May 5, 2003

Researchers develop rapid test for SARS

By Ron Sauder

School of Medicine researchers have demonstrated the validity of a rapid laboratory test capable of determining whether a patient has SARS (Severe Acute Respiratory Syndrome).

Frederick Nolte, professor of pathology, said the polymerase chain reaction (PCR) test in his Emory Hospital molecular diagnostic laboratory took about four hours to confirm the presence of the SARS virus fragment in a sample provided by a laboratory in Germany.

The German laboratory, the Bernhard Nocht Institute for Tropical Medicine, announced last month in a New England Journal of Medicine paper that it had identified and sequenced a novel coronavirus that appears to be the cause of SARS.

Nolte tested a fragment of the coronavirus’ RNA consisting of about 300 base pairs in the BNI-1 region that had been isolated by the German lab. He said synthesis of the chemical probes and primers used to identify and amplify that specific sequence of genetic material was the most time-consuming part of the test at Emory.

In PCR, minuscule traces of viruses or other genetic material can be duplicated and amplified chemically.

The technique is capable of detecting the presence of about 100 copies of the virus per milliliter in a patient sample, which would equate to a very low level of infection, Nolte said.

The test, which takes about four hours to run once the sample is prepared, cannot be done in a doctor’s office but would have to be sent to a relatively sophisticated hospital or clinical laboratory. It can be applied to sputum, mucus or blood samples.

Many researchers around the world are working to find positive diagnostic tests since SARS remains an elusive diagnosis based primarily on patients’ symptoms and history, including overseas travel to Asia. The CDC has announced that only a fraction of suspected cases of SARS in the United States are regarded as “probable.”
The SARS epidemic has been concentrated in Asia and Toronto, Canada.