By Mary Welch

Chiron Corp. has filed two more lawsuits, this time against Gilead Sciences Inc. and Agouron Pharmaceuticals Inc., claiming infringement of its hepatitis C (HCV) protease patents.

Chiron, of Emeryville, Calif., alleged the firms are in violation of U.S. patent Nos. 5,371,017, 5,585,258, and 5,597,691. These are the same three patents involved in lawsuits Chiron filed last week against Vertex Pharmaceuticals Inc., of Cambridge, Mass., and its partner, Eli Lilly and Co., of Indianapolis. (See BioWorld Today, Aug. 3, 1998, p. 2.)

"This suit is exactly like the previous one," said Jim Knighton, Chiron's vice president of investor relations. "There may be more suits coming. We are going to continue to protect our patents. Any company we believe is in violation will be sued."

Chiron, which identified hepatitis C in 1989, offered to make its patents available to companies working to discover drugs for treatment of the virus. The company, which is pursuing its own research and product development activities for HCV, offered non-exclusive licenses to its patents related to the HCV NS 3 protease. So far, four companies have agreed to the non-exclusive licensing rights and talks with others are under way.

"We're still talking to companies about non-exclusive licensing opportunities," said Knighton. "We're continuing talks on this side, just as we're continuing, on the litigation side, to make sure no one violates our patents."

Agouron, of La Jolla, Calif., is "confident that we do not infringe on any patents and that this matter will be resolved quickly with no material adverse effect to the company and its operations," said Donna Nichols, vice president of corporate affairs.

Agouron, like Chiron, has a history of successful discoveries in the area of HCV. In October 1996, Agouron solved the crystallized structure of the HCV protease, Nichols said. Currently, the company has several antiviral hepatitis C programs in early clinical stages.

Gilead, of Foster City, Calif., has not been served with the complaint. "We have seen the statement Chiron issued," said Lana Lauher, director of corporate communications. "But we have not been served, and therefore, we have no further comment."

Chiron's stock (NASDAQ:CHIR) closed Tuesday at $16.50, down $0.125. Gilead's shares (NASDAQ:GILD) ended the day at $22.50, down $1.187. Agouron (NASDAQ:AGPH) was at $24.562, down $1.062. *