Bioengineered Hookworms Deliver Therapeutic Antibodies in Hamsters

Hookworms—parasitic roundworms—infect nearly 500 million people worldwide, especially in under-resourced tropical places.¹ These stout, nearly one-centimeter-long, J-shaped worms latch onto the inner surface of people’s small intestines, where they feed on blood.

Severe infections in high-risk populations like children and pregnant people could result in anemia, gastric discomfort, or developmental issues. But hookworms do not multiply within hosts, which keeps infection under check in most individuals.² Thus, people can largely tolerate infections without the parasitic worms disrupting their health. Given this property, scientists have explored approaches for hookworm-based therapeutic deliveries.³

Building on this, researchers recently bioengineered hookworms to produce and deliver a toxin-neutralizing antibody in hamsters.⁴ Their approach, published today in Nature Communications, paves the way towards the development of a transgenic hookworm platform to continuously deliver therapeutics in a safe manner.

“The hookworm has spent millions of years perfecting how to assure long-term survival inside a human host and how to get molecules out of its body and into ours,” said study author Makedonka Mitreva, an infectious disease and microbiome researcher at Washington University School of Medicine (WashU Medicine), in a statement. “We asked, ‘What if we could add one more molecule to the roughly 1,000 things the worm already secretes, something therapeutically useful to people?’” she said.

For the study, Mitreva and her team focused on using hookworms to produce and deliver an antibody that neutralizes tetrodotoxin, a lethal neurotoxin produced by marine animals like puffer fish. They first tested whether the proteins that hookworms secrete naturally interfered with the antibody’s properties. In vitro assays using neurons revealed that the antibody neutralized tetrodotoxin even in the presence of hookworm secreted proteins.

Next, by digging into the literature, the researchers identified two regions in the genome of the Ancylostoma ceylanicum hookworm where they could safely insert the antitoxin-coding gene. Inserting foreign elements within these regions would not affect surrounding gene activity while allowing consistent target protein expression. Assessing the editing efficiency after carrying out CRISPR-Cas9-based modifications helped the researchers narrow down on the genomic region most easily accessible.

Mitreva and her team then used a CRISPR-based approach to knock-in the antitoxin-coding gene into this region in immature A. ceylanicum eggs. They let these mature into larvae, which they fed to hamsters.

To investigate the success of their pipeline, the researchers collected blood from the hamsters. Immunoassays revealed that blood from the hamsters infected with transgenic hookworms partially neutralized tetrodotoxin, while animals infected with wild type hookworms did not.

“What we demonstrated here is that the concept works end-to-end: You can insert a gene, the worm produces the protein, the protein gets out of the worm, and it is functionally active in the host,” said Mitreva. Future studies could help assess the safety of such a delivery approach in humans. “That’s a fundamentally different kind of pharmaceutical biofactory platform, and we think it opens possibilities that are very hard to achieve with any other platform,” she said.