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A $25 Blood Test Could Detect Every Virus That has Ever Infected You
Every time a virus gets you sick, your immune system keeps a record. This essentially becomes a kill list that lets your body recognize and readily dispatch of any virus that tries to invade again. Scientists have now created $25 test blood test that prints out this list—an easy and cheap way to find out every virus that's ever made you sick.
To understand how this test, called VirScan, works, you need to know a bit about human immunity. The immune system responds to a viral infection by making antibodies, proteins that then bind to viral proteins and render them useless. Small amounts of these antibodies keep circulating in your blood even after you recover. They lie in wait for the next time you encounter that virus.
Existing tests for viruses—say for HIV or hepatitis C—in fact already look for these antibodies. What makes VirScan different is that it can look for antibodies matching virtually every virus known to infect humans at once. That's 1000 strains from 206 species.
http://gizmodo.com/a-25-blood-test-could-detect-every-virus-thats-ever-in-1709096154
[Also Covered By]: http://www.eurekalert.org/pub_releases/2015-06/hhmi-yvi060115.php
[Abstract]: http://www.sciencemag.org/content/348/6239/aaa0698
VirScan Blood Test to Identify Past Exposure to All Known Human Virus Infections
Harvard University Medical School US researchers have developed a blood test that can determine past exposure to every known human virus infection. It examines virus-specific antibodies present in a drop of blood using bacteriophages:
Prof Stephen Elledge from the Harvard University Medical School US, who led the research team, told Science in Action that the new technique will overcome this limitation [of testing limited numbers of virus strains]: "You can ask questions about all viruses rather than have to do things one at a time, so it allows you to discover connections between different populations or different diseases amongst groups of people. Now that we can look at all viruses, it's a complete game-changer."
Researchers have been working out the genetic sequence - the blueprint - of all human viruses for many years. The team used this information to generate a pool of bacteriophage - viruses that grow easily in the laboratory - with each bacteriophage expressing a tiny fragment of this human-virus blueprint on its surface. Antibodies present in a drop of human blood could then be used as bait to go fishing in this phage pool - only bacteriophage that express protein fragments recognised by the antibodies in the blood sample will be caught. Sequencing the bacteriophage DNA reveals the human viruses that an individual has been exposed to.
The team used their test to interrogate sera obtained from more than 500 people of different ages and living in different global locations. The data showed that the number of virus infections detected in people increased during life. The study also suggested that those living in the US were exposed to fewer infections than people living in South Africa, Thailand or Peru. The greatest number of virus infections that were detected in any single individual was around 80, but the average number was only 10. Prof Elledge thought that this was because some individual virus protein fragments can represent many related viruses.
Commenting on the significance of the new technique Will Irving, professor of virology at the University of Nottingham said: "It is a technology which is probably best applied on a population-basis rather than an individual patient basis. "Whilst its accuracy in defining who had HCV or HIV infection could be massaged up to very respectable levels, I'd be nervous about using it as a diagnostic test to see if an individual patient has HIV infection. "However, it will be a fabulous tool for looking at virus-disease associations which are speculative, or even currently unknown. For example, primary biliary cirrhosis (PBC) has been reported, controversially, to arise from viral infection, so it would be great to compare the virome of PBC patients with those without the disease. Maybe you'd identify a consistent pattern suggesting a specific viral cause.
Original Submission1 Original Submission2
(Score: 0) by Anonymous Coward on Friday June 05 2015, @11:52AM
I was told that minute mutation leads to practically infinite variety of common cold viruses that we don't bother cooking up vaccine/treatment for it. How could this test for all of those?
(Score: 3, Informative) by takyon on Friday June 05 2015, @12:22PM
"In total over 200 different viral types are associated with colds." - Wikipedia.
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(Score: 0) by Anonymous Coward on Friday June 05 2015, @12:26PM
So this test catches all/most of these cold viruses?
(Score: 3, Informative) by takyon on Friday June 05 2015, @12:38PM
It looks like many cold viruses (rhinovirus) get recognized as 1 "species".
Both snippets from the EurekaAlert release:
"VirScan works by screening the blood for antibodies against any of the 206 species of viruses known to infect humans."
"As a group, the bacteriophage displayed all of the protein sequences found in the more than 1,000 known strains of human viruses."
http://news.sciencemag.org/biology/2015/06/new-test-could-reveal-every-virus-thats-ever-infected-you [sciencemag.org]
http://www.realclearscience.com/journal_club/2015/06/04/your_viral_history_in_a_drop_of_blood_109246.html [realclearscience.com]
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(Score: 0) by Anonymous Coward on Friday June 05 2015, @12:54PM
Thanks for the reply. Looks like there are at least two points of contention:
1. Semantics of viral "species"
2. Relationship between an antibody type and a viral species (one-to-one, one-to-many, none-to-one, etc.)
(Score: 1, Interesting) by Anonymous Coward on Friday June 05 2015, @02:51PM
Takyon,
Different AC here. I take issue with this explanation. If antibodies are what make us immune to each cold virus, and the test finds one antibody that recognizes all the different cold viruses, then there should be no symptoms of the later colds. Also 'surprisingly people have generated the exact same antibodies'... this flies in the face of how antibodies are though to be generated. I don't want to read tfa here but I suspect these studies are fatally flawed in some way and they are making shit up to account for the nonsensical results.
(Score: 1, Interesting) by Anonymous Coward on Friday June 05 2015, @08:59PM
Perhaps they are detecting binding to some normal human peptide. Take AA 141-196 from here (corresponding to the "surprising" peptide in Fig 3A of the paper):
http://www.uniprot.org/uniprot/P03423.fasta [uniprot.org]
We get the sequence:
Plug into blast (where it says "Enter accession number(s), gi(s), or FASTA sequence(s)") and choose Organism: "Homo sapiens (taxid:9606)", everything else could be left as defaults.
http://blast.ncbi.nlm.nih.gov/Blast.cgi?PROGRAM=blastp&PAGE_TYPE=BlastSearch&LINK_LOC=blasthome [nih.gov]
Then we find homology to a glutamate transporter under various names, but also "NACHT, LRR and PYD domains-containing protein 9 [Homo sapiens] "
http://www.ncbi.nlm.nih.gov/protein/NP_789790.2 [nih.gov]
There are a number of ways to explain this, including coincidence. But that result is quite surprising using their interpretation that the people have all been previously infected with the same virus.
(Score: 2) by takyon on Friday June 05 2015, @09:46PM
http://en.wikipedia.org/wiki/Endogenous_retrovirus [wikipedia.org] ?
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(Score: 0) by Anonymous Coward on Friday June 05 2015, @09:55PM
I'm not sure if those show up in BLAST searches. Most of the proteins are not expressed (at least supposedly), but we'd have to check the BLAST code/documentation to find out.