The Control of Rinderpest in Tanzania between 1997 and 1998

In January 1997, Tanzania requested international assistance against rinderpest on the grounds that the virus had probably entered the country from southern Kenya. Over the next few months, a variety of attempts were made to determine the extent of the incursion by searching for serological and clinical evidence of the whereabouts of the virus. At the clinical level, these attempts were hampered by the low virulence of the strain, and at the serological level by the lack of a baseline against which contemporary interpretations could be made. Once it became apparent that neither surveillance tool was likely to produce a rapid result, an infected area was declared on common-sense grounds and emergency vaccination was initiated. The vaccination programme had two objectives, firstly to prevent any further entry across the international border, and secondly to contain and if possible eliminate rinderpest from those districts into which it had already entered. On the few occasions that clinical rinderpest was subsequently found, it was always within this provisional infected area. Emergency vaccination campaigns within the infected area ran from January to the end of March 1997 but were halted by the onset of the long rains. At this time, seromonitoring in two districts showed that viral persistence was still theoretically possible and therefore a second round of emergency vaccination was immediately organized. Further seromonitoring then indicated a large number of villages with population antibody prevalences of over 85%. These populations were considered to have been `immunosterilized'. Although no clinical disease had been observed in them, it was decided to undertake additional vaccination in a group of districts to the south of the infected area. Serosurveillance indicated that rinderpest could have been present in a number of these districts prior to vaccination. Serosurveillance in 1998 suggested that numerous vaccinated animals had probably moved into districts outside the infected and additional vaccination areas, but did not rule out the continued presence of field infection.     

伊氏锥虫弱毒株免疫家兔的T细胞应答反应

以ANAE染色法和~3H-TdR掺入的淋巴细胞转化试验,测定了伊氏锥虫弱毒株免疫家兔的T细胞动态变化.结果,免疫兔外周血T细胞增殖反应在免疫后第24d达到高峰,ANAE阳性细胞百分率这72.65%,对照组仅为41.2%;约1周后,出现抑制性T细胞,其增殖反应也明显减弱,最后完全被抑制.而外源性白细胞介素2的加入,可解除这种免疫抑制.攻虫后,特异性T细胞应答反应未再出现强烈的回忆反应,但伊氏锥虫弱毒株免疫家兔获得9/12的保护.因此,T细胞在这种抗锥虫免疫中,没有起到主导作用.     

应用RT-PCR对新城疫病毒分离株毒力的快速鉴定

根据新城疫病毒 (NDV)强、弱毒株在 F蛋白裂解位点氨基酸组成和序列上的差异 ,参照有关文献 ,设计了 3对引物 (A B,A C,A D)。引物 A B能从 L a Sota、B1 、 系和强毒 F4 8E8的含毒尿囊液中扩增出 36 2 bp的核酸片段 ,引物 A C仅能从强毒 F4 8E8的含毒尿囊液中扩增出 2 5 4 bp的片段 ,引物 A D仅能从 L a Sota、B1 、 系的含毒尿囊液中扩增出 2 5 4 bp片段。 3对引物均不能从 IB、IBD、AI的含毒尿囊液和正常鸡胚尿囊液中扩增出特异片段。从发病鸡群中分离的 3株 NDV毒株均被 A C引物扩出 ,它们的鸡胚平均死亡时间 (MDT)分别为 5 1.8、5 3.2、5 2 .6 h,1日龄雏鸡脑内接种指数 (ICPI)为 1.6 5、1.6 3、1.6 0 ,证明是 NDV强毒。利用 RT- PCR对 NDV人工感染鸡最早可于攻毒后第 2天从病鸡气管中检测到 NDV,其次为泄殖腔和脾、肾。利用 RT- PCR对 NDV毒力的鉴定结果与传统生物学试验的测定结果完全吻合 ,但前者可在 2 4 h内直接对组织匀浆进行诊断 ,具有快速、简便和敏感的特点     

多花黑麦草新品系产量及农艺性状研究初探

试验对多花黑麦草新品系的植物学性状、农艺性状、生长动态及拔节期营养物质含量进行了研究。结果表明,多花黑麦草新品系生育期为234 d,生长发育迅速,特别是冬春季生长优势明显;年产草量(DM)可达15 469kg/hm2;植株高大,叶量丰富、叶片宽大,拔节期粗蛋白含量达16.17％,表现出明显的优良牧草性状;在南方亚热带地区生长良好,是优良的多花黑麦草新品系。     

李氏杆菌研究进展

李氏杆菌病是一种重要的人畜共患传染病 ,主要由单核细胞增多性李氏杆菌引起 ,呈世界性分布。文章回顾了李氏杆菌的分离鉴定、培养、分型等生物学特性以及与其毒力有关的基因功能方面的研究进展 ,着重就该病诊断和检测的重要性以及 EL ISA和 PCR检测方法进行了概述 ,同时对该病的免疫预防和今后的研究重点进了探讨     

伪狂犬病病毒Fa株gp63（gI） 基因核苷酸序列测定及分析

对我国最早分离的伪犬病病毒（pseudorabies virus,PRV)Fa株糖蛋白gp63(gI)基因核苷酸序列及的氨基酸序列作了测定与分析，完整的gp63(gI)结构基因从起始密码子ATG到终止密码子TGA共有1050个核苷酸残基，编码由439个氨基酸残基构成的多肽链，4种核苷酸残基的构成比分别为：G35．9％，11.33%,T11.81%,C40.95%,G C含量达76．85％，PRV Fa株gp63基因核苷酸序列与Nice株的相比，两者同源性达98．13％，仅存在3个核苷酸残基的缺失变异，氨基酸推导序列分析表明，糖蛋白gp63具有典型膜蛋白特征，与Nice株相比，同源性为97．42％，gp63基因起始密码子由3个连续的ATG组成，ATG上游区域内无启动子调控区序列。     

高效脂肪酶产生真菌的筛选、鉴定及产酶条件优化

研究旨在筛选高产脂肪酶活性的菌株,并鉴定其菌属及确定其最佳产酶条件。采集富含油脂的土壤,通过溴甲酚紫平板法进行菌株分离筛选,并采用橄榄油乳化法测定脂肪酶活力。利用真菌ITS序列通用引物进行PCR扩增,将测序结果Blast比对,并建系统发育树。采用正交试验设计优化产酶条件。通过筛选得到1株产脂肪酶的真菌菌株GW-1,经鉴定为黑曲霉Aspergillus niger。经单因素试验和正交试验得到该菌的最佳产酶条件为:葡萄糖0.5%、黄豆粉2.0%、橄榄油1.0%、MgSO4.7H2O 0.1%、pH值9.0、接种量8%、装液量50 ml/250 ml、发酵4 d。在此发酵条件下,其产酶活力可达39.82 U/(ml.min)。试验结果显示,访菌株在产脂肪酶能力上具有显著优越性,且菌株GW-1产酶活力较优化前高出19.96 U/(ml.min),提高了100.50%。     

副猪嗜血杆菌血清5型岳阳株对昆明小鼠淋巴器官损伤的研究

为探讨副猪嗜血杆菌(HPS)对免疫器官的损伤,本实验将HPS血清5型岳阳株及其茵体裂解物分别接种昆明小鼠,结果显示:HPS血清5型岳阳株及其菌体裂解物,均能够引起昆明小鼠颈淋巴结细胞凋亡和坏死.组织病理学检测可见脾脏红髓扩张、白髓萎缩、淋巴细胞衰减;胸腺病变较轻,皮质部局灶性淋巴细胞坏死和散在性细胞凋亡.此外,免疫器官损伤与剂量相关,随菌量的增大病变更为明显.HPS血清5型岳阳株及其菌体裂解物对昆明小鼠淋巴器官有明显的损伤作用.     

血浆极低密度脂蛋白浓度的双向选择对肉鸡腹脂、肝脂和产肉性能的影响

对零世代８周龄血浆极低密度脂蛋白（ＶＬＤＬ）浓度进行降低腹脂的间接选择，一世代取得了明显效果：腹脂和肝脂向两极分化，其中肌胃脂和肝脂选择反应较大。低血浆ＶＬＤＬ的选择使腹脂降低，肝脂增加，对产肉性状未产生不利影响。９周龄腹脂率、板油率和肌胃脂率在高ＶＬＤＬ系分别高于低ＶＬＤＬ系２１％，１６％和５１％；肌胃脂率品系间差异极显著（Ｐ＜０．００１）。品系与性别互作对肌胃脂率有明显影响（Ｐ＜０．０５）。腹脂、肌胃脂存在性别差异，腹脂率雌性略高于雄性，而肌胃脂率雄性高于雌性。９周龄肝脂率，高ＶＬＤＬ系显著低于低ＶＬＤＬ系（Ｐ＜０．０１），雌性高于雄性。一世代８周龄血浆ＶＬＤＬ产生了直接选择反应，血浆ＶＬＤＬ浓度，高ＶＬＤＬ系高于低ＶＬＤＬ系。血浆ＶＬＤＬ存在性别差异，雄性高于雌性。一世代高、低ＶＬＤＬ系血浆ＶＬＤＬ和腹脂的变异系数仍然很大，继续对其选择仍然有效。由于血浆ＶＬＤＬ属中等遗传力，并且家系间差异显著，因此，在世代选育中应采取家系结合个体选择法