Analysis molecular mimicry between protozoa Giardia intestinalis and autoantigens implicated in autoimmune reactive arthritis: potential cross-reactivity

Introduction : Giardia intestinalis (G. intestinalis) is an intestinal parasite that infected between 200 and 300 million people worldwide. Some patients developed reactive arthritis after infection clearance. Molecular mimicry could induce cross reactivity to generate autoimmune disease. Objective : To evaluate the potential molecular mimicry between autoantigens implicated in in reactive arthritis and G. intestinalis antigens using in silico analysis. Methodology : Similarity between autoantigens and protozoa antigens was analyzed using PSI-BLAST. After, shared regions were identified performing binary alignments. Using 3D structures retrieved from protein data bank or modelled B cell epitopes were predicted with Ellipro tool. Epitopes predicted were visualized on 3D structure with Pymol software. Results : In total, six of thirty-nine autoantigens report for reactive arthritis-associated showed similarity with proteome reported for G. intestinalis. autoantigens were included in the study and compared against the G. intestinalis proteome. These autoantigens shared up 30% with homologues from protozoa. We have that the autoantigens that showed the greatest identity were Alpha enolase with Enolase and HSP 60 Chaperonin 60, Putative TCP-1/cpn60 chaperonin family protein, 60 kDa of groel chaperonin. Sixty-eight epitopes with scores greater than 0.7 were identified from G. intestinalis antigens. Conclusion : Six G. intestinalis antigens are identified that mimic reactive arthritis autoantigens, with moderate levels of identity that could explain a cross-reactivity involved in the development of the autoimmune response reported in patients who suffered from the infection.