Enterocytozoon hepatopenaei (EHP), one of the etiologic agents of Hepatopancreatic Microsporidiosis (HPM), continues to inhibit production in shrimp aquaculture. As the disease spreads across the world and affects aquaculture production, farmers, feed producers, and researchers continue to develop genetically resistant lines of shrimp, preventatives, and treatments.
EHP is an obligate parasite and currently there is no in vitro culture method to propagate the parasite in a reproducible manner. To aid the aquaculture community in developing treatments to overcome EHP, researchers at the Aquaculture Pathology Laboratory at the University of Arizona conducted challenge studies in which specific pathogen free (SPF) Penaeus vannamei were injected into the hepatopancreas with a fresh inoculum prepared from known EHP-infected animals. In less than two weeks following injection, challenged animal display lesions in the hepatopancreas that are pathognomonic of EHP infection, and the parasite load was quantified by real-time PCR. There is currently no in vitro propagation method for EHP and the inoculum is not viable when store at -20 0C or at -80 0C, leaving researchers with no option but to propagate EHP in live animals.
This rapid propagation method has been implemented in 11 challenge studies since December 2021 in research conducted by the researchers at the Aquaculture Pathology Laboratory, and its collaborators. The data presented will demonstrate the efficacy of this challenge method, demonstrate its benefits, and present the challenges associated when working with this emerging disease.
Key words: Penaeus vannamei, Enterocytozoon hepatopenaei, EHP challenge model