Expression patterns and structural modelling of Hsp70 and Hsp90 in a fish-borne zoonotic nematode Anisakis pegreffii

Heat shock proteins (HSPs) are essential molecular chaperones that are highly conserved across organisms. They have a pivotal function in responding to thermal stress and are responsible for many cellular functions. Here, we aimed to elucidate the possible roles of Hsp70 and Hsp90 in the life cycle of the parasitic nematode Anisakis, particularly third- and fourth-stage larvae, from cold-blooded fish to warm-blooded marine mammals or accidentally to human hosts. We examined the expression profiles of Hsp70 and Hsp90 in different developmental stages of Anisakis pegreffii. The open reading frame of Hsp70 of A. pegreffii was 1950 bp, and deduced amino acid sequence showed high homology with those of other nematodes. Heatmap analysis revealed sequence identity of Hsp70 and Hsp90 in 13 important parasitic species, human and yeast. On heatmap and phylogenetic analysis, ApHsp70 and ApHsp90 shared the highest amino acid sequence identity with other nematodes and formed a monophyletic clade. The three-dimensional (3D) structure prediction of the newly characterized ApHsp70 and known ApHsp90 gene showed highly conserved motifs between A. pegreffii and other species. Quantitative real-time PCR and western blot analysis revealed higher mRNA and protein expression for ApHsp70 and ApHsp90 in fourth- than third-stage larvae, with higher mRNA and protein expression for ApHsp70 than ApHsp90. ApHsp70 and ApHsp90 may play important roles in Anisakis in response to thermal stress and might be important molecules in the development of A. pegreffii, which has implications for its control.