What’s one thing you never leave your house without? Your keys? A mask? How about a bag of horseshoe crab blood?
Likely not, but it never hurts to be prepared. The fluorescent blue blood of this ancient crustacean has some powerful disease-fighting properties, and is playing a critical role in the development of a COVID-19 vaccine.
According to the Detroit Free Press, the horseshoe crab was first used in medicine in 1963. Scientists Jack Levin and Frederik Bang knew the horseshoe crab’s resilient immune system helped it thrive for millions of years, throughout mass extinctions, ice ages, and other global shifts. And their initial experiments with horseshoe crab blood in 1956 showed an efficient way to harness the power of this impressive immunity.
By the 1970s, the scientists had developed the Limulus amebocyte lysate (LAL) test using horseshoe crab blood. It acts as an alarm system in the presence of a dangerous bacteria. When a sample from a patient is mixed with the horseshoe crab blood-derived lysate, it will either clot or change color, informing doctors of how best to treat the patient and save more lives.
The LAL test, “has unequivocally elevated the quality and safety of injectable pharmaceutical drugs and medical devices, and that includes all of vaccines that protect us,” said John Dubczak, an executive director with Charles River Laboratories.
“All pharmaceutical companies around the world rely on these crabs. When you think about it, your mind is boggled by the reliance that we have on this primitive creature,” said Barbara Brummer, state director for The Nature Conservancy in New Jersey.
As National Geographic reports, the horseshoe crab’s immune system makes them valuable, and also puts them at risk.
“Every year, pharmaceutical companies round up half a million Atlantic horseshoe crabs, bleed them, and return them to the ocean— after which many will die,” NatGeo reports. “This practice, combined with overharvesting of the crabs for fishing bait, has caused a decline in the species in the region in the past few decades.”
The overfishing of horseshoe crabs isn’t just depleting this one species, it’s depressing a larger ecosystem, from the migratory shorebirds who eat the crabs to gain strength for trans-oceanic flights, or striped bass, flounder and Diamondback terrapins who feed on crab eggs.
We’re not the only species who depends on the horseshoe crabs, but science has yet to replicate the health benefits of their luminous blue blood.
Mass harvesting horseshoe crabs is not sustainable given the demand, and Lysate is expensive. A gallon of the substance costs about $60,000 to produce. Synthetic alternatives have been developed, but are not yet deemed as safe as crab-derived lysate, according to the USP-NF.
Despite the cost, LAL is reliable, and will be used to test any COVID-19 vaccine used in the United States. According to the Free, it will be sourced domestically, too, ” from four production facilities in South Carolina, Massachusetts, Maryland and Virginia.”
So, how much horseshoe crab blood is needed to produce 5 billion doses of a COVID-19 vaccine? About three days worth of normal production followed by a day of testing. Not nearly enough to push the species onto the IUCN Red List, but what happens when the next outbreak comes along?
Learn more in the video below.