病毒学报

从以软脚为主要临床症状,以肝、脾表面有多量灰白色坏死点,肾肿大及出血为主要病变的病番鸭肝、脾组织中分离到5株病毒(MW9710、MW9803、MW9806、MW9809和MW9810)。雏番鸭和雏鹅经人工感染后出现与自然病例相同的临床症状和病理变化,并能回收到病毒。樱桃谷鸭、麻鸭和鸡人工感染不发病。经电镜观察,病毒呈球形,正二十面体,立体对称,无囊膜,有双层衣壳,直径为60nm～73nm,病毒粒子在胞浆中增殖。病毒对乙醚、氯仿、胰蛋白酶、50℃处理1h和3%甲醛处理不敏感。对pH3处理2h、60℃处理30min和紫外线照射敏感。1mol/LMg Cl2不能增强病毒的感染力。病毒核酸型为dsRNA,病毒核酸具有禽呼肠孤病毒的特征:有10条带,按其大小可分为三类:大片段(L1～L3)、中片段(M1～M3)和小片段(S1～S4)。但是MW9710株的M2和S1～S4片段的迁移率明显不同于鸡关节炎病毒(ARV)S1133株,而与番鸭呼肠孤病毒法国株(89330、89026株)的核酸电泳图谱极为相似。在血清中和试验中,ARVS1133和MW9710株互不交叉。并且,以针对ARVS1基因的特异性引物XZ11、XZ12对MW9710株等进行RT PCR扩增,只能从ARV中扩增出特异性条带;而以MDRV89026株S1基因的特异引物HP11、HP12进行RT PCR扩增,只能从MW9710等分离毒株中扩增出特异性条带。上述结果表明,MW9710株等5

Five virus strains (MW9710, MW9803, MW9806, MW9809 and MW9810) were isolated from the liver and spleen of the infected Muscovy ducks. The Muscovy ducks inoculated with MW9710 strain showed pathological effects similar to that of field cases, and the virus could be recovered from the tissues of these birds. The viron was shown spherical, no envelope, with double-layered capsid, 60nm-73nm in diameter by electron microscopy, belonged to dsRNA virus and had no haemagglutination activity. The MW9710 strain was resistant to ether, chloroform, trypsin, FUDR, formalin and heat (50℃, 1h), but sensitive to ultraviolet rays, heat (60℃,30min) and pH3. The Muscovy duck is the most susceptible animal to MW9710 strain. The PAGE analysis of the viral genome revealed that MW9710 genome was related to avian reovirus (ARV), composed of ten segments of dsRNA (L1-3?M1-3 and S1-4). The pattern of the electrophoresis was very similar to that of Muscovy duck reovirus (MDRV-89330 and MDRV-89026), but there were significant differences from that of ARV S1133 strain. The MW9710 strain had no cross-reactivity to the antiserum against ARV S1133, and ARV S1133 had no cross-reactivity to the antiserum against MW9710 strain in the cross-neutralization tests. Moreover, the viral genome of MW9710 strain could be amplified only with the primers specific for S1 gene of MDRV, but not with the primers specific for S1 gene of ARV by RT-PCR. Thus, these results demonstrate that the MW9710 strain is the pathogen of the disease mentioned above and belongs to Muscovy duck reovirus, Orthoreovirus Reoviridae.