Pathogenicity of Acute Hepatopancreatic Necrosis Disease (AHPND) on the freshwater prawn, Macrobrachium rosenbergii, and Pacific White Shrimp, Penaeus vannamei, at various salinities

Acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio parahaemolyticus (Vp _AHPND), is a lethal disease to Penaeus vannamei shrimp. To determine the pathogenicity of Vp _AHPND to giant river prawn (Macrobrachium rosenbergii), three immersion challenges were performed at a range of salinities. In the first trial, M. rosenbergii were challenged to observe the extent of AHPND infection. The second trial had P. vannamei exposed to Vp _AHPND at low salinities to observe the effect. Results showed the Vp _AHPND caused infection in P. vannamei at 5–20 ppt with survival rates ranging from 0% to 65%. The third trial simultaneously exposed M. rosenbergii and P. vannamei to Vp _AHPND to determine the effect of AHPND in two species while in identical environments. In trials I and III, M. rosenbergii did not show any mortality and no pathology indicative of AHPND were noted. In challenges II and III, P. vannamei exhibited 0% to 65% survival and were AHPND positive by histology and PCR. These findings indicate that M. rosenbergii held in salinities of 20 ppt and lower are not susceptible to AHPND at a dose of 1x10⁶ CFU/ml, which was lethal to P. vannamei at all salinities tested.