H5亚型禽流感病毒反应原性差异及ELISA检测方法的研究

在获得禽流感病毒多克隆抗体及H5亚型特异性单克隆抗体的基础上,建立了H5亚型特异性抗原捕捉ELISA检测方法。通过分析不同单克隆抗体与不同禽流感毒株的反应性差异,筛选高特异性和高敏感性的H5亚型单克隆抗体。优化反应条件,确定包被抗体、检测抗体及酶标抗体的最佳工作浓度,进行敏感性、特异性、重复性及稳定性分析,并与斑点ELISA、H5N1多重RT-PCR或病毒分离鉴定的结果相比较,同时使用该方法对野外样品进行了检测。结果表明,该方法敏感、特异,具有良好的重复性和稳定性,可用于检测临床样品、鸡胚培养物及细胞培养物中的H5亚型禽流感病毒。     

禽流感病毒H5HA、H7HA、H9HA亚型夹心ELISA方法的建立

将禽流感病毒(AIV)H5、H7、H9血凝素亚型标准血清中的IgG作为包被抗体,H5、H7、H9血凝素亚型单克隆抗体作为第二抗体,建立了双抗体夹心ELISA(AC-ELISA)方法,并优化了反应条件.结果表明:单抗和标准血清最适工作质量浓度分别为5、10 mg/L,标准阳性血清于4℃包被12 h,二抗作用条件为37℃作用1 h,封闭条件为37℃作用1 h,酶标抗体工作条件为1∶5 000稀释后,37℃作用1 h,底物作用条件为37℃作用10 min.阴阳性抗原临界值为0.274～0.332.本方法具有很高的特异性和敏感性.     

检测流感病毒H5亚型抗体竞争ELISA方法的建立及初步应用

本研究采用灭活的H5亚型禽流感纯化病毒包被ELISA反应板,以辣根过氧化物酶标记的HA蛋白单克隆抗体作为竞争检测抗体,建立了检测H5亚型流感病毒抗体的竞争ELISA(C-ELISA)方法.实验结果表明:抗原最佳包被浓度为8.27ug/mL(1:800),酶标抗体最佳稀释倍数为1:800,待检血清最佳稀释倍数为1:10.对已知阳性样品的检测结果表明,本研究中所建立的竞争ELISA方法的敏感性高于经典的血凝抑制方法(HI).特异性试验表明该ELISA方法仅能检测H5亚型流感病毒抗体,具有良好的特异性.对临床样品检测表明C-ELISA与HI 方法的符合率达到93%以上.该方法可以对不同种属动物血清H5亚型流感病毒抗体进行快速定量的检测,为H5亚型流感病毒流行病学调查与抗体的检测提供了一种快速、方便、敏感的方法.     

H5N1和H9N2亚型禽流感病毒型特异性抗原捕捉ELISA检测方法的建立

采用禽流感病毒多克隆抗体及型特异性单克隆抗体，研究建立了型特异性抗原捕捉ELISA检测方法，用于检测H5N1和H9N2亚型禽流感病毒。优化了反应条件，确定了包被抗体、检测抗体及酶结合物的最佳工作浓度，对该方法的敏感性、特异性、重复性及稳定性进行了分析，并与病毒分离鉴定的结果进行了比较。结果表明，该方法敏感、特异，具有良好的重复性和稳定性，可用于临床样品及鸡胚、细胞培养物中禽流感病毒的检测。     

H7亚型禽流感病毒微滴式逆转录数字PCR检测方法的建立

本文建立了一种H7亚型禽流感病毒微滴式逆转录数字PCR方法,为H7亚型禽流感病毒核酸的定量检测和临床低浓度样品的诊断提供一种检测技术。根据H7亚型禽流感病毒的HA基因,设计了1对特异性的引物和探针,建立了H7亚型禽流感病毒的微滴式逆转录数字PCR方法,对该方法的特异性、敏感性和重复性进行了评价,并初步应用于临床样品的检测。结果为,该方法的最低检出限为3 copies/μL;与H1亚型、H3亚型、H6亚型禽流感病毒、新城疫病毒、鸡马立克氏病病毒、鸡传染性贫血病毒和鸡传染性法氏囊病病毒无交叉反应;检测12次200倍稀释的H7N9亚型禽流感病毒(Re-2株)的核酸,变异系数为3.38%;检测了30份临床样品,结果均为阴性。结果表明,该方法的敏感性高,特异性和重复性好,适用于H7亚型禽流感病毒的临床检测和标准物质的标定。     

H5、H9亚型禽流感分子鉴别诊断方法的建立

为了快速、敏感、特异地鉴别诊断禽流感,根据H5、H9亚型禽流感病毒HA基因序列的保守区域设计出并合成2对特异性引物,利用这2对引物对H5、H9亚型禽流感病毒的HA基因片段进行二联RT-PCR扩增,并对二联RT-PCR检测方法进行敏感性及特异性试验。结果表明:这2对引物能特异性地扩增出H5、H9亚型禽流感病毒HA基因片段,大小分别为490bp和686bp;该检测方法敏感性高,特异性强;初步建立了快速、敏感、特异地鉴别检测H5、H9亚型禽流感病毒的分子诊断方法。     

禽流感病毒H7亚型竞争ELISA抗体检测方法的建立

将禽流感病毒H7亚型标准抗原作为免疫原免疫BALB/c小鼠,取免疫合格的脾细胞与骨髓瘤细胞(SP2/0)进行融合。通过血凝抑制试验,筛选得到12株杂交瘤细胞上清具有HI效价,且与禽流感病毒H7亚型阳性血清间具有较好的竞争效果。将竞争效果最好的1H11细胞扩大培养后制备腹水,获得的单克隆抗体具有效价高、特异性好等特点。使用H7标准抗原包被ELISA板,将HRP标记的单克隆抗体作为竞争抗体,建立了一种禽流感病毒H7亚型竞争ELISA抗体检测方法。利用该方法对待检血清进行测试,与HI试验有99.3%的符合率,说明试制的禽流感病毒H7亚型竞争ELISA抗体检测试剂盒可以用来检测禽流感病毒H7亚型抗体,且操作简便快捷,可批量操作,大样本检测鸡群抗体水平。     

H3亚型猪流感病毒抗原捕捉ELISA检测方法的建立

为快速检测H3亚型猪流感病毒(SIV),本研究将一株H3N2亚型SIV特异性单克隆抗体(MAb)进行纯化,建立了以多抗作为包被抗体,MAb作为检测抗体的H3亚型SIV抗原捕捉ELISA (AC-ELISA)方法.并对该方法的特异性和敏感性进行了分析,其敏感性是血凝试验的4倍,与猪繁殖与综合征病毒、猪圆环病毒、猪瘟病毒、猪细小病毒以及H1、H5、H9亚型SIV均没有明显的交叉性反应,批间和批内重复试验变异系数均小于10％.应用建立的AC-ELISA方法对84份H3亚型SIV实验室感染样品进行检测与鸡胚滴定病毒结果符合率达90.47％.本实验建立的AC-ELISA方法具有良好的特异性和敏感性,可用于H3亚型SIV的临床检测.     

H5亚型禽流感病毒的逆转录环介导等温扩增(RT-LAMP)检测技术

根据GenBank中H5N1亚型流感病毒HA基因保守区的序列,设计1组对应HA序列6个区域的4条特异性引物进行核酸扩增,建立RT-LAMP反应体系,优化LAMP反应条件,最佳等温扩增反应条件为65℃保温60min。扩增后产物加入核酸染色剂SYBRⅠ和4 mmol/L Mg2+,结果可视。扩增产物可用特异性内切酶KpnⅠ进行酶切鉴定。用已建立的RT-LAMP技术检测临床样品,检测结果与RT-PCR方法一致。RT-LAMP技术整个检测过程只需1~2 h,不需要PCR仪和成像系统,仅需要一恒温水浴锅即可完成试验。通过特异性、敏感性试验,验证了建立的RT-LAMP技术可以作为一种操作简单,灵敏性、特异性高的检测H5亚型禽流感病毒的方法。     

H3亚型禽流感病毒血凝素特异性单克隆抗体的制备

以H3亚型禽流感病毒(AIV)免疫BALB/c小鼠,取其脾细胞与SP2/0骨髓瘤细胞融合,用血凝抑制试验(HI)筛选阳性杂交瘤细胞并克隆化。结果获得了4株针对H3亚型禽流感病毒血凝素的单克隆抗体,分别命名为1D7、1F9、5A4、5F5。这些单克隆抗体小鼠腹水HI效价为212～214。用H1、H6、H10亚型禽流感病毒各2株,H4、H5、H9和新城疫病毒(NDV)各1株进行特异性试验。结果表明:所有这些单抗仅与H3亚型AIV发生特异性HI反应,而不与其他亚型AIV及NDV反应。用28株H3亚型禽流感病毒进行排谱试验,结果证明:4株单抗均具有广谱性,其中1F9、5A4、5F5与受试的28株H3亚型AIV均反应,而1D7只与其中的26株反应。以上单抗将为控制畜禽及人类的流感提供必需的诊断试剂。     

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.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

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.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

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.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

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