Chiron's Nucleic Acid Testing System Selected by Australian Red Cross Blood Service to Screen Country's Blood Supply / New NAT Technology Will Be Used to Test B

EMERYVILLE, Calif. (PROTEXT) - Chiron Corporation (Nasdaq: CHIR) today announced that the Australian Red Cross Blood Service (ARCBS) will use the company's nucleic acid testing (NAT) system to screen the country's entire blood supply for hepatitis C (HCV) and the human immunodeficiency virus-1 (HIV). Chiron's combination HIV/HCV test, developed and manufactured by Gen-Probe Incorporated, is expected to be fully implemented in Australia by mid-2000. The advanced screening test, which incorporates sophisticated new technology, will be used to routinely screen the Australian blood supply, approximately one million blood donations per year. "The ARCBS's adoption of NAT technology is another step towards ensuring the Australian blood supply remains among the safest in the world," said Rajen Dalal, president of Chiron Blood Testing. "Chiron's system is the only test available that allows blood centers to simultaneously detect both HCV and HIV," he added. Currently, donated blood and plasma are routinely screened with antibody tests, which detect the body's immune response, to protect the population from blood-borne diseases such as HIV and HCV. In contrast, NAT is capable of directly detecting small amounts of infectious viruses in blood, further increasing the safety of the blood supply. In addition, Chiron's NAT system, which utilizes Gen-Probe's proprietary transcription-mediated amplification (TMA), enables users to perform testing using either pooled donations or in a single-donor format. All current non-NAT blood screening protocols utilize single-donor testing rather than pooling multiple donations, and regulatory authorities worldwide have expressed their interest in ultimately using single-donor testing with NAT. "Our goal in implementing NAT is to effectively add an extra layer of safety to our blood supply," said Robert Hetzel, M.D., chief executive officer of the Australian Red Cross Blood Service. "We chose Chiron because we saw the potential of the TMA technology, and we were attracted by the complete package that Chiron offered us including the provision of instrumentation, software, and training support," he added. Under the agreement, Chiron, through its Australian subsidiary, will assist in the implementation of testing to screen every blood donation collected by ARCBS. Testing will be conducted at five ARCBS testing sites. Initially, two of the sites, making up approximately 20 percent of the country's blood supply, will conduct single-donor testing while the remaining sites will screen using small sample pools. FDA-regulated studies are currently being conducted in the U.S. under investigational new drug (IND) applications to evaluate the performance of TMA technology and to demonstrate the effectiveness of NAT for improving the safety of donated blood and blood products. Currently more than 70 percent of U.S. blood donations are being tested using Chiron's NAT system. Regulatory approval for Chiron's NAT system has been obtained in France and is expected in Australia early next year. About Transcription Mediated Amplification Technology Researchers have demonstrated that TMA technology efficiently amplifies the nucleic acids of a virus, providing direct detection of the infection. This provides for earlier identification of even small amounts of virus particles in the blood stream. 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. Chiron's nucleic acid test, the CHIRON(R) HIV-1/HCV TMA Assay, is intended to detect HIV-1 and/or HCV viral RNA in human plasma. 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, Inc., 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. For further information, visit the company's website at www.chiron.com . This document contains forward-looking statements that are subject to risk and uncertainty. There are a number of factors that could cause the company's actual performance to differ materially from expectations. These and other factors investors should consider are more thoroughly described in the company's Securities and Exchange Commission filings, including the Form 10-Q and Form 10-K. ots Original Text Service: Chiron Internet: http://www.newsaktuell.de Contact: Julie Wood, Senior Director, Corporate Communications and Investor Relations, 510-923-6686, or Gabrielle Friedly, Manager, Corporate Communications, 510-923- 6905, both of Chiron Web site: http://www.chiron.com Subscribers please note that material bearing the slug "PROTEXT" is not part of CTK's news service and is not to be published under the "CTK" slug. Protext is a commercial service providing distribution of press releases from clients, who are identified in the text of Protext reports and who bear full responsibility for their contents.