驴源抗犬细小病毒IgG抗体的制备及其抗病毒活性的分析

为制备驴源抗犬细小病毒(canine parvovirus,CPV)抗体,首先利用F81猫肾细胞扩增CPV-2a病毒株,经甲醛灭活和氢氧化铝胶乳化,制成CPV灭活疫苗,病毒滴度为10-8.5 TICD50,然后通过肌肉分点注射免疫驴,连续免疫3次(第1次注射3mL,后2次各注射6mL),每次免疫前采血,分析驴血清的抗体滴度和中和抗体效价;利用盐析法和离子交换层析法分离和纯化驴血清IgG。用IgG处理幼犬(50mg/kg),用CPV-2a毒株对IgG处理的犬进行攻毒,分析IgG抗CPV的活性。结果显示,免疫3次后驴血清的CPV抗体滴度为1∶8 192,中和抗体效价为28.5。用制备的IgG处理幼犬未发现不良反应,经CPV-2a攻毒实验证实IgG处理犬的发病率和死亡率分别为33%,0%,均明显低于非处理组(分别为100%,83%),说明制备的驴源IgG具有明显的抗CPV活性。     

犬细小病毒母源抗体及其对免疫接种的影响

犬细小病毒母源抗体可通过胎盘和初乳转移给仔犬。初生犬一周内血清中母源抗体HI效价为1:128～1:256,6用龄时HI效价降至1:8～1:32。母源抗体效价>1:16时接种犬细小病毒灭活苗。仅有33％的犬产生免疫应答;HI≤1:16时,对接种灭活苗或弱毒苗均产生免疫应答。     

靶向融合犬细小病毒DNA疫苗免疫犬试验研究

为了评价靶向融合犬细小病毒DNA疫苗pVAX1-CTLA-4125-VP2228在自然宿主体内的免疫应答和攻毒保护效果,试验选用CPV抗体阴性犬24只,分为4组,分别为第Ⅰ组(pVAX1-VP2228免疫)、第Ⅱ组(pVAX1-CTLA-4125-VP2228免疫)、第Ⅲ组(pVAX1免疫)、第Ⅳ组(弱毒苗免疫),每组6只犬,间隔4周免疫1次,免疫3次。采用CPV酶联免疫吸附试验(ELISA)、CPV微量中和试验和CPV血凝抑制试验(HI)检测抗体水平。免疫3次后进行攻毒试验,观察保护效果。结果表明:血清中IgG含量第Ⅱ组高于第Ⅰ组,差异极显著(P0.01);中和抗体效价,第Ⅱ组高于第Ⅰ组,差异极显著(P0.01);第Ⅱ组出现HI抗体,而第Ⅰ组未出现HI抗体;攻毒后发现pVAX1-CTLA-4125-VP2228、pVAX1-VP2228具有较好的保护力。说明CTLA-4125能够有效增强自然宿主对VP2228的免疫应答作用,可为进一步研究靶向融合DNA疫苗的作用机制奠定基础。     

蛋鸡首免乙型脑炎病毒后卵黄抗体变化规律的研究

本试验旨在研究疫苗、免疫剂量和注射方式对卵黄抗体效价规律的影响,探讨制备抗猪乙型脑炎病毒卵黄抗体蛋鸡的最佳免疫程序。选用无免疫褐羽蛋鸡180只,随机分成18组,每组10只。1、2组均为对照组,注射无菌生理盐水;3~10组采用皮下和肌肉两种注射方式,并依次注射灭活苗0.2、0.5、1.0和1.5 mL;11~18组同样采取两种注射方式,依次免疫相同剂量弱毒苗。各试验组分别于免疫前1 d、免疫后第3、7、10、14、18、21和28天采集当日鸡蛋6枚,提取卵黄抗体,测定效价。试验结果显示,1~6、11、12组卵黄抗体效价均为0,未产生明显免疫应答;7~10组注射灭活苗后7 d,平均卵黄抗体效价达到峰值,抗体持续时间为14 d;13~18组注射弱毒苗后14 d达到最高值,抗体持续时间为21 d;注射剂量相同但注射方式不同的两组之间比较,卵黄抗体效价差异不显著（P>0.05）;相同注射方式,相同疫苗的各试验组间,随着免疫剂量的增加卵黄抗体效价逐渐加强,且差异显著（P<0.05）。以上结果表明,肌肉或皮下两种注射方式,蛋鸡产生明显免疫应答至少需要免疫灭活苗1.0 mL或弱毒苗0.5 mL。比较弱毒苗与灭活苗,灭活苗刺激机体产生的抗体速度较快,但维持时间较短;较少剂量弱毒苗就可刺激机体产生抗体,但速度慢、维持时间长。     

犬细小病毒细胞毒蜂胶佐剂灭活抗原对山羊的免疫效果研究

应用犬细小病毒(CPV)细胞毒,F81细胞系传代培养增殖病毒,以该细胞毒液经甲醛灭活后制备成蜂胶佐剂灭活抗原,用以免疫山羊,观察其免疫效果.结果显示,以5mL/只恒定剂量接种山羊,经4次连续免疫后CPV抗体水平整体较低,第28天测定HI效价在27(1∶3128),而以5mL/只递增剂量4次连续免疫山羊后,抗体水平整体较高,第28天测定,抗体HI效价在29(1∶512),较恒定剂量免疫组高2个滴度水平.结果表明,采用犬细小病毒细胞毒蜂胶佐剂灭活抗原高免山羊可获得高效价的特异性抗血清.     

肉仔鸡后海穴免疫新城疫疫苗的应用研究

后海穴注射灭活苗同时点眼Lasota弱毒苗，对1日龄和5日龄AA肉仔鸡进行免疫。通过血清HI抗体的测定和强毒攻击发现，至免后42天HI抗体效价仍然维持较高水平且强毒攻击全部保护。通过与颈部皮下注射灭活苗同时Lasota点眼组进行对比发现，后海穴免疫组不但能产生较理想的免疫保护力，而且还在增重和病死淘率方面具有优势；而且免后42天解剖灭活苗注射部位没有发现肉芽肿等肉眼可见病变。结论：肉仔鸡在1日龄时用ND灭活苗经后海穴注射同时用ND弱毒苗点眼免疫，就能使肉仔鸡的整个饲养周期中免受ND的侵害。     

重组禽流感灭活苗和禽流感灭活苗对鸡免疫效果的观察

用重组禽流感灭活苗接种10日龄、14日龄和21日龄的SPF鸡,接种后HI抗体效价无显著差异。将H5N1和H5N2疫苗分别接种21日龄SPF鸡,结果表明,H5N1和H5N2均能刺激SPF鸡产生较高的HI抗体;分别接种三黄鸡,接种后21 d,H5N1能刺激三黄鸡产生较高的HI抗体;而H5N2不能刺激三黄鸡产生合格的HI抗体,与SPF鸡免疫组相比差异显著。经过二次接种,HI抗体平均为8.9 log2,与SPF鸡组接种后42 d的各组相比差异不显著,而与一免后21 d的各组HI抗体效价相比差异显著。表明应用禽流感灭活苗对三黄鸡免疫接种,必须进行二免方可达到理想免疫效果,而应用重组禽流感灭活苗对三黄鸡进行免疫接种,一次免疫即可获得较高的HI抗体效价。     

犬细小病毒灭活疫苗的免疫效果

利用猪红细胞吸附释放犬细小病毒(CPV)的特性,制备了灭活疫苗。对6头2～3月龄幼犬进行免疫试验,结果表明:临床上未出现异常和排毒现象;一次免疫后 HI 效价≥80,二次免疫后 HI 效价≥160,20周后仍维持在160以上;攻毒后全部得到保护,高 FACPV 组和貂肠炎苗组(分别为5/6、3/7)。对照组21头有18头出现临床症状。     

新剂型兔瘟疫苗的研究

经血凝抑制和攻毒试验结果表明，在含有相同抗原量制备的疫苗，兔瘟油乳剂灭活疫苗比兔瘟组织灭活苗免疫后血清ＨＩ抗体效价高３．２５￣６．０ｌｏｇ２，即使油乳剂灭活疫苗仅为组织灭活苗四分之一的抗原量，免疫后血清ＨＩ抗体效价还高１ｌｏｇ２。油乳剂灭活苗免疫兔第５０天其血清ＨＩ抗体未见下降，而组织灭活苗免疫后第２６天已开始下降。虽然接种二种剂型的疫苗攻毒后均具有１００％的保护率，但血清ＨＩ抗体效价消长情况证明     

三黄鸡禽流感免疫抗体消长变化规律的研究

对禽流感免疫抗体的消长变化进行了初步研究。将150只三黄鸡随机分为5组,用禽流感灭活油乳剂疫苗和禽流感灭活疫苗免疫试验组三黄鸡;14日龄时,对试验一、二、三、四组鸡进行首免,剂量为0.3mL/只;在35日龄时,对试验二、四组鸡进行二免,剂量为0.2mL/只;在21、28、35、42、49、56、63、70、77日龄采血,用血凝抑制(HI)试验测定各组三黄鸡血清中HI抗体效价。结果表明,禽流感灭活疫苗一次免疫即可使三黄鸡产生高效价的HI抗体,且持续时间较长;禽流感灭活油乳剂疫苗需要二次免疫才能使三黄鸡产生较高效价的HI抗体。     

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