HAMILTON, Mont. -- Ribi Immunochem Research Inc. said that it was awarded a U.S. patent covering derivatives of monophosphoryl lipid A (MPL) immunostimulant.

The patent, U.S.P. 4,987,237, covers composition and the means to prepare various derivatives of MPL. These derivatives may be linked to other biologically active molecules, including antigens, other immunomodulators, fluorescent probes and antibodies.

MPL is an attenuated form of the endotoxin produced by gram- negative bacteria, said Kent Myers, a Ribi research scientist and the first-named inventor on the patent. A potent activator of the immune system, endotoxin was chemically modified by Ribi researchers to retain this ability while eliminating its harmful effects, Myers said.

Ribi developed an MPL conjugate using a peptide antigen, which it aims to use as the basis for more potent vaccines.

In Phase I/II studies of MPL in surgical patients who were at high risk of developing septic shock, infection rates dropped to 12 percent from a normal rate of 35 percent, said Robert Ivy, Ribi's president and chief executive officer.

Ribi said it is talking with several potential co-marketing partners for MPL. -- Karen Bernstein

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