In what can only be classed as a breakthrough in medicine, a team at Washington University in St. Louis found a way to make an universal test that can identify virtually any known virus. The method works by analyzing bodily samples for signature genetic markers unique to each virus. It’s surprisingly accurate, as the researchers report the test not only identified the viruses on par with standard tests, but found additional ones which would have otherwise gone unnoticed. Once it passes extensive clinical trials, doctors using the test could come up with a complete list of viral infections harbored inside a patient’s body, correctly diagnose their condition and apply the right treatment. In some situations, it could mean the difference between life and death.
It’s easy to forget that we are home to trillions–perhaps quadrillions–of viruses on our healthiest days. These are inert to our good health, however, and some actually live in complete symbiosis with our bodies acting as a second guard to the immune system. The Washington University researchers were only interested in the bad ones, and while new deadly strains of viruses are identified on a regular basis, the most common ones are well documented genetically speaking. These still number in the thousands though, which makes diagnosis difficult for doctors. Because they have to know what to look for based on symptoms, tests could miss some viruses because the bugs are in low levels. Then there are infections whose symptoms haven’t surfaced yet, merely incubating until the time is ripe.
The universal viral test – the ViroCap – doesn’t require doctors know what to look for beforehand, says pediatrics professor Gregory Storch. “It casts a broad net and can efficiently detect viruses that are present at very low levels. We think the test will be especially useful in situations where a diagnosis remains elusive after standard testing or in situations in which the cause of a disease outbreak is unknown,” he said.
How ViroCap works
A doctor first collects sample from the patient, either stool, blood or nasal secretions, then enriches the nucleic acid from DNA and RNA viruses. Each virus has unique stretches of DNA or RNA, so using a computational approach ViroCap compares the genetic material from the sample with a database. Overall, the scientists pulled 2 million or so stretches of DNA and RNA from every virus known to plague man or beast.
Two sets of experiments were performed. In the first, samples submitted to a diagnostic virology laboratory from 14 adults were analyzed with ViroCap and compared to standard tests. Harmful viruses were detected in only 10 patients by standard tests, and even then common ones like parechovirus, influenza B and herpes virus weren’t identified. The second experiment involved 10 children struck with unexpected fever. Standard tests identified 11 viruses, but ViroCap found another seven. Over the two sets, the number of detected viruses jumped from 21 to 32, marking a 52% improvement in absolute viral detection. In one particular situation, standard testing misguidedly labeled one of the viruses as influenza A, which causes the common flu. ViroCap, however, found the virus was in fact a rather harsh subtype of H3N2. Not that serious in this situation, but in other cases this could certainly make the world of a difference.
The sample sizes for both sets is quite small. It will take another couple of years of extensive tests before ViroCap can be used in practice safely and confidently. Considering it involves serious gene splicing and sequencing, ViroCap also sounds expensive. By the time it comes out in regular field duty in hospitals, however, gene sequencing might cost pennies. Right now it costs a couple thousand dollars, which is still a lot cheaper than the millions of dollars it used to take 12 years ago.
There’s more good news. Storch says the test could be adapted to detect pathogens other than viruses – bacteria, fungi and other microorganisms.
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