A one-day conference in Barcelona, Spain, on Friday on"Advances in HCV Diagnosis and Treatment" heard MickeyUrdea of Chiron Corp. report on the latest wrinkle in hiscompany's assay for detecting and quantifying hepatitis C virusin human serum.

The meeting was co-sponsored by Chiron, Schering-Plough andJohnson & Johnson's Ortho division.

Urdea, who is vice-president for nucleic-acid systems R&D atChiron (NASDAQ:CHIR) of Emeryville, Calif., described the test,trademarked Quantiplex, as "a signal amplification methodbased on branched oligodeoxyribonucleotides (bDNA)," whichhe has developed over the past 10 years.

In a telephone interview, Urdea explained to BioWorld: "It is atechnique based on signal amplification, not like PCR's targetamplification. We actually detect the target nucleic acid, such asRNA from HCV, directly, without making more of it. So wedetect it at its physiologic concentration."

The new version of the assay that he unveiled here, whichChiron calls its "1.5 series," has "a significantly improvedmolecular detection limit -- 8,000 equivalents per 50microliters of serum," Urdea told the gathering in Spain.

Meanwhile, he added, the original Quantiplex has tested serumsamples from more than 800 HCV-infected individuals

Its "first substantial publication," Urdea told BioWorld, came inSaturday's Lancet, under the title "Significance of serumhepatitis C virus RNA levels in chronic hepatitis C." It reporteda quantitative study at the University of Florida, Gainesville, ofHCV viremia in 47 patients with chronic non-A, non-Bhepatitis, piggybacked on a clinical trial of interferon-atherapy.

Strikingly, 29 patients who owed their infection to virus-contaminated blood transfusions had higher viremia levelsthan did 13 health workers and intravenous drug users. Elevenwho made a complete, sustained response to the interferontherapy had lower viremia pre-treatment than did 15 completeresponders who relapsed after the drug was stopped, and 20non-responders.

The paper's lead author, Johnson Lau, concluded that "mode ofacquisition is an important determinant of HCV viremias, andpatients with low viremia levels are more likely to respond tointerferon in a sustained fashion."

Lau, an associate professor of hepatobiliary disease at theuniversity's medical school, told BioWorld: "Previously,physicians just said, 'Treat the patient and do some simpleblood test,' and defined that as a response to therapy. But nowwe say that by using this bDNA test you can predict how likelythe patient is to respond to interferon."

He observed that amplifying the signal is an advantage overprevious methods "because the amount of virus in blood is solow we need a new method to detect and quantitate it."

"Three or four groups in Japan have already confirmed ourfindings," Lau added.

So far, Urdea told BioWorld, "Quantiplex is a research-use-onlyproduct. The issues right now are, 'What are its potentialclinical uses -- if any?' That is the question we're asking peoplelike Johnson Lau to take a look at."

-- David N. Leff Science Editor

(c) 1997 American Health Consultants. All rights reserved.

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