Harnessing Antibodies as Pathogen Hunters

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On a microscopic level, humans face an existential threat every day. All sorts of tiny pathogens, like bacteria and viruses, work constantly to get inside our bodies, reproduce, and continue their species—which, unfortunately for us, often leads to disease and sometimes death.

Luckily, humans and other mammals have developed a few ways to avoid that fate. Over millions of years, our immune systems evolved to spot invaders and destroy them before they strike, keeping our bodies safe and healthy.

A key part of that system—a class of proteins called antibodies—constantly patrol our tissues for specific threats that have attacked the body before. When an antibody spots a pathogen it recognizes, it can latch onto the invader, block some of its functions, and send out a signal to the rest of the immune system to come dispatch the bad guy.

They’re elegant molecules, says Chuck Shoemaker, and can be used for a variety of medical therapies. Shoemaker, a professor in the Department of Infectious Disease and Global Health at Cummings School, is currently working to harness antibodies’ unique skillset as pathogen hunters. Ultimately, he says, he’s aiming to turbocharge their abilities in the lab, and use the resulting über-antibodies as components of new treatments for deadly diseases.

Shoemaker works specifically with antibodies from camelids (animals like alpacas), which have a simpler structure than most other mammalian antibodies and can much more easily be re-engineered for use in therapies or diagnostic tests.

“We can link two or more antibodies together as a single protein,” says Chuck Shoemaker. “We can design them to target almost any disease agent—from cancer cells to infectious pathogens—with high potency and specificity.”In order to make these molecules, Shoemaker immunizes an alpaca against a specific pathogen, then takes a blood sample that contains its antibody-producing cells. He then extracts the DNA that codes for those antibodies, edits it in the lab, and use it to create enhanced new antibody molecules.

“Using that method, we can link two or more antibodies together as a single protein. Such molecules can then perform new functions not possible with conventional antibodies,” he says. “We can design them to target almost any disease agent—from cancer cells to infectious pathogens—with high potency and specificity.”

The antibodies themselves don’t always do the dirty work. Their job is often to act as a kind of homing device that can guide other molecules in the body to a specific target. But the fact that they can latch onto a specific target themselves isn’t small potatoes—in fact, it can sometimes be enough to stop a disease in its tracks, Shoemaker says. If his lab-made antibodies attach themselves to the business end of a toxic molecule, he notes, they can effectively stop that molecule from interacting with anything else, rendering it harmless.

Fending Off Botulism

During recent work with scientists at New York University and Massachusetts General Hospital, Shoemaker’s team did just that. In a pair of studies recently published in the journal Science Translational Medicine, he and his colleagues showed…



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