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[SANTIAGO] A new diagnostic method which can detect from just a drop of blood current and past viral infections in a person, could allow treatments to be improved, new vaccines to be designed, and the evolution of viral infections in large populations to be tracked.

Named VirScan by the researchers who developed it at Howard Hughes Medical Institute in the United States, the method analyses the antibodies produced by the human immune system against any of the 206 types and more than a thousand virus strains.

As the immune system continues to produce these antibodies decades after an infection, VirScan can detect the viral attacks even after they have been eliminated, the researchers say. Existing diagnostic systems can identify only a single viral attack.

To develop the method, the researchers synthesised more than 93,000 small pieces of DNA of different segments of antibodies and introduced these into viruses capable of infecting bacteria (bacteriophages). They then sequenced the DNA of these bacteriophages and compared the sequences obtained with a collection of genetic material from antibodies to identify which viruses were present in the analysed sample.

VirScan was tested on 569 people in South Africa, Thailand, Peru and the US, and was able to discover that each person had, on average, antibodies against ten types of virus.

People from South Africa, Peru and Thailand tended to have antibodies that fight against more viruses than those from the US. Some viruses were common in adults, but not in children who had not yet been exposed to them. The most common viruses were those for mononucleosis and the common cold.

Stephen Elledge, one of the co-authors of the work published in Science (5 June), says processing 100 blood samples can take only two or three days and it will be even quicker when they perfect the method.

"Now that we have discovered that the majority of people have antibodies against very common viruses, this immune response could be used to increase the effect of vaccines," Elledge tells SciDev.Net.

Hidde Ploegh, biology professor at the Massachusetts Institute of Technology in the US, believes that "now it will be possible to detect all the viruses that have attacked an individual and to do the same for many people owing to the method’s ease and speed" in getting results.

"The latter will allow it to determine how viral infections spread, which viruses affect people in different climatic areas and continents, and to study, for example, the relationship between viral infections and autoimmune diseases."

>Link to summary article for the article in Science

This article has been produced by SciDev.Net's South-East Asia & Pacific desk.