First report on Enterocytozoon hepatopenaei (EHP) infection in Pacific white shrimp (Penaeus vannamei) cultured in Korea

The microsporidian Enterocytozoon hepatopenaei (EHP) is an intracellular parasite that is a critical threat to the global shrimp farming industry. This parasite replicates in the hepatopancreas and midgut, and infected shrimp exhibit reduced feeding and growth retardation. In this study, we describe the first known EHP infection in the Pacific white shrimp ( Penaeus vannamei ) cultured in Korea. Histopathological examination showed basophilic inclusions in the hepatopancreatic tubule epithelial cells of the infected shrimp. PCR targeting small subunit (SSU) rRNA sequences showed that the resultant EHP sequences from the shrimp culture pond was >99.0% identical to EHPs found in Southeast Asian countries, but were distant from the Latin American isolate. We also compared the nucleotide sequences of the EHP spore wall protein (SWP) gene from the cultured shrimp and pond water to those from other EHPs from different geographical locations. Phylogenetic analyses using the sequenced SSU rRNA and SWP genes confirmed the close resemblance of the newly isolated Korean EHP to those from Southeast Asian countries, suggesting that it might have been introduced from those countries. The emergence of EHP in Korea will have a significant impact on shrimp production; therefore, the presence and prevalence of EHP in shrimp culture in addition to its pond water should be monitored carefully to control its spread in the Korean shrimp culture industry. • Enterocytozoon hepatopenaei (EHP) infection in Pacific white shrimp ( Penaeus vannamei ) is firstly confirmed in Korea. • The newly isolated EHP in Korean shrimp farms were closely related to those reported from Southeast Asian countries. • Subsequent enforcement of quarantine policies against EHP is urgently required in Korea.