羊口疮的研究

Studies on Orf in Sheep and Goats

本文报道了对羊口疮的病原学、流行病学、实验病理学、血清学诊断以及免疫预防等问题所进行的系列研究结果。应用电镜技术,首次在国内观察到了羊口疮的病原——羊口疮病毒。对该病毒的某些生物学特性和理化学特性进行研究的结果表明,该病毒的感染范围比较广泛,对干燥耐受性强,对热、紫外光和福马林敏感;在奶山羊睾丸细胞上生长良好,CPE变化显著,并有多倍性现象;通过系统取样和超薄切片,在电镜下观察到了病毒在培养细胞中的主要复制过程,以及培养细胞本身的亚微结构变化。试用差速离心联用30—45％蔗精密度梯度超速离心,能有效地提纯病毒,为纯化痘类病毒提供了一种较为理想的方法。中性无离子去污剂TritonX—100与2—巯基乙醇联合,可使病毒裂解,便于分离囊膜蛋白亚单位;用SDS—PAGE分析法,发现病毒最少可泳动出28条多肽区带,而病毒的囊膜亚单位则由18条多肽区带组成。将病毒亚单位作为抗原免疫羔羊,可激发羊只产生抗全病毒抗体和迟发性变态反应,这在国内属首次报道。流行病学的调查表明,羊口疮在甘肃省存在历史已久,分布广泛,对养羊业危害严重;病的自然感染主要见于绵羊和山羊,以羔羊最为易感,除口唇感染外,未见其他临诊病型;采取不同地区的病羊痂皮在羊体作交叉免疫试验,未发现病毒有型别差异。人工感染病羊的血常规检查和血清蛋白的电泳分析未见异常;病理组织学变化以表皮的网状变性、真皮的炎性浸润和结缔组织增生为最特征。首次在国内将反向间接血凝、对流免疫电泳、酶联免疫吸附,琼脂凝胶扩散以及血清中和等五种血清学方法用于羊口疮的诊断,填补了国内在这方面的空白,其中前三种方法在当时的国外文献中也未见有报道。以改良、完善现行方法为目的,对活毒苗免疫接种法作了系统的研究,证明是一种行之有效的应急性免疫措施,有在疫区推广应用的价值;对灭活苗所进行的探索性试验表明,灭活的病毒似能激发羊体产生一定程度的免疫,为今后进一步提高灭活苗的免疫效果以及研究其在实践中应用的可能性打下了有益的基础。

A series of experiments on an orf—like disease, which spread widely in sheep and goats in Gansu province from year to year, were conducted. The orf virus was found in lip—scabs from naturally affected animals using transmission electron microscope. This was the first report for the cause of the Orf—like disease in this country. The virus had a relatively wide range of infection, the cattte, dogs and rabbits being infected experimentally in addition to sheep and goats, lt was dry—resistant and appeared to be sensitive to heat, violet ray and formalin. The cell line of suckling kid tastes grew the viruses well and gave evident CPE. The phenomenon of polyploidy was found in cell cultures. A main virus—replicative process in cell cafture and the submicrostructural changes of the cultured cells themselves were studied and seen under electron microscope. The viruses ceuld be purified successfully by density gradients centrifugation. The neutral nonionic detergent Triton Ⅹ—100 treated with 2-ME disrupted the viruses and removed their surface tubules and envelopes effectively. The SDS-PAGE of purified viruses gave a complex pattern of at least 28 polypeptides, whereas the subunits were made. up by 18 fragments. Lambs injected with virus subunits generated antibodies to the whole viruses and delayed allergic reactions. Epizootiological investigations revealed that there was no type difference among virus strains collected from different arcas in Gansu province, using crossing immunization in lambs. No Changes were observed with routine hematological examinations and electrophoretic analyses in experimentally infected animals. The histopathological patterns consisted basically of reticular degeneration of the epidermis, inflammatory infiltration of the corium and proliferation of the connective tissue. Five Serodiagnosed methods of reversed indirect HA countercurrent immuno-electrophoresis ELISA. AGID and sereoneutralization were established firstly at home. The conventional immunization method of using five viruses introduced by Glover was improved and perfected in certain aspects. It seemed to be a useful method for controlling orf in flocks where the disease already broke out. An exploring test for the inacti rated vaccine was worked out according to Mathiesen (1985). The preliminary results showed that the inactivated viruses were likely to have the animals immunized stimutate a certain degree of immunity.