New test can detect all viral infections in people

Washington: Researchers have developed a new test that can detect virtually any virus that infects people and animals, including the Ebola virus.

Current tests are not 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 senior author Gregory Storch, professor at the Washington University School of Medicine.

"It casts a broad net and can efficiently detect viruses that are present at very low levels," Storch said.

The study demonstrates that in patient samples the new test - called ViroCap - can detect viruses not found by standard testing based on genome sequencing.

The new 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.

The researchers evaluated the new test in two sets of biological samples - for example, from blood, stool and nasal secretions - from patients at St Louis Children's Hospital.

In the first, standard testing that relied on genome sequencing had detected viruses in 10 of 14 patients. But the new test found viruses in the four children that earlier testing had missed.

Standard testing failed to detect common, everyday viruses - influenza B, a cause of seasonal flu; parechovirus, a mild gastrointestinal and respiratory virus; herpes virus 1, responsible for cold sores in the mouth; and varicella-zoster virus, which causes chickenpox.

In a second group of children with unexplained fevers, standard testing had detected 11 viruses in the eight children evaluated.

But the new test found another seven, including a respiratory virus called human adenovirus B type 3A, which usually is harmless but can cause severe infections in some patients.

In all, the number of viruses detected in the two patient groups jumped to 32 from 21, a 52 per cent increase.

"The test is so sensitive that it also detects variant strains of viruses that are closely related genetically," said corresponding author Todd Wylie, an instructor of pediatrics.

The study was published in the journal Genome Research.