Soon to be available from the good docs at Washington University in St. Louis:
Many thousands of viruses are known to cause illness in people and animals, and making a diagnosis can be an exhaustive exercise, at times requiring a battery of different tests. That’s because current tests aren’t sensitive enough to detect low levels of viral bugs or are limited to detecting only those viruses suspected of being responsible for a patient’s illness.
“With this test, you don’t have to know what you’re looking for,” said the study’s senior author, Gregory Storch, MD, the Ruth L. Siteman Professor of Pediatrics. “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.”
Results published online in September in the journal Genome Research demonstrate that in patient samples the new test – called ViroCap – can detect viruses not found by standard testing based on genome sequencing. The test could be used to detect outbreaks of deadly viruses such as Ebola, Marburg and severe acute respiratory syndrome (SARS), as well as more routine viruses, including rotavirus and norovirus, both of which cause severe gastrointestinal infections.
Developed in collaboration with the university’s McDonnell Genome Institute, the test sequences and detects viruses in patient samples and is just as sensitive as the gold-standard polymerase chain reaction (PCR) assays, which are used widely in clinical laboratories. However, even the most expansive PCR assays can only screen for up to about 20 similar viruses at the same time.
How does it do it?
To develop the test, the researchers targeted unique stretches of DNA or RNA from every known group of viruses that infects humans and animals. In all, the research team included 2 million unique stretches of genetic material from viruses in the test. These stretches of material are used as probes to pluck out viruses in patient samples that are a genetic match. The matched viral material then is analyzed using high-throughput genetic sequencing. As completely novel viruses are discovered, their genetic material could easily be added to the test, Storch said.
I had been thinking someone would figure out how to do a differential analysis, by which I mean the signal of a ‘clean’ blood sample would be known, and then the difference between that signal and the signal of the current sample could be analyzed and decoded. Yes, that’s very much an arm wave. These folks seem to have taken the standard approach and put it on steroids, so far as I can tell. Very effective, so far, but it’s rather like detecting computer viruses – looking for known sequences of bits in order to detect a virus. That new one is the one that may slip by….
(h/t Melissa Breyer @ TreeHugger.com)
