| In this paper, crawfish as animal model was applied to study the infection characteristics and dynamic distribution of shrimp White spot syndrome virus (WSSV). In addition, a genomic fragment of WSSV was sequenced and analyzed, and an ORF in it was cloned and expressed in S. co/i. 1. Crawfishes as animal model were infected with WSSV to study various infection characteristics, including infection temperature, infection route, successive infection, median lethal dose (LD,o), immunity against virus and virus conservation etc. The results suggested that crawfishes usually died within 27d after infection at the temperature of 2225. The infection was sped up when temperature rised. Low temperature had a more obvious effect on infection. Both by injection and by oral taking, WSSV could infected crawfishes successfully. Soaking with WSSV failed to infect crawfishes. Bacterium detection of both healthy and infected crawfishes showed that Eerobacter cloacae infection existed after the virus infection. The median lethal dose (LD50) was 10 6/ml WSSV. Crawfishes immunized with inactivated WSSV couldn be protected against challenge of WSSV. WSSV from whole crawfishes other than from homogenate was superior and could be recovered successfully after frozen at -30t for 1 year. 2. As experimental model, crawfishes were inoculated with WSSV and immersed in anti-virus drugs Fukang and Bangke solutions of various concentrations. It demonstrated that these drugs could decrease the infectivity of WSSV and delay the death time of crawfishes. In addition, two disinfectants could suppress but couldn抰 kill the virus when they were incubated with WSSV at 37C for 10 minutes respectively. 3. MAb-mediated ELISA and Dot-blot for detection of WSSV were established. WSSV was purified from infected crawfishes and the purified virons was used as antigen to immunize BalB/C mice. Four MAbs, designated as I B1, 1 E4, 4E6 and 4E5, were obtained by hybridoma technique. One of them (4E5), reacted with an approximately 37.5K viral protein band in Western blotting analysis, was selected for establishment of MAb-mediated indirect ELISA. A genomic fragment of WSSV sized 400bp recovered from recombinant plasmid pAFD, was labeled with Digoxigenin as a probe for establishment of Dot-blot. Both by MAb-mediated ELISA and by Dot-blot, WSSV in infected crawfishes could be detected. The results of the two methods were compatible and Dot-blot was more sensitive than ELI SA. 4. Dot-blot and MAb-mediated ELISA were applied to detect dynamic distribution of WSSV Qingdao strain within I 20h and 72h in crawfishes inoculated WSSV Qingdao strain by oral taking and injection respectively. Stomach epithelium, intestine epithelium, heart, gill, haemolymph, muscle, hepatopancreas, hypoderm, comiective tissue and ovary of infected crawfish were examined for WSSV. In both groups, WSSV was first detected in heamolymph at 12h p.i. and then disappeared. Again it was detected at 96h p.i. only in oral infection group and maintained till l2Oh p.i., but it didn appear till 72h p.i. in injection group. WSSV in heart, muscle was detected at 36h p.i. in oral infection group and 24h p.1. in injection group respectively, and then increased generally. In addition, WSSV in intestine epithelium, connective tissue, ovary of oral infection group and intestine epithelium, hypoderm, ovary of injection group could also be detected. In dead crawfishes after I 20h and 72h postinfectlon in both groups, WSSV could be detected in...
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