Prehistoric crabs help test vaccine safety

These bizarre looking creatures predate even the dinosaurs. For 450 million years they've patrolled our oceans. Despite being named horseshoe crabs, these living fossils aren't related to crabs at all, reveals community science manager Nivette Perez-Perez of the Delaware Center for the Inland Bays.

Nivette Pérez-Pérez: "Horseshoe crabs, in, in difference of their common name, they're not crabs. They're actually arthropods that are related to spiders and scorpions. This is a female, and one of the ways to see that is this first pair of legs. They're actually pinchers."

They've been utilised within the biomedical industry since the 1970s. A special component within their blood, called limulus amebocyte lysate, can be used to detect bacterial endotoxins. This is vital for testing against bacteria that contaminates medications, needles, joint replacements and also vaccines.

Its use has spiralled, reports Glenn Gauvry, president of a horseshoe crab conservation society.

Glenn Gauvry: "One of the things that has always been tested with this test is vaccines. So we've got vaccines around the world for all kinds of things, but we now have a whole new wave of vaccines being produced and developed for the battle against Covid. And they're being tested on, on the same test made from the horseshoe crab blood."

An annual total of around 500,000 horseshoe crabs are harvested and bled for this vital extract. Of these, 15 percent don't survive, which, combined with other threats they face, makes it imperative that an alternative to their blood is found. A new synthetic compound called recombinant factor C is in development through Swiss biotech company Lonza. However, it still has regulatory challenges to overcome.

Meanwhile, in the US, volunteers on Delware's beaches continue to monitor the horseshoe crab's breeding season. Laurel Sullivan's an education coordinator at the Delaware Department of Natural Resources.

Laurel Sullivan: "We have the largest spawning population in the world in the Delaware Bay. So it's something that people in this area take very seriously and they're really passionate about, because it's something that's really unique to this area."

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