News Release

Chiron reports on discovery of novel men B vaccine candidates based on whole genome sequencing of Neisseria meningitidis by TIGR

Peer-Reviewed Publication

Noonan/Russo Communications

Emeryville, CA, March 9, 2000 -- Chiron Corporation (Nasdaq: CHIR) today announced that its research team located in Siena, together with collaborators at The Institute for Genomics Research (TIGR) in Rockville, Maryland, and the University of Oxford, have determined the complete genome sequence for Neisseria meningitidis, the bacterium primarily responsible for meningococcal disease. Chiron also reported that it has used this detailed information on the microorganism's genetic structure to identify novel vaccine candidates against meningococcal B disease. This research, reported in the March 10, 2000 issue of Science, demonstrates the important role genomics can play in the development of commercial products.

"Conventional research approaches to develop effective vaccines against different strains of group B meningococcus have failed," said Rino Rappuoli, Ph.D., co-author of the Science papers and Chiron's vice president of vaccine research. "A genomics-based approach is a completely novel paradigm and allowed the discovery of many vaccine candidates which will be used for developing new methods of protection."

Dr. Rappuoli added, "Through this research we also have a better understanding of the disease process. Using these insights, we are creating a vaccine capable of protecting against the broad diversity of invasive strains of this virulent microorganism. This progress could only have been achieved by the collaboration of three groups, each with unique expertise, in sequencing the genome (TIGR), in the biology and pathogenesis of the bacterium (Oxford), and in vaccine development (Chiron)".

Traditional approaches to vaccine development against meningococcal B disease have proved problematic in eliciting a strong immune response against multiple strains of the disease. Using information gained from sequencing the entire genome, researchers were able to identify new surface proteins. These newly discovered proteins behave differently from those previously identified and are present across a wide range of strains. Researchers have also shown that these proteins can stimulate an antibody response capable of killing the bacterium, a property known to correlate with vaccine efficacy in humans. Work is now underway to identify the most promising vaccine candidate(s). The final vaccine will contain one or more of these surface-expressed proteins.

The term "meningococcal disease" actually encompasses five different infective diseases caused by Neisseria meningitidis (A, B, C, Y, and W135). Chiron currently has a conjugate vaccine against meningococcal C disease approved in the United Kingdom. However, there is no approved vaccine against meningococcal B disease, the most prevalent form of the infection in the United States and Europe. As an interim step, Chiron is working with the National Institutes of Health in Norway to market a first-generation vaccine against meningococcal B disease that has been shown to be effective against a specific strain of the disease.

In 1997, Chiron and TIGR established a collaboration to sequence the genome of Neisseria meningitidis in order to develop a vaccine against meningococcal B disease. Under the terms of the agreement, Chiron has the exclusive right to commercialize vaccine products resulting from the collaboration. TIGR will receive milestone payments and royalties on any such commercialized pharmaceutical products.

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About Chiron Corporation
Chiron Corporation has an established vaccines business based in Europe. Its subsidiaries, Chiron Behring in Germany and Chiron SpA in Italy, are market leaders in their respective countries. Chiron also sells its products internationally through multinational healthcare organizations and local distributors.

Chiron Corporation, headquartered in Emeryville, California, is a leading biotechnology company that participates in three global healthcare markets: biopharmaceuticals, vaccines, and blood testing. The company is applying a broad and integrated scientific approach to the development of innovative products for preventing and treating cancer, infectious diseases, and cardiovascular disease. For further information, visit the company's website at www.chiron.com .

This document contains forward-looking statements that are subject to risk and uncertainty. There are a number of factors that could cause the company's actual performance to differ materially from expectations. These and other factors investors should consider are more thoroughly described in the company's Securities and Exchange Commission filings, including the Form 10-Q and Form 10-K.

Contacts:

Julie Wood
Senior Director, Corporate Communications
and Investor Relations, 510.923.6686

Jennifer Wyckoff
Communications Specialist, 510.923.3103

Amy Giller
Noonan/Russo Communications, Inc.
415.677.4455 ext. 206

Ernie Knewitz
Noonan/Russo Communications, Inc.
44.171.726.4452

Note to Editors: The full text of the papers can be viewed at www.science.org .


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