FDA grants marketing approval to Gen-Probe.

The Food and Drug Administration granted marketing approval to Gen-Probe, Inc. recently for the nation's first approved blood test for West Nile virus.

The San Diego-based company, best known for tests for hepatitis C and HIV, rose to the FDA's challenge in 2002 to begin developing such a test. The urgency extended from the discovery that the virus could be transmitted through donated blood.

Gen-Probe developed the test known as Procleix WNV with San Francisco Bay Area's Chiron, Inc. Gen-Probe's Stock, traded on the Nasdaq stock exchange under the symbol GPRO, rose $3.01, or 6 percent the day after the approval to close at $49.18 on Dec. 2, but dropped slightly to level off at $47.60 by the close of market Dec. 6.

While Procleix WNV was being tested at blood centers across the nation, Gen-Probe said the test intercepted about 1,500 units of blood infected with West Nile virus, preventing as many as 4,500 people from receiving contaminated blood.

In the United States this year, 2,775 cases of West Nile virus have been reported this year, according to the federal Centers for Disease Control and Prevention. There have been 854 cases reported in California this year--one in San Diego County.

Gen-Probe, which has 900 employees and was founded in 1983, reported net income of $54.6 million in 2004.