Acetylcholinesterase secretion by parasitic nematodes—II. Trichostrongylus spp

Unusually high levels of acetylcholinesterase (AChE) were found in the nematode parasites Trichostrongylus axei, T. colubriformis and T, retortaeformis. In T. colubriformis the enzyme was located in the oesophageal and excretory glands of the parasitic stages. The highest level/unit wt was found in the fourth-stage larvae, which per worm had a comparable level to that in adult worms because the excretory gland was fully developed in the fourth-stage larvae. In acrylamide gel electrophoresis, T. axei and T. colubriformis AChE and esterases were similar but differed from those present in T. retortaeformis. Globulins prepared from the sera of sheep and guinea-pigs infected with T. colubriformis complexed with T. colubriformis and T. axei AChE, but not with esterases nor with AChE from T. retortaeformis, Nippostrongylus brasiliensis, Oesophagostomum radiatum or O. venulosum. Complexing of AChE to globulins did not inhibit the enzymic function of this enzyme.