( Rigel Program to be Presented at Keysto...)Rigel Ubiquitin Ligase Program Identifies Molecules With Anti-HIV,Activity,Health

SOUTH SAN FRANCISCO, Calif., March 27, 2007 /PRNewswire-FirstCall/ -- Rigel today announced that Yonchu Jenkins, Ph.D., Associate Director of Virology, will be presenting on the company's efforts to develop a small molecule therapeutic to treat patients with the Human Immunodeficiency Virus (HIV) infection at the Keystone Symposium in British Columbia on March 27th and 29th. Dr. Jenkins will present both a poster and an oral presentation entitled, the Identification of Novel Antiretroviral Compounds by Targeting HIV Vif Function.

Dr. Jenkins and her colleagues at Rigel are investigating ways to inhibit Vif, a specific viral protein produced by HIV that is essential for its replication. Inside HIV-infected cells, the invading protein, Vif, neutralizes the potent anti-viral activity of a host human protein called Apobec3G. By recruiting Apobec3G into an ubiquitin ligase complex, Vif enables the subsequent degradation of Apobec3G, thus eradicating it from HIV-infected cells. When Vif is absent, Apobec3G's potent anti-viral activity renders HIV virus particles non-infectious. Rigel is exploring a number of small molecule compounds aimed at modulating the intracellular ubiquitin ligase signaling pathways utilized by Vif so that Apobec3G will remain active in the presence of HIV and impede the virus from replicating.

"Our approach focuses on restoring the body's natural ability to fight the virus by means of a ubiquitin ligase target. By focusing on a host target, rather than a viral target we may create a new class of anti-retroviral therapeutics," said Donald G. Payan, M.D., Executive Vice President and Chief Scientific Officer of Rigel. "Rigel is uniquely positioned to pursue this target given our extensive experience in the ubiquitin ligase field and in the virology area," he added.

For further information on Rigel's HIV program, Dr
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