Recombinant Paraprobiotics as a New Paradigm for Treating Gastrointestinal Nematode Parasites of Humans
Gastrointestinal nematodes (GINs) of humans, e.g., hookworms, negatively impact childhood growth, cognition, nutrition, educational attainment, income, productivity, and pregnancy. Hundreds of millions of people are targeted with mass drug administration (MDA) of donated benzimidazole (BZ) anthelmintics. However, BZ efficacy against GINs is suboptimal, and reduced/low efficacy has been seen. Developing an anthelmintic for human MDA is daunting: it must be safe, effective, inexpensive, stable without a cold chain, and massively scalable. Bacillus thuringiensis (Bt) crystal protein 5B (Cry5B) has anthelmintic properties that could fill this void. Here we develop an API (Active Pharmaceutical Ingredient) form of Bt Cry5B compatible with MDA. We expressed Cry5B in asporogenous Bt during vegetative phase, forming cytosolic crystals. These Bacteria with Cytosolic Crystals (BaCC) were rendered inviable (inactivated BaCC or IBaCC) with food-grade essential oils. IBaCC potency was validated in vitro against nematodes. IBaCC was also potent in vivo against human hookworm infections in hamsters. IBaCC production was successfully scaled to 350 liters at a contract manufacturing facility. A simple fit-for-purpose formulation to protect against stomach digestion and powdered IBaCC were successfully made and used against GINS in hamsters and mice. A pilot histopathology study and blood chemistry workup showed that five daily consecutive doses of 200 mg/kg Cry5B IBaCC (the curative single dose is 40 mg/kg) was non-toxic and completely safe. IBaCC is a safe, inexpensive, highly effective, easy-to-manufacture, and scalable anthelmintic that is practical for MDA and represents a new paradigm for treating human GINs.