Because invertebrates lack an adaptive immune system, they had to evolve effective intrinsic defense strategies against a variety of microbial pathogens. This ancient form of host defense, the innate immunity, is present in all multicellular organisms including humans. The innate immune system of the Japanese horseshoe crab Tachypleus tridentatus, serving as a model organism, includes a hemolym...

Protease inhibitors play a decisive role in maintaining homeostasis and eliciting antimicrobial activities. Invertebrates like the horseshoe crab have developed unique modalities with serine protease inhibitors to detect and respond to microbial and host proteases. Two isoforms of an immunomodulatory two-domain Kazal-like serine protease inhibitor, CrSPI-1 and CrSPI-2, have been recently identi...

Complement C3 plays an essential role in the opsonization of pathogens in the mammalian complement system, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. To understand the molecular mechanism of C3b deposition on microbes, we characterized two types of C2/factor B homologs (designated TtC2/Bf-1 and TtC2/Bf-2) identified from the horseshoe crab Tachypl...

This year celebrates the 30th anniversary of the licensing of Limulus amebocyte lysate (LAL) by the US Food and Drug Administration (FDA) as a test for the presence of endotoxin in biologicals, pharmaceutical drugs, and medical devices. LAL is currently recognized by several major pharmacopoeias and is used worldwide. That a suitable alternative for the detection of endotoxin has not supplanted...