白斑综合征病毒感染梭子蟹试验及组织病理学观察

利用对虾白斑综合征病毒WSSV，采用注射和投喂方式，对养殖三疣梭子蟹（Portunus trituberculatus）进行人工感染，以确定WSSV对养殖梭子蟹的易感性和可能存在的潜在危害。结果发现，在水温24—25℃条件下，病毒注射感染组全部发病，10-16d全部死亡；投喂组死亡率33％；对照组未出现死亡。采用荧光定量PCR对各试验组梭子蟹的肌肉和肝胰腺混合物进行WSSV检测，发现注射感染组阳性检出率为100％，均为强阳性；投喂组阳性检出率为50％；对照组的阳性检出率均为O。光镜下可观察到感染梭子蟹的肝胰腺、肌肉组织、鳃组织的靶细胞核肿大、变形，并出现以坏死为主的变质性病变；电镜下病变组织细胞中可见形态、大小与WSSV一致的病毒粒子。由此表明：对虾WSSV可以感染三疣梭子蟹，并表现出明显的病理症状，感染与病毒的数量以及梭子蟹自身的体质、环境条件密切相关。

Artificial infection for Portunus trituberculatus by WSSV and histopathological observation

In order to ascertain the susceptibility and the potential danger of WSSV to the cultured Portunus trituberculatus, the healthy crabs were inoculated with WSSV by intramuscular injection and feeding. The results showed that the crabs in the group of intramuscular injection all became diseased and died at 10 to 16 days after being inoculated; the mortality of the group of feeding was 33%, and that of the control group was 0. Real-time PCR assay was developed in this study for quantitative analysis of WSSV in muscle and hepatopancreas. Detectable rates of WSSV from intramuscular, feeding and control groups were 100%, 50% and 0 respectively. Histopathological observation showed that the nucleus of target cells in the hepatopancreas, atrial muscle, and gill became swollen and distorted, servere vacuolation and necrosis of epithelial cells of hepatopancreas and gill, as well as the atrial muscle fibres were obviously observed. Under electron microscope,virus particles with the same size and morphological features as WSSV were seen in the abnormal tissue cells. In conclusion, the WSSV can infect Portunus trituberculatus and cause obvious histopathological changes in the crab tissues, and additionally, the degree of the infection of WSSV was closely related to the amount of virus, as well as the crab's health and environment conditions.