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) systemto screen the country's entire blood supply for hepatitis C (HCV)and the human immunodeficiency virus-1 (HIV). Chiron'scombination HIV/HCV test, developed and manufactured by Gen-ProbeIncorporated, is expected to be fully implemented in Australia bymid-2000. The advanced screening test, which incorporatessophisticated new technology, will be used to routinely screenthe Australian blood supply, approximately one million blooddonations per year. "The ARCBS's adoption of NAT technology is another steptowards ensuring the Australian blood supply remains among thesafest in the world," said Rajen Dalal, president of Chiron BloodTesting. "Chiron's system is the only test available that allowsblood centers to simultaneously detect both HCV and HIV," headded. Currently, donated blood and plasma are routinely screenedwith antibody tests, which detect the body's immune response, toprotect the population from blood-borne diseases such as HIV andHCV. In contrast, NAT is capable of directly detecting smallamounts of infectious viruses in blood, further increasing thesafety of the blood supply. In addition, Chiron's NAT system,which utilizes Gen-Probe's proprietary transcription-mediatedamplification (TMA), enables users to perform testing usingeither pooled donations or in a single-donor format. All currentnon-NAT blood screening protocols utilize single-donor testingrather than pooling multiple donations, and regulatoryauthorities worldwide have expressed their interest in ultimatelyusing single-donor testing with NAT. "Our goal in implementing NAT is to effectively add an extralayer of safety to our blood supply," said Robert Hetzel, M.D.,chief executive officer of the Australian Red Cross BloodService. "We chose Chiron because we saw the potential of the TMAtechnology, and we were attracted by the complete package thatChiron offered us including the provision of instrumentation,software, and training support," he added. Under the agreement, Chiron, through its Australiansubsidiary, will assist in the implementation of testing toscreen every blood donation collected by ARCBS. Testing will beconducted at five ARCBS testing sites. Initially, two of thesites, making up approximately 20 percent of the country's bloodsupply, will conduct single-donor testing while the remainingsites will screen using small sample pools. FDA-regulated studies are currently being conducted in theU.S. under investigational new drug (IND) applications toevaluate the performance of TMA technology and to demonstrate theeffectiveness of NAT for improving the safety of donated bloodand blood products. Currently more than 70 percent of U.S. blooddonations are being tested using Chiron's NAT system. Regulatoryapproval for Chiron's NAT system has been obtained in France andis expected in Australia early next year. About Transcription Mediated Amplification Technology Researchers have demonstrated that TMA technology efficientlyamplifies the nucleic acids of a virus, providing directdetection of the infection. This provides for earlieridentification of even small amounts of virus particles in theblood stream. Current tests, which rely on antibody or viralprotein detection, take much longer since antibodies are formedin response to the infectious agents. This can be as long as 22days for HIV and up to 80 days or more for HCV according to TheNew England Journal of Medicine (1996; 334(26)). TMA technologyhas the potential to reduce detection time, or the "windowperiod," by about 50 percent for HIV and by 70 percent or morefor HCV. Chiron's nucleic acid test, the CHIRON(R) HIV-1/HCV TMAAssay, is intended to detect HIV-1 and/or HCV viral RNA in humanplasma. About Chiron Blood Testing Chiron Blood Testing is a leading provider of products used bythe blood banking industry to ensure safety of the world's bloodsupply and to protect the public health. Through its jointbusiness with Ortho-Clinical Diagnostics, Inc., Chiron developsand markets immunoassay screening and supplemental tests forblood-borne infectious diseases, such as hepatitis B and C, andAIDS. The company also manufactures RIBA SIA confirmatory tests,as well as hepatitis and retroviral antigens. In addition, Chironis collaborating with Gen-Probe Incorporated in the developmentand marketing of improved infectious disease blood screeningtests incorporating novel and highly sensitive nucleic acidamplification technology. About Chiron Corporation Chiron Corporation, headquartered in Emeryville, California,is a leading biotechnology company that participates in threeglobal healthcare markets: biopharmaceuticals, vaccines and bloodtesting. The company is applying a broad and integratedscientific approach to the development of innovative products forpreventing and treating cancer, infectious diseases andcardiovascular disease. For further information, visit thecompany's website at www.chiron.com . This document contains forward-looking statements that aresubject to risk and uncertainty. There are a number of factorsthat could cause the company's actual performance to differmaterially from expectations. These and other factors investorsshould consider are more thoroughly described in the company'sSecurities and Exchange Commission filings, including the Form10-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, orGabrielle Friedly, Manager, Corporate Communications, 510-923-6905, both of Chiron Web site: http://www.chiron.com

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