病毒感染與免疫 英文 Viral infection and immunity

1、病毒感染與免疫 英文 Viral infection and immunityOutlineSection I Viral pathogenesisTransmission routesForms of viral infectionsPathogenesis of viral infectionsSection II Antiviral immunityI. Innate immunityII. Specific immunitySection 1 Viral pathogenesisI. Transmission routesThe route of viral infection A.

2、Horizontal transmission B. Vertical transmissionA. Horizontal transmissionRespiratory tractAlimentary canalSkin and mucous membraneGenital tractBlood: Injection, transfusion, transplantationArthropod-bornecivet catB. Vertical Transmission Through placenta congenital infections, congenital deformity

3、Through birth canal infection of newbornVertical Transmission The viruses which can result in congenital infections： rubella virus cytomegalovirus (CMV) herpes simplex virus (HSV) hepatitis B virus (HBV) human immunodeficiency virus (HIV)III. Virus Spread in the Host Local Replication and Local Spre

4、ad Dissemination from the Portal of Entry Multiplication in Target OrgansA. Local Replication & Local Spread B. Dissemination from the Portal of EntryDissemination through BloodstreamViremiaDissemination through Nerves Through Bloodstreame.g.PoliovirusMeasles virusMumps virusThrough Nervese.g.Rabies

5、 virusHerpesvirusPoliovirusII. Forms of viral infections Acute viral infectionPersistent viral infection Types of Viral InfectionChronic infection Latent infectionSlow infection Natural history of acute and persistent human infections.A. Chronic infectionContinued presence of infectious virus follow

6、ing the primary infection and may include chronic or recurrent disease. Virus can be continuously detected. HBV, ect. B. Latent infectionvirus is usually not detectable but patient may have periodic out-breaks of disease.characterized by the lack of demonstrable infectious virus between episodes of

7、recurrent disease HSV-1 in trigeminal ganglion HSV-2 in lumbar and sacral ganglia Latency and recurrence in herpes simplex virus infections Cold sores caused by herpes virus type 1Recurrence of Latent virus infections Shingles caused by varicella-zoster virus Recurrence of Latent virus infections C.

8、 Slow virus infectioncharacterized by a long preclinical period extending for months or years from the time of exposuresubacute progressivecaused by ：Lentivirus (HIV) unconventional virus ( prion).III. Pathogenesis of viral infectionsPathogenesis of viral infectionsA. Direct damage to infected host

9、cellsB. Immunopathological injuryA. Direct damage to infected host cellsCytocidal infectionSteady state infectionIntegration and transformation1. Cytocidal infection Most productive infections are called cytocidal infection because they kill the host cells.Cytopathic effect (CPE): CPE are morphologi

10、c changes of host cells which infected by cytocidal virus, including cell swollen and round, cell lysis, or necrosis, and the formation of inclusion body, or polykaryocytesCPECPENormal cellsCytopathic effect virus inclusion bodies In the some of virus-infected cells, round or oval patches with diffe

11、rent color and structure can be observed at the light microscope. It is : Aggregation of virus particles Traces of the virus multiplication Virus induced cell reactants Rabies virus inclusion bodiesnegribodyPolykaryocytesRSV infectec cellsMeasels virus infected cells2. Steady state infectionViral nu

12、cleic acid remain in specific host cells indefinitely; progeny virus may or may not be produced. Features :Commonly induced by enveloped virusVirus release by budding child virus New antigens may be produced-so, the infected cells may be attacked by host immune system 3. Integration and transformati

13、onIntegrationAll or part of virus nucleic acid becomes integrated into the genome at specific or any site in host cells.Outcomes: is closely related to tumor formation.B. Immunopathological injuryHypersensitivityInflammation cytokineImmune inhibitionEscape of immune responseSection IIAntiviral immun

14、ityAntiviral immunityInnate Defenses Adaptive defensesIFNSkinNK cellsMacrophageHumoral immunityCellular immunityNeutralizing antibodyCTLI. Innate immunityInnate immune factors against viral infectionSkin-mucous membraneInterferonsNatural killer cellmacrophages a heterogeneous group of glycoproteins

15、produced by human and other animal cells after viral infection (or after exposure to other inducers.) Functions of IFNs: anti-virus, anti-tumor, immunomodulationInterferon (IFN)Innate Defenses principal source inducer IFN- leukocyte virus/dsRNA IFN- fibroblast virus/dsRNA IFN- lymphocyte antigen / m

16、itogenInterferonsInnate Defenses IFN genes normally are not expressedThe strong inducers: Viruses and double-stranded RNAs Induction is not specific for a particular virus Induction IFN- /IFN- Interferon (IFN)one of the first lines of defense against virusesconfer resistance to infection to other ce

17、lls. do not act directly on the virus, it acted on the cells to make them resistant to viral infection NK cells or IFNNonspecific Defenses Action of IFN- /IFN- act by induce the synthesis of three cell-encoded proteins 2,5-oligoadenylate synthetaseRibonucleaseProtein kinase RInterferonsNK cellDirect

18、ly lysed virus infected cellsno “l(fā)ag phase” Effective Early No antigen-specificNK cellII. Adaptive immunityHumoral immunity Neutralizing antibodyAntibodies which bind to the virus, usually to the peplomer and capsomer, and block the virus from binding and entering into host cellIgG, IgM, IgA can “neutralize” extracellular virusesNeutralizing AntibodyIgA confers protection against viruses that enter through the respiratory and g