Called ‘ViroCap,’ this new diagnostic technology is able to discover more viruses in patient samples, as compared to PCR genome sequencing tests
It could be the ultimate multi-analysis medical laboratory test ever. Researchers at Washington University School of Medicine in St. Louis have developed a diagnostic test that they claim tests for any virus infecting people and animals.
Viruses Make for a Popular Research Subject
Are virus tests going, well, viral? It was just a few weeks ago that Dark Daily reported on research at Howard Hughes Medical Institute (HHMI) aimed at unlocking virus detection beyond one pathogen at a time. (See Dark Daily, “Researchers at Howard Hughes Medical Institute Develop Blood Test That Reveals a Patient’s Viral History; Could Reduce Unnecessary Clinical Laboratory Testing,” December, 30, 2015.)
The HHMI research resulted in VirScan, an alternative to medical laboratory tests that test for specific viruses one at a time, and which can detect all diseases a patient has had over his or her lifetime, according to an HHMI news statement about the new technology.
Discovering Disease in Patients When No Recent Medical History Is Available
The HHMI researchers published a study on their VirScan blood test in the journal Science just a couple of months ahead of Washington University’s announcement about ViroCap.
Like VirScan, ViroCap, could make it possible for doctors to uncover diseases when they don’t know what to suspect in their patients.
“With [ViroCap], you don’t have to know what you’re looking for. 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 [clinical laboratory] testing or in situations in which the cause of a disease outbreak is unknown,” declared the study’s senior author, Gregory Storch, MD, Washington University Professor of Pediatrics.
ViroCap could save thousands of lives and be the biggest medical breakthrough in years, noted an article in Nature World Report.
ViroCap Could Help Medical Laboratories Control Healthcare Costs
For pathologists and medical laboratory executives, ViroCap is another diagnostic test technology worth watching. ViroCap may help labs control costs associated with over test utilization. That’s because it has the propensity to detect many diseases associated with elusive and tiny viruses.
And ViroCap’s sensitivity could even lead to a shake-up in the use of popular polymerase chain reaction (PCR) tests for many purposes. Furthermore, further validation of the ViroCap technology may eventually help it become the public health laboratories’ “go-to” test for rapid detection of potential infectious disease outbreaks.
Motivated to Enhance Virome Sequencing
On a mission to enhance virome sequencing, the researchers at Washington University School of Medicine collaborated with the McDonnell Genome Institute. Current medical laboratory tests, the team said, seem to lack the sensitivity needed to detect low levels of viral bugs.
To prove their point, ViroCap went head to head, so to speak, with the clinical laboratory industry’s gold-standard PCR tests. ViroCap could hypothetically test for any virus, while a PCR test screens for up to 20 viruses at once, an article in Natural Society reported.
Findings Show Sensitive ViroCap Spots More Viruses
ViroCap sequences and detects viruses in patient samples and was “just as sensitive” as PCR assays, the study proclaimed. ViroCap also discovered low levels of viral presence. Here is how the research progressed:
1. Two sets of blood, stool, and nasal samples were secured from St. Louis Children’s Hospital patients harboring unknown viruses;
2. In one sample set, PCR detected viruses in 10 out of 14 patients. But it overlooked viruses in four children. In addition to detecting the viruses PCR found, ViroCap also detected the viruses PCR missed: influenza B, herpes virus 1, a gastrointestinal virus, and the chickenpox virus;
3. In a second group of children with fevers, PCR detected 11 viruses in eight patients. ViroCap found those 11 as well as seven additional viruses.
In summary, ViroCap detected 32 viruses while standard PCR genome testing found 21. So, the new test made possible a 52% increase in virus detection over PCR testing, the study suggested.
“ViroCap substantially enhances metagenomic shotgun sequencing (MSS) for a comprehensive set of viruses, and has utility for research and clinical applications,” the authors wrote in the journal Genome Research.
Possible Potential for ViroCap
Researchers envision the test’s usefulness during outbreaks of deadly viruses such as Ebola, Marburg, and severe acute respiratory syndrome (SARS). It could also be of value to detect routine viruses such as rotavirus and norovirus, the researchers stated.
“The test is so sensitive that it also detects variant strains of viruses that are closely related genetically,” explained corresponding study author Todd Wylie, MD, Instructor of Pediatrics, Washington University.
And ViroCap may be a resource to physicians who face a variety of diagnostic and financial issues, which Block Scientific, Inc., a medical laboratory equipment supplier in New York lists on their website as:
• Difficulty in identifying a virus due to its smaller size and ability to avoid detection, as compared to bacteria and other microbes;
• Disease and physician uncertainty;
• Viruses’ ability to allude a variety of tests; and/or
• High viral testing costs.
Indeed, some viruses require expensive detection kits. One example is a test for the Ebola virus that costs $1,000 per individual test, reported Nature World.
How Does ViroCap Work?
The ViroCap test uses genome sequencing as it detects viruses. Researchers explained ViroCap’s test parameters as follows:
• A whopping two million unique stretches of genetic material from viruses were included;
• Material stretches work as probes, plucking out viruses in patient samples that are deemed a genetic match; and
• Matched viral material is analyzed using high-throughput genetic sequencing.
Next Steps for ViroCap
More research is needed before ViroCap earns a place in the electronic test catalogs of the nation’s medical laboratories. However, the test is publicly available to scientists and clinicians worldwide. Meanwhile, its developers already see potential beyond virus detection. ViroCap could be modified to detect and identify bacteria, fungi, and other pathogens as well, they said.
Pathologists and lab executives should stay tuned as their colleagues experiment with ViroCap technology. Ultimately, the biggest benefit the test may offer is its potential to save lives when other diagnostics are challenged to address perplexing conditions caused by tiny, hidden viruses.
—Donna Marie Pocius