Chiron Seeks OK for West Nile Virus Test

Chiron Corp. and Gen-Probe Inc. said Tuesday that U.S. regulators had accepted their application to sell a blood test for West Nile virus, a potentially fatal mosquito-borne disease that infected thousands of Americans last year.

The test would detect West Nile in donated blood by screening for the virus’ genetic material. Chiron, which has become the third-largest U.S. biotechnology company by selling vaccines, blood tests and drugs, expects to sell the product for the U.S. mosquito season, which is from June through September.

Swiss drug maker Roche Holding, which also is working on a West Nile blood test that it hopes will be ready this summer, is Chiron’s chief rival for this type of product, Deutsche Bank Securities Inc. analyst Dennis Harp said.

“It’s a strong positive for the company to be associated with an infectious disease that has caught a lot of attention,” said John McCamant, editor of Medical Technology Stock Letter.

Shares of Chiron rose 31 cents to $39.02 on Nasdaq. Gen-Probe gained 5 cents to $24.05, also on Nasdaq.

The virus, first diagnosed in the U.S. in 1999 during a New York outbreak, can lead to encephalitis, a brain inflammation. A U.S. outbreak of the virus last year infected 4,161 people and caused 277 deaths, affecting 39 states.

A version of Chiron’s West Nile test, called Procleix, is used by blood banks to screen for HIV, the virus that causes AIDS. Gen-Probe, a San Diego-based maker of DNA tests, developed Procleix.

Chiron, based in Emeryville, Calif., trails Thousand Oaks-based Amgen Inc. and South San Francisco-based Genentech Inc. in yearly sales.