Analysis on the infecting ability of different concentrations of Enterocytozoon hepatopenaei (Microsporidia, Microsporea, Chytridiopsida) in Exopalaemon carinicauda (Decapoda, Caridea, Palaemonidae)

Abstract Exploring the relationship between the number of Enterocytozoon hepatopenaei (EHP) in the ambient water and its infecting ability in Exopalaemon carinicauda , we set up 6 EHP-concentration groups of 0, 10 1 , 10 2 , 10 3 , 10 4 , and 10 5 . Subsequently, we compared the differentiation of the number of EHP copies in different tissues, the change in hepatopancreas structure, and the inducible nitric oxide synthase and NO in the haemolymph. Our result showed: the number of EHP copies in each tissue would increase significantly following the increase of EHP concentration in the water. The highest EHP copy numbers were found in hepatopancreas at the same infection condition. Additionally, EHP copy numbers in hepatopancreas were positively correlated with infection time. Furthermore, histopathological results showed the damage to the hepatopancreas had severed with the concentration of EHP increasing. Also, iNOS activity and NO content in the haemolymph of shrimp were affected by the different EHP concentrations. This study revealed significant differences in the infection ability of different concentrations of EHP spores.