Natural Infection of White Spot Syndrome Associated Virus (WSSV) in Penaeid Shrimps- An Analysis of WSSV Infection in Wild-caught Penaeus monodon Female Broodstocks

• Main Authors: Ho, Ching Hui, 賀勤惠
• Other Authors: Kou, Guang-Hsiung;Lo, Chu-Fang
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/84768144010631470413

碩士 === 國立臺灣大學 === 動物學系 === 84 === White spot syndrome associated virus (WSSV) is the causative agent of a disease causing mass mortalities of cultured shrimps. The detection of WSSV has been performed by polymerase chain reaction (PCR). The sensitivity of two- step PCR with nested primers was found to be higher than that of one-step PCR alone, one-step PCR with southern blot, and one-step PCR with dot blot, and so two-step PCR was used in the subsequent parts of this study. Except for the hepatopancreas and nerve tissues, WSSV was present in the other organs of the seriously infected spawners; in the lightly spawners only of the organs were positive in two-step WSSV PCR; all the organs of the uninfected spawners were WSSV negative in two-step WSSV PCR. Using a light microscope to observe histopathological changes in seriously infected spawners, degenerated cells were found to be characterized by hypertrophied nuclei being stained homogeneously in some organs. This phenomenon was particularly distinct in the cuticular epidermis. We used in situ hybridization to confirm that the cell degeneration was caused by WSSV. Each cell with a clearly hypertrophied nuclei gave a positive signal and degenerated cells with non-obviously hypertrophied nuclei were also positive, and were thus rendered distinguishable from normal uninfected cells. Using in situ hybridization, some of the follicle cells, oogonia and chromatin nucleolus oocytes in the ovary of the seriously infected spawners were found to be infected by WSSV. From July 1995 to February 1996, 48 broodstock specimens of P. monodon were caught from the wild. Six of these were positive in one-step WSSV PCR and 30 were positive in two-step WSSV PCR, giving a rate of infection of 62.5%.