人卫7版微生物24病毒的感染与免疫

Chapter 24 Viral Infection and Immunity,Pathogenicity of viruses,Viral spread,传播途径,呼吸道消化道创伤感染接触感染血液传播性传播节肢动物媒介,病毒的传播途径,Transmission,Horizontal transmission Vertical transmission,Horizontal transmission,the transmission of viral infection between members of the same species that are not in a parent-child relationship. 其传播途径包括:呼吸道、消化道、泌尿生殖道、眼和破损皮肤等,also known asmother-to-child transmission, is thetransmission of aninfectionor other disease from mother to child immediately before and after birth during the perinatal period(围产期).,胎盘、产道,乳汁,Vertical transmission,主要通过胎盘或产道传播-HBV、CMV、HIV、风疹病毒,四(2)、垂直传播发生的过程产后,新生儿疱疹,单纯疱疹病毒,Pathogenicity of viruses,Effects of viral infection on cells Cytocidal effect (杀细胞效应) Steady state infection (稳定状态感染) Inclusion body formation(包涵体形成) Apoptosis (细胞凋亡) Integrated virus infection and transformation (基因整合与细胞转化),Cytocidal infection：病毒在宿主细胞内复制完毕，短时间内释放大量子代病毒即造成细胞死亡，多见于无包膜杀伤性强的病毒。,抑制宿主细胞代谢（阻断细胞的核酸和蛋白质合成） 影响细胞溶酶体，膜通透性或破坏，释放出溶酶体酶 病毒结构蛋白的毒性作用,机 制,Cytocidal effect,Kill the host cellsDue to the inhibition of host cell DNA, RNA or protein synthesispolioviruses destroy anterior horn cells respiratory viruses kill respiratory epithelium,病毒在细胞内增殖引起细胞裂解死亡多见于无包膜病毒：脊灰病毒、鼻病毒、腺病毒,Cytocidal infection,Cytopathic Effect to epithelial cells caused by adenovirus,uninfected,early infection,late infection,slides from CDC,正常猴肾细胞（左）与HSV感染的猴肾细胞（右）,Steady state infection,viral nucleic acid remain in cells, progeny virus may or may not producedBudding virions and viral peptides associate with the cell membrane change the antigenic characteristicsbe attacked by the immune systemdiehepatitis B does not cause pathology in liver, immune response is the cause of most of the damage,稳定状态感染：某些病毒进入细胞后能够复制，却不引起细胞裂解、死亡，在相当长的一段时间内细胞和病毒并存，同时增殖，细胞病变缓慢且轻。多见于有包膜病毒，出芽方式释放子代。,有些病毒蛋白有融膜特性，使细胞膜融合形成多核巨细胞。细胞膜成份改变，嵌合有病毒特异性抗原，被机体抗体或CTL所识别并清除。,宿主细胞变化,Steady state infection,Viral proteins are processed in an infected cell.,包涵体形成,Definition: nuclearorcytoplasmicaggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication in abacteriumor aeukaryoticcell and usually consist of viralcapsidproteins.,(Inclusion body formation),cytoplasmic（痘病毒）nucleus（疱疹病毒）Both（麻疹病毒）,唯一具有诊断意义的是内基小体,Negri body,位置 意义,狂犬病毒包涵体 内基小体,巨细胞病毒包涵体,Apoptosis,病毒感染细胞后，直接由病毒本身的作用或间接地作为诱导因子引发细胞凋亡。,凋亡的细胞,左 ：正常胸腺细胞右：凋亡胸腺细胞（凋亡小体）,Integrated virus infection and transformation,少数病毒感染细胞后病毒的DNA整合到宿主细胞的染色体上，促进细胞的DNA合成，促进细胞增生或细胞转化即细胞形态转变，增殖加快，失去细胞间的接触抑制等。 是病毒致肿瘤的原因之一,培养的小鼠正常胰腺细胞（左）与转化细胞（右）,Immune response to infection,抗体介导的免疫病理作用： 、型超敏反应细胞介导的免疫病理作用：CTL、自身抗原致炎性细胞因子的病理作用： IFN-、TNF-、IL-1免疫抑制作用：HIV、CMV,（三）病毒的免疫逃逸,反映病毒毒力的另一重要因素是病毒的 免疫逃逸能力。 病毒的免疫逃逸机制多样。,三、病毒感染的类型,隐性感染,显性感染,急性感染,持续性感染,潜伏感染,慢性感染,慢发病毒感染,急性病毒感染的迟发并发症,隐性感染Inapparent (subclinical) infection,病毒感染后不引起临床症状,显性感染Apparent (clinical) infection,病毒感染后引起临床症状,Definition: A covert viral infection in which a degree of equilibrium is established between the virus and the hosts immune system, resulting in an infection of long duration. Classification: Chronic virus infection 慢性 Latent virus infection 潜伏 Slow virus infection 慢发,持续性感染,持续性病毒感染有病毒和机体两方面的因素,机体免疫功能弱，无力完全清除病毒； 病毒存在于受保护的部位或病毒发生突变, 可以逃避宿主免疫作用； 某些病毒的抗原性弱，难以产生免疫应答； 有些病毒在感染过程中产生DIP，干扰病毒的增殖，因而改变病毒的感染过程，形成持续性感染； 病毒基因整合在宿主细胞的基因组中，长期与宿主细胞共存。,病毒感染后有很长的潜伏期，经数 年，数十年后，可发生某些进行性疾 病，最终死亡。如HIV、狂犬病病毒。,病程长，病毒可检出，如HBV。,某些病毒在显性或隐性感染后，病毒基因存在于细胞内，有的病毒潜伏于某些组织器官内而不复制。但在一定条件下，病毒被激活又开始复制，使疾病复发，,慢发病毒 感染,持续性感染,慢性感染,潜伏感染,急性病毒感染的迟发并发症,急性感染后1年或数年，发生致死性的病毒病，如亚急性硬化性全 脑炎（SSPE）。,Definition: A latent infection is a phase in certain viruses life cycles in which after initial infection, virus production ceases. However, the virus genome is not fully eradicated. The result of this is that the virus can reactivate and begin producing large amounts of viral progeny without the host being infected by new outside virus.,Latent virus infection,Definition: A persistent viral infection characterized by a long preclinical period extending for months or years from the time of exposure.,Slow virus infection,急性和持续性病毒感染类型比较,Virus and tumors,病毒与人类肿瘤发生有着密切联系。 细胞转化是肿瘤形成的第一步，但不是形成肿瘤的必经步骤。 长时间无限增殖的细胞比正常细胞更易于突变或基因重排。,与人类肿瘤相关的病毒,第二节 抗病毒免疫,Nonspecific Immune Defense specific Immune Defense,Nonspecific Immune Defense,nonspecific mechanisms1. Interferon (IFN)2. NK cells3. various hormones, temperature and phagocytes,Interferon,Definition:,Any of a group of glycoproteins that are produced by different cell types in response to various stimuli, such as exposure to a virus, bacterium, parasite, or other antigen, and that prevent viral replication in newly infected cells