沙门氏菌对鱼类的致病作用及治疗试验观察

用沙门氏菌50115号菌对银鲫(Caiassius auratus gibelio)及小白鼠(km)攻毒(7.5×108个菌感染)成功,而且鱼对该菌比小白鼠更敏感,症状更突出;银鲫的24 h LD50为3×107个/mL;抑菌实验结果表明红霉素、痢特灵、庆大霉素、二氯异氰尿酸钠对该菌有抑制作用;把二氯异氰尿酸钠、痢特灵、红霉素,三种药物按0.4 mg/kg、1 mg/kg、0.4 mg/kg三种剂量对病鱼进行药浴,并结合投喂相应药饵,治愈率分别为60%、100%、80%.     

猪增生性肠炎模型的建立及其病理学研究

为了复制猪增生性肠炎病的模型并进行病理学观察,试验将临床检测胞内劳森菌为阴性的6～7周龄非免疫健康仔猪6头随机分为攻毒组(4头)与对照组(2头),攻毒组口服接种猪源胞内劳森菌GXNN株30 mL/头·次,对照组口服接种无菌稀释液30 mL/头·次.感染后分别于21天和56天剖杀感染组仔猪2头和对照组仔猪1头,观察病理变化并采集病变组织器官.结果表明:感染猪临床上出现短暂的体温升高、轻度腹泻等症状,粪便中检出胞内劳森菌.剖检可见腹股沟淋巴结及肠系膜淋巴结呈灰白色肿胀,肠系膜小血管扩张、充血;回肠黏膜褶皱呈脑回状;肝脏出现局部轻度淤血.组织病理学主要表现为猪回肠、结肠集合淋巴小结增多、增大,腺窝内杯状细胞消失,部分腺窝不成熟的上皮细胞增生,腺窝之间的周围组织有嗜酸性粒细胞和淋巴细胞浸润;肝脏的窦状隙有局灶性出血,其他组织器官病变不明显.经过免疫组化和原位杂交试验可见回肠、结肠的腺窝内和腺上皮细胞的胞浆内有染成棕黄色或蓝紫色的菌体.     

猪链球菌2型感染普通仔猪模型的建立及其病理学观察

试验采用普通长白系仔猪建立猪链球菌2型动物模型,并进行详细的病理学观察。将8头仔猪随机分为试验组和对照组,用猪链球菌2型菌血静脉接种试验组,对照组接种生理盐水2 mL/头。攻毒猪5 d内全部死亡, 主要表现为脑膜炎、心外膜炎、关节炎和败血症等典型症状和病理变化,与自然感染情况相似。从感染死亡猪肺、脾、肝、心中均分离到与攻毒菌株相同的细菌。证明猪链球菌2型菌血静脉接种普通长白系仔猪可以复制出典型病例,成功建立了动物模型,对SS2致病性研究具有重要意义。     

嵌合型猪圆环病毒(PCV1-2)及PCV2 ORF2真核表达质粒对商品猪的免疫保护

应用本实验室构建的嵌合型猪圆环病毒(PCV1-2)及真核表达质粒pcDNA3.1/V5-His-ORF2作为免疫原免疫母源抗体ELISA效价在0.07～0.60不等的商品猪,9头猪随机分为4组,1组(3头)肌肉注射免疫103.5TCID50的PCV1-2/头,2组(2头)肌肉注射真核表达质粒200μg/头,3组(2头)肌肉注射空载体(pcDNA3.1)200 μg/头,4组(2头)不免疫作为攻毒对照组.于免疫后42 d,PCV1-2组及真核表达质粒组产生了PCV2抗体.免疫后42 d所有组攻毒PCV2和PRRSV,剂量分别为2×104.5TCID50/头和106TCID50/头.攻毒后21 d,攻毒对照组猪淋巴结比免疫组显著肿大,免疫组猪血清、淋巴结中PCV2病毒载量低于对照组,攻毒对照组猪淋巴结中PCV2抗原含量高于免疫组.这些结果表明,嵌合型PCV1-2及真核表达质粒肌肉注射免疫商品猪后,对PCV2感染能产生保护性免疫应答,有可能成为候选疫苗.     

MPAIV、NDV Lasota株分别与较低致病性禽源E.coli的联合感染试验

以 2× 1 0 5EID50 的低致病性禽流感病毒 ( mildly pathogenic avian influenza virus,MPAIV)、2× 1 0 6 EID50 新城疫病毒 L asota株( Newcastle disease virus Lasota strain,NDVL asota)气管内注射 1 0日龄 SPF鸡 ,2 4h后 ,同剂量、同法重复感染一次 ;48h后 ,分别气管内注射较低致病性禽病原性大肠杆菌 1 2 0( O1 8)和 1 73( O2 6 )株 ,2× 1 0 7CFU/羽 ,2 4h后同剂量、同法重复攻毒一次 ,连续观察 1 0d。结果 :MPAIV单独感染组死亡率为 53% ;NDV Lasota株单独攻毒组未见死亡 ;大肠杆菌 1 2 0株单独攻毒组死亡率为 40 % ,1 73株单独攻毒组死亡率为 7% ;MPAIV与大肠杆菌1 2 0株联合攻毒组的死亡率为 87% ,NDV L a-sota株与 1 2 0株联合攻毒组的死亡率为 40 % ;MPAIV与大肠杆菌 1 73株联合攻毒组的死亡率为 80 % ,NDV Lasota株与 1 73株联合攻毒组的死亡率为 2 0 %。     

猪支原体肺炎活疫苗经肌肉注射的免疫效果评价

猪支原体肺炎活疫苗(168株)是一种以肺内注射途径免疫的弱毒活疫苗。为了拓展猪支原体肺炎活疫苗的免疫途径,评估猪支原体肺炎活疫苗(168株)配合佐剂以肌肉注射方式免疫猪群后的攻毒保护效果,选取20头7日龄猪肺炎支原体(Mycoplasma hyopneumoniae,Mhp)阴性仔猪,将其随机平均分成4组,分别为健康对照组、感染对照组、肌肉注射免疫组和肺内注射免疫组。在免疫后采集血样并检测其中的Mhp IgG抗体,在首次免疫后42 d人工感染Mhp组织毒(JS株),攻毒28 d后评估肺脏的病变情况并测定支气管肺泡灌洗液(BALF)中的Mhp含量。结果显示：免疫后肌肉注射免疫组动物产生了明显的Mhp特异性血清IgG抗体,而肺内注射免疫组动物在攻毒前未见明显的血清抗体;肌肉注射免疫组和肺内注射免疫组的攻毒保护率分别平均为88.89%和75.93%,且组间无显著性差异;感染对照组的BALF中Mhp单位含量极显著高于肌肉注射免疫组和肺内注射免疫组(P<0.01),2个免疫组间无显著性差异。结果表明：猪支原体活疫苗配合佐剂后经肌肉注射免疫可产生较好的免疫攻毒保护效果。本研究为猪支原体肺炎活...     

使用猪三联苗的防疫效果观察及对猪瘟免疫期抗体效价测定

猪三联苗免疫51—60日龄断奶前仔猪对猪瘟免疫期试验,是用人工接种猪瘟强毒致病的猪与试验猪、对照猪一起同圈感染,其结果免疫51日龄仔猪经7.5个月100%保护;免疫60日龄仔猪经6个月75%保护;另一组免疫60日龄仔猪经9个月,感染观察22天均健活,用猪瘟毒1毫升肌注后,对照猪于15天死亡,免疫猪100%保护。免疫猪与对照猪在攻毒前采取血清,用中和反应测定猪瘟免疫抗体及其效价的结果,共测14头中有5头猪血清中无中和抗体,家兔体温呈现热反应(其中对照猪3头均死亡,另2头免疫猪死亡一头,感染发病耐过1头),另9头免疫猪血清有中和抗体,试验兔无体温反应,攻猪瘟毒后均健活。被检血清中和效价一般在4—32倍之间。免疫7.5个月组的猪中和效价个别达到128倍,免疫9个月组的猪也有达到64倍的。田间试验免疫15,225头,其中发生反应17头,占11/千,死亡3头,占2/万,留养观察6236头,发病率9.64%,死亡率1.59%,没有猪瘟、猪丹毒病的发生。     

猪伪狂犬病毒变异株(Fujian-LY)对免疫仔猪的致病性研究

本实验室2014年从福建省龙岩市某规模化猪场疑似猪伪狂犬病发病仔猪的脑组织中分离到1株猪伪狂犬病毒变异株,命名为PRV Fujian-LY株。为了研究Fujian-LY株对免疫仔猪的致病性,将8头20龄的PRV抗原、gE抗体均为阴性,gB抗体均为阳性仔猪随机分为3组,其中2组(每组3头猪)分别通过肌肉注射和滴鼻接种Fujian-LY株,第3组2头仔猪做阴性对照。试验仔猪接种病毒24h后体温均开始升高,随着病程发展,呼吸系统症状明显,滴鼻接种组仔猪发病明显快于肌肉注射组,所有攻毒仔猪虽均有发病但未出现死亡。通过病理剖检、PCR鉴定、病毒分离培养、易感动物感染试验及gE抗体ELISA检测证实Fujian-LY株人工攻毒试验成功。gE抗体检测结果表明所有攻毒仔猪攻毒后7dPRV gE抗体开始阳转。对发病仔猪剖检可见,脑积液明显增多,脑膜血管充血,并伴有出血等典型的伪狂犬病病理变化。病理切片观察结果显示发病仔猪脑实质中小血管扩张充血,血管周围有淋巴细胞包围"血管套"现象,其他主要脏器也均有明显的病理变化。试验结果表明PRV Fujian-LY株为伪狂犬病毒强毒株。     

我国南方猪高热病的研究(Ⅰ)——大肠杆菌的分离、鉴定和致病性测定

从湖南3个高热病发病猪场11头病死猪的病料组织中均分离出了大肠杆菌,经血清学鉴定,鞭毛抗原(K88、K99、987P和F41)全为阴性反应。经过157种菌体抗原血清学检测,血清型为5、6、15、22、32和83型。药物敏感试验结果表明,分离的大肠杆菌对大多数常用药物耐药,对氟喹诺酮和头孢类药物敏感。将其中4头猪原代分离的大肠菌培养物以原倍(2×107个/mL)、104和108稀释的菌液分别感染18~22 g小白鼠,原倍菌液感染的小白鼠12/30在感染后24 h内出现死亡,而104和108稀释菌液感染的小白鼠均健活;将未经除菌的病死猪组织悬液、过滤除菌的组织悬液、大肠杆菌、过滤除菌的组织悬液及大肠杆菌分别感染30日龄左右的健康小猪,除未经除菌的组织悬液感染猪3/3发病,2/3死亡外,其余所有感染猪只出现体温升高,升幅达1~2℃,减食,精神萎靡,但没有死亡;将死亡猪再次分离到的大肠杆菌感染小白鼠和猪,小白鼠12/15出现死亡,感染猪只出现体温升高(超过1℃),没有出现死亡。结果证明:大肠杆菌在高热病的发病过程中只起协同诱发作用,引起猪发病死亡的真正原因可能是病毒感染。     

伪狂犬病毒变异株（JS-2012）对仔猪的致病性研究

本实验室2012年从江苏省太仓市某发病猪场分离到1株变异的伪狂犬病毒,命名为JS-2012。为了研究该分离株对仔猪的致病性,将12头15日龄的伪狂犬病毒阴性仔猪随机分为3组,其中2组（每组5头猪）分别通过肌肉注射和滴鼻接种JS-2012毒,第3组2头猪做空白对照。接种病毒的仔猪在攻毒后24 h体温均开始升高,4 d后开始死亡,死亡率为100%。临床观察发现,滴鼻组仔猪发病死亡明显快于肌肉注射组。对病死猪进行剖解,均可见大脑血管扩张并出血等典型的伪狂犬病病理变化。病理切片显示猪的脑蛛网膜下腔严重出血,其他各脏器也均有严重病理变化。结果表明该变异株JS-2012为伪狂犬强毒毒株。     

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.