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 (DRB1*1502, DQB1*0601, 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.
Guarneri
Fabrizio
F
Istituto di Dermatologia, Policlinico Gaetano Martino, Università di Messina, Messina, Italy. f.guarneri@tiscali.it
Guarneri
Claudio
C
Benvenga
Salvatore
S
D000485:Allergens / Q000235:genetics / Q000276:immunology*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017163:Anisakis / Q000235:genetics* / Q000276:immunology*; D000947:Antigens, Helminth / Q000235:genetics / Q000276:immunology*; D003429:Cross Reactions; D005189:False Positive Reactions; D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D015801:Helminth Proteins / Q000235:genetics / Q000276:immunology*; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D014335:Tropomyosin / Q000235:genetics / Q000276:immunology*
D000485:Allergens; D000947:Antigens, Helminth; C488436:HLA DRB1*04:04 antigen; D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D015801:Helminth Proteins; D014335:Tropomyosin