Morin inhibits fructose bisphosphate aldolase activity and resists Cryptosporidium parvum infection.

Cryptosporidium parvum is a zoonotic intestinal protozoan that causes severe diarrhea in children and immunocompromised individuals. The lack of effective therapies underscores the urgent need for novel drug targets. As C. parvum primarily relies on glycolysis for energy, fructose-1,6-bisphosphate aldolase (FBA) represents a promising target. Here, we characterized CpFBA and evaluated its potential as a therapeutic target. Sequence analysis revealed that CpFBA contains a signature domain associated with the type I fructose-bisphosphate aldolase superfamily and adopts a tetrameric structure. CpFBA protein localizes to both the cytoplasm and membrane of C. parvum sporozoites and presents in C. parvum excretory-secretory products (ESPs). Recombinant CpFBA protein (rCpFBA) exhibits typical aldolase activity, with a higher affinity for fructose-1,6-bisphosphate (FBP) (Km = 81.23 μM). Subsequently, molecular docking computationally predicted that morin may potentially bind to CpFBA. Anti-CpFBA serum or morin treatment significantly reduces glucose uptake and ATP levels of C. parvum sporozoites, and decreases parasite number in vitro. In C. parvum-infected suckling mice, morin treatment (60 mg/kg/day) significantly reduces oocyst shedding by 61.8%, alleviates C. parvum-induced weight loss and intestinal damage, preserves the expression of tight junction proteins (ZO-1, occludin), and suppresses the production of pro-inflammatory cytokines. These findings suggest that CpFBA is a promising drug target against C. parvum, and the natural compound morin resists C. parvum infection.