HIV检查ppt课件

《HIV检查ppt课件》由会员分享，可在线阅读，更多相关《HIV检查ppt课件（57页珍藏版）》请在装配图网上搜索。

1、Retroviruses1学习交流PPT Retroviruses are enveloped,single-stranded plus-sense RNA viruses.They encode an enzyme called reverse transcriptase that converts the RNA genome into a double-stranded DNA copy that subsequently becomes integrated into the host cell DNA.2学习交流PPTRetroviruses structureRetroviruse

2、s structure3学习交流PPT Retroviruses are classified into three families:Oncoviruses,(onco-,“related to a tumor”)Lentiviruses,(lenti-,“related to slow”)Spumaviruses,(human foamy virus)Spumaviruses has not yet been definitely associated with disease in humans.Representatives of two major groups are consid

3、ered in this chapter:the oncoviruses and the lentiviruses.4学习交流PPT Members of the oncoviruses subgroup of retroviruses have long been associated with a variety of cancers in animals,including leukemias,lymphomas,and sarcomas,but until recent years had not been found to infect humans.The first human

4、retrovirus,human T-cell leukemia virus type I(HTLV-1),was discovered in the late 1970s.It was shown to cause adult T-cell leukemia,a rare malignancy found only in Japan,Africa,and the Caribbean.A relative of HTLV-1,HTLV-2,has been associated with a few rare cases of T-cell malignancies,including hai

5、ry cell leukemia,but its precise role in these diseases remains unclear.5学习交流PPTH Hu um ma an n I Im mm mu un no od de ef fi ic ci ie en nc cy y V Vi ir ru us s(H HI IV)V)The virus that causes AIDS First exposed in 1981 in central Africa,infection unknown Has killed more than 20 million people With

6、3.1 million people dying last year alone.Estimated 45 million people that we know of are currently living with HIV6学习交流PPT The most important disease resulting from a human retrovirus infection,acquired immunodeficiency syndrome(AIDS),is caused by either of two lentviruses termed human immunodeficie

7、ncy viruses types 1 and 2(HIV-1 and HIV-2).A devastating disease,for which there is no present cure.7学习交流PPT8学习交流PPT Viruses are also etiologic factors in the development of several types of human tumors,including two of great significance worldwide-cervical cancer and liver cancer.At least 15%of al

8、l human tumors worldwide have a viral cause.These viruses are cancer associated viruses or human cancer viruses or tumor viruses.9学习交流PPTHIV and AIDSHIV and AIDSan infectious agentan infectious agent 1979-5 cases of Pneumocystis cariniiWith giemsa stain at high magnification,the faint bluish dot-lik

9、e intracystic bodies of Pneumocystis carinii in lung are seen in this cytologic preparation from a bronchoalveolar lavageIn Los Angeles 1967-1978 only two cases of Pneumocystis carinii pneumoniaAll Homosexual10学习交流PPTHIV and AIDSHIV and AIDSWith dissemination to extrapulmonary sites,Pneumocystis car

10、inii tends to produce foci with prominent calcification,as seen in the kidney here grossly.11学习交流PPTHIV and AIDSHIV and AIDSan infectious agent Kaposis Sarcomaan infectious agent Kaposis SarcomaEarly 1981 MMWR:5 cases of Kaposis sarcomaHitherto:rare(immunocompromization)1981-26 cases of Kaposis sarc

11、oma Young San Francisco and New York All Homosexuals 12学习交流PPT HIV is a retrovirus,a member of the lentivirus genus,and exhibits many of the physicochemical features typical of the family.The unique morphologic characteristic of HIV is a cylindrical nucleoid in the mature virion.The diagnostic barsh

12、aped nucleoid is visible in electron micrographs in those extracellular particles that happen to be section at the appropriate angle.The virion is about 100-120nm in diameter,and because it contains two copies of the RNA genome,it is diploid.13学习交流PPT14学习交流PPT The RNA genome is coated with the nucle

13、ocapsid protein(NC),and the RNA-protein complexes are enclosed in a capsid(CA)composed of multiple subunits.Like all enveloped viruses,the membrane is acquired during budding from the host cell,but the surface glycoproteins(SU,also called gp120)and transmembrane glycoproteins(TM,also called gp 41)fo

14、und in the envelope are virally encoded.In addition to the structural proteins,the virion core contains three virus specific proteins that are essential for viral replication:reverse transcriptase(RT),protease(PR),and integrase(IN).15学习交流PPT The virus contains the three structure genes required for

15、a replicating retrovirus-gag,pol,and env.Up to six additional genes regulate viral expression and are important in disease pathogenesis in vivo.HIV-1 contains,in addition to the gag,pol,and env genes,an array of other genes(tat,rev,vef,vif,vpr,and vpu).Expression of these genes requires mRNA splicin

16、g,and all apparently encode proteins that serve regulatory or accessory roles during the infection.Tat is transcriptional activator that promotes synthesis of full-length viral transcripts.Rev promotes export of unspliced and partially spliced transcripts to cytoplasm.Vef down-regulates CD4 to promo

17、te virus release and also down-regulates MHC-I to interfere with immune recognition.Vpu targets CD4 destruction and virion release.Vpr promotes transport of subviral particles into nucleus of nondividing cells.Vpu and Vif increase efficiency of in fection and yield of virus.Activation of CD4 T lymph

18、ocytes virus increases virus production.16学习交流PPT The regions of greatest divergence among different isolates are localized to the env gene,which codes for the viral envelope proteins.The SU(gp120)product of the env gene contains binding domains responsible for virus attachment to the CD4 molecule a

19、nd coreceptors,determines lymphocyte and macrophage tropisms,and carries the major antigenic determinants that elicit neutralizing antibodies.The TM(gp41)env product contains both a transmembrane domain that anchors the glycoprotein in the viral envelope and a fusion domain that facilitates viral pe

20、netration into target cells.The divergence in the envelope of HIV complicates efforts to develop an effective vaccine for AIDS.17学习交流PPTMajor retroviral genes and proteins of HIV18学习交流PPTSurface glycoproteinTransmembrane proteinmatrixcpsidnucleocapsidReverse transcriptase19学习交流PPTVirus replication T

21、he virions adsorb to cellular membrane receptors and enter the cell by direct fusion with the plasma membrane.For HIV-1,the virion attachment protein is the SU glycoprotein gp120,and the cellular receptor is the CD4 molecule.All primate lentiviruses use as a receptor the CD4 molecule,which is expres

22、sed on macrophages and T lymphocytes.A second coreceptor in addition to CD4 is necessary for HIV-1to gain entry to cells.The second receptor is required for fusion of the virus with the cell membrane.20学习交流PPT The virus first binds to CD4 and then to the coreceptor.These interactions cause conformat

23、ional changes in the viral envelope,activating the gp41 fusion peptide and triggering membrane fusion.The HIV-1transmembrane TM protein gp 41 is responsible for fusion of the viral and cell membranes,leading to entry of the virion core complex into the cytoplasm of the cell.21学习交流PPT Fusion activity

24、 may also play an important role in amplification of the effects of the virus infection,particularly during the later stages of the infection,because infected cells expressing viral glycoproteins in their membranes readily fuse with uninfected CD4+T lymphocytes to form large syncytia.This process ap

25、pears to provide a means for cell-to-cell transmission of the virus that bypasses the usual extracellular phase and may contribute to the overall depletion of CD4 lymphocytes in an infected individual.22学习交流PPT Soon after entry of the viral core into the cytoplasm of the infected cell,the RNA is cop

26、ied into double-stranded DNA by reverse transcriptase,the virion-associated DNA polymerase.The overall processes referred to as reverse transcriptase and results in a linear DNA molecule that enters the nucleus and integrates more-or-less at random into a host cell chromosome.Once the viral genetic

27、information has been converted to DNA and integrated,it essentially becomes part of the cellular genome.The viral genes,called the provirus,are therefore replicated and faithfully inherited as long as the infected cell continues to divide.Special sequences contained within the RNA are duplicated dur

28、ing the reverse transcription prosess so that the integrated provirus contains identical long terminal repeats(LTRs)at its ends.23学习交流PPT The LTR sequences contain the appropriate promoter,enhancer,and other signals required for transcription of the viral genes by the host RNA polymerase II.DNA poly

29、merase activity,the reverse transcriptase possesses an RNase H activity that is responsible for degrading the RNA portion of the DNA-RNA hybrid(RNA/DNA)produced in the first phase of reverse transcription.The immediate product of reverse transcription is a linear double-stranded DNA molecule that is

30、 flanked by the LTR sequences.The viral integrase(IN)catalyzes the integration of the linear DNA into host DNA.24学习交流PPT The choice of a target site for integration into the cellular DNA appears,however,to be nearly random.The replication process is completed by transcription of the proviral DNA by

31、the host RNA polymerase II.Virus particles mature and emerge from infected host cells by budding from cytoplasmic membranes.The viral protease then cleaves the Gag and Pol proteins from the precursor polyprotein,producing an infectious virion prepared for reverse transcription when the next cell is

32、infected.25学习交流PPTReplicationReplication26学习交流PPT27学习交流PPT28学习交流PPTHIV Viruse Classification Lentiviruses have been isolated from many species including at least 26 different African nonhuman primate species.There are two distinct types of human AIDS viruses:HIV-1 and HIV-2.The two types are disting

33、uished on the basis of genome organization and phylogenetic(evolutionary)relation-ship with other primate lentiviruses.29学习交流PPTVariation HIV-1 possesses the most error-prone reverse transcriptase.The consequence of this high error rate is that each time the viral RNA is reverse transcribed,one to t

34、wo new mutations are introduced into the resulting DNA.Because the process of transcription of the integrated proviral DNA to produce new viral genomes is also error prone,mutant genomes accumulate rapidly over the course of an infection.30学习交流PPT The end result is a quasi-species that accounts for

35、the many nucleotide differences observed between different isolates(even from the same infect individual)and for the variability of the SU envelope protein gp120.It may explain,in part,the failure of the immune system to contral the infection and also the increases in viral virulence that appears to

36、 occur during the course of the infection31学习交流PPTDisinfection and inactivation HIV is completely inactivated by treatment for 10 minutes at room temperature with any of the following:10%household bleach,50%ethanol,35%isopropanol,1%Nonidet P40,0.5%lysol,0.5%paraformaldehyde,or 0.3%hydrogen peroxide.

37、The virus is also inactivated by extremes of pH(pH 1.0,pH 1.3).However,when HIV is present in clotted or unclotted blood in a needle or syringe,exposure to undiluted bleach for at least 30 seconds is necessary for inactivation.HIV is readily inactivated in liquids or 10%serum by heating at 56 for 10

38、 minutes,but dried proteinaceous material affords marked protection.32学习交流PPTPathogenesis and symptomatologyA.Pathogenesis and pathology The typical course of untreated HIV infection spans about a decade.Stages include the primate infection,dissemination of virus to lymphoid organs,clinical latency,

39、elevated HIV expression,clinical disease,and death.The duration between primary infection and progression to clinical disease averages about 10 yesrs.In untreated cases,death usually occurs within 2 years after the onset of clinical symptoms.Following primary infection,there is a 4-to 11-day period

40、between mucosal infection and initial viremia;the viremia is detectable for about 8-12 weeks.Vrius is widely disseminated throughout the body during this time,and the lymphoid organs become seeded.33学习交流PPT An acute mononucleosis-like syndrome develops in many patients(50%-75%)3-6weeks after primary

41、 infection.There is a significant drop in numbers of circulating CD4+T cells at this early time.An immune response to HIV occurs 1 week to 3 months after infection,plasma viremia drops,and levels of CD4 cells rebound however,the immune response is unable to clear the infection completely,and HIV-inf

42、ected cells persist in the lymph nodes.This period of clinical latency may last for as long as 10 years.During this time,there is a high level of ongoing viral replication.It is estimated that 10 billion HIV particles are produced and destroyed each day.Eventually,the patient will develop constituti

43、onal symptoms and clinically apparent disease,such as opportunistic infections or neoplasms.34学习交流PPTB Clinical features Symptoms of acute HIV infection are nonspecific and include fatigue,rash,headache,nausea,and night sweats.AIDS is characterized by pronounce suppression of the immune system and d

44、evelopment of a wide variety of severe opportunistic infections or unusual neoplasms.The more serious symptoms in adults are often preceded by a prodtone(“diarrhea and dwindling”)that can include fatigue,malaise,weight loss,fever,shortness of breath,chronic diarrhea,white patches on the tongue(hairy

45、 leukoplakia,oral candidiasis)disease symptoms in the gastrointestinal tract from the esophagus to the colon are a major cause of debility.35学习交流PPT The predominant causes of morbidity and mortality among patients with late-stage HIV infection are opportunistic infections,i.e.severe infections induc

46、ed by agents that rarely cause serious disease in immune competent individuals.Opportunistic infections usually do not occur in HIV-infected patients until CD4+T cells counts have dropped from the normal level of about 1000cells/L to less than 200 cells/L.36学习交流PPT AIDS patients exhibit a marked pre

47、disposition to the development of cancer,another consequence of immune suppression.AIDS-associated cancers include non-Hodgkin,s lymphoma(both systemic and central nervous system types),Kaposi,s sarcoma,cervical cancer,anogenital cancers,and Hodgkin,s lymphoma Kaposi,s sarcoma,is now 20,000 times mo

48、re common in untreated AIDS patients than in the general population.Kaposi,s sarcoma,associated herpesvirus,or HHV8,appear to be causally related to be cancer.37学习交流PPT The cardinal feature of HIV infection is the depletion of T helper-inducer lymphocytes-the result of HIV replication in this popula

49、tion of lymphocytes as well as the death of uninfected T cells by indirect mechanisms.The T cells express the CD4 phenotypic marker on their surface.The CD4 molecule is the major receptor for HIV;it has a high affinity for the viral envelope.The HIV coreceptor on lymphocytes is the CXCR4 chemokine r

50、eceptor.Monocytes and macrophages play a major role in the dissemination and pathogenesis of HIV infection.Curtain subsets of monocytes express the CD4 surface antigen and therefore bind to the envelope of HIV.Unlike the CD4 T lymphocyte,the monocyte is relatively refractory to the cytopathic effect

51、s of HIV,so that the virus not only can survive in this cell but also can be transported to various organs in the body(such as the lungs and brain).38学习交流PPT Infected macrophages may continue to produce virus for a long period of time.The HIV coreceptor on monocytes and macrophages is the CCR5 chemo

52、kine receptor.In the brain,the major cell types infected with HIV appear to be the monocytes and macrophages,and this may have important consequences for the development of neuropsychiatric manifestations associated with HIV infection.Infected pulmonary alveolar macrophages may play a role in the in

53、terstitial pneumonitis seen in certain patients with AIDS.39学习交流PPTC.Immunity HIV-infected persons develop both humoral and cell mediated responses against HIV-related antigens.Antibodies to a number of viral antigens develop soon after infection.Most infected individuals make neutralizing antibodie

54、s against HIV,directed against the envelope glycoprotein.However,the levels of neutralizing activity are low;many anti-envelope antibodies are nonneutralizing.It is believed that the dense glycosylation may inhibit binding of neutralizing antibody to the envelope protein.The envelope glycoprotein sh

55、ows great sequence variability.This natural variation may allow the evolution of successive of resistant virus that escape recognition by existing neutralizing by neutralizing antibodies.40学习交流PPTLaboratory diagnosis Evidence of infection by HIV can be detected in three ways:a)virus isolation,b)sero

56、logic determination of antiviral antibodies,and c)measurement of viral nucleic acid or antigens.41学习交流PPTA.Virus isolation HIV can be cultured from lymphocytes in peripheral blood.The most sensitive virus isolation technique is to cocultivate the test sample with uninfected,mitogen-stimulated periph

57、eral blood mononuclear cells.The vast majority of HIV-1 antibody-positive persons will have virus that can be cultured from their blood cells.However,virus isolation techniques are time consuming and laborious and are limited to research studies.PCR amplification techniques are more commonly used fo

58、r detection of virus in clinical specimens.42学习交流PPTB.Serology Most individuals will have detectable antibodies within 6-12 weeks after infection,whereas virtually all will be positive within 6 months.Test kits are commercially available for measuring antibodies by enzyme-linked immunoassay(EIA).If

59、properly performed,these test have a sensitivity and specificity exceeding 98%.antibodies to viral core protein p24 or envelope glycoprotein gp41,gp120,or gp160 are most commonly detected.simple,rapid tests for detecting HIV antibodies are available for use in laboratories ill-equipped to perform EI

60、A test.The simple tests are based on principles such as agglutination or immunodot reactions.43学习交流PPTC.Detection of viral nucleic acid or antigens Amplification assays such as the RT-PCR,DNA PCR,AND bDNA tests are commonly used to detect viral RNA in clinical specimens.The HIV RNA levels are import

61、ant predictive markers of disease progression and valuable tools with which to monitor the effectiveness of antiviral therapies.44学习交流PPTPrevention and treatment45学习交流PPTA.Transmission route The HIV virus is transmitted between humans in three ways:sexually,perinatally,and by exposure to contaminate

62、d blood or body fluids.The virus has been demonstrated in particularly high titers in semen and cervical secretions,and the majority of cases result from sexual contact.The presence of other sexually transmitted diseases such as syphilis,gonorrhea,or herpes simplex type 2 increases the risk of sexua

63、l HIV transmission as much as a hundredfold because the inflammation and sores facilitate the transfer of HIV across mucosal barriers.46学习交流PPT Transfusion of infectious blood or blood products is an effective route for viral transmission.For example,over 90%of hemophiliac recipients of contaminated

64、 clotting factor concentrates in the United states(before HIV was detected)developed antibodies to HIV.Injection users of illicit drugs are commonly infected through the use of contaminated needles.Injection drug use accounts for a substantial proportion of new AIDS cases.The risk of perinatal trans

65、mission from an infected mother to her child has been estimated to range from 15%to 40%.Infants can become infected in uterus,during the birth process,or more commonly,through breastfeeding.47学习交流PPT The routes of transmission(blood,sex,and birth)described above account for almost all HIV infections

66、.Transmisson does not occur through day-to-day nonsexual contact with infected individuals or through insect vectors,because of the fragility of the virus and the need for direct mucosal or blood contact.48学习交流PPTB.Prevention Without control by drugs or vaccines,the only way to avoid epidemic spread of HIV is to maintain a lifestyle that minimizes or eliminates the high-risk factors discussed above.Because HIV may be transmitted in blood,all donor blood should be tested for antibody.Infected per