Molecular cloning, expression, and characterization of a putative activation-associated secreted protein from Angiostrongylus cantonensis

Abstract

Activation-associated secreted protein (ASP) had been found in many helminthes, which was associated with pathogenesis and stage transition. A complementary DNA (cDNA) sequence encoding a putative two-domain ASP was obtained from an Angiostrongylus cantonensis fourth-stage larvae cDNA library, which we designated as AgASP. The cDNA of AgASP contains an open reading frame encoding 424 amino acids, the first 19 residues being a putative secretion signal. The expression pattern of this protein was investigated by real-time polymerase chain reaction and Western blot. We found that this protein expressed most highly in the brain-stage larvae (Lbr) of this parasite and existed in the excretory/secretory products of this stage. Immunofluorescence showed it existed in the lumen of the Lbr. The recombinant protein can be recognized by the infection sera from mice (nonpermissive host), while it cannot be recognized by infection sera from rats (permissive host). The infiltration of neutrophils in infected nonpermissive host can be lessened by immunizing this host with this protein (immunized vs control group, 13.7 ± 10.2 vs 65.5 ± 19.2). These findings suggest that this protein plays a role in the pathogenesis of human angiostrongyliasis and is worthy of further study.

Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen

“…Helminth ASPs modulate host leucocyte activity and recruit neutrophils by neutrophil receptor binding (Ansell et al 2013). Additionally, ASP was identified in a cDNA library of L 4 A. cantonensis larvae and a recombinant version of this protein was recognized by sera from infected mice but not from infected rats (Yang et al 2013 b ). The ASP gene was highly transcribed in brain stage L 4 larvae, and immunization of mice with recombinant ASP before infection reduced neutrophil infiltration in mouse brains, implicating ASPs as being directly involved in the pathogenesis of AEM (Yang et al 2013 b ).…”

Angiostrongylus Cantonensis-Conditioned Culture Medium Induces Myelin Basic Protein Alterations via Erk1/2 and NF-κB Activation in Rat RSC96 Schwann Cells

“…Additionally, Yang et al has mentioned that the activationassociated secreted protein expressed most highly in the brain-stage larvae (L3 stage) of A. cantonensis and played a role in the pathogenesis of human angiostrongyliasis (31). Moreover, L3 larvae, maintenance in vitro, kept high infective rate to the snail and rat (32). Therefore, we used L3 stage A. cantonensis-conditioned culture medium to treat rat RSC96 Schwann cells to investigate the mechanism of MBP alteration in vitro.…”