病毒的遗传与变异.ppt
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1、Viral Genetics and Variation 病毒的遗传与变异,Conceptions,Genetics遗传: After virus replicates , the characters on the progeny virus are similar with the previous generation. Variation变异: After virus replicates , the characters on the progeny virus are different with the previous generation.,一、 Variation mech
2、anism 病毒变异的机制,Heritable variation遗传型变异 因病毒遗传物质核酸发生了改变,导致其变异后的性状可遗传给子代病毒。 Non- Heritable variation非遗传型变异 又称基因产物的相互作用,因病毒核酸并未发生改变,所以此变异一般不能遗传。,(一) Heritable variation 遗传型变异,Virulence changes Conditional lethal mutant 条件致死突变株 eg. temperature sensitive (ts) mutant Host-range mutant (hr) 宿主范围突变株 Drug-res
3、istant mutant 耐药突变株,1、Gene Mutation 基因突变,Recombination 两个病毒基因组间核酸序列交换、组合 Reassortment ( segmented genomes) RNA viruses: influenza virus 分节段的RNA病毒基因组之间,通过基因片段交换使子代基因组发生突变 病毒基因组与细胞基因组之间的重组,2 、Recombination / Reassortment 重组与重配,3 、integration整合,(二) Non-Heritable variation 非遗传型变异,Interactions:when two g
4、enetically distinct viruses infect a cell. 4 different phenomena can ensue继发 (1) Phenotypic mixing or transcapsidation 表型混合与核壳转移 (2)genotype mixing 基因型混合 (3)enhancement 增强 (4)complementation 互补,(1) Phenotypic mixing表型混合,The genome of virus A can be coated with the surface protein of virus type B 两株病
5、毒共同感染同一细胞时,一种病毒复制的核酸被另一病毒所编码的蛋白质衣壳或包膜包裹,不是遗传物质的交换,而是基因产物的交换 transcapsidation核壳转移: 无包膜病毒发生的表型混合,(2)genotype mixing 基因型混合,Genome A + genome B same capsid衣壳 Capsid A + capsid B same envelope包膜 实质:核酸未重组合,没有遗传性,(3)enhancement 增强 两病毒混合培养,一病毒能增强另一病毒的产量,(4)complementation互补,Classification of Viruses 病毒的分类,国
6、际病毒分类委员会ICTV,By 2001 -66 families科, 9 subfamilies亚科 -244 genera属 For humans and animals -24 families, -DNA: 7; RNA: 17 for humans,basis of classification 病毒分类依据,Virion structure and proteries病毒结构与性质 Virion morphology and size病毒大小和形态 Symmetry of nucleocapsids 核衣壳对称性 Envelope 有无包膜 Physicochemical prop
7、erties 理化特性 Antigenic properties抗原性 Biologic properties生物学特性,Viroids(类病毒),Viroids are small (250-400nt , Nucleotide), RNA molecules with a rod-like secondary structure ,which possess no capsid or envelope ,which are associated with certain plant diseases. 很小 (250-400nt),杆状 RNA 分子,有二级结构 无衣壳或包膜 在核内增殖,
8、严格细胞内寄生 多与植物疾病相关,satellites卫星病毒 / Virosid拟病毒,特点:1 是RNA病毒 ,500-2000bp 2 复制需要辅助病毒 3 与辅助病毒基因无同源性 4 所致疾病与辅助病毒无关 有两类:一类可编码自身衣壳蛋白 另一类为卫星病毒RNA分子,Prions 朊粒,consist of a single type of protein molecule with no nucleic acid component. These agents are associated with diseases such as Creutzfeldt-Jakob disease
9、克雅病(亚急性海绵状脑病) in humans, scrapie痒病in sheep & bovine spongiform encephalopathy (BSE)牛海绵状脑病in cattle.,Chapter 19,Viral Infection and Immunity,病毒的感染与免疫,This chapter will focus on,Conceptions Horizontal and Vertical transmission水平传播及垂直传播, inapparent and apparent infection隐性感染及显性感染, Persistent viral infe
10、ction持续性病毒感染, Latent infection潜伏性感染, Chronic infection慢性感染, Slow virus infection慢发病毒感染, Inclusion body包涵体 Questions Describe the types and routes of viral infection. What is interferon干扰素? List the bioactivities of it?,Section 1 Viral Infection 病毒的感染,Viral infection: the process of virus entering an
11、d multiplying in the human or animal body. 病毒侵入人及动物机体并在其中增殖的过程 Viral pathogenesis: the interaction between viral & host factors that leads to disease.,a. A particular disease may be caused by several viruses that have a common tissue tropism取向 (preference选择). e.g., HAV, HBV, HCV, HDV, HEV, etc hepat
12、itis. b. A particular virus may cause several different diseases or no observable引人注意的 symptoms. e.g., HSV单纯疱疹病毒-1pharyngitis咽炎, herpes labialis 唇疱疹,genital herpes生殖道疱疹, encephalitis脑炎, keratoconjunctivitis角膜结膜炎.,The characteristic of viral infection,Respiratory tract 痰、唾液、飞沫、气溶胶 Alimentary tract 饮水
13、、食物 Skin 动物咬伤、昆虫叮咬 Blood 输血、注射、针刺、器官移植 Genital tract 性交 Urinary tract 洗浴 placenta, birth canal 孕期、分娩,I. tract of viral infection 感染途径,II. Modes of viral transmission 传播方式,Horizontal transmission水平传播: direct host-to-host transmission of viruses. 人与人不同个体间的传播 Vertical transmission垂直传播: the transmission
14、 of viruses from parent to the young via placenta, birth canal. 亲代通过胎盘或产道传给子代,Local infection Systemic infection Direct contact :细胞细胞 blood:侵入部位血液 neural system:感染部位神经元,III. Routes of transmission 播散方式, Unapparent infection 隐性感染 (subclinical infection): Virus multiply in the host cells without causi
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