Chiron Corporation announced that the U.S. Food and Drug Administration (FDA) has accepted the investigational new drug (IND) application submitted by Chiron's collaborator, Gen-Probe Incorporated, for an assay to screen blood donations for West Nile virus, a blood-borne pathogen transmitted by mosquitoes. The nucleic acid test (NAT) assay, marketed by Chiron and developed by Gen-Probe, is expected to be available for use under the IND in time for the upcoming U.S. mosquito season.

"West Nile virus only emerged as a threat to the safety of the blood supply in 2002. This assay reflects the commitment of both Chiron and Gen-Probe to move quickly to meet a critical public health need," said Jack Goldstein, president, Chiron Blood Testing. "We were able to respond rapidly because of the nature of the Procleix system, which allows this assay to use the same instrumentation as the currently approved HIV-1/HCV test. We are working with our customers to ensure that they will be ready to implement the new assay and meet the timeline established by federal health officials."

West Nile virus is transmitted by mosquitoes carrying the virus. Infection with the virus can cause mild disease with flu-like symptoms or more severe disease characterized by encephalitis or meningitis. The FDA called upon the blood testing industry last year to develop an NAT assay to detect West Nile virus by mid-year 2003. Out of a total of more than 3,500 cases of West Nile infections documented in the U.S. last year, approximately 21 were believed to have been caused by blood transfusions or transplants, according to the FDA.

In 2002, Gen-Probe Incorporated received FDA approval for the Procleix HIV-1/HCV Assay, an NAT test designed to detect the presence of all known HIV-1 subtypes and hepatitis C virus (HCV) genotypes during the very early stages of infection, when those agents cannot be detected by immunodiagnostic screening technologies. The Procleix HIV-1/HCV Assay is currently available commercially in 16 countries.

Chiron and Gen-Probe are currently developing the Procleix Ultrio Assay, which adds an assay for hepatitis B virus (HBV) to the test for HIV-1 and HCV. The HBV component of this assay has the potential to close the window period between infection and detection of hepatitis B from 59 to 34 days, a reduction of 42% over currently available tests. European marketing evaluations for the Procleix Ultrio Assay are anticipated to begin in the first half of 2003. U.S. clinical trials are expected to begin in the second half of 2003.