HAEMOLYMPH PATHOLOGICAL RESEARCH ON WHITE SPOT SYNDROME (WSS) OF CHERAX QUADRICARINATUS

White spot syndrome virus (WSSV) as the pathogenic agent caused acute and lethal infect ion of shrimp, resulting in mass economic losses to shrimp aquaculture industry all around the world especially in China. In recent years, the cultivation of redclaw crayfish (Cherax quadricarinatus) is developing, and the disease of C. quadricarinatus is one of the major factors in its culture and even causes redclaw crayfish to die. The viral disease was found in polyculture of redclaw crayfish with Penaeus vannamei To explore the pathogenic mechanism of C. quadricarinatus infected by WSSV (white spot syndrome virus), the pathological research in haemolymph on WSS of C. quadricarinatus infected by WSSV artificially was studied by means of Wright-Geimsa staining and electron microscope techniques. The results indicated that total haemocyte count in diseased shrimps was lower heavily than that in healthy shrimps (P6 cell/mL and 53.18×106 cell/mL respectively in 72h experimental shrimp and danger experimental shrimp, and was higher heavily than that in healthy shrimps (17.37×106 cell/mL, P P >0.05) after treated with WSSV-infected. The main micro-pathological changes of haemocyte showed that there was a decreasing hemocytes in haemolymph smear from diseased shrimps, in which the number of AH was lower heavily than that in healthy shrimps and the number of large granule hemocyte was higher than that in healthy shrimps. Synchronously broken and disintegrated cells could often be seen in the haemolymph smear, and contractive nucleus and anamorphic nuclear membrane in hyaline hemocyte, bubbles in denaturalized small granule hemocyte, pyknosis nucleus and bulgy cells in large granule hemocyte. There was a typical haemolysis in danger experimental shrimp. The ultra- micro-pathological changes showed that there were necrotic changes in every kind of haemocytes. Golgi apparatus was transmutative, mitochondria was damaged and incomplete in structure; Parts of nuclear membrane were anamorphic and parts of nucleus were contractive, while nucleus heterochromatinization in blood cells; Organelle and chromatin were dissolved, kytoplasm was dropsical in danger haemocytes, while cells were necrotic. There were clear WSSV in certain hemocyte nucleus of diseased shrimps. WSSV was a kind of baculovirus under transmission electron microscope (TEM), and the sizes of which were (99—118) nm × (189—321) nm. Its size and shape was consistent with WSSV which has been reported.