Biotechnology efforts to conserve horseshoe crabs through the development of recombinant factor C-based endotoxin test

Abstract

During Gram-negative bacterial infection, endotoxin released from the outer membrane of the bacteria interacts with host sensor/receptor proteins to drive infl ammatory responses. In severe persistent infection, septic shock ensues. Therefore endotoxin, which is ubiquitous, poses a threat to the biotechnology and healthcare industries. The quality assurance for injectable drugs and medical devices started with the slow, less effi cient and expensive pyrogen test using rabbits. In 1970, the US Food and Drug Administration (FDA) approved the Limulus amoebocyte lysate (LAL) for testing endotoxin contamination. However, the LAL test requires the harvesting and bleeding of the horseshoe crab. Problems with the specificity of LAL to endotoxin and the potential for negative effects on horseshoe crab populations have called for an alternative reliable endotoxin test. Here, we review biotechnology efforts into recombinant Factor C (rFC), the endotoxin-inducible sensor protein in LAL, which establishes the foundation of a synthetic and rapid detection of endotoxin. Incidentally, in its “Guidance for Industry—pyrogen and endotoxin testings”, the US FDA has listed the rFC-based PyroGene® assay as an alternative endotoxin testing method. The industry has been slow to take the lead in using this highly sensitive test, which has been well-validated by the manufacturer. It is noteworthy that the rFC satisfi es the typical analytical characteristics used in method validation (USP chapter). Thus, the sooner rFC can be accepted to replace the traditional LAL assay, the quicker and surer it will be to conserve horseshoe crabs, a threatened “living fossil”.