The horseshoe crab's fluorescent blue blood is its best line of defense against toxins. For 40 years, humans have harnessed that same power to help keep us safe.

GREENVILLE, S.C. – Allen Burgenson had a job, his father explained as they stood on the sand.

This was Allen's first fishing trip, but he wasn't going to take anything from the bay. He was to return the water's gifts to the deep, where they'd belonged for hundreds of millions of years. 

If he spotted a horseshoe crab on its back, his father said as he held Allen's hand, that meant it was in trouble and needed Allen's help to get home. Allen just had to flip it over. Its 10 legs could make it the rest of the way back to the crashing waves. 

Allen did just that on that day in 1963 in Sandy Hook, New Jersey, when he was 3 years old. That's what he still does today. Whenever Burgenson enjoys a stroll along the East Coast, he is still a lookout for the stranded sea creature that's unlike anything else on the planet.

In 1963, Burgenson didn't know that inside each of those ancient animals he saved was something that would help save millions of us during his lifetime.

In 2020, the horseshoe crab is poised to assume a vital role in a drug the whole world awaits, a COVID-19 vaccine.

Around the same time Burgenson was a boy on a beach, Jack Levin and Frederik Bang collaborated on horseshoe crab blood experiments. Their work led to a process that channels the almost magical force of the horseshoe crab's immune system, one that's helped the animal survive longer than most of the species that ever roamed the Earth or scurried across the ocean floor. 

'The world's health care can thank the horseshoe crab'

Since the late 1970s, horseshoe crab blood has been approved to make what's called the Limulus amebocyte lysate test, or the LAL test – an alarm system triggered by a type of bacteria that can cause fever, and in some cases, death.

It works like this: A mixture of lysate is made from the horseshoe crab's amebocyte or blood cells. That fluid is added to whatever material a researcher is testing for safety. Depending on the test, the fluid will either clot or change color to signal the presence of a dangerous toxin.

John Dubczak, an executive director with Charles River Laboratories, one of the companies licensed by the U.S. Food and Drug Administration to produce the LAL test, said it "has unequivocally elevated the quality and safety of injectable pharmaceutical drugs and medical devices, and that includes all of vaccines that protect us."

The crab usually no bigger than about 19 inches across, has a significance that outsizes its foot – or claw – print. The Limulus polyphemus, or Atlantic horseshoe crab, lives only up and down the East Coast and a small part of Central America. Less than half a million horseshoe crabs were brought to biomedical facilities in 2018, according to the most recently published data from the Atlantic States Marine Fisheries Commission.

"The world's health care can thank the horseshoe crab," Burgenson said. 

On Sept. 16, Robert Redfield, director of the Centers for Disease Control and Prevention, told a Senate panel that a vaccine might not be ready until next year. On the same day he testified, the novel coronavirus cases totaled about 30 million globally, and there were about 942,000 associated deaths. 

No matter what vaccine in trial wins the race to market, LAL will be the standard to test the safety of any materials that go into the medication, as well as the final product itself. All of that LAL will come from four production facilities in South Carolina, Massachusetts, Maryland and Virginia.

The demand of 5 billion COVID-19 vaccine doses won't be a burden, said Burgenson, chair of the Horseshoe Crabs Advisory Panel to the Atlantic States Marine Fisheries Commission. He estimated that at most, the facilities would need about three days of normal production to provide the material needed to test the vaccine's safety, and one of those days of production to test the vaccine itself.

This gift will be given by an animal that's been long misunderstood and maligned, said Burgenson, a microbiologist with almost 40 years of experience in the pharmaceutical industry.

The horseshoe crab has long been overlooked and overfished. Humans are the biggest threat to the invertebrate whose ancestry traces to the age before the dinosaurs, more than 400 million years before humans walked the Earth. 

And when we did finally meet them, we didn't even get the thing's name right. Turns out, the horseshoe crab is not even a crab.


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