San Diego, CA, October 1, 1998 - Gen-Probe Incorporated announced today that it will receive $4.3 million from the National Heart, Lung and Blood Institute (NHLBI) to develop a nucleic acid amplification test for human immunodeficiency virus type 2 (HIV-2) and hepatitis B virus (HBV) for use in blood screening. These funds, which will be provided over a 30 month period, are in addition to Gen-Probe's current $7.7 million 3-year contract for development of tests for HIV-1 and hepatitis C virus.

The Gen-Probe test is designed to improve the safety of the blood supply by directly detecting the virus. Current tests detect antibodies and antigens associated with the virus, which may not be detectable for weeks or months after infection. The use of DNA probe testing will reduce the "window" period for transmission of these viruses. For example, the "window" for detection of HIV-1 is expected to decrease from 16 days to 11 days.

This NHLBI contract will enable Gen-Probe to complete the development of these tests, conduct human clinical trials with approximately 30,000 individuals at a minimum of three sites, and then submit the clinical data to the Food and Drug Administration for final review and approval. Under the terms of the NHLBI contract, the new blood screening products for HIV-2 and HBV, which are under development, should be available and in use in blood banks across the country by year-end 2001. Gen-Probe is also developing the TIGRIS™ instrument, a fully automated system, which will be used to perform these tests.

Henry L. Nordhoff, president and chief executive officer of Gen-Probe stated, "These additional funds reflect the progress we are making in bringing ultra-sensitive nucleic acid test systems to the routine clinical laboratory. We are very pleased to be a partner in helping to ensure that the blood supply will be as safe as the latest technology allows. As a result of our tests, fewer persons will be at risk of acquiring HIV or hepatitis via blood transfusions."

Gen-Probe, a San Diego-based company, is the recognized world leader in the development, manufacture and commercialization of diagnostic products based on its patented genetic probe technologies. The company has received 40 FDA clearances and approvals for genetic probe tests to detect a wide range of microorganisms, including Chlamydia, Mycobacterium tuberculosis and Neisseria gonorrhoeae. In 1997 Gen-Probe recorded revenues of $93.6 million and is one of the few profitable biotechnology companies. It is also one of the largest biotechnology firms in San Diego, employing over 500 people. The company recently announced a strategic alliance with Chiron Corporation to develop, manufacture and market nucleic acid probe assay systems for blood screening and certain areas of diagnostics.

Gen-Probe is a wholly owned subsidiary of Chugai Pharmaceutical Co., Ltd. Chugai, a major pharmaceutical company in Japan, spends a higher percentage of its sales on research and development than any other large Japanese pharmaceutical company.

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