Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

ASSESSING INFECTIVITY OF FECAL STRING OBTAINED FROM EHP INFECTED Penaeus vannamei SHRIMP AT DIFFERENT SALINITIES

L. F. Aranguren Caro*, F. Alghamdi, Y. Alrehaili, A. Alazwari, S. Algetham, K. Debelder, J. Lin, H. N. Mai & A. K. Dhar
Aquaculture Pathology Laboratory
School of Animal and Comparative Biomedical Sciences
University of Arizona, 1117 E  Lowell St. Tucson, Arizona, USA, 85721
 *lfarangu@email.arizona.edu
 

Enterocytozoon hepatopenaei (EHP)  is an emerging pathogen that affects P. vannamei  shrimp  in  many  SE Asian countries including  Indonesia, Vietnam,  China, Thailand, India and Malaysia.  In the western hemisphere,  EHP  was reported for the first time in 2016 in farmed P. vannamei . Infected shrimp exhi bit reduced feeding and severely retarded growth. EHP is an enteric pathogen that replicates in the cytoplasm of tubule epithelial cells in the hepatopancreas. Anecdotal evidence suggest that  EHP seems to be more prevalent in grow-out ponds where the salinity is high (>15 ppt) compared to grow-out ponds with low salinities (<5 ppt) . .  Considering that Penae us vannamei shrimp is an euryhaline species which is now farmed worldwide in wide range of salinities, we were interested to determine if EHP is able to replicate in low salinities.

In this study, we describe d an experimental infection using fecal strings from  known EHP-infected P. vannamei  as a source inoculum. S pecific P athogen Free (SPF) P. vannamei shrimp were maintained at different salinities including 2 ppt, 15 ppt and 30 ppt  and continuously challenged using fecal string  over a period of three weeks . Infectivity of EHP containing fecal strings to animals reared at different salinities were confirmed by conventional PCR and histology . PCR  data showed  positive results in shrimp maintained at 2ppt, 15ppt and 30 ppt with higher prevalence at 2 ppt.  H&E histology where animals reared at 2 ppt salinity displayed higher levels of infection compared to animals reared at 15 and 30 ppt, respectively.  The results  showed th at EHP can replicate well in shrimp maintained at low salinities.