植物病毒分子群体遗传学研究进展

植物病毒群体遗传学的2个中心任务是定量描述病毒种群内的遗传变异及阐明该变异的机制.植物病毒自然种群遗传结构通常包括1-2种优势的序列变异类型和一些低频率的序列变异类型,即具有准种遗传结构特征.植物病毒种群遗传多样性水平和病害暴发以及流行时间有一定的相关性.另外,植物病毒种群遗传结构中还存在超群种群类型.一些生物学特性可能取决于准种内的不同变种间的相互作用.如决定适应能力、寄主范围及致病性变异等.植物寄主—昆虫介体—病毒三者间的协同进化关系是植物病毒种群遗传结构保存相对稳定的主要因素.描述植物病毒种群遗传结构特征为构建更有效的病害防治策略提供了依据.     

Virus population dynamics and acquired virus resistance in natural microbial communities

Viruses shape microbial community structure and function by altering the fitness of their hosts and by promoting genetic exchange. The complexity of most natural ecosystems has precluded detailed studies of virus-host interactions. We reconstructed virus and host bacterial and archaeal genome sequences from community genomic data from two natural acidophilic biofilms. Viruses were matched to their hosts by analyzing spacer sequences that occur among clustered regularly interspaced short palindromic repeats (CRISPRs) that are a hallmark of virus resistance. Virus population genomic analyses provided evidence that extensive recombination shuffles sequence motifs sufficiently to evade CRISPR spacers. Only the most recently acquired spacers match coexisting viruses, which suggests that community stability is achieved by rapid but compensatory shifts in host resistance levels and virus population structure.     

马铃薯M病毒生物学特性研究

测定马铃薯M病毒(Potato virus M,PVM)寄主范围,并作PVM接种条件优化试验。结果表明,PVM仅侵染15种指示植物中的4种,各种植物症状表现不同。苋色黎(Chenopodium amaranticolor)和千日红(Gomphrena globosa L.)接种叶片上产生枯斑,可作为PVM枯斑寄主;36号烟(Nicotiana occidentalis"pi")系统发病,新生叶片产生皱缩、泡斑、叶边缘卷曲等症状,植株长势矮小,可作为PVM系统侵染鉴定寄主;PVM系统侵染番茄(Lycopersicon pimpinellifolium)速度快,但无症状,番茄可作为PVM繁殖寄主。PVM虽可侵染不同生育期寄主,以接种中上部叶位侵染效果最好,但在不同寄主不同叶位分布并不一致,番茄体内中部叶片病毒含量相对较高,在苋色黎上则分布较均匀。明确PVM最适培养温度为23~29℃。最高稀释度64倍时(OD405=0.201)仍可成功侵染苋色黎。为PVM纯毒源扩繁及制备该病毒抗血清提供基础数据。     

Local interactions select for lower pathogen infectivity

Theory suggests that the current rapid increase in connectivity and consequential changes in the structure of human, agricultural, and wildlife populations may select for parasite strains with higher infectivity. We carried out a test of this spatial theory by experimentally altering individual host movement rates in a model host/pathogen system by altering the viscosity of their environment. In our microevolutionary selection experiments, the infectivity of the virus was, as predicted by the theory, reduced in the most viscous populations. We therefore provide empirical support for the theory that population structure affects the evolution of infectious organisms.     

The Empidemiology of Wheat Rosette Stunt in Hulunbeir District of Inner—Mongolia

The virus disease threatening wheat production in Hulunbeir District of Inner-Mongolia was identified as NCMV(Northern Cereal Mosaic Virus)or WRSV(Wheat Rosette Stunt Virus)by test of host range,transmission,virus particle and serology.The main vector for spreading the virus is planthopper,Laodelphax striatellus(Fallen),Which overwinters in the stubbles of wheat underground.The overwintered viruliferous nymphs emerged in late Pril is responsible for the early infection of the disease.Agropyron repens,an important perennial weed in cultivated regions,is also an important wild host of the virus and its vector.Severe loss is induced when wheat is infected before 3-leaf stage.The disease incidence could be predicted by a model with the population and viruliferous rate of overwintered vectors as independent variables.     

DNA of Rous sarcoma virus: its nature and significance

Purified preparations of Rous sarcoma virus (an avian tumor virus with an RNA genome) contain small amounts of double-stranded DNA. This DNA cannot be hybridized to viral RNA, but will reanneal completely with the DNA of avian cells. Extensive substitution of bromodeoxyuridine for thymidine in "viral" DNA does not photosensitize the biological activity of the virus. These observations indicate that the DNA associated with Rous sarcoma virus is derived from the DNA of the avian host cell, and is probably devoid of any function in the life cycle of the virus.     

粉纹夜蛾核型多角体病毒在同源寄主细胞系中复制和连续传代的研究

本文研究了粉纹夜蛾单粒包埋核型多角体病毒(TnSNPV)在同源寄主细胞系Tn5B_(1—4)中的生长特性。结果表明,接种36h 后,无包涵体游离病毒(TnSNPV—NOV)的增殖达到高峰;在60代的连续传递过程中,TnSNPV-NOV 毒力随传递代数的增加而减低,但不明显。传至60代时仍可保持感染力1×10~5TCID_(50)(组织感染中量)/mL;而多角体的毒力变化十分显著,前几代能使粉纹夜蛾幼虫死亡率迭95%以上,传递到30代以后产生的多角体对粉纹夜蛾的幼虫几乎失去毒力;多角体的产量也明显降低,前几代病毒在每个细胞中可达670PIB,但20代以后,每细胞中多角体的产量仅在100PIB 以下.     

木毒蛾核多角体病毒林间大面积防治试验效果分析

小面积和大面积防治试验证明,不同浓度的NPV制剂,一旦施入林内,即可引起病毒病的流行,并显著地降低木毒蛾幼虫的虫口密度。只要喷洒量达到2.0×10~(10)PIB/亩,防治效果可达82—85％。防治的适期应掌握在5月15日至5月25日,林间4—6龄幼虫占85％左右为宜。林间防治试验结果表明,病毒比化学农药(80％DDVP和40％乐果)的防治效果良好。     

A gene for an extended phenotype

Manipulation of host behavior by parasites and pathogens has been widely observed, but the basis for these behaviors has remained elusive. Gypsy moths infected by a baculovirus climb to the top of trees to die, liquefy, and "rain" virus on the foliage below to infect new hosts. The viral gene that manipulates climbing behavior of the host was identified, providing evidence of a genetic basis for the extended phenotype.     

Local actin polymerization and dynamin recruitment in SV40-induced internalization of caveolae

Simian virus 40 (SV40) utilizes endocytosis through caveolae for infectious entry into host cells. We found that after binding to caveolae, virus particles induced transient breakdown of actin stress fibers. Actin was then recruited to virus-loaded caveolae as actin patches that served as sites for actin "tail" formation. Dynamin II was also transiently recruited. These events depended on the presence of cholesterol and on the activation of tyrosine kinases that phosphorylated proteins in caveolae. They were necessary for formation of caveolae-derived endocytic vesicles and for infection of the cell. Thus, caveolar endocytosis is ligand-triggered and involves extensive rearrangement of the actin cytoskeleton.     

Nucleotide sequence of the transforming gene of avian myeloblastosis virus

Avian myeloblastosis virus is defective in reproductive capacity, requiring a helper virus to provide the viral proteins essential for synthesis of new infectious virus. This virus arose by recombination of the nondefective helper virus and host cellular sequences present within the normal avian genome. These latter sequences are essential for leukemogenic activity. The complete nucleotide sequence of this region is reported. Within the acquired cellular sequences there is an open reading frame of 795 nucleotides starting with the initiation codon ATG (adenine, thymine, guanine) and terminating with the triplet TAG. This open reading frame could code for the putative transforming protein of 265 amino acids with a molecular weight of approximately 30,000.     

Functional regions of the envelope glycoprotein of human immunodeficiency virus type 1

The envelope of the human immunodeficiency virus type 1 (HIV-1) plays a central role in the process of virus entry into the host cell and in the cytopathicity of the virus for lymphocytes bearing the CD4 molecule. Mutations that affect the ability of the envelope glycoprotein to form syncytia in CD4+ cells can be divided into five groups: those that decrease the binding of the envelope protein to the CD4 molecule, those that prevent a post-binding fusion reaction, those that disrupt the anchorage of the envelope glycoprotein in the membrane, those that affect the association of the two subunits of the envelope glycoprotein, and those that affect post-translational proteolytic processing of the envelope precursor protein. These findings provide a functional model of the HIV envelope glycoprotein.     

大麦黄条点花叶病毒的分布及其分离物的遗传多样性

【目的】明确大麦黄条点花叶病毒（Barley yellow striate mosaic virus,BYSMV）在中国北方小麦主产区的分布及其种群遗传多样性,为病害流行预警和防控提供理论依据。【方法】2008-2016年,在河北、山东、江苏、安徽、河南、陕西和山西等7个省66个县/市/区田间,采集了864份疑似病毒病症状的植物样品。提取样品总RNA,利用一步法三重RT-PCR技术检测样品中的BYSMV、水稻黑条矮缩病毒（Rice black-streaked dwarf virus,RBSDV）和北方禾谷花叶病毒（Northern cereal mosaic virus,NCMV）。利用RT-PCR扩增获得BYSMV的L和N基因片段,克隆并测定核苷酸序列,应用MEGA、DnaSP和PAML等软件分析BYSMV分离物的系统进化和遗传多样性特征。【结果】从48个县/市/区采集的336份样品中检测到BYSMV,检出率为38.89%,该病毒主要分布于陕西、河北、山西和山东,另外,河南及安徽北部亦有分布,江苏徐州和邳州仅局部发生。基于BYSMV的L、N基因序列构建的系统发育树均可将分离物划分为2个亚组,亚组I中的分离物其来源涉及全部7个省份,而亚组II中的分离物仅来自陕西和山西2个省,基于L基因序列系统发育分析表明亚组II分离物与伊朗的分离物亲缘关系较近,BYSMV的遗传分化与分离物的地理来源相关,而与寄主植物、发生时间无明显相关性。运用RDP程序包的7个软件进行基因重组分析显示没有支持重组的证据。选择压力分析显示,亚组内和亚组间的ω（dN/dS）值（0.02-0.19）远小于1,表明群体正承受净化选择。L和N基因的单倍型多样性（Hd）值（0.90909和0.99524）均大于0.5、核苷酸多样性（π）值（0.01324和0.01224）均高于0.005,表明中国BYSMV群体遗传多样性丰富。基于L和N基因片段的遗传分化研究显示,东部和西部群体的遗传分化系数（F_ST）值（0.32201和0.37326）均大于0.25,且统计检验差异显著,表明东部和西部的BYSMV群体严重分化;基因流（Nm）值（0.53和0.42）均小于1,说明有限的基因流是促使群体发生遗传分化的主要原因。【结论】BYSMV在中国北方小麦主产区分布广泛,河北、山东、江苏、安徽、河南、陕西和山西等地均有不同程度的发生。BYSMV群体具有丰富的遗传多样性,且东部和西部群体之间存在严重的遗传分化。     

TLR3 deficiency in patients with herpes simplex encephalitis

Some Toll and Toll-like receptors (TLRs) provide immunity to experimental infections in animal models, but their contribution to host defense in natural ecosystems is unknown. We report a dominant-negative TLR3 allele in otherwise healthy children with herpes simplex virus 1 (HSV-1) encephalitis. TLR3 is expressed in the central nervous system (CNS), where it is required to control HSV-1, which spreads from the epithelium to the CNS via cranial nerves. TLR3 is also expressed in epithelial and dendritic cells, which apparently use TLR3-independent pathways to prevent further dissemination of HSV-1 and to provide resistance to other pathogens in TLR3-deficient patients. Human TLR3 appears to be redundant in host defense to most microbes but is vital for natural immunity to HSV-1 in the CNS, which suggests that neurotropic viruses have contributed to the evolutionary maintenance of TLR3.     

Transmission of equine influenza virus to dogs

Molecular and antigenic analyses of three influenza viruses isolated from outbreaks of severe respiratory disease in racing greyhounds revealed that they are closely related to H3N8 equine influenza virus. Phylogenetic analysis indicated that the canine influenza virus genomes form a monophyletic group, consistent with a single interspecies virus transfer. Molecular changes in the hemagglutinin suggested adaptive evolution in the new host. The etiologic role of this virus in respiratory disease was supported by the temporal association of rising antibody titers with disease and by experimental inoculation studies. The geographic expansion of the infection and its persistence for several years indicate efficient transmission of canine influenza virus among greyhounds. Evidence of infection in pet dogs suggests that this infection may also become enzootic in this population.     

靶向甲型流感病毒血凝素的人源单克隆抗体研究进展

甲型流感病毒感染性强,宿主广泛,主要感染禽类,其次为哺乳动物。当跨物种传染事件发生时,有可能造成流感大流行,因此,对病毒实施及时有效的监控,以及研发抗流感病毒药物刻不容缓。流感病毒表面的糖蛋白血凝素在病毒入侵宿主细胞的过程中发挥了关键的作用,可作为单克隆抗体药物的主要靶点。针对血凝素的单克隆抗体能够有效抑制病毒传播,保护宿主。因此,本文综述了目前报道的针对甲型流感病毒血凝素糖蛋白的人单克隆抗体,为后续抗流感药物的研发提供新的思路和展望。     

A型流感病毒研究进展

从A型流感病毒宿主范围、病毒结构、病毒蛋白种类及功能、流感大流行、禽流感病毒跨种传播等方面综述了目前A型流感病毒研究的最新进展,旨在为今后A型流感病毒的研究提供借鉴和参考。     

西花蓟马对寄主植物的危害及其影响机理研究进展

总结了西花蓟马对寄主植物形态和生理特征的危害,以及作为媒介传毒的为害影响,剖析了西花蓟马对寄主植物为害影响的途径和内在机理,旨在明确西花蓟马与不同寄主植物之间的内在关系,为预防和控制西花蓟马的传播扩散提供依据。     

Large shifts in pathogen virulence relate to host population structure

Theory on the evolution of virulence generally predicts selection for an optimal level of virulence determined by trade-offs with transmission and/or recovery. Here we consider the evolution of pathogen virulence in hosts who acquire long-lived immunity and live in a spatially structured population. We show theoretically that large shifts in virulence may occur in pathogen populations as a result of a bistability in evolutionary dynamics caused by the local contact or social population structure of the host. This model provides an explanation for the rapid emergence of the highly virulent strains of rabbit hemorrhagic disease virus.     

牛病毒性腹泻病毒与宿主细胞的相互作用研究

自1946年Olafson等首次在美国纽约州发现牛病毒性腹泻病毒(BVDV)以来,该病毒在世界各地广泛流行和传播,尤其对一些畜牧业发达国家的奶业和牛肉业造成了巨大损失.了解牛病毒性腹泻病的致病机理,研制出更加安全可靠有效的疫苗,对控制该病的发生和蔓延尤为重要.对BVDV的病原学、生物学特性以及对宿主细胞的相互作用等进行了阐述,以期为BVDV的预防及治疗奠定基础.