ABSTRACT
A fragment sized 400bp of White spot syndrome virus（WS SV，formerly de signated NOSV），recovered from recombinant plasmid pAFD, was labeled with Digox igenin as a probe to detect dynamic distribution of WSSV within 120h and 72h in crawfishes（Cambarus proclarkii） inoculated WSSV by oral taking and injecti on r espectively. Stomach epithelium, intestine epithelium, heart, gill, haemolymph, muscle, hepatopancreas, hypoderm, connective tissue and ovary of infected crawfi shes were examined for WSSV. In both groups, WSSV was first detected in heamoly mph at 12h p.i. and then disappeared. Again it was detected at 96h p.i. only in oral infection group and maintained till 120h p.i., but it didn't appear at 72h p.i. in injection group. WSSV in heart, muscle was detected at 36h p.i. in oral infection group and 24h p.i. 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 g roup could also be detected. In dead crawfishes after 120h and 72h p.i. in two groups, WSSV could be detected in all the examined tissues and it demonstrated t hat systemic infection occurred in the animales. The tissue containing more amo unts of WSSV was hypoderm in oral infection group, while intestine epithelium, g ill, hypoderm, ovary in injection infection group. It deduced that WSSV first a ppears in haemolymph and then goes into heart, muscle and other tissues and prol iferates in them. Once again, WSSV is released into heamolymph resulting in syst emic infection till crawfishes' death.