Monday 22 February 2021

Industry Drivers in the Development of Recombinant Lysate


With recombinant lysate, a recombinant protein is an artificially produced (and often purified) protein. The recombinant process occurs, in general terms, when recombinant DNA encoding a protein is introduced into a host organism to express foreign proteins. This process requires the use of specialized expression vectors together with restructuring by foreign coding sequences.


Tim Sandle has written a review of recombinant lysate for use with the bacterial endotoxin test.


The idea for the use of recombinant lysate is to provide a reagent that reacts in the same way as the natural cascade within the four species of horseshoe crab: (Limulus polyphemus, Tachypleus tridentatus, Tachypleus gigas, and Carcinoscorpius rotundicauda). The cloning technology serves an alternative to the fishing and bleeding of horseshoe crabs (where bleeding is performed through a large dorsal blood sinus called the pericardium). In addition, the use of recombinant technology to substitute the specific pathway seeks to address the concern with some lysates that also detect beta glucans through the activation of factor G. A further advantage with recombinant lysates stems from the production of the test reagent through the use of cell culture.  This may result in the supply of a more consistent product.


From around 2003 recombinant lysate has been commercially available, albeit not recognized by any compendia until 2016. However, it has only been in the past few years that manufacturing has become more consistent and subsequently a number of quality control testing laboratories have been looking into the use of recombinant lysate. This somewhat gradual process is attributable to a clash between drivers (seeking to conserve horseshoe crabs, albeit with the mortality rate an imprecise and often contested figure)4 and points of hesitancy (regulatory uncertainty, lack of standardization, imprecise validation requirements and so on). As of 2021, recombinant lysate will become an established alternative to the traditional LAL test within Europe but within the U.S., when a new chapter appears, a greater level of comparative validation will be required in order to show equivalence. While this disparity is understandable, and this article attempts to show this through a discussion of the historical perspective, the current situation is a disservice to laboratory users. Much of what has been written on rFC to date has looked at things from a U.S.-centric perspective (rather than U.S. and European) and from a supplier or regulatory perspective; this article embraces the laboratory user perspective.


The reference is:


Sandle, T. (2020) Historical Milestones and Industry Drivers in the Development of Recombinant Lysate for Bacterial Endotoxin Testing, American Pharmaceutical Review, at:


Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (

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