In vivo and in silico investigations on the efficacy of albendazole against Enterocytozoon hepatopenaei (EHP) infecting Penaeus vannamei

The microsporidian Enterocytozoon hepatopenaei (EHP) is an intercellular spore former that causes hepatopancreatic microsporidiosis (HPM), a commercially important disease in Penaeus vannamei (white leg shrimp) farming. In this study, albendazole an inhibitor of β-tubulin polymerization in microsporidians was evaluated for its efficacy in reducing EHP infection in P. vannamei. EHP-infected shrimps were exposed to 1, 5, 10, 25, 50 and 75 mg L−1 of albendazole and evaluated for the reduction in EHP DNA copy numbers at 3, 6, 9, 12, 15, 18, 21, 24 days post-exposure (dpe) by absolute quantitative real-time PCR (RT-qPCR) assay. The expressions of antioxidant enzyme genes viz., cytosolic manganese superoxide dismutase (cMnSOD), catalase (CAT) and glutathione peroxidase (GPx); haemolymph aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were assessed at 24 dpe. A maximum of about 98% reduction in EHP DNA copies was observed in the shrimps treated with 75 mg L−1 per day for 24 days. A significant upregulation in relative expressions of GPx genes and a downregulation cMnSOD and CAT genes were observed in shrimps exposed to 25, 50 and 75 mg L‐1 at 24 dpe. A significant reduction in haemolymph AST and ALT levels was observed upon treatment with 25, 50 and 75 mg L−1 at 24 dpe and there are no significant changes in ALP. A virtual molecular docking between albendazole and EHP encoded β-tubulin revealed a best binding interaction with the presence of 11 hydrogens bonds, multiple non-covalent bonds and a very much lower solvation-free energy gain of −15.6 kcal mol−1 in the active sites of protein interactions. Thus, this study identified albendazole as a potential drug to control EHP infection in shrimp, which might help to combat the production losses caused by EHP.