue of  the journal Science had an article about a new diagnostic test which scans the blood for antibodies to any of 206 virus species and over 1,000 strains that infects people. It is a DNA test that focuses on this specific topic. Although specific might not be the right word here because most diagnostic tests will test for a single pathogen such as HIV.

Research vs. Clinical Use

It is not clear yet how this could be used in a clinical diagnostic setting. Currently it is mostly of interest to researchers. One problem in terms of disease treatment is that antibodies aren’t formed immediately and the build over time. So in some sense you are looking at history and not the present.

For research, scientists are starting to use this test to look and see what viruses people have been exposed to and if that leads to any diseases such as cancers and various chronic diseases due to that exposure.

The test is called VirScan and currently costs about $25. A number of people were tested in the US, Peru, South Africa and Thailand. On average people had been exposed to 10 of the different species although some were much higher. (If you have caught a cold on multiple occasions, and each time it was caused by a different strain of rhinovirus, it will only show up as one infection and one species.)

It was interesting that people in the US had antibodies to a lot fewer viruses than people in the other three countries. It is not known if this is due to genetic differences, different local strains of viruses, cultural differences, sanitation differences or something else.

Where the Headlines are Overblown

The test rarely had false positives and picked up 90% of known infections. But, adults will have been exposed to more than 10 viruses over their lifetime and they aren’t showing up. The immune response fades over time, so this test will pick up more recent infections but it isn’t clear yet how far back it will detect viral infections.

An interesting and unexpected finding was the similarity in the response to different viruses. It was thought that each person responded differently, but it turned out that the antibodies of each person targeted the same amino acids for any given virus. That could lead to new therapies or vaccines.