家蚕蛹表达的重组Vp28疫苗对克氏原螯虾免疫反应的影响

将含有对虾白斑综合征病毒囊膜蛋白Vp28基因的重组杆状病毒HyNPV-Vp28感染家蚕(Bombyx mori)蛹,配制成药饵持续口服免疫克氏原螯虾35天后,螯虾血细胞的吞噬百分比和吞噬指数比对照组显著提高(P＜0．05)；血清中的抗菌活力、溶菌活力、酚氧化酶活性、超氧化物歧化酶活性以及血清和肝胰腺组织中的酸性磷酸酶、碱性磷酸酶活性均显著提高(P＜0．05)。免疫35天后进行口服攻毒,20天内rVp28疫苗组的累积存活率达66．67%,与对照组和对照蚕蛹组比差异显著(P＜0．05),PRP分别达64．29%和58．33%。rVp28疫苗组存活虾的胃、肠、鳃、甲壳下上皮和肝胰腺等病毒侵染的靶组织进行组织病理检测均无病毒感染,DIG标记核酸探针斑点杂交和PCR检测也呈阴性反应；而试验濒死虾的组织都呈现典型的病变特征,病毒DNA检测均为阳性反应。本研究表明,口服免疫家蚕蛹表达的囊膜蛋白Vp28具有增强螯虾机体免疫功能的作用,对应用免疫措施预防对虾的病毒性疾病具有重要意义。

INFLUENCE OF WHITE SPOT SYNDROME VIRUS ENVELOPE PROTEIN Vp28 EXPRESSED IN SILKWORM (BOMBYX MORI) PUPAE ON IMMUNE RESPONSE IN PROCAMBARUS CLARKII

Silkworm (Bombyx mori) pupae infected with recombinant baculovirus HyNPV-Vp28 were made vaccine,which was mixed with feed at a ratio of 2% (w/w). Procambarus clarkii were orally administered. The results of immune analysis showed that the phagocytic percent and phagocytic index of hemocytes increased significantly when compared the rVp28 treatment with control treatments (P < 0.05). Compared with control groups,the antibiotic activity, bacteriolytic activity and activities of phenoloxidase, superoxide peroxidation in serum in the rVp28 group were greatly increased (P < 0.05). The activities of acid phosphatase and alkaline phosphatase in serum and hepatopancrease tissues in rVp28 treatment were significantly higher than control treatments (P < 0.05). Vaccination with rVp28 showed that the cumulative survival,compared with control treatments, was significantly higher (P < 0.05). An oral challenge on the 35th day post-vaccination was followed,PRP values were then 64.29% and 58.33%, respectively. The epidermal cells of stomach, midgut, hepatopancreas, gill and epithelial tissue of moribund crayfishes were histologically characterized by hypertrophied nuclei and highly stained cells, but there was normal structure in the survivors-vaccinated after WSSV challenge. WSSV DNA was detected by PCR and Dot-blot with DIG-labeled DNA probe. The positive results were observed in stomach, hepatopancreas and gut of the moribund crayfishes and survivors in control groups, while negative reaction was observed in the tissues of survivors in rVp28 group. Vp28 expressed in silkworm (Bombyx mori) pupae played a role in improving the immune function of crayfish.