红螯光壳螯虾白斑综合症血液病理学研究

采用Wright-Geimsa染色法和电镜技术对人工感染的红螯光壳螯虾(Cherax quadricarinatus)白斑综合症(White spot syndrome,WSS)血液病理学进行了研究。结果显示:患病螯虾血细胞总数、透明细胞(AH)数量极显著减少(P<0.01),大颗粒细胞(LGH)极显著增加(P<0.01);病毒感染后3种血细胞大小均有增加趋势,透明细胞和大颗粒细胞的核质比(NP)较感染病毒前极显著下降(P<0.01)。显微病理学变化主要表现为血涂片中血细胞明显减少,病变、破损或解体的细胞增多,至濒死期螯虾血液呈典型的溶血状态。超微病理学变化表现为血细胞受到了损伤。高尔基体变形、线粒体结构模糊破损;核膜变形核固缩、细胞核高度异染色质化;濒临死亡的螯虾血细胞细胞器和染色质溶解,胞浆水肿,细胞溶解坏死。在患病螯虾的血细胞核中清晰可见WSSV粒子。

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(P<0.01).The number of their overall hemocytes decreased 63.94% and 89.7% respectively in 72h experimental shrimp and danger experimental shrimp.Three kinds of blood cells,the hyaline hemocyte(AH),the small granule hemocyte(SGH) and the large granule hemocyte(LGH) were distinguished according to the morphology,structure and the size of granule.The percentage of AH,SGH and LGH were 47.51%,34.46% and 17.37% respectively in the control shrimp.After shrimps infected with WSSV,the percentage of AH in diseased shrimps was lower heavily than that in healthy shrimps(P <0.01),but the percentages of LGH in diseased shrimps were 57.81×106cell/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 <0.01);The percentage change of SGH was small relatively.The sizes of three blood cells were all increasing trend after treated with WSSV-infected,in which the LGH increased from 25.33 μm×19.09 μm to 34.45 μm×26.68 μm.The nuclear cytoplasmic ratio(NP) of AH and LGH had a sharp decline after treated with WSSV-infected(P <0.01),and the NP of LGH was all less than 1,in which indicated that the nucleus of LGH of crayfishes was smaller and cytoplast was more;The NP of small granule was not significantly different(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.