应用套式RT-PCR快速检测鸭坦布苏病毒

鸭坦布苏病毒是新发现的一种可引起鸭产蛋下降、生长迟缓和死亡的黄病毒。目前尚无可靠的快速诊断方法用于该病毒的检测。本研究根据鸭坦布苏病毒E基因序列,设计了2对重叠引物P1、P2和P3、P4,建立了检测鸭坦布苏病毒的套式RT-PCR方法,该套式RT-PCR比一般PCR敏感性高10倍。采用该方法对安徽省、河北省、山东省、浙江省、上海市等地发病鸭场的63份样品进行了检测,阳性检出率为48/63（76.2%）,而病毒分离率仅为13/63（20.6%）。由此表明,与其他方法相比较,本试验所建立的套式RT-PCR方法具有快速、敏感、特异优点,可用于鸭坦布苏病毒的流行病学调查及病毒的检测。     

鸭坦布苏病毒RT-PCR检测方法的建立

为快速检测鸭坦布苏病毒(DTMUV),根据鸭坦布苏病毒E蛋白的基因序列设计一对特异性PCR引物,并以鸭坦布苏病毒基因组为模板,建立了鸭坦布苏病毒的特异性RT-PCR检测方法,进行了特异性和敏感性试验,并用该方法对采自江苏地区的疑似病料进行了检测。结果表明:该方法可以特异性地扩增出鸭坦布苏病毒E蛋白基因保守区514 bp的序列,和对照的其他鸭病毒无交叉反应;敏感性较好,最低可检测到1 fg的基因组;临床样品的检出率为100%。说明所建立的RT-PCR检测方法特异性强、敏感性高,可用于临床快速诊断鸭坦布苏病毒。     

鸭坦布苏病毒病RT-PCR检测方法的建立

鸭坦布苏病毒病是近年来新发的危害养鸭业较严重的传染病之一。自2019年疑似病例在云南发生以来,给云南养鸭业造成严重损失。针对鸭坦布苏病毒(DTMUV)保守的非结构蛋白NS5基因序列,设计1对引物,建立DTMUV的RT-PCR检测方法。该方法特异性地扩增出718 bp,检测的敏感度为3.24 pg/μL;对鸭肝炎病毒、新城疫病毒、禽腺病毒、减蛋综合征病毒和禽流感病毒均无扩增条带;应用建立的RT-PCR方法检测临床疑似病料,阳性结果经测序证明感染DTMUV。为鸭坦布苏病毒病的病原检测提供了一种快速方法。     

科技前沿

正中国农科院成功研制"鸭坦布苏病毒病活疫苗"近日,中国农业科学院上海兽医研究所科研人员率先从发病鸭场分离鉴定出引起雏鸭高热、食欲不振、生长迟缓、产蛋下降乃至停止新发鸭传染病的病原,将之命名为"坦布苏病毒(Tembusu virus,TMUV)",并成功研制出"鸭坦布苏病毒病活疫苗(FX2010-180P株)"。据科研人员介绍,该病毒与登革热病毒、西尼罗河病毒、乙型脑炎病毒均为黄病毒科黄病毒属的病毒。研究     

鸭坦布苏病毒病的防控

正鸭坦布苏病毒病是由黄病毒科、黄病毒属的坦布苏病毒引起病鸭瘫痪、产蛋鸭产蛋骤降为特征的一种病毒性传染病。主要侵害种鸭、蛋鸭、肉鸭,鹅偶有发生,又称为鸭出血性卵巢炎、鸭黄病毒病。自2010年4月份在中国首次流行以来,给我国水禽业带来巨大损失。本文将从该病的流行特点、临床及剖检症状、诊断方法及防控措施四个方面进行阐述。1鸭坦布苏病毒病的流行特点     

鸭坦布苏病毒E基因重组杆状病毒的构建与间接ELISA检测方法的建立

研究旨在建立基于真核表达的鸭坦布苏病毒(DTV)E蛋白的诊断鸭坦布苏病毒病的间接ELISA方法。利用Bac-to-Bac杆状病毒昆虫表达系统,构建含有DTV E基因的重组杆状病毒。用重组病毒感染昆虫细胞后,SDS-PAGE鉴定出55 ku左右的表达蛋白,Western blot检测该蛋白具有很好的反应原性。以重组Bacmid DTV E蛋白作为包被抗原,建立间接ELISA检测方法。利用该方法对135份来自江苏省的樱桃谷鸭血清样品进行检测,发现其血清阳性率达79.3%。表明建立的间接ELISA检测方法特异性强、重复性好、敏感性高,可以用于鸭坦布苏病毒病的临床诊断。     

鸭胚中鸭坦布苏病毒的分离与鉴定

从山东省某种鸭场送检的鸭胚中分离到1株鸭坦布苏病毒(TMUV),命名为SDBZ株。根据Gen Bank上已发表的TMUV NS3基因序列设计一对引物,利用RT-PCR对该分离株NS3基因扩增并测序,将获得的SDBZ株NS3基因与Gen Bank中的11株TMUV及10株其他黄病毒属病毒基因进行对比分析。结果表明,该分离株NS3与Gen Bank上已发表的TMUV-WZDu、SDLY、JS804的同源性可达98.9%,与其他黄病毒属病毒基因同源性较低,为53.7%~77.2%。该研究结果为证明TMUV垂直感染提供了流行病学依据。     

禽黄病毒套式RT-PCR检测方法的建立及应用

禽黄病毒病是新发的一种疫病,可引起鸭、鹅和鸡等家禽产蛋和采食量下降及死亡。本研究旨在建立一种快速诊断方法用于临床诊断及流行病学调查。根据GenBank发表的鹅黄病毒JS804株全基因序列,应用Primer Premier 5.0软件设计了2对特异性引物,建立了禽黄病毒套式RT-PCR检测方法。结果:该套式RT-PCR方法具有特异性强、敏感性高的特点,最低病毒检测量为101.89TCID50/0.1 mL,比普通RT-PCR方法敏感性高1 000倍。应用该方法对江苏地区疑似禽黄病毒病的70份鹅病料、4份鸭病料、12份鸡病料进行检测,总阳性率为58.14%,而用普通RT-PCR方法检测的阳性率仅为17.44%。结果表明,禽黄病毒套式RT-PCR检测方法具有快速、特异、敏感的特点,可用于禽黄病毒感染的临床诊断和流行病学调查。     

鸭坦布苏病毒病的研究进展

鸭坦布苏病毒属于黄病毒科黄病毒属的一种单股正链RNA病毒,该病毒引发的鸭坦布苏病毒病从2010年开始在我国流行,并迅速蔓延至多个地区。该病主要侵害鸭的生殖系统,以产蛋量急剧下降为主要特征,肉鸭、雏鸭主要症状为站立困难,步态不稳。文章综述了鸭坦布苏病毒病的病原学特征、临床症状、病理变化、诊断方法和防控措施的最新研究进展,以期为该病的深入研究和防控提供参考。     

鸭坦布苏病毒病的防控

<正>鸭坦布苏病毒病是由黄病毒科、黄病毒属的坦布苏病毒引起病鸭瘫痪、产蛋鸭产蛋骤降为特征的一种病毒性传染病。主要侵害种鸭、蛋鸭、肉鸭,鹅偶有发生,又称为鸭出血性卵巢炎、鸭黄病毒病。自2010年4月份在中国首次流行以来,给我国水禽业带来巨大损失。本文将从该病的流行特点、临床及剖检症状、诊断方法及防控措施四个方面进行阐述。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Evaluation of the Microbiological Status of Milk and Various Structures in Mammary Glands from Naturally Infected Dairy Cows

A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the Nigerian derived savanna

Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L₃) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L₃ developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.