Leiden, The Netherlands, April 3, 2001 - Crucell N.V. (NASDAQ: CRXL, EAX Amsterdam: CRXL), a leading biotechnology company focused on the discovery of unique drug targets on disease associated cells and on the development of huMADETM biopharmaceuticals, today announced that Merck & Co., Inc (NYSE: MRK) is applying Crucell's PER.C6 technology in its HIV-1 vaccine program.

Merck is conducting early (Phase I) clinical trials using novel vaccine technology that their scientists hope will lead to the development of a vaccine that can effectively prevent the development of AIDS from HIV infection, as well as treat HIV infection in infected patients taking anti-retroviral therapy. Merck utilizes an extensively modified adenovirus (adenovirus is a cause of the common cold), that is grown on Crucell's PER.C6 cell line. Crucell and Merck signed an agreement in October 2000, granting Merck an exclusive commercial license to Crucell's PER.C6 platform to develop vaccines for the prevention and treatment of certain diseases. Yesterday is the first public announcement specifying Merck's application of PER.C6 in HIV vaccine development. The agreement provides for up-front and ongoing fees and royalty and milestone payments paid by Merck to Crucell, and further provides Merck the option of extending the exclusivity to cover three additional diseases in the future.

During the first public presentation of animal and cellular immune response data delivered yesterday at the Keystone Symposium in Keystone, Colorado, Dr. Emilio Emini, who heads Merck's HIV-vaccine research, described the experiments that led Merck to begin human testing of the experimental AIDS vaccine in February. In his presentation, Dr. Emini showed that the adenovirus based vaccine provoked a killer-cell response sufficiently strong in monkeys exposed to the AIDS-like virus, that they remained healthy, even though they still harbor small amounts of the virus.

Dr. Dinko Valerio, President and Chief Executive Officer, says: "We are happy to be able to announce that Merck has selected our technology to help develop its experimental HIV-vaccine. This is an important agreement for Crucell as it is our first exclusive license with one of the leading vaccine companies."

In 2000, more than 5 million people were infected with HIV virus, bringing the total number of people living with HIV/AIDS at the end of 2000 to approximately 36 million, according to AIDS Epidemic Update, UNAIDS.

Crucell's PER.C6 is used in HIV Vaccine