New test could help reduce exposure to bloodborne pathogens

June 17, 2015

One of the biggest dangers of bloodborne pathogens is that many people who are exposed to them do not get tested and therefore are unaware they could be putting others in danger. This is one of the reasons why having a culture of safety, which encourages healthcare workers to report any injuries from needlestick is so important. In addition, it's also crucial that medical organisations have comprehensive reporting and risk assessment procedures in place, to ensure professionals and patients are as protected as possible.

A team at Harvard University Medical School have developed a test that could help minimise the risk posed to healthcare workers, by identifying past exposure to any known human infection with one simple blood test. 

Published in the journal Science, it is hoped their work will not only limit exposure to bloodborne pathogens through a more accurate diagnosis procedure but could also lead to better insight into how viruses develop into diseases.

When someone is exposed to an infection, the immune system creates antibodies, which are designed to fight the virus and recognise a small fragment of the virus. This makes their interaction very specific. By looking at the infections fought by the immune system, the test is able to decode a person's history by using a single drop of blood. 

The test relies on the fact that virus-specific antibodies can survive for years after an infection has been treated. This means that looking at which antibodies are present in a person can give a detailed record of what viruses they have been exposed to.

Until recently, this technique could only be used to identify a small number of viruses, but advances in synthetic biology and rapid gene sequencing means it is possible to analyse more than 1,000 strains of human viruses with a single drop of blood. 

By generating a pool of bacteriophage, each expressing a tiny fragment of the human virus history on its surface, the team were able to use the antibodies in the blood to identify only the bacteriophage that expressed protein fragments recognised by the antibodies in the blood sample.

By sequencing the bacteriophage DNA, the team could see the human viruses that the person has been exposed to.

It is hoped the $25 (£16) test could transform the battle against bloodborne pathogens, making screening much easier and quicker and reducing the chance that people will infect others. 

Speaking to Science in Action, Professor Stephen Elledge from the Harvard University Medical School, who led the research team, said the new technique would overcome the problems experienced in the past with gene sequencing.

Professor Elledge estimates that their VirScan test can process 100 samples in two to three days.

“Normally, when a doctor wants to know if someone’s been infected with a virus, they have to guess what the virus is, and then look specifically for that virus,” Professor Elledge, who conducted the project at Brigham and Women’s Hospital in Boston, told the Guardian. 

“This could lead to a diagnostic where people go annually to their doctor and get their viral history recorded. It could certainly discover viral infections that are serious and that a patient didn’t know they had,” he said.

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