Differential proteolytic activity in Anisakis simplex s.s. and Anisakis pegreffii, two sibling species from the complex Anisakis simplex s.l., major etiological agents of anisakiasis Molina Fernández, Dolores Benítez Rodríguez, Rocío Adroher Auroux, Francisco Javier Malagón Martínez, David Nematodes Parasites Anisakiasis Sibling species of Anisakis simplex s.l. Peptidases This is the accepted preprint. Article published in Acta Tropica 195: 44-50 (2019). © 2019 Elsevier B. V. All rights reserved. Downloadable from: https://linkinghub.elsevier.com/retrieve/pii/S0001706X18306971 or https://doi.org/10.1016/j.actatropica.2019.04.003. Proteolytic activity was studied in two sibling species of Anisakis (Nematoda: Anisakidae), A. simplex s.s. and A. pegreffii, throughout their in vitro development from third larval stage (L3) from the host fish (L3-0h) to fourth larval stage (L4) obtained in culture. Proteases have a significant role in the lifecycle of the parasite and in the pathogen-host relationship. Proteolytic activity peaks were detected at pH 6.0 and 8.5. Protease activity was detected in all the developmental stages of the two species studied at both pH values. These pH values were used for assaying with specific inhibitors which permitted the determination of metalloprotease activity, and, to a lesser extent, that of serine and cysteine protease. Aspartic protease activity was only detected at pH 6.0. At this pH, L4 larvae showed higher proteolytic activity than L3 larvae in both species (p<0.001), the majority of activity being due to metalloproteases and aspartic proteases, which could be related to nutrition, especially the latter, as occurs in invertebrates. At pH 8.5, proteolytic activity was higher in A. simplex s.s. than in A. pegreffii (p<0.01). At this pH, the majority of activity was due to metalloproteases in all developmental phases of both species, although in L3-0h, the activity of these proteases was significantly higher (p<0.03) in A. simplex s.s. than in A. pegreffii. This could be related to the greater invasive capacity of the former. Serine proteases have frequently been implicated in the invasive capacity and pathogenicity of some parasites.This may be related to the significantly higher activity (p≤0.05) of serine protease in all the larval stages studied of A. simplex at pH 6.0. In summary, there are interspecific differences in proteases that have been related to pathogenesis in nematodes. These differences could thus be contributing to the previously reported differences in pathogenicity between these two Anisakis species. 2024-02-21T07:22:43Z 2024-02-21T07:22:43Z 2019-04-14 journal article Molina-Fernández, D., Benítez, R., Adroher, F. J., & Malagón, D. (2019). Differential proteolytic activity in Anisakis simplex s.s. and Anisakis pegreffii, two sibling species from the complex Anisakis simplex s.l., major etiological agents of anisakiasis. Acta Tropica, 195, 44–50. https://doi.org/10.1016/j.actatropica.2019.04.003 https://hdl.handle.net/10481/89412 10.1016/j.actatropica.2019.04.003 eng open access Elsevier B. V.