Chiron Files Infringement Suit in Japan Against Roche On HCV Patent.

EMERYVILLE, Calif.--(BW HealthWire)--April 16, 1998--Chiron Corporation (NASDAQ:CHIR) announced today that it has filed suit against Nippon Roche K.K. in the Tokyo District Court in Japan for infringement of Japanese Patent No. 2,656,995 (the '995 patent).

Nippon Roche currently markets hepatitis C polymerase chain reaction (HCV PCR) assays. The suit asks for a preliminary injunction to prevent further infringement by Nippon Roche as well as a permanent injunction and unspecified damages.

Chiron scientists cloned HCV in 1987 following five years of research. It was the first time a virus was cloned before it had been grown in tissue culture or otherwise isolated. Since the initial discovery, Chiron has been granted in excess of 100 HCV-related patents in over 20 countries. In 1989, Chiron formed a joint business with Ortho Diagnostics systems, Inc. (Ortho), a Johnson & Johnson Company for immunodiagnostic testing for HCV.

With the support of Ortho, Chiron has pursued enforcement of its position against infringers in the HCV immunodiagnostic testing market. Previously, Chiron and Ortho have been granted injunctions against Organon Teknika and International Murex Technologies Corporation (Murex) by the U.K. and Dutch courts. In addition, the Opposition Division of the European Patent Office has upheld the validity of Chiron's basic European HCV patent over the challenge of F. Hoffman LaRoche AG (Roche), the parent of Nippon Roche. Chiron and Ortho currently have a pending legal action in Germany against Roche for infringing the European patent by selling HCV immunoassay kits in Germany. Chiron also has pending legal actions in the U.S. and the Netherlands against Roche for infringing its HCV patents by selling HCV PCR kits in the U.S. and Europe.

Chiron has developed its proprietary Quantiplex(TM) branched DNA (bDNA) probe assay to quantitate HCV RNA for use in following the course of disease and monitoring therapy. In Japan, Chiron granted distribution rights to Daiichi Pure Chemicals Co., Ltd. (DPC) for the Quantiplex HCV RNA assay. In 1994, DPC obtained the import license from Koseishou (Ministry of Health and Welfare), and has successfully established the HCV quantitative market in Japan.

Chiron Corporation, headquartered in Emeryville, California, USA, near San Francisco, is a leading biotechnology company that combines diagnostic, vaccine, and therapeutic strategies for controlling disease. Chiron participates in three global markets; diagnostics, including immunodiagnostics, critical care diagnostics, and new quantitative probe tests; pediatric and adult vaccines; and therapeutics, with an emphasis on oncology and infectious diseases. Chiron also has research programs underway in gene therapy, gene transfer, combinatorial chemistry, and recombinant proteins targeted towards oncology, cardiovascular and infectious diseases.

CONTACT: Chiron Corporation

Jim Knighton, 510/923-6055 (Investor Relations)

or

Chiron Diagnostics

Judith Rossi, 508/660-4875 (Corporate Communications)