Investigations into the effects of plant derived cysteine proteinases on tapeworms (cestoda)
Mansur, Fadlul Azim Fauzi Bin (2013) Investigations into the effects of plant derived cysteine proteinases on tapeworms (cestoda). PhD thesis, University of Nottingham.
Gastrointestinal (GI) helminths pose a significant threat to the livestock industry and are a recognized cause of global morbidity in humans. Control relies principally on chemotherapy but in the case of nematodes is rapidly losing efficacy through widespread development and spread of resistance to conventional anthelmintics and hence the urgent need for novel classes of anthelmintics. Cysteine proteinases (CPs) from papaya latex have been shown to be effective against three murine nematodes Heligmosomoides bakeri, Protospirura muricola and Trichuris muris in vitro and in vivo and against the economically important nematode parasite of sheep Haemonchus contortus. Preliminary evidence suggests an even broader spectrum of activity with efficacy against the canine hookworm Ancylostoma ceylanicum, juvenile stages of parasitic plant nematodes of the genera Meloidogyne and Globodera and a murine cestode Hymenolepis microstoma in vitro. This project focused on tapeworms. Using 2 different rodent cestodes Hymenolepis diminuta and Hymenolepis microstoma and 1 equine cestode Anoplocephala perfoliata I have been able to show that CPs do indeed affect cestodes whether young newly hatched scoleces in vitro (by causing a significant reduction in motility leading to death of the worms) or mature adult worms in vitro (by causing a significant reduction in motility leading to death of the worms) and in vivo (resulting in a significant, but relatively small, reduction in worm burden and biomass), despite no effects on worm fecundity. Although only minimally efficacious against Hymenolepis microstoma and moderately efficacious against Hymenolepis diminuta in vivo, efficacy was enhanced by the synergistic effects of the immune system demonstrated against Hymenolepis diminuta in the non-permissive host. The results offer the possibility that with further refinement, CPs may be developed into broad spectrum anthelmintics that in addition to their marked effects on nematodes also remove any concurrently residing tapeworms.
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