Quorex Pharmaceuticals Inc.

Quorum sensing, or the control of gene expression in response to cell density, is used by a wide variety of bacteria—both Gram-negative and Gram-positive—to regulate physiological functions, including signaling the onset of pathogenesis in a host and the acquisition of nutrients. Signaling molecules called autoinducers, which are produced by bacteria and accumulate in the external environment as the bacterial cells grow, enable this communication system. When a bacterial population achieves a threshold density—a quorum—the concentration of autoinducers reaches a certain concentration and triggers a signal transduction cascade in the bacteria. Quorum sensing was first discovered in the early 1980s when researchers found that the accumulation of a certain chemical autoinducers triggered bioluminescence in the marine bacterium, Vibrio fisherii. Similar autoinducers later were found to induce the expression of virulence factors in the Gram-negative pathogen, Pseudomonas aeruginosa. In Gram-positive bacteria, such as Staph aureus, a separate quorum mechanism triggers virulence via a peptide autoinducer molecule.

But these initial observations were species specific—none of them could readily form the basis of a platform for the development...