DYNAMICS OF VIBRIO SP PJ IN ORGANS OF ORALLY INFECTED KURUMA PRAWN, PENAEUS-JAPONICUS

Kuruma prawns (Penaeus japonicus) were experimentally infected with Vi brio sp. PJ by the oral administration. At 3, 6, 8, 10, 12, 24, 36, an d 48 h post-inoculation, prawns were sampled to determine the cell num ber and distribution of the pathogen in various organs by viable cell count and the enzyme-labeled antibody technique (ELAT). Vibrio sp. PJ was detected by culture method from the stomach and hemolymph at 3 h a nd from the hemolymph and almost all the organs sampled at 6 h post-in oculation. However, the pathogen started to disappear from all the org ans from 8 h to 12 h. At 12 h, it reappeared in the hepatopancreas and lymphoid organs. Twenty-four hours after inoculation, the pathogen wa s detected from the hemolymph and all the organs except the stomach an d gills, and at 36 h the pathogen was found distributed in all the org ans. Principally the same distribution pattern of the pathogen was fou nd by ELAT. These results seem to indicate that the process in the pat hogenesis of Vibrio sp. PJ infection in orally challenged kuruma prawn s consist of five stages namely, establishment of the pathogen, distri bution of the pathogen, clearance of the pathogen by host prawn, secon dary multiplication of the pathogen, and systemic infection. The resul ts also suggest that the pathogen multiplied in the stomach in the est ablishment stage and in the hepatopancreas and lymphoid organs in the secondary multiplication stage.