HIV－1gag基因重组痘苗病毒的构建和高效表达

Ｇａｇ蛋白是人Ⅰ型免疫缺陷病毒（ＨＩＶ－１）重要的结构蛋白，可诱导机体产生体液和细胞免疫应答。本试验将ＨＩＶ－１不同长度的长末端重复序列（ＬＴＲ）和全长的ｇａｇＯＲＦ置于痘病毒启动子控制下，经过同源重组、红细胞吸附试验筛选和间接免疫荧光试验鉴定，分离了６株重组痘苗病毒。免疫印迹（Ｗｅｓｔｅｒｎｂｌｏｔ）和免疫酶试验检测表明，６株病毒均能表达ｇａｇ基因，其中以ｖ１６ＬＧ△２的Ｇａｇ蛋白表达量最高，占细胞裂解物上清的５．１９％，相当于１４．７μｇ／１０６细胞，接近杆状病毒的表达产量。重组蛋白主要为ｐ５５ｇａｇ蛋白前体，但也有一部分被加工，生成成熟蛋白ｐ２４ｇａｇ、ｐ１７ｇａｇ及其中间蛋白。表达的重组蛋白可形成病毒样粒子（ＶＬＰ），并可诱导小鼠产生抗Ｇａｇ蛋白抗体     

以GIS为基础的禽流感预测预警研究进展

GIS是一种对地理环境等方面数据进行储存、分析、加工和呈现的综合工具。利用GIS可以把流感病例的相关数据与气候、环境和社会等数据进行整合和分析,通过统计学或数学模型,找到影响流感发生和传播的风险因素,对流感的发生趋势进行预测和可视化预警。国内外学者利用GIS在禽流感风险因素分析和预测等方面做了大量研究,包括对人感染H7N9流感、高致病性H5亚型禽流感、野禽流感风险因素和预测的研究,不同基因型病毒分布特征的研究,兽医决策辅助应用研究等。这些研究对指导兽医流行病学研究人员将GIS更好地应用于禽流感防控具有帮助意义。     

北京郊区散养鸡及鸡蛋沙门氏菌带菌情况调查

目的：和方法采用菌落PCR法和细菌培养法调查北京郊区三个散养鸡场的鸡蛋和鸡粪样沙门氏菌的带菌情况,并对两种方法的检测结果进行比较。结果 PCR检测结果表明北京郊区散养鸡粪便沙门氏菌平均阳性率90.87%,蛋内沙门氏菌平均阳性率40%;细菌培养结果表明散养鸡鸡粪平均沙门氏菌阳性率82.3%,蛋沙门氏菌平均阳性率33.3%。结论与传统细菌培养方法相比,菌落PCR法在数值上可提高散养鸡鸡粪和鸡蛋沙门氏菌检出率。     

Nitrogen balance in barrows fed low-protein diets supplemented with essential amino acids

This study was conducted to determine the effect of addition of essential amino acids (EAA) to low-protein diets on N balance in barrows. Thirty barrows (Duroc × Yorkshire) with an initial BW of 36 kg were fed 5 corn- and soybean meal-based diets containing 13.6 to 18.2% crude protein (CP) for 10 d in a randomized complete block design. The 18.2% CP diet was formulated without addition of EAA (Lys, Met or Thr). The other diets contained 13.6 to 16.5% CP and were supplemented with EAA to provide 0.83% true digestible lysine equal to that in the 18.2% CP diet. Fecal, urinary, and total N excretion as well as N retention (g/d) decreased with decreasing dietary CP level (P < 0.01). The apparent digestibility of N was almost the same for the 18.2 and 16.5 CP diets, but the value was 2% higher (P = 0.07) than that for the 13.6% CP diet. These findings indicate that, compared with the 18.2% CP diets, supplementation with three EAA to the lowest-protein diets (13.6 CP) is inadequate for maximum intestinal protein digestion, amino acid absorption, or tissue protein deposition in growing barrows.     

Efficacy of different dosages of ivermectin injectable against the Hypoderma spp. in yaks

A chemotherapy trial was conducted to determine the lowest dosage of injectable preparation of ivermectin against Hypoderma spp. infestation in yaks in Tibetan areas in Tianzhu county, Gansu province, in northwest of China. One hundred and sixty yaks were randomly divided into four groups of 40 yaks for the trial. The first three groups were treated by subcutaneous injection in the neck with 0.1% ivermectin (respectively, 1, 5, 10 microg/kg body weight). The fourth group was not treated and considered as control group. All the experiments were performed in November 2000 and the animals were examined for the presence of warbles in the next March and May. The results indicated that there was no warbles found on the back of treated animal while third stage larvae were palpated on back of some of the yaks in control group. It is concluded that dosage of 1 microg/kg ivermectin injectable was sufficient to kill or stop development of larvae of Hypoderma spp. in naturally infected yaks if administrated in November.     

畜产品质量安全体系的建立与监管

人们常常会问:现在能吃什么?放心奶、放心肉真能让人放心么?2008年9月石家庄三鹿奶粉事件,2009年2月份广州发生多人中毒的"瘦肉精"(盐酸克伦特罗)事件。问题食品成为当今人们的焦点话题。随着     

重组伪狂犬病病毒SA215(C)株的构建及其对小鼠的免疫原性

为了研制猪2型圆环病毒（PCV2）基因工程疫苗,以伪狂犬病病毒（PRV）基因缺失疫苗株SA215为病毒载体,通过同源重组,构建了共表达PCV2ORF2基因和绿色荧光蛋白基因重组伪狂犬病病毒SA215（C）株。经PCR、Southern blotting、Western blotting等证实SA215（C）构建正确,并能表达具有活性的ORF2基因蛋白和荧光蛋白。SA215（C）在IBRS-2、ST细胞中的增殖滴度与亲本株SA215相比无显著差异,表明外源基因的插入不影响病毒增殖。用SA215（C）免疫BALB/c小鼠10周后检测免疫小鼠PCV2抗体和PRV中和抗体及细胞免疫反应。结果显示,SA215（C）诱导小鼠产生了PCV2和PRV抗体并出现PCV2的细胞免疫反应。另外,以105TCID50的SA215（C）株接种BALB/c小鼠,接种后28d再接种1次,2次接种后2周,用107TCID50PRVFa和PCV2强毒联合进行攻击,结果免疫小鼠抵抗住强毒的攻击,获得了保护;表明该毒株具有很强的免疫原性,为研制安全、有效的PCV2-PRV二价基因工程疫苗奠定了基础。     

猪瘟病毒保护性抗原E2基因的克隆及在原核细胞中的表达

应用ＲＴ－ＰＣＲ分两段扩增猪瘟病毒（ＨＣＶ）石门株Ｅ２基因,然后对其进行了克隆。利用两个片段重叠部分的单一ＢｇｌⅡ位点,将它们连接成为完整的Ｅ２基因,并克隆到ＰＵＣ１９质粒中,获得重 质粒ＰＨＣＦ２。另设计一对引物,以ＰＨＣＦ２为模板扩增出不含信号肽的Ｅ２基因,然后将其克隆到表达载体质粒ｐＢＶ２２０和ＰＥＴ＿２８ａ（＋）中,获得重组质粒ＰＢＶＥ２和ＰＥＴＥ２,用酶切,ＰＣＲ和序列分析鉴定Ｅ２基因插     

如何训练犬如厕

训练犬如厕应从小犬一到家时开始,通常是在幼犬6周至8周时.由于幼犬的内脏和膀胱很小,因此它需要频繁地便溺.当它显示出要排泄(这很快成为显而易见的事),你应先把一张报纸铺在地板合适的地方.     

益生菌对致病性大肠杆菌在雏鸡消化道内的作用效果

1日龄雏鸡120只,随机分为6组,用不同的方法处理后,对各组雏鸡7个部位（嗉囔、腺胃、十二指肠、空肠、回肠、盲肠、直肠）消化道黏膜黏附的O78进行分离计数,研究禽致病性大肠杆菌在雏鸡消化道的分布,比较益生菌对禽致病性大肠杆菌O78在不同雏鸡动物模型中的抑制作用。结果表明：禽致病性大肠杆菌O78主要定植在雏鸡的嗉囔、盲肠和直肠;抗生素处理组和非处理组在灌服益生菌后24、48、72、96h与对照纽相比,各消化道部位定植的O78均有不同程度的降低,说明益生菌对禽致病性大肠杆菌O78。具有较强的抑制能力;未处理组的雏鸡消化道内黏附的O78菌数低于抗生素处理组,说明益生菌在抑制病原菌同时可促进消化道有益菌群的生长,从而防止致病菌的感染。