Chiron Receives Approval in France to Market Nucleic Acid Blood Tests For HIV-1 and HCV / First NAT Blood Tests Approved Worldwide

Chiron Corporation (Nasdaq: CHIR) today announced that it received approval from the French Ministry of Health (AFSSAPS) to market to blood banks throughout France its combination nucleic acid test (NAT) to simultaneously detect human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV). The combination HIV/HCV test, developed and manufactured by Gen-Probe Incorporated, is marketed by Chiron. Previously the Ministry of Health had mandated that the entire blood supply of France, 2.7 million blood donations per year, be screened by the year 2000 for HCV using a nucleic acid testing method. The action by the French government makes France the first nation to formally grant marketing approval for the advanced screening technology. "We believe Chiron's TMA combination assay further enhances the safety of France's blood supply, which is already very safe due to stringent regulation and controls," said Professor Philippe Rouger, president of the French Society of Blood Transfusion and managing director of the National Institute of Blood Transfusion. "We believe Chiron's TMA assay is an easy and efficient addition to the routine screening of blood donations." "This approval of NAT tests is a major milestone. France wants to quickly implement new, more sensitive technology that has the capability of identifying viral contaminants in blood sooner after a donor is infected than immunoassay screening technologies," said Rajen Dalal, president of Chiron blood testing. "The AFSSAPS is respected as a leading regulatory agency and its timely decision will be noted by authorities around the world." The test, called the CHIRON(R) HIV-1/HCV TMA Assay, is intended to detect HIV-1 and/or HCV viral RNA in human plasma, and it will be used to screen blood donations on individual donor specimens. Chiron's NAT kit utilizes transcription-mediated amplification (TMA), a technology developed by San Diego-based Gen-Probe Incorporated. The use of the TMA-based kit, with the associated hardware and software, enables blood bank technicians to screen large numbers of samples quickly and with low risk of contamination. These features make it possible to rapidly identify infected donations without delaying the routine supply of blood components. Alternative NAT methods are more complex and time consuming. Currently, donated blood and plasma are routinely screened with immunoassays to protect the population from blood-borne diseases such as HIV and HCV. Nucleic acid testing is a new technology capable of directly detecting even small amounts of infectious viruses in blood. In the United States, FDA-regulated studies are now being conducted under an Investigational New Drug Application (IND) to evaluate the performance of Chiron's assays, and to demonstrate the effectiveness of nucleic acid testing for improving the safety of donated blood and blood products. Approximately 70 percent of U.S. whole blood donations are being tested using the CHIRON(R) HIV-1/HCV TMA Assay. About Transcription Mediated Amplification Technology Researchers have demonstrated that TMA technology, by efficiently amplifying the nucleic acids of the virus, allows direct detection of the infection. Current tests, which rely on antibody or viral protein detection, take much longer since antibodies are formed in response to the infectious agents. This can be as long as 22 days for HIV and up to 80 days or more for HCV according to The New England Journal of Medicine (1996; 334(26)). TMA technology has the potential to reduce detection time, or the "window period," by about 50 percent for HIV and by 70 percent or more for HCV. About Chiron Blood Testing Chiron Blood Testing is a leading provider of products used by the blood banking industry to ensure safety of the world's blood supply and to protect the public health. Through its joint business with Ortho-Clinical Diagnostics, Chiron develops and markets immunoassay screening and supplemental tests for blood- borne infectious diseases, such as hepatitis B and C, and AIDS. The company also manufactures RIBA SIA confirmatory tests, as well as hepatitis and retroviral antigens. In addition, Chiron is collaborating with Gen-Probe Incorporated in the development and marketing of improved infectious disease blood screening tests, incorporating novel and highly sensitive nucleic acid amplification technology. About Chiron Corporation Chiron Corporation, headquartered in Emeryville, California, is a leading biotechnology company that participates in three global healthcare markets: biopharmaceuticals, vaccines and blood testing. The company is applying a broad and integrated scientific approach to the development of innovative products for preventing and treating cancer, infectious diseases and cardiovascular disease. This approach is supported by research strengths in recombinant proteins, genomics, small molecules, gene therapy and vaccines. For further information, visit the company's website at www.chiron.com. ots Original Text Service: Chiron Corporation Internet: http://www.newsaktuell.de Contact: Julie Wood, Director, Corporate Communications and Investor Relations, 510-923-6686, or Gabrielle Friedly, Manager, Corporate Communications, 510-923-6905, both of Chiron Corporation Web site: http://www.chiron.com