副猪嗜血杆菌16S rRNA基因的克隆及序列分析

本研究旨在从分子水平对副猪嗜血杆菌湖南分离株进行鉴定,并用16S rRNA序列分析不同血型副猪嗜血杆菌之间的遗传关系。利用PCR扩增副猪嗜血杆菌的16S rRNA,应用ClustalX 1.81程序对序列进行比对,再用Phylip 3.67程序MP法和Mage 4.0程序NJ法绘制种系发育树,并用Puzzle 5.2程序构建最大似然树,同时利用DNAStar 5.0中的Megalign程序进行同源性分析。结果显示,所获得的16S rRNA序列长度均为783 bp,湖南分离株与已知5型副猪嗜血杆菌位于同一分枝。结果表明,湖南分离株属于5型副猪嗜血杆菌,为副猪嗜血杆菌的分子流行病学和其相关疾病的诊断奠定基础。     

乌兰察布型华北驼绒藜品种栽培驯化试验研究

乌兰察布型华北驼绒藜[Ceratoides arborescens（Losinsk．）Tsienet C．G．Ma cv．Wulanchabu]是采集内蒙古乌拉特中旗和后旗、四子王旗荒漠草原野生的华北驼绒藜种子,经10多年引种驯化栽培选育而成的新品种。选择性能优良的植株采收种子．在内蒙古农牧业科学院四子王基地及其周边地区进行品种比较试验、区域试验、生产试验及推广应用。研究发现,该品种具有以下优点：①植株高大,根系发达;②抗旱、耐寒、耐瘠薄,耐盐碱,适应性强;③营养丰富,适口性好,生长速度快,产草量高。在驯化选育的过程中。对驼绒藜属内的植物及其他牧草在干旱地区的建植进行了对比,结果该品种显示出苗率高、成苗率高、产量高且稳定的特点,育苗建植有比较显著的经济效益,在生态治理和改良盐荒地方面表现优异。生产利用中主要推广小面积育苗大面积移栽技术种植乌兰察布型华北驼绒藜。     

荒漠草原区“科尔沁型”华北驼绒藜丰产试验

试验对“科尔沁型”华北驼绒藜进行不同的水肥耦合处理,并在不同生物期对其进行了生物量观测。试验结果表明,410g丰产素与水以1：1000体积比混合喷洒200L、浇水8000L的条件下,“科尔沁型”华北驼绒藜的产量可以大幅度提高,播种后第3年其干草产量可由天然条件下的2460kg／hm^2提高到5430kg／hm^2.     

H_5亚型禽流感病毒灭活疫苗免疫效果评价试验

选取我省中标的两种类型6个批次的H5亚型禽流感病毒灭活疫苗,双盲条件下,在黄羽肉鸡中进行免疫效果比对试验。于14、35天龄进行两次免疫,在21、28、35、42、49、56、63、77、91、105和113 d进行抗体检测,结果全期平均免疫抗体水平超过6l og2,各批次疫苗间的免疫抗体水平略有差异。本次试验初步明确了H5亚型禽流感灭活疫苗接种后的抗体消长规律,为疫苗选择和免疫程序的制定提供依据。     

A review of Ireland's waterbirds,with emphasis on wintering migrants and reference to H5N1 avian influenza

Ireland is characterised by its diversity and large abundance of wetlands, making it attractive to a wide variety of waterbirds throughout the year. This paper presents an overview of Ireland's waterbirds, including ecological factors relevant to the potential introduction, maintenance, transmission and spread of infectious agents, including the H5N1 avian influenza virus, in Ireland. Particular emphasis is placed on five groups of wintering migrants (dabbling and sieving wildfowl, grazing wildfowl, diving wildfowl, waders and gulls), noting that the H5N1 avian influenza virus has mainly been isolated from this subset of waterbirds. Ireland's wetlands are visited during the spring and summer months by hundreds of thousands of waterbirds which come to breed, predominantly from southern latitudes, and during the autumn and winter by waterbirds which come from a variety of origins (predominantly northern latitudes), and which are widely distributed and often congregate in mixed-species flocks. The distribution, feeding habits and social interactions of the five groups of wintering migrants are considered in detail. Throughout Ireland, there is interaction between different waterbird populations (breeding migrants, the wintering migrants and resident waterbird populations). There is also a regular and complex pattern of movement between feeding and roosting areas, and between wetlands and farmland. These interactions are likely to facilitate the rapid transmission and spread of the H5N1 avian influenza virus, if it were present in Ireland.     

Novel swine influenza virus subtype H3N1 in Italy

To date, three subtypes of swine influenza viruses, H1N1, H1N2, and H3N2 have been isolated in Italy. In 2006, a novel swine influenza virus subtype (H3N1) was isolated from coughing pigs. RT-PCR performed on lung tissues, experimental infection in pigs with the novel isolate, and cloning the virus by plaque assay confirmed this unique H and N combination. The novel isolate was also antigenically and genetically characterized. Genetic and phylogenetic analysis showed that the complete HA gene of the H3N1 strain has the highest nucleotide identity to three Italian H3N2 strains, one isolated in 2001 and two in 2004, whereas the full length NA sequence is closely related to three H1N1 subtype viruses isolated in Italy in 2004. The remaining genes are also closely related to respective genes found in H1N1 and H3N2 SIVs currently circulating in Italy. This suggests that the novel SIV could be a reassortant between the H3N2 and H1N1 SIVs circulating in Italy.     

Molecular characterization of low pathogenic avian influenza viruses, isolated from food products imported into Singapore

We have completed the genetic characterization of all eight gene segments for four low pathogenic avian influenza (LPAI) viruses. The objective of this study was to detect the presence of novel signatures that may serve as early warning indicators of the conversion of LPAI viruses to high pathogenic avian influenza (HPAI) viruses. This study included three H5N2 and one H5N3 viruses that were isolated from live poultry imported into Singapore as part of the national avian influenza virus (AIV) surveillance program. Based on the molecular criterion of the World Organisation for Animal Health (OIE), sequence analysis with the translated amino acid (aa) sequence of the hemagglutinin (HA) gene revealed the absence of multibasic aa at the HA cleavage site, identifying all four virus isolates as LPAI. Detailed phylogenetic tree analyses using the HA and neuraminidase (NA) genes clustered these isolates in the Eurasian H5 lineage, but away from the HPAI H5 subtypes. This analysis further revealed that the internal genes clustered to different avian and swine subtypes, suggesting that the four isolates may possibly share their ancestry with these different influenza subtypes. Our results suggest that the four LPAI isolates in this study contained mainly avian signatures, and the phylogenetic tree for the internal genes further suggests the potential for reassortment with other different circulating avian subtypes. This is the first comprehensive report on the genetic characterization of LPAI H5N2/3 viruses isolated in South-East Asia.     

Interspecies transmission of equine influenza virus (H3N8) to dogs by close contact with experimentally infected horses

In horse populations, influenza A virus subtype H3N8 (equine influenza virus, EIV) is a very important pathogen that leads to acute respiratory disease. Recently, EIV has emerged in dogs, and has become widespread among the canine population in the United States. The interspecies transmission route had thus far remained unclear. Here, we tested whether the interspecies transmission of EIV to dogs could occur as a result of close contact with experimentally EIV-infected horses. Three pairs consisting of an EIV-infected horse and a healthy dog were kept together in individual stalls for 15 consecutive days. A subsequent hemagglutination inhibition test revealed that all three dogs exhibited seroconversion. Moreover, two of the three dogs exhibited virus shedding. However, the dogs exhibited no clinical signs throughout the course of the study. These data suggest that the interspecies transmission of EIV to dogs could occur as a result of close contact with EIV-infected horses without clinical symptoms. Although the interspecies transmission of EIV is unlikely to become an immediate threat to canine hygiene, close contact between EIV-infected horses and dogs should be avoided during an EI epidemic.     

干扰素对鸡胚内H9N2亚型禽流感病毒滴度的影响

为探讨干扰素在动物上的运用,笔者利用H9N2亚型禽流感病毒与不同剂量干扰素（IFN）一起接种鸡胚,运用HA方法测定病毒效价,研究了干扰素干扰H9N2亚型禽流感病毒在鸡胚内增殖的情况,试验结果表明,高中低剂量干扰素都有抑制病毒增殖的作用,而3个试验组之间没有明显差异（P>0.05）。但是在一定的时间内,高剂量组干扰素与中低剂量组相比能够明显的抑制病毒增殖,表明高剂量组干扰素在一定时间内抑制H9N2禽流感病毒的作用比较明显,这在生产中有一定的应用价值。     

铝对小麦根尖细胞壁过氧化物酶活性和过氧化氢含量的影响

以2个小麦基因型鉴-864(耐性)和扬麦5号(敏感)为材料,采用溶液培养方法研究了铝胁迫下小麦根系伸长、根尖铝含量、根尖细胞壁过氧化物酶活性和H2O2含量的变化。结果表明,随着铝浓度的提高,小麦根系伸长受铝抑制程度加剧,根尖铝含量也明显升高;但敏感基因型根尖铝含量较高,根系伸长受抑程度更为明显。在铝胁迫下,2个小麦基因型根尖可溶态愈创木酚过氧化物酶(GPX)和松柏醇过氧化物酶(CAPX)活性没有显著变化,细胞壁离子键结合态GPX和CAPX的活性则随着铝浓度的提高而显著升高,H2O2含量也呈现类似的趋势;而敏感基因型过氧化物酶活性升高和H2O2积累更为明显。因此,铝胁迫下,小麦敏感基因型根尖细胞壁离子键结合态GPX和CAPX活性升高而引起H2O2积累,促进根系木质化和细胞壁氧化交联,导致根细胞壁刚性提高而伸展能力降低,是其根系伸长受到严重抑制的原因。