Abstract

White spot syndrome virus (WSSV) can cause 100% cumulative mortality to farmed shrimp, and there is increasing concem over the possible introduction of this virus into wild shrimp and crab populations in the Gulf of Mexico. In this contribution, we compare the mortality rate of WSSV infected Farfantepenaeus duorarum to Litopenaeus vannamei. In addition, we demonstrate that the stone crab (Menippe adina) is susceptible to WSSV infection.\We used an experimental procedure that is based on a mathematical epidemiology model to compare the survival of F. duorarum to L. vannamei from exposures to WSSV. The experimental procedure involved exposing 12 uninfected susceptible shrimp to a single infected shrimp cadaver for a specified period of time and then isolating the exposed shrimp individually to determine the number of deaths. Menippe adina were challenged by injection of a homogenate containing WSSV and exposed per os to WSSV infected tissue. The L. vannamei used in the experiment were obtained ftom the United States Marine Shrimp Farming Program, and F. duorarum and M. adina were obtained ftom the wild.\The mean mortality rate from a WSSV exposurewas 0.81 for L. vannamei, and 0.75 for F. duorarum. A statistical difference was not detected in final mean mortality rates between L. vannamei and F. duorarum. From the M. adina challenge, two of the four crabs injected with WSSV died, and both of those were found to be histologically positive for WSSV associated lesions. In addition to the WSSV inclusions, basophilic, intranuclear inclusions were found in hypertrophied nuclei of hepatopancreatic cells which may be caused by another pathogen. Our results suggest F. duorarum is as susceptible to mortality ftom WSSV as L.vannamei, and that M. adina is susceptible to infections by WSSV.

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