HIV-1C亚型DNA疫苗诱导小鼠免疫反应的研究

 构建含中国流行株HIV-1 C亚型核心蛋白gag基因的重组质粒pVAX-gag,并在体外进行了表达与鉴定.同时构建了含此gag基因的原核表达质粒pGEX-gag,表达纯化并鉴定重组蛋白Gag.以质粒pVAX-gag免疫Balb/C小鼠后,用ELISpot和流式细胞仪检测其细胞免疫反应.再以纯化后的重组蛋白Gag作为包被抗原,用ELISA检测其体液免疫反应.结果显示重组质粒pVAX-gag免疫小鼠后可有效地诱导机体产生细胞免疫和体液免疫反应,且免疫剂量和免疫效果存在一定的正相关性.重组原核表达质粒pGEX-gag的表达产物能与抗p24单克隆抗体发生特异性反应,可用于抗HIV抗体检测.     

A group specific anamnestic immune reaction against HIV-1 induced by a candidate vaccine against AIDS

The first experimental immunization of humans against the AIDS retrovirus, HIV-1, was started in a series of HIV seronegative, healthy volunteers in November 1986. For the primary vaccination recombinant vaccinia virus (V25) expressing the complete gp160 env protein of the HTLV-IIIB strain of HIV-1 was introduced by scarification. This elicited a weak primary response which we subsequently attempted to enhance by additional immunizations (boosting), using four different immunization protocols. We report here that intravenous injection of paraformaldehyde-fixed autologous cells infected in vitro with V25 (individual D.Z.) gave the best results. This individual received second and third boosts of intramuscular gp160 derived from an HTLV-IIIB clone using the hybrid vaccinia virus/bacteriophage T7 expression system. An anamnestic humoral and cellular immune reaction was achieved for over one year after the original vaccination, with high levels of antibodies to the viral envelope, and neutralizing antibodies against divergent HIV-1 strains such as HTLV-IIIB and HTLV-IIIRF (also called HTLV-III HAT) after the first boost. In addition, group-specific cell-mediated immunity and cell-mediated cytotoxicity against infected T4 cells were obtained after the primary vaccine and enhanced by the boosts. Finally, skin tests showed both immediate and delayed hypersensitivity to gp160 in vivo. Although this protocol is not practical for a large scale vaccine trial, our results show for the first time that an immune state against HIV can be obtained in man.     

Genetic organization of a chimpanzee lentivirus related to HIV-1

Simian immunodeficiency viruses have been isolated from four species of monkey, the 'captive' macaque and mangabey and the 'feral' African green monkey and mandrill. While none of these viruses is a replica of HIV-1, the macaque and mangabey viruses represent correct genetic models for HIV-2, possessing exactly the same complement of genes. Recently a lentivirus has been identified in two wild chimpanzees (Pan troglodytes troglodytes) in Gabon, west equatorial Africa, and isolated from one of them. This virus is referred to as SIVCPZ. Sera from these animals cross reacted with all the HIV-1 proteins including the envelope glycoproteins. Here, we describe the molecular cloning and sequencing of an infectious proviral clone of SIVCPZ. The overall genetic organization was the same as that of HIV-1, but phylogenetic analysis revealed that the sequence was more divergent than any HIV-1 sequence reported so far. The vpu gene product, found only in the type 1 viruses, was particularly different (64% divergent to HIV-1BRU) suggesting that the SIVCPZ represents a distinct subtype. These findings indicate that there is a larger pool of simian lentiviruses than previously suspected and revives debate as to the origins of HIV-1.     

Lymphocyte activation by HIV-1 envelope glycoprotein

Cell activation by phytohaemagglutinin, phorbol ester and by the supernatant of phytohaemagglutinin-stimulated peripheral blood mononuclear cells induces the expression and cytopathic effects of latent human immunodeficiency virus type-1 (HIV-1) in vitro. The lymphocyte surface protein CD4 has been identified as a receptor for HIV-1 and binds the viral envelope glycoprotein (gp120). In the light of evidence indicating that one natural function of CD4 is as a growth factor receptor, we examined the ability of native gp120 to activate resting CD4-bearing lymphocytes. Our results indicate that gp120 has innate biological activity as a result of a specific interaction with CD4, inducing increases in intracellular levels of inositol trisphosphate and of calcium, and in interleukin-2 receptor expression and cell motility.     

HIV-1和HBV复合型DNA免疫的初步研究

近年的研究表明,在啮齿类和非人灵长类免疫带有编码病毒和细菌抗原基因的质粒ＤＮＡ可以激发体液和细胞免疫应答．在本实验中,将ＨＢＶ的Ｓ基因和ＨＩＶ－１的ｇｐ１６０基因以融合形式插入到载体ｐｃＤＮＡ３中,其能表达ＨＢｓＡｇ和ｇｐ１６０的融合蛋白,并将此质粒ＤＮＡ分别直接注射到Ｂａｌｂ／ｃ小鼠和Ｓｗｉｓ小鼠．三次免疫后,用ＥＬＩＳＡ的方法初步检测ＨＢｓＡｇ和ｇｐ１６０抗原特异的抗体免疫应答均为阳性．结果说明,带有ＨＢＶ和ＨＩＶ－１融合基因的质粒ＤＮＡ直接免疫小鼠后,均激发了小鼠产生相应的免疫应答反应,这个结果为研究和生产多价疫苗提供了新的思路     

Antibody neutralization and escape by HIV-1

Neutralizing antibodies (Nab) are a principal component of an effective human immune response to many pathogens, yet their role in HIV-1 infection is unclear. To gain a better understanding of this role, we examined plasma from patients with acute HIV infection. Here we report the detection of autologous Nab as early as 52 days after detection of HIV-specific antibodies. The viral inhibitory activity of Nab resulted in complete replacement of neutralization-sensitive virus by successive populations of resistant virus. Escape virus contained mutations in the env gene that were unexpectedly sparse, did not map generally to known neutralization epitopes, and involved primarily changes in N-linked glycosylation. This pattern of escape, and the exceptional density of HIV-1 envelope glycosylation generally, led us to postulate an evolving 'glycan shield' mechanism of neutralization escape whereby selected changes in glycan packing prevent Nab binding but not receptor binding. Direct support for this model was obtained by mutational substitution showing that Nab-selected alterations in glycosylation conferred escape from both autologous antibody and epitope-specific monoclonal antibodies. The evolving glycan shield thus represents a new mechanism contributing to HIV-1 persistence in the face of an evolving antibody repertoire.     

Complete mutagenesis of the HIV-1 protease

Retroviruses encode a protease which needs to be active for the production of infectious virions. A disabling mutation in the protease results in the production of non-infectious virus particles and examination of proteins from these mutant virions reveals unprocessed Gag and Gag-Pol precursor proteins, the substrates of the viral protease. Each amino acid of the HIV-1 protease was individually mutated using a simple mutagenesis procedure which is capable of introducing and identifying missense mutations in each residue of a protein. Phenotypic screening of these mutants in a heterologous assay system reveals three regions within the protease where multiple consecutive amino-acid residues are sensitive to mutation. These results show that random mutagenesis can be used to identify functionally important regions within a protein. Mutants with conditional phenotypes have also been identified within this collection.     

HIV-1 pol基因人工miRNA的构建和功能分析

以miR-155为基础骨架,根据HIV-1pol基因序列设计并合成4对miRNA寡聚单链DNA,构建4个人工miR-pol,并对其进行功能分析.qPCR结果显示,4个人工miR-pol对pol基因都具有一定的沉默效果,其中miR-pol-4的沉默效率最高,达76％.进一步的实验证实miR-pol-4不会影响被转染细胞的活性,也不会对细胞干扰素的表达产生影响.此外,HIV-1假病毒实验显示,miR-pol-4对HIV-1的复制具有良好的抑制作用.因此,所获得的miR-pol-4将可为进一步的抗HIV-1感染研究提供基础.     

Cyclophilin A retrotransposition into TRIM5 explains owl monkey resistance to HIV-1

In Old World primates, TRIM5-alpha confers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells. Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells. Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (ref. 1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA. Here we show that knockdown of owl monkey CypA by RNA interference (RNAi) correlates with suppression of anti-HIV-1 activity. However, reintroduction of CypA protein to RNAi-treated cells did not restore antiviral activity. A search for additional RNAi targets unearthed TRIMCyp, an RNAi-responsive messenger RNA encoding a TRIM5-CypA fusion protein. TRIMCyp accounts for post-entry restriction of HIV-1 in owl monkeys and blocks HIV-1 infection when transferred to otherwise infectable human or rat cells. It seems that TRIMCyp arose after the divergence of New and Old World primates when a LINE-1 retrotransposon catalysed the insertion of a CypA complementary DNA into the TRIM5 locus. This is the first vertebrate example of a chimaeric gene generated by this mechanism of exon shuffling.     

Potential of community-wide chemotherapy or immunotherapy to control the spread of HIV-1

Whether zidovudine (3'-azido-3'-deoxythymidine, AZT) should be offered to symptomless individuals infected with human immunodeficiency virus type-1 (HIV-1), in the hope of delaying or even preventing progression to AIDS, has been much debated. The discussion has focused on the efficacy of the drug in delaying progression to disease, the severity of its side-effects, and the likelihood of its prolonged and widespread use resulting in zidovudine-resistant strains of the virus. Little attention has been given to the degree to which treatment reduces the infectiousness of symptomless patients, and to the concomitant implications for the overall transmission rate of HIV-1 in the community. Here we use simple mathematical models to show that community treatment with antiviral drugs or immunotherapies that lengthen the incubation period of AIDS without significantly reducing the infectiousness of treated individuals, can increase the rate at which HIV-1 infection spreads (which is fairly obvious) and can even, under certain circumstances, increase the AIDS-related death rate in the community (which is less obvious).     

The inner-nuclear-envelope protein emerin regulates HIV-1 infectivity

Primate lentiviruses such as human immunodeficiency type 1 (HIV-1) have the capacity to infect non-dividing cells such as tissue macrophages. In the process, viral complementary DNA traverses the nuclear envelope to integrate within chromatin. Given the intimate association between chromatin and the nuclear envelope, we examined whether HIV-1 appropriates nuclear envelope components during infection. Here we show that emerin, an integral inner-nuclear-envelope protein, is necessary for HIV-1 infection. Infection of primary macrophages lacking emerin was abortive in that viral cDNA localized to the nucleus but integration into chromatin was inefficient, and conversion of viral cDNA to non-functional episomal cDNA increased. HIV-1 cDNA associated with emerin in vivo, and the interaction of viral cDNA with chromatin was dependent on emerin. Barrier-to-autointegration factor (BAF), the LEM (LAP, emerin, MAN) binding partner of emerin, was required for the association of viral cDNA with emerin and for the ability of emerin to support virus infection. Therefore emerin, which bridges the interface between the inner nuclear envelope and chromatin, may be necessary for chromatin engagement by viral cDNA before integration.     

4H-甲基咪唑苯二氮HIV-1抑制剂的定量构效关系研究

利用密度泛函理论计算了14种HIV抑制剂的4H-甲基咪唑苯二氮（TIBO）的分子性质。利用主成分分析（PCA）和聚类分析（HCA）减少了子变量的个数,从而使这些变量能有效地对抗HIV活性的4H-甲基咪唑苯二氮TIBO衍生物进行分类。主成分分析法表明,EH OMO、μ、LogP、Q A、QB和MR参数能够有效地把所研究的药物分为活性强的抗HIV病毒药物和活性弱的抗HIV病毒药物。聚类分析方法得到的结果与主成分分析得到的结果类似。为了检验结论是否正确,利用化学计量学方法,使用主成分分析法和分层聚类分析法对其他4个抗HIV活性的合成化合物进行了分析,其中3个被认为是活性强的抗HIV病毒药物,这与临床试验结果一致。主成分分析法和分层聚类分析法为新的抗HIV病毒的TIBO药物的分类提供了一个可信的规律。