A new paraprobiotic-based treatment for control of Haemonchus contortus in sheep

Abstract

Haemonchus contortus is a critical parasite of goats and sheep. Infection by this blood-feeding gastrointestinal nematode (GIN) parasite has significant health consequences, especially in lambs and kids. The parasite has developed resistance to virtually all known classes of small molecule anthelmintics used to treat it, giving rise in some areas to multidrug resistant parasites that are very difficult to control. Thus, new anthelmintics are urgently needed. Bacillus thuringiensis (Bt) crystal protein 5B (Cry5B), a naturally occurring protein made by a bacterium widely and safely used around the world as a bioinsecticide, represents a new non-small molecule modality for treating GINs. Cry5B has demonstrated anthelmintic activities against parasites of monogastric animals, including some related to those that infect humans, but has not yet been studied in a ruminant. Here we show that H. contortus adults are susceptible to Cry5B protein in vitro . Cry5B produced in its natural form as a spore-crystal lysate against H. contortus infections in goats had no significant efficacy. However, a new Active Pharmaceutical Ingredient (API) paraprobiotic form of Cry5B called IBaCC (Inactivated Bacterium with Cytosolic Crystals), in which Cry5B crystals are encapsulated in dead Bt cell wall ghosts, showed excellent efficacy in vitro against larval stages of H. contortus and relative protein stability in bovine rumen fluid. When given to sheep experimentally infected with H. contortus as three 60 mg/kg doses, Cry5B IBaCC resulted in significant reductions in fecal egg counts (90%) and parasite burdens (72%), with a very high impact on female parasites (96% reduction). These data indicate that Cry5B IBaCC is a potent new treatment tool for small ruminants in the battle against H. contortus .

An inactivated bacterium (paraprobiotic) expressing Bacillus thuringiensis Cry5B as a therapeutic for Ascaris and Parascaris spp. infections in large animals

“…1 B). As has been shown with all other parasitic nematodes tested [ 31 , 47 ], intoxication of A. suum by Cry5B IBaCC was dependent upon Cry5B protein since incubation of parasites in the presence of IBa control lacking Cry5B but otherwise identical to IBaCC resulted in no intoxication (detailed in Materials and Methods). These in vitro data indicated that Cry5B IBaCC, but not the inactivated bacterium B. thuringiensis with empty vector (IBa), has potential to impact A. suum infections in vivo .…”

“…Continuing human MDA campaigns and veterinary parasite control strategies would therefore benefit substantially with the addition of new anthelmintics against ascarid parasites with the following requirements: highly and broadly potent against this family of helminths, and safe, inexpensive, and massively scalable for MDA. We have recently described an active pharmaceutical ingredient (API) called IBaCC (see below) containing the Bacillus thuringiensis (Bt) Crystal (Cry) protein Cry5B that is effective against human hookworm infections in rodents and against Haemonchus contortus infections in sheep and that meets all the requirements for MDA [ 31 , 32 ]. Cry5B itself was shown to be active against A. suum in pigs when delivered as a live spore-crystal lysate (SCL) [ 33 ].…”

Recombinant Paraprobiotics as a New Paradigm for Treating Gastrointestinal Nematode Parasites of Humans

“…On a molar concentration scale, Cry5B IBaCC is 175× more effective at clearing hookworms than albendazole ( 66 ). High efficacy of Cry5B IBaCC against Haemonchus contortus infections in small ruminants (sheep) has also just been reported ( 67 ).…”

In vitro characterization of Haemonchus contortus trehalose-6-phosphate phosphatase and its immunomodulatory effects on peripheral blood mononuclear cells (PBMCs)

“…Haemonchus contortus is a nematode parasite that feeds on the blood of ruminants as a source of nutrition, causing serious effects and even death to grazing ruminants worldwide, especially to small ruminants [ 47 , 48 ]. In this study, we cloned and expressed the gene encoding HcGOB, a key enzyme of the trehalose synthesis pathway of H. contortus and found that the rHcGOB protein was recognized by the sera from a goat infected with H. contortus .…”