2株贝氏隐孢子虫鸡源分离株对雏鸡的致病性比较

为了解不同地区鸡源贝氏隐孢子虫的致病特点,对收集到的郑州、林州两地区鸡源贝氏隐孢子虫卵囊经雏鸡传代扩增纯化后,分别以1×106个卵囊量接种3日龄罗曼公雏鸡,从其排卵囊情况、临床症状和病理学变化比较了2个分离株的致病情况。结果表明:2个隐孢子虫分离株均主要引起雏鸡呼吸道症状和法氏囊炎病变;接种雏鸡均于感染后第4天开始排卵囊,林州株和郑州株排卵囊持续期分别为23 d和13 d;排卵囊高峰期均为感染后第8~12天。雏鸡感染2个地区鸡源贝氏隐孢子虫分离株后,排卵囊量及排卵囊规律存在差异。     

鸭源贝氏隐孢子虫对鸡的致病性

设计3个不同剂量的鸭源隐孢子虫试验感染2日龄雏鸡,通过临床症状、增重、排卵囊规律和法氏囊指数及寄生器官组织扫描电镜观察,证实贝氏隐孢子虫160万个卵囊感染即可引起明显的呼吸道症状,发病鸡增重显著降低,法氏囊严重萎缩。贝氏隐孢子虫致病程度和排卵囊规律与感染剂量相关,主要病变表现呼吸道病变和法氏囊炎症。     

隐孢子虫卵囊形态学观察及动物交叉感染试验

作者观察了从湖南６种动物分离出的隐孢子虫卵囊的光镜下形态，并以鸡源、牛源和猪源隐孢子虫卵囊人工感染实验动物作交叉感染性研究。结果鉴定出隐孢子虫３个种，即贝氏隐孢子虫（Ｃ．ｂａｉｌｅｙｉ），寄生于鸡、鸭；微小隐孢子虫（Ｃ．Ｐａｒｖｕｍ），寄生于牛、山羊、猪、家兔和小鼠；鼠隐孢子虫（Ｃ．ｍｕｒｉｓ），寄生于牛。交叉感染结果表明，来自鸡的隐孢子虫可以感染雏鸡和雏鸭，而不能感染小鼠和家兔；来自牛的隐孢子虫可以感染小鼠和家兔而不能感染雏鸡，来自猪的隐孢子虫可以感染小鼠而对雏鸡无感染性。作者认为，哺乳类和鸟类的隐孢子虫可能在宿主纲的水平上具有宿主持异性。     

广东鸡,鸭隐孢子虫种类鉴定与致病性研究

从有患轻微呼吸道症状的鸡和鸭的粪便中分离到隐孢子虫卵囊，并在其组织切片中观察到隐孢子虫。根据卵囊的形态和大小、虫体寄生部位，确定鸡、鸭均为贝氏隐孢子虫感染。用上述鸡、鸭粪便中分离的卵囊，分别经口感染２日龄鸡和鸭各１５只以探索其致病性。感染鸡出现明显呼吸道症状，将引起死亡，气管、支气管、气囊、肺和法氏囊出现大体与显微病变。感染鸭则症状和病变都较鸡轻。结果表明：鸭对贝氏隐孢子虫感染的抵抗力比鸡强。     

贝氏隐孢子虫鸡胚和雏鸡增殖模型筛选抗隐孢子虫药物试验

为探讨复方磺胺对甲氧嘧啶、磺胺二甲基嘧啶、地克珠利和阿奇霉素4种药物对鸡胚和雏鸡人工感染模型中鸡源贝氏隐孢子虫的作用,筛选有效防治隐孢子虫药物,采用鸡胚培养和人工感染雏鸡模型,分别以各组鸡胚发育状况、鸡胚中卵囊量、雏鸡精神状态、排卵囊规律、体质量变化、发病率、死亡率等为观察指标,考察这4种药物对隐孢子虫的作用。结果显示,使用复方磺胺对甲氧嘧啶、磺胺二甲基嘧啶、地克珠利、阿奇霉素组鸡胚中虫体数分别为阳性对照组的15.05%、88.71%、77.42%、68.82%。复方磺胺对甲氧嘧啶可缓解人工感染雏鸡隐孢子虫病临床症状,感染雏鸡发病率降低20%,死亡率降低13.13%,且可使排卵囊强度降低。结果表明,复方磺胺对甲氧嘧啶以一定剂量连续使用一定时间对雏鸡贝氏隐孢子虫病有潜在治疗作用。     

鹌鹑源火鸡隐孢子虫生物学特性研究

利用鹌鹑源火鸡隐孢子虫（Cryptosporidium meleagridis）分别感染雏鸡、雏鸭、雏鸵鸟和小白鼠研究其致病性.结果能成功感染雏鸡、雏鸭和小白鼠,但不能感染雏鸵鸟.2个感染组雏鸡主要在感染后第3天引起雏鸡强烈的腹泻症状,但非免疫抑制组比免疫抑制组症状稍轻,此外,免疫抑制组的鸡出现了多个排卵囊高峰;感染相同剂量的2个试验组雏鸭的排卵囊显露期均较雏鸡短,非免疫抑制组雏鸭的排卵囊规律呈一过性,2组雏鸭均未出现明显的临床症状;免疫抑制组小白鼠出现多个排卵囊高峰,显露期持续24 d,正常组小白鼠的排卵囊规律呈一过性.根据肠黏膜涂片,抗酸染色观察发现主要虫体寄生于雏鸭的回肠;通过病理组织学切片和电镜观察发现虫体主要寄生于雏鸡的回肠和小白鼠的十二指肠,但均主要引起肠绒毛的大量脱落,黏膜上皮细胞肿胀,炎性细胞浸润.试验证明鸭为鹌鹑源C.meleagridis的新宿主,但敏感性较低;鹌鹑源C.meleagridis不感染非洲雏鸵鸟.发现鹌鹑源C.meleagridis在鹌鹑、鸡和鸭体内寄生部位与小鼠体内寄生部位有明显差异.     

雏鸡贝氏隐孢子虫人工感染试验

作者对69只2日龄雏鸡进行了隐孢子虫的人工感染试验。试验分3组,每只口服贝氏隐孢子虫钝种卵囊分别为1.73×10~7、8.5×10~6和1.94×10~6个。于接种后第3天粪便中首次出现卵囊,第9—17天为排卵囊高峰期,排卵囊可长达35天。人工感染隐孢子虫后雏鸡的严重发病与死亡多见于接种后第14—21天。临床上出现严重的呼吸道症状。主要表现为:呼吸严重困难、气喘、伸颈、张口呼吸和打喷嚏。病鸡精神沉郁,眼半闭,翅下垂,站立不稳或独卧一侧,严重者则饮、食欲废绝,并于发病后2—3日内死亡,共死亡35只,死亡率为50.8%。病理剖检可见喉头与气管水肿,渗出物增多。有时气管内可见到块状的纤维素性渗出物,严重者在气管内形成一灰白色的凝固物。肺充血发炎、表面湿润,泡沫状渗出物增多。肺腹侧多有灰白色硬斑,气囊混浊,渗出物增多。肾灰白色肿胀。刮取气管及法氏囊粘膜作成涂片,经染色后可见到大量各发育期的隐孢子虫虫体。病理组织学观察可在喉头、气管、肺脏、直肠、泄殖腔及法氏囊粘膜表面找到大量的球形虫体。用透射电镜及扫描电镜观察发现鸡隐孢子虫均寄生在粘膜上皮细胞的表面,并不进入上皮细胞内部。在虫体寄生部位的粘膜绒毛层受害严重,大量上皮细胞脱落和破损,呼吸道有明显的炎性病变。     

不同禽源贝氏隐孢子虫分离株对鹌鹑致病性的比较研究

本研究旨在观察不同禽源贝氏隐孢子虫(Cryptosporidium baileyi)对鹌鹑的致病性差异。采用光镜、扫描电镜等技术研究了鸡源、鸭源、鹌鹑源、白文鸟源、鸵鸟源贝氏隐孢子虫分离株对10日龄鹌鹑的致病性。结果表明,感染鹌鹑均出现腹泻和呼吸道症状,排卵囊持续期11~18 d,虫体寄生于喉头、气管、法氏囊和泄殖腔。其中鸭源C.baileyi感染组鹌鹑发病率和死亡率分别为82.5%、25%,鸡源C.baileyi(郑州株)感染组发病率和死亡率分别为77.5%、12.5%,鹌鹑源C.baileyi感染组发病率、死亡率分别为37.5%和17.5%。本研究结果提示,不同禽源C.baileyi对鹌鹑有一定致病性,其致病性强弱存在差异。     

不同禽源贝氏隐孢子虫分离株对雏鸡致病性比较研究

为研究不同禽源贝氏隐孢子虫对雏鸡的致病性差异,人工感染3日龄雏鸡鸡源、鸭源、鹌鹑源、白文鸟源贝氏隐孢子虫.结果发现,各感染组雏鸡潜隐期均为4d,显露期为11～18 d,均未发生死亡,但其增重均受影响.鸡源C.baileyi(林州株)、C.baileyi(郑州株)和鸭源C.bailey(郑州株)感染组雏鸡临床症状较为明显,发病率较高,分别为71.4％、85.7％和77.1％,剖检可见气管有较多粘液分泌物,法氏囊粘膜充血肿胀,平均增重较不感染对照组分别减少34.5、53.1和19.7 g；鹌鹑源C.bailey(武陟株)和白文鸟源C.bailey(郑州株)感染组雏鸡仅部分表现轻微临床症状,发病率分别为31.4％和28.6％,平均增重较不感染对照组分别减少39.7和43.1g.结果表明不同禽源C.bailey对雏鸡均有不同程度的致病性,以鸡源和鸭源C.baileyi致病性较强.     

鸡柔嫩艾美耳球虫广西株的分离与鉴定

目的建立一种简单、实用的单卵囊分离方法，并对一株广西柔嫩艾美耳球虫进行分离。方法采用电泳制胶槽来制作琼脂块进行球虫单卵囊的分离，单卵囊实验感染9只1日龄雏鸡，感染后收集粪便，用饱和盐水漂浮法进行卵囊检测。纯种卵囊经口感染10只1日龄雏鸡，观测卵囊寄生部位、最短孢子化时间，以及其潜在期和排卵高峰期。结果2只雏鸡粪便中检出卵囊，单卵囊感染成功率为22％。通过对其中一株球虫的研究，根据其卵囊的形状、大小、寄生部位、潜在期、卵囊最短孢子化时间、排卵高峰期等生物特征，鉴定该株球虫为柔嫩艾美耳球虫（Eimeria tenella）。结论本研究成功建立一种单卵囊分离技术，可作为球虫单卵囊分离的常规方法。     

Effect of broiler chicken age on susceptibility to experimentally induced Cryptosporidium baileyi infection

Clinical signs of respiratory tract disease were observed in chickens that were inoculated intratracheally with 1 x 10(6) oocysts of Cryptosporidium baileyi at 2 or 14 days of age (10 chickens/group), but not in chickens inoculated at 28 or 42 days of age (10 chickens/group). Orally inoculated chickens in all age groups (10 chickens/group) did not develop clinical signs of disease. Orally and intratracheally inoculated chickens in all age groups were infected, as determined by the finding of cryptosporidia in tissue sections of the trachea, bursa of Fabricius, and cloaca, and by the recovery of oocysts from their feces. Chickens inoculated at 2 and 14 days of age excreted oocysts for a longer period and had greater numbers of cryptosporidia in their tissues, compared with chickens inoculated at 28 and 42 days of age.     

Cryptosporidium baileyi: effects of intra-abdominal and intravenous inoculation of oocysts on infectivity and site of development in broiler chickens

Developmental stages of Cryptosporidium baileyi were observed on the epithelium of the larynx, trachea, primary and secondary bronchi, air sacs, bursa of Fabricius, and cloaca of 12 chickens inoculated intra-abdominally with oocysts. All 12 birds inoculated intra-abdominally developed clinical signs of respiratory disease and had gross lesions of airsacculitis at necropsy. Developmental stages of C. baileyi and clinical signs of disease were not observed in 12 chickens inoculated intravenously with oocysts. The response of chickens to intra-abdominal inoculation of oocysts was similar to responses recorded following intratracheal inoculation of oocysts in previous studies.     

ChMDA5通路参与传染性法氏囊病病毒致雏鸡法氏囊损伤的研究

传染性法氏囊病病毒（IBDV）为dsRNA病毒,可造成雏鸡法氏囊损伤进而发生免疫抑制;MDA5是能够特异性识别dsRNA病毒的模式识别受体。为研究鸡MDA5（chMDA5）信号通路在IBDV致雏鸡法氏囊病理损伤中的作用,试验选取50只14日龄SPF雏鸡随机分为IBDV感染组和空白对照组,每组25只,IBDV感染组雏鸡通过点眼、滴鼻感染IBDV JIC7株病毒液,0.6 mL·只^-1,空白对照组雏鸡经相同途径给予相同剂量无菌PBS,感染IBDV后第1、4、7、21及35天采集雏鸡法氏囊。采用qRT-PCR方法检测法氏囊中IBDV载量,chMDA5及chMDA5信号通路衔接蛋白（chIPS-1）、转录因子（chIRF3和chNF-κB）、下游产物细胞因子（chIFN-β、chTNF-α、chIL-1β、chIL-6） mRNA水平变化;间接免疫荧光法检测chMDA5蛋白表达变化,传统病理学方法检查法氏囊病理组织学变化。结果发现,雏鸡感染IBDV后,其法氏囊中chMDA5、chIPS-1、chIRF3、chNF-κB、chIFN-β、chTNF-α、chIL-1β、chIL-6的表达量均显著高于对照组,且法氏囊组织发生形态损伤,上述变化趋势与IBDV载量变化基本一致。结果表明,雏鸡法氏囊chMDA5及其信号转导通路可被IBDV激活,参与到IBDV感染雏鸡法氏囊损伤与抗损伤过程中。     

Performance and oocyst shedding in broiler chickens orally infected with Cryptosporidium baileyi and Cryptosporidium meleagridis

To study effects of experimental cryptosporidiosis, broiler chickens were infected per os with 5 x 10(5) oocysts of Cryptosporidium baileyi and Cryptosporidium meleagridis. In the first experiment, chickens were infected with oocysts of C. baileyi at the age of 7, 14, and 21 days. In the second experiment, chickens were infected with oocysts of C. baileyi, C. meleagridis, or both cryptosporidial species at the age of 7 days. Although clinical signs of infection were apparent, neither final live weight nor mortality was significanty influenced in chickens infected with a single Cryptosporidium species. In chickens infected with C. meleagridis, the growth retardation was observed in the 2-wk period after infection. The compensatory growth, however, started when the oocyst shedding had ceased. The number of oocysts in excreta specimens of chickens infected with C. meleagridis was two to three times lower than in excreta of chickens infected with C. baileyi. Chickens infected with both C. baileyi and C. meleagridis (5 x 10(5) oocysts of each) had significantly lower final live weight and worse feed efficiency than chickens of other groups. Concurrent infection did not influence individual C. baileyi or C. meleagridis oocyst shedding.     

Experimental cryptosporidiosis and infectious bursal disease virus infection of specific-pathogen-free chickens

Specific-pathogen-free chickens orally inoculated at 4 days of age with a moderately pathogenic vaccine strain of infectious bursal disease virus (IBDV) and/or at 5 days of age with Cryptosporidium baileyi oocysts remained free of overt clinical signs throughout a 16-day period postinoculation (PI). The prepatency period for C. baileyi oocyst shedding was shorter in chickens receiving higher numbers of oocysts, but once shedding was detected, there were no obvious differences in shedding patterns among groups receiving 10(3) through 10(6) oocysts. On days 8 and 16 PI, cryptosporidia were located primarily in the bursae of Fabricius. IBDV exposure was associated with bursal follicle atrophy, whereas C. baileyi infection resulted in bursal epithelial hypertrophy and hyperplasia, mild follicle atrophy, and heterophil infiltration of the bursal mucosa. Examination of experimental groups of 30 birds each indicated that concurrent infection with both agents resulted in more severe bursal lesions, more infected birds, and greater numbers of cryptosporidia in infected tissues. At the termination of the trial, 16 days PI, Cryptosporidium infection was associated with a 6% decrease in mean body weight compared with controls.     

The effect of heating against Cryptosporidium oocysts

The effect of heat treatment was examined against oocysts of Cryptosporidium parvum, Cryptosporidium muris and chicken Cryptosporidium sp. isolated in Japan. The oocysts of these species were exposed at 50, 55, 60 and 70 degrees C for 5, 15, 30 and 60 sec in water bath, respectively. To determine the infectivity of heated oocysts, the nice and chickens were inoculated with the treated oocysts and the oocyst output in the feces after inoculation was examined. In C. parvum and chicken Cryptosporidium sp., the oocysts were not detected from mice or chickens which were received oocysts heated at 55 degrees C for 30 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec. In C. muris, the oocysts were not detected from mice which were received oocysts heated at 55 degrees C for 15 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec. Consequently, it was clarified that the infectivity of Cryptosporidium oocysts to mice and chickens was lost by heating at 55 degrees C for 30 sec, 60 degrees C for 15 sec and 70 degrees C for 5 sec.