猪繁殖与呼吸综合征病毒GP5蛋白的原核表达及多克隆抗体制备

为体外表达猪繁殖与呼吸综合征病毒（PRRSV）糖基化囊膜蛋白GP5,以及制备其多克隆抗体,以PRRSV PC疫苗株RNA为模板,应用RT-PCR扩增GP5基因,并克隆至原核表达载体pET-32a（+）,构建重组表达载体pET-32a-GP5。经过酶切和测序鉴定后,将阳性重组质粒转化到大肠杆菌BL21（DE3）感受态细胞中,加入IPTG低温诱导表达。使用亲和层析法纯化PRRSV GP5蛋白。然后将纯化的蛋白免疫北京大耳白兔制备多克隆抗体,并进行酶联免疫吸附试验（ELISA）和间接免疫荧光分析（IFA）。结果显示,表达的PRRSV GP5原核蛋白以可溶性和包涵体两种形式存在,相对分子质量大约30 kDa;制备的GP5蛋白多克隆抗体ELISA效价可达1:64 000;IFA检测显示,制备的多克隆抗体能够识别PRRSV。重组PRRSV GP5蛋白及其多克隆抗体的成功制备为PRRSV血清学检测方法的建立提供了良好的生物学材料。     

Serological evidence for exposure to bovine viral diarrhoea virus in sheep co-grazed with beef cattle in New Zealand

ABSTRACT

Aims: To determine whether sheep that co-grazed with cattle that were suspected to be positive for bovine viral diarrhoea (BVD) virus had serological evidence of exposure to the virus.

Methods: Eighteen commercial farms that routinely co-grazed cattle and sheep in the same paddocks were recruited through purposive sampling. The recruiting veterinarians identified nine farms with cattle herds that were known or highly suspected to be positive for BVD and nine farms that were considered to be free of BVD. Blood samples were taken from 15 ewes aged 1 year on each farm and samples were submitted to a commercial diagnostic laboratory to test for antibodies against pestiviruses using an ELISA. All samples that were positive were then tested using a virus neutralisation test (VNT)for antibodies against BVD virus.

Results: Of the 270 blood samples, 17 were positive for pestivirus antibodies by ELISA and these originated from two farms that were known or suspected to have BVD virus-positive cattle. None of the samples from the nine flocks co-grazed with cattle herds that were known or suspected to be BVD virus-negative were positive for pestivirus antibodies. Within the two positive farms, 2/15 samples from the first farm and 15/15 samples from the second farm were antibody-positive. When the 17 positive blood samples were submitted for VNT, all 15 samples from the second farm tested positive for BVD virus antibodies with the highest titre being 1:512.

Conclusions and clinical relevance: In this small sample of New Zealand sheep and beef farms with suspected BVD infection in cattle, there was evidence of pestivirus exposure in co-grazed sheep. Although we were unable to confirm the origin of the exposure in these sheep, these findings highlight that farmers who are trying to eradicate BVD from their cattle should be mindful that the infection may also be circulating in sheep, and both populations should be considered a possible risk to each other for generating transient and persistent infections. Further work is needed to estimate the true prevalence of New Zealand sheep flocks that are affected by BVD and the associated economic impacts.     

关于反刍家畜瘤胃消化代谢调控的一些认识

<正>牛、羊等反刍家畜饲料中70%～85%的可消化干物质和50%粗纤维在瘤胃(包括网胃)内消化,因此,瘤胃消化在整个反刍家畜消化过程中占有特殊重要的地位。瘤胃被比喻是具厌氧性活体连续发酵罐,在微生物的主导下,瘤胃内进行一系列复杂的消化代谢过程(即发酵过程)。但它必须具备厌氧性微生物生存     

苜蓿中草酸含量的测定及煮制对其含量影响研究

紫花苜蓿营养丰富,越来越受到大家的青睐,但苜蓿中的草酸会对人体健康产生间接影响.本文通过对比实验研究了煮制对苜蓿中草酸含量的影响情况.结果显示:新鲜苜蓿中含有一定量的草酸,但煮制后能去除约75％的草酸,故水煮苜蓿是有效去除草酸并保留营养成分的首选方法.     

三种不同方法显示仔猪小肠肌间神经元的比较

本研究采用小肠铺片NADPH-d组化法、NADH-d组化法和抗NF免疫组化法分别对0日龄、5日龄、28日龄仔猪的肌间神经元进行了比较研究。结果表明:NADPH-d组化法可以选择性的标记合成NO的神经元亚群,大部分阳性肌间神经元符合DogielI型神经元的形态特征;NADH-d组化法可以非选择性的标记大部分神经元,且采用该法观察到的肌间神经元的密度明显高于NADPH-d组化法,但该法不能清晰的显示肌间神经丛的细微结构,不适合用于神经元类型的观察;抗NF免疫组化法可以清晰的显示肌间神经元的突起,28日龄仔猪体积较大的阳性神经元主要为DogielI型和DogielII型神经元。     

甘肃省集约化养猪场猪伪狂犬病的调查

伪狂犬病是由伪狂犬病病毒（ＰＲＶ）引起的多种动物的一种急性传染病，对猪的危害尤其严重，主要引起怀孕母猪流产、死胎或木乃伊胎以及产弱仔等，导致新生仔猪大量发病死亡，病死率可高达１００％；同时对成年猪呈现隐性感染或上呼吸道卡他性病症，给养猪业造成严重的经济损失。本病已在世界上５０多个国家发生暴发或流行，近几年在我国也有不少报道在集约化养猪场暴发流行了本病。甘肃省猪传染病的发病率也相当严重，仅１９９７年全省集约化养猪场和养猪专业户的各种传染病发病率就达１１％～１６％。病死猪７．１万头，病死率２．５％，…     

乳牛曲霉病的诊断

１９９９年７月循化县积石镇韩某家的１头乳牛和１头哺乳犊牛发生以流涎、流泪、呼吸困难、腹泻为特征的疾病。急宰后送检肺、肝、肾及淋巴结，经调查和化验，确诊为曲霉病。１病因调查本户共养４头牛，本病发生在１头乳牛和哺乳犊牛，另２头育肥公牛未见发病。本户牛舍狭窄采光不良，恰逢３ｄ阴雨，空气湿度相对大，平均气温３０℃左右。牛舍及运动地泥泞不堪，空气流通不畅，卫生状况不佳。牛的饲养标准过高，每头每天饲喂精料 １０ｋｇ，配方：玉米３０％，麸皮４２％，豆饼２５％，盐和其它矿物质３％。上述贮存饲料均有不同程度霉变，…     

圈养条件下北极熊的饲养繁殖

对大连森林动物园圈养条件下北极熊的饲养管理、发情交配、繁殖及幼仔人工育幼等方面进行了研究与分析,为北极熊在动物园的饲养与繁殖,尤其在人工育幼方面取得了大量的基础数据,希望对北极熊的圈养繁殖起到一定的推动作用。     

褐藻胶低聚糖生物活性研究进展

综述近年来褐藻胶低聚糖在抑菌、抗肿瘤、调节免疫、促生长、抗氧化等生物活性方面的研究,展望褐藻胶低聚糖的应用前景。