新城疫病毒融合蛋白裂解位点基因的分离克隆及在原核细胞中的表达

用ＳＰＦ鸡胚繁殖新城疫病毒（ＮＤＶ）Ｆ４６Ｅ９株（强毒）、ＬａＳｏｔａＥ４株（弱毒），对病毒进行纯化，抽提ＲＮＡ。用１对均为２７个碱基的引物进行ＲＴ－ＰＣＲ，扩增出了２个毒株的融合蛋白裂解位点（Ｆｃ）基因。将Ｆｃ基因定向克隆入ｐＵＣ１８的ＥｃｏＲＩ和ＳａｌⅠ位点之间，获得２个毒株Ｆｃ基因克隆ｐＵＣＦ４６Ｆｃ和ｐＵＣＬａＦｃ，用ＥｃｏＲＩ／ＳａｌⅠ双酶切法、ＰｓｔⅠ单酶切法、ＰＣＲ法和核酸探针法对其进行了鉴定。将鉴定好的ＬａＳｏｔａＥ４Ｆｃ基因定向导入表达载体质粒ｐＢＶ２２１，获得重组子ｐＢＶＬａＦｃ。ＰＣＲ和内切酶酶切法鉴定表明，Ｆｃ插入的位置和方向都正确无误。用Ｅ．ｃｏｌｉＤＨ５α通过热诱导法进行了表达。用ＳＤＳ－ＰＡＧＥ和Ｗｅｓｔｅｒｎ－ｂｌｏｔ法检测了表达产物。结果表明，有１条能够与ＮＤＶ多抗反应的特异条带，分子量约１５７００，与预期大小一致，说明是Ｆｃ基因的表达产物     

大白菜主要病害综合防治技术

本文对近几年大白菜三大病害的防治研究成果进行了综述。     

徐州地区牛流行热病毒的分离与鉴定

1991年夏秋之交徐州市各奶牛场暴发牛流行热。为确诊该病,采集了发病高热期抗凝血,进行了病毒分离和鉴定试验。病料经处理后,直接接种于BHK_21细胞,传至第二代可见典型的CPE。电镜下观察到80—150nm弹状病毒颗粒。分离毒的理化特性、核酸类型及中和试验结果均与标准BEFV相一致,证实该分离病毒为牛流行热病毒。     

东北亚四国（地区）SMV株系毒力比较

将我国，韩国，日本及俄罗斯远东地区的ＳＭＶ株系与鉴别寄主交互接种测定其毒力。结果指出采用外国的株系鉴别寄坟难以区分我国株系毒力。同样，用我国鉴别寄坟也难以区分外国毒株的毒力，所测定的我国９个株系的１３个代表毒株全部能侵染最抗病的鉴别寄主韩国的Ｂｕｆｆａｌｏ和日本的Ｈａｒｏｊｏｙ。     

Control of rabies: epidemiology of rabies in Asia and development of new-generation vaccines for rabies

Rabies is an enzootic viral disease widespread throughout the world. Although it is a vaccine-preventable disease, the annual number of human deaths caused by rabies is estimated to be 32,000 in Asia. Phylogenetic analysis based on sequence data of the partial N gene of rabies viruses in Asia has shown that the viruses are divided into five genogroups, distributed in Middle East, South Asia, South East Asia, Malay, and Arctic regions. The genetic relationships among these rabies viruses agree basically with the results of previous studies. Meanwhile, new types of vaccines are being developed by applying gene manipulation techniques to rabies virus in order to overcome the disadvantages of current vaccines. This article reviews the molecular epidemiology of rabies in Asia and progress made in the development of new-generation rabies vaccines with the goal of elimination or control of rabies in Asia.     

Dengue hemorrhagic fever with special emphasis on immunopathogenesis

Dengue virus infections are a serious cause of morbidity and mortality in most tropical and subtropical areas of the world; Southeast and South Asia, Central and South America, and the Caribbean. Dengue virus infection can be asymptomatic or causes two forms of illness, dengue fever (DF) and dengue hemorrhagic fever (DHF), which is the severe form of dengue illness and often fatal. Pathogenesis of DHF has been analyzed, and two mechanisms are considered to be responsible. These include dengue serotype cross-reactive immune responses and virulence of the virus. The immunopathological mechanisms include a complex series of immune responses. Rapid increase in the levels of cytokines, especially TNF-, and chemical mediators play a key role in inducing unique clinical manifestations of DHF such as plasma leakage, shock, and hemorrhagic manifestations. It is understood that the process is initiated by infection with a virulent dengue virus, often in the presence of antibodies that enhance dengue virus infection in secondary infection, and then triggered by rapidly elevated cytokines and chemical mediators that were produced by intense immune activation. However, complete understanding of the entire pathological mechanism is far from complete, and further studies are still needed.     

Semen alterations in porcine rubulavirus-infected boars are related to viral excretion and have implications for artificial insemination

Porcine rubulavirus (PoRV), also known as blue eye disease (BED) of swine, causes respiratory and reproductive problems in pigs at several developmental stages. To study the effect of PoRV infection on semen production, five boars were infected with 1 x 10(6) TCID(50)/ml of PoRV strain PAC-3 and evaluated for 59 days post inoculation (DPI). Infected boars developed reproductive tract pathology that included swelling of the testes and epididymides. Analysis of the semen showed that the infection had little effect on semen production in four animals, but semen from one boar showed severe alterations in sperm concentration, motility, and morphology. When motility was analyzed in BTS-diluted semen after 24, 48, or 72 h, alterations were detected in all boars. Furthermore, viral antigen was detected in semen, the seminal plasma fraction, or sperm fraction from all boars. These results showed that PoRV is excreted via semen and, therefore, artificial insemination is a potential route of dissemination.     

Deduced Amino Acid Sequences Surrounding the Fusion Glycoprotein Cleavage Site and of the Carboxyl-terminus of Haemagglutinin–Neuraminidase Protein of the Avirulent Thermostable Vaccine Strain I-2 of <Emphasis Type="Italic">Newcastle disease virus</Emphasis>

A single-tube RT-PCR technique generated a 387 bp or 300 bp cDNA amplicon covering the F₀ cleavage site or the carboxyl (C)-terminus of the HN gene, respectively, of Newcastle disease virus (NDV) strain I-2. Sequence analysis was used to deduce the amino acid sequences of the cleavage site of F protein and the C-terminus of HN protein, which were then compared with sequences for other NDV strains. The cleavage site of NDV strain I-2 had a sequence motif of ¹¹² RKQGRLIG¹¹⁹, consistent with an avirulent phenotype. Nucleotide sequencing and deduction of amino acids at the C-terminus of HN revealed that strain I-2 had a 7-amino-acid extension (VEILKDGVREARSSR. This differs from the virulent viruses that caused outbreaks of Newcastle disease in Australia in the 1930s and 1990s, which have HN extensions of 0 and 9 amino acids, respectively. Amino acid sequence analyses of the F and HN genes of strain I-2 confirmed its avirulent nature and its Australian origin.     

Resistance to plant viruses: Obtaining genes by non-conventional approaches

Summary Plant viruses cause considerable losses to crops and none of the three current approaches to disease control are likely to give the long-term answer. The new concept of non-conventional protection, in which the expression of a viral or virus-related sequence in the plant genome interferes with the virus infection cycle, holds considerable promise for designing new resistance or protection genes. A series of targets in the viral genome is identified and a range of mechanisms for attacking those targets is discussed. There are several current systems which have been proved to give protection, at least to a certain extent, and many systems which are being researched upon for the future. Some of these are described to give a picture of the current situation and of the thinking for the future. The problems of field deployment of the transgenic plants are discussed, especially those associated with the risk to the environment. Various questions which molecular biologists and plant breeders will have to consider include what are desirable characters to have in protection genes and how these new genes should be deployed.     

植物抗病毒基因工程研究进展

简要讨论了近年来植物抗病毒基因工程的方法策略,主要有:植物自身的抗病毒基因策略、来源于病毒的抗性基因策略、干扰素、核酶等抗性策略;并分析了其存在问题及发展趋势。