Cross-reactivity of Anisakis simplex: possible role of Ani s 2 and Ani s 3.

BACKGROUND

Anisakis simplex is a fish parasite that can cause allergy in humans. The multiple cross-reactivities of this nematode make diagnostic tests for allergy unreliable, because of frequent false-positive results. To date, only four allergens of A. simplex have been characterized, but their role in cross-reactivity is largely unknown.

METHODS

We performed an amino acid sequence homology analysis, according to the Food and Agriculture Organization/World Health Organization (FAO/WHO) criteria, to identify allergens likely to be cross-reactive with Ani s 2 (paramyosin) and Ani s 3 (tropomyosin) of A. simplex. Next, within segments shared by Ani s 2 or Ani s 3 and homologous proteins, we searched for the occurrence of binding motifs of human leukocyte antigen (HLA) alleles (DRB11502, DQB10601, or DRB1*0404) known to be genetic risk factors for the development of allergy to A. simplex.

RESULTS

We identified a number of proteins belonging to various organisms, which are significantly similar to (and therefore are likely to cross-react with) Ani s 2 and Ani s 3. The presence of binding motifs of HLA DRB1*0404 in Ani s 2, Ani s 3, and homolog proteins also supports our hypothesis.

CONCLUSIONS

Our results provide a possible molecular explanation of some cross-reactivities reported for A. simplex, and suggest additional ones.