鸭坦布苏病毒病卵巢病变标准的判定

Criterion of Ovarian Lesions of Duck Tembusu Virus Disease

【目的】了解产蛋鸭感染鸭坦布苏病毒后卵巢病变产生的进程和卵巢病变规律,为采用产蛋鸭卵巢病理变化检查法进行疫苗效力检验提供依据。【方法】70只260日龄产蛋樱桃谷鸭,以0.5m L/只(含100DID50)的剂量经胸部肌肉接种鸭坦布苏病毒(HB株)强毒。观察试验鸭的临床症状,统计每日产蛋数和采食量。攻毒后2 d,每只鸭经翅静脉采血,分离血清,经卵黄囊途径接种5枚6日龄SPF鸡胚,每胚0.1m L。接种后置37℃条件下继续孵化,24 h死亡鸡胚弃去。采用RT-PCR方法测定24—72 h死亡鸡胚的DTMUV核酸,将1/5或以上鸡胚死亡且DTMUV核酸阳性的鸭判为DTMUV感染鸭。攻毒后4—10 d,每日剖杀10只鸭,观察和分析生殖系统病变。统计病变率,检查输卵管内是否有蛋,卵泡是否变形、出血和破裂,依据病变率和病变,确定检查内容和病变卵巢的判定时间和标准。【结果】(1)攻毒后3、4、5、6 d,鸭几乎不采食,产蛋数明显下降。攻毒后7 d,鸭精神状况好转;攻毒后8 d,采食量开始回升。(2)70只鸭中,除1只鸭的病毒分离结果为阴性外,其余69只鸭的病毒分离结果均为阳性,病毒分离阳性率为98.6%(69/70)。(3)攻毒后4—10 d,共64只产蛋期鸭的生殖器官可以判定。(4)攻毒后4、5、6、7、8、9和10 d,卵巢病变率分别为66.7%(6/9)、100%(10/10)、100%(10/10)、100%(9/9)、100%(9/9)、100%(9/9)和100%(8/8)。(5)除攻毒后4 d有2只鸭输卵管中有蛋外,其余62只鸭输卵管中均无蛋,无蛋率为96.9%(62/64)。(6)攻毒后4—10 d,96.9%(62/64)鸭的卵泡变形,96.9%(62/64)鸭的卵泡出血,95.3%(61/64)鸭的卵泡变形和出血,34.4%(22/64)卵泡破裂。【结论】(1)确定卵巢病理变化检查时间为攻毒后7—8 d;(2)具有变形或出血病变之一,判病变卵泡。输卵管内无蛋且有3个及以上病变卵泡,判为病变卵巢。

【Objective】The objective of this study is to understand the process and regularities of ovarian lesions on ducks infected with duck Tembusu virus, and to provide data for the efficiency evaluation of vaccine using laying ducks ovary pathological inspection.【Method】Seventy 260-day-old laying cherry ducks were inoculated intramuscularly with duck Tembusu virus （HB strain） at dosage of 0.5ml（100 DID50）/duck. Clinical symptoms were observed, and the egg production and feed intake were recorded daily. Serum samples were collected from all ducks for virus isolation via wing vein on 2 days post inoculation （dpi）. Each serum sample was inoculated into five 6-day-old SPF chicken embryos via yolk-sac route at the inoculum of 0.1 ml per embryo. Then they were hatched at 37℃ further. The chicken embryos died in 24h were abandoned. The viral nucleic acid was detected by RT-PCR in the death chicken embryos during 24-72 h. If there were more than one （including one） death chicken embryos, and the nucleic acid testing was positive, then it was concluded that virus isolation was positive. On 4-10 dpi, 10 ducks were necropsied and the gross lesions of the reproductive system were observed every day. The pathologic rate was calculated, and the gross lesions of the reproductive system were conducted including whether there were eggs in the fallopian tube, whether the follicle was deformed, hemorrhaged or ruptured or not. According to the statistical pathologic rate, the time, the content of the examination and the criterions for determining lesion ovary were confirmed. 【Result】 （1） Feed intake and egg production decreased significantly on 3-6 dpi. The mental state of the duck on 7 dpi improved, and feed intake began to rise on 8 dpi. （2） Virus isolation of 70 ducks were all positive except one duck. The virus positive isolation rate was 98.6% （69/70） on 2 dpi. （3） On 4-10 dpi, a total of 64 laying duck reproductive organs can be determined. （4） On 4-10 dpi, the ovarian lesions rate were 66.7% （6/9）, 100% （10/10）, 100% （10/10）, 100% （9/9）, 100% （9/9）, 100% （9/9） and 100% （8/8） respectively. （5） Eggs were found in fallopian tube of 2 ducks among 10 ducks that were necropsied on 4 dpi, and there was no egg found in fallopian tube of the remaining 62 ducks. The egg negative rate was 96.9（62/64）. （6） On 4-10 dpi, the proportion of deformed follicular duck and hemorrhaged follicular duck were both 96.9% （62/64）, and the proportion of deformed and hemorrhaged follicular duck was 95.3%（61/64）, while the proportion of ruptured follicular duck was 34.4% （22/64）.【Conclusion】 （1） The time for the examination of the pathological changes of ovary was determined as 7 to 8 dpi. （2） The criterion of abnormal follicle is that one of the lesions of deformation and hemorrhage or both were found. The criterion of lesion ovary is that three abnormal follicles or more appeared and no egg in the fallopian tube.