Analysis of the antigenicity in mice of biotinyl enzymes from Anisakis simplex and other nematodes

Abstract

We analyzed the antigenicity of biotinyl enzymes contained in somatic extracts from Anisakis simplex and other parasite nematodes and show in this report that these molecules are an important source of cross-reactivity problems among these nematodes. Cross-reactivity was most pronounced among members of the superfamily Ascaridoidea. These results suggest that the presence of biotinyl enzymes in whole somatic extracts of A. simplex and other parasites may make serodiagnostic assays based on this kind of antigenic preparation unreliable.

Anisakis simplex: from Obscure Infectious Worm to Inducer of Immune Hypersensitivity

“…A possible reason for IgE detection of antibodies in a healthy population is a subclinical or undiagnosed gastric (without allergy) anisakiasis, and this could explain the high prevalence of specific IgE in both the Spanish and the Japanese populations (4,69). Other possible explanations for the existence of IgE against A. simplex without clinical manifestations may include (i) cross-reactivity with other nematodes (26,167); (ii) the presence of a "panallergen," such as tropomyosin, which occurs in crustaceans, insects, and mites (23, 96, 108)-some authors suggest that IgE can be stimulated by invertebrate tropomyosins in general (22); (iii) cross-reactivity due to carbohydrates or phosphorylcholine (35,96,167,271); and (iv) cross-reactivity with glycans present in glycoproteins of other nematodes or the presence of biotinyl enzymes that can stimulate the production of IgE in some patients (166).…”

“…In the 1990s, attempts to improve diagnostic techniques for anisakiasis led to the isolation of a MAb (An2) by Japanese authors that recognized an ES product of 40 to 42 kDa (284). cDNA encoding the target antigen was then cloned by Sugane et al (255), and Spanish authors developed five further MAbs, among which was UA3, whose target antigen is recognized by antibody in most patients with an antigen capture ELISA (166,167). Interestingly, UA3 was found to be useful for both anisakidosis and allergy diagnosis, the latter using an O-deglycosylated antigen (165).…”

Natural antibodies to nematode biotinyl-enzymes in human sera

“…However, the levels of anti-BE IgG1 antibodies were relatively low for most individuals (mean OD 0.391; range: 0.038±1.6); only 16/ 126 subjects (12.7%) showed absorbance values higher than 0.5 using non-deglycosylated antigen. Surprisingly, the cleavage of O-glycosidic linkages from the A. simplex antigen signi®cantly increased (P<0.0001) recognition by IgG1 antibodies, in such a way that all the normal 13). Interestingly, none of the 125 normal sera tested showed IgE antibodies (mean 0.1695 kU/l; range 0.011±0.56 kU/l; estimated cut-o for this isotype 0.6 kU/l) (Fig.…”

“…Furthermore, recent studies in our laboratory have revealed that BEs present in A. simplex are antigenic in mice, and that antibodies induced against these BEs cross-react with BEs from other nematodes (e.g., Toxocara, Ascaris) [13]. This suggests the existence of common epitopes, in accordance with the conservative nature of these enzymes [3,21,10,7,18,25,22,13,11].…”

“…Furthermore, recent studies in our laboratory have revealed that BEs present in A. simplex are antigenic in mice, and that antibodies induced against these BEs cross-react with BEs from other nematodes (e.g., Toxocara, Ascaris) [13]. This suggests the existence of common epitopes, in accordance with the conservative nature of these enzymes [3,21,10,7,18,25,22,13,11]. Since BEs have been identi®ed in numerous organisms, including animals, bacteria (e.g., E. coli) and plants [3,4,9,27,12], it seems likely that humans are continuously exposed to these antigens by the oral route, possibly leading to induction of antibodies or even to allergic reactions if IgE antibodies are induced.…”