Proteolytic activity in the adult and larval stages of the human roundworm parasite Angiostrongylus costaricensis

Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis, a widespread human parasitism in Latin America. This study aimed to characterize the protease profiles of different developmental stages of this helminth. First-stage larvae (L1) were obtained from the faeces of infected Sigmodon hispidus rodents and third-stage larvae (L3) were collected from mollusks Biomphalaria glabrata previously infected with L1. Adult worms were recovered from rodent mesenteric arteries. Protein extraction was performed after repeated freeze-thaw cycles followed by maceration of the nematodes in 40 mM Tris base. Proteolysis of gelatin was observed by zymography and found only in the larval stages. In L3, the gelatinolytic activity was effectively inhibited by orthophenanthroline, indicating the involvement of metalloproteases. The mechanistic class of the gelatinases from L1 could not be precisely determined using traditional class-specific inhibitors. Adult worm extracts were able to hydrolyze haemoglobin in solution, although no activity was observed by zymography. This haemoglobinolytic activity was ascribed to aspartic proteases following its effective inhibition by pepstatin, which also inhibited the haemoglobinolytic activity of L1 and L3 extracts. The characterization of protease expression throughout the A. costaricensis life cycle may reveal key factors influencing the process of parasitic infection and thus foster our understanding of the disease pathogenesis.

Genetic variability in isozymes of Angiostrongylus malaysiensis.

The genetic difference between Angiostrongylus malaysiensis and A. cantonensis was assayed by electrophoretic analysis of isozymes. Six enzymes were analyzed using 5% polyacrylamide gel electrophoresis. Seven of 10 loci, namely GPI-1, GPI-2, HK-1, HK-2, MDH-1, MDH-2 and PGM-2, were shown to be polymorphic, but the remaining 3 loci, LDH, ME and PGM-1, were not. Both A. malaysiensis and A. cantonensis were polymorphic at 6 of the loci (p = 0.600) with heterozygosity H of 0.286 and 0.151, respectively. The Nei's genetic distance (D) between A. malaysiensis and A. cantonensis was 0.27470. This value indicates the level of interspecific variation within a genus. Through isozyme analysis, the present study demonstrated that A. malaysiensis of Japan is a valid species, separate from A. cantonensis.

Glycolytic enzymes in juvenile and adult Angiostrongylus cantonensis.

In extracts of adult Angiostrongylus cantonensis, the activities of enzymes including glucokinase, phosphoglucoisomerase, phosphofructokinase, aldolase, triosepho sphate isomerase, glyceraldehydephosphate dehydrogenase, phosphoglycerokinase, phosphoglyceromutase, enolase, pyruvate kinase, lactate dehydrogenase, pyruvate decarboxylase, alcohol dehydrogenase, glucose 6-phosphate dehydrogenase, glycerophosphate dehydrogenase and pyruvate dehydrogenase complex were demonstrated. The present of significant activity of glycerophosphate dehydrogenase and glucose 6-phosphate dehydrogenase may indicate the possibility of an operative of alpha-glycerophosphate and pentose phosphate pathway.