BioWorld International Correspondent

PARIS - Euroscreen SA has been granted a U.S. patent covering a specific G protein-coupled receptor sequence in the human CCR5 receptor.

The Belgian company is focusing on research into the therapeutic potential of G protein-coupled receptors.

CCR5 is a chemokine receptor that is found on the surface of T cells and plays a central role in the mechanism by which human immunodeficiency virus binds to and enters white blood cells. It is thus a major target in the search for therapies for HIV infection.

Patent No. 6,448,375 covers a protein containing a specific portion of CCR5 and thus the full-length, wild-type amino acid sequence of CCR5. It also covers the important delta-32 mutation of the CCR5 gene sequence, which encodes a nonfunctional version of the receptor present in people who display natural immunity to HIV infection. In addition, the patent includes a complete description of the pharmacology of the receptor. Euroscreen, of Brussels, has filed an equivalent patent application in Europe.

The company stresses that its patent is the first to establish a direct role for the CCR5 receptor in HIV infection, saying it "directly challenges" the patent (No. 6,025,154) issued to Human Genome Sciences Inc., of Rockville, Md., for the same receptor in February 2000. Euroscreen President and CEO Pierre Nokin said that is "a purely genomic patent that simply describes the sequence, but with a few mistakes." In particular, it wrongly describes four amino acid sequences. Moreover, the HGS patent does not claim a role for CCR5 in HIV infection, he said.

Nokin told BioWorld International that Euroscreen now possesses full intellectual property rights to the CCR5 receptor and its role in HIV infection, so that all biopharmaceutical companies developing CCR5 as a therapy for AIDS will now have to obtain a license from Euroscreen. The company already concluded one licensing agreement with New York-based Pfizer Inc. in May (see BioWorld International, May 29, 2002), and Nokin said that several other companies are known to be engaged in research and development programs targeting the CCR5 receptor for the development of novel anti-HIV drugs.

"This is an important patent and HIV is an important market, and Euroscreen expects to receive a significant boost to its revenues as a result of concluding further licensing agreements, helping the company to grow without having to obtain funds externally," Nokin said. The company earned revenues of €6 million in 2001 and more or less broke even, as it has done every year since it was founded in 1994, Nokin said.

Euroscreen is focusing on G protein-coupled receptors because they are cell membrane proteins that are known to be potential therapeutic targets in many disease areas. Using its high-throughput AequoScreen cellular assay platform to identify new activators (or ligands) of G protein-coupled receptors that have therapeutic potential, Euroscreen produces recombinant cell lines and membrane preparations, as well as providing screening and cloning services.

In the case of CCR5, the G protein-coupled receptor to which certain HIV-blocking chemokines (naturally produced small molecules) bind, Euroscreen's research established a link between that receptor and the entry of viral genetic material into the cell, revealing its crucial role in the process of HIV infection. At the same time, it discovered that the process does not occur in people who express the delta-32 mutation of the CCR5 gene.