Chiron Corporation announces merger with Viagene, Inc. anticipated to be effective on September 29, 1995 and treatment of non-electing shares in the merger.

EMERYVILLE, Calif.--(BUSINESS WIRE)--Sept. 21, 1995--Chiron Corp. (NASDAQ: CHIR) announced today that, if approved by stockholders of Viagene, Inc. (NASDAQ: VIGN), the merger (the "Merger") of Viagene with and into a wholly owned subsidiary of Chiron is expected to be effective on September 29, 1995.

Upon consummation of the Merger, each outstanding share of Viagene's common stock (except for shares held directly or indirectly by Chiron and shares as to which appraisal rights have been perfected under Delaware law) will be converted into (i) $9 in cash ("Cash Consideration") or (ii) 0.155 shares of Chiron Common Stock, provided that the number of shares of Viagene's common stock to be exchanged for Cash Consideration and the number of shares of Viagene's common stock to receive Stock Consideration will be adjusted, if necessary, on a pro rata basis so that 40 percent of such shares (except for shares held directly or indirectly by Chiron or by any direct or indirect subsidiary of Chiron) will be converted into the right to receive Cash Consideration and 60 percent of such shares (except for shares held directly or indirectly by Chiron or any direct or indirect subsidiary of Chiron and any shares as to which appraisal rights have been perfected under Delaware law) will be converted into the right to receive Stock Consideration.

Viagene stockholders may elect to receive either Stock Consideration or Cash Consideration in the Merger, but, regardless of such election, may receive a combination thereof as a result of the foregoing adjustments.

An election to receive Cash Consideration or Stock Consideration is required to be made on forms of election, which have been previously furnished to Viagene's stockholders. Additional forms of election may be requested either in writing to Continental Stock Transfer & Trust Company, 2 Broadway, New York, New York 10004 or by telephone at 212/509-4000, extension 227.

For an election by a Viagene stockholder to be effective, a form of election must be properly completed and returned, together with all stock certificates representing shares of Viagene's Common Stock held by such stockholder (or a proper guarantee of delivery), to Continental Stock Transfer & Trust Company, 2 Broadway, New York, New York 10004 by 5 p.m., Eastern Daylight Time, on September 27, 1995 (the "Election Deadline").

A Viagene stockholder who does not submit an effective form of election prior to the Election Deadline will be deemed to have indicated that such stockholder has no preference as to receipt of Cash Consideration or Stock Consideration in the merger. As permitted by the Merger Agreement, Chiron will treat all shares owned by such stockholder as shares in respect of which an election to receive Stock Consideration has been made.

CONTACT: Chiron Corp.

Larry Kurtz, 510/601-2476

Kimberly Kraemer, 510/601-2412