Enterocytozoon hepatopenaei (EHP), the etiologic agent of Hepatopancreatic Microsporidiosis (HPM), has emerged as one of the most problematic infectious diseases in shrimp aquaculture over the last ten years. To further investigate the disease biology and to evaluate efficacy of candidate therapeutics in controlling HPM, the University of Arizona has developed an EHP challenge method. The EHP challenge method involves amplifying EHP inoculum in live shrimp (Penaeus vannamei) by directly injecting EHP inoculum in the hepatopancreas of shrimp. Subsequently, EHP-injected animals can be sacrificed at 15 days post-injection, hepatopancreas dissected and used for an oral challenge of Specific pathogen Free (SPF) shrimp. Although an EHP challenge method is available, the effect of EHP infection on growth under laboratory challenge conditions was unproven. This study is aimed to quantify the effect of the disease progression on growth rate in Pacific white shrimp, P. vannamei, and black tiger shrimp, P. monodon.
The EHP experimental challenges involving P. monodon and P. vannamei were run side-by-side under the same environmental conditions. Animals were fed using automatic feeders throughout the day. The duration of the study was 45 days and the growth rate of EHP-infected animals and healthy animals were measured at Days 0, 15, 30 and 45 post-infection. At each time point, a subset of animals were sampled to quantify the EHP infection using H&E histology and qPCR. The results will reveal how under identical rearing conditions (e.g. feeding rates, stocking densities,rearing condition) in a laboratory experimental challenge, EHP infection affects the growth rate of P. monodon and P. vannamei.
Key words: Penaeus vannamei, Penaeus monodon, Enterocytozoon hepatopenaei, EHP, Hepatopancreatic Microsporidiosis, HPM