重组腺相关病毒-阳离子脂质体载体的构建及评价

目的探讨重组腺病毒相关病毒（rAAV）-阳离子脂质体（LyoVec）复合载体的构建方法及其转染率评价。方法构建rAAv～GFP，rAAv—LyoVec复合载体及rAAV—GFP—LyoVec。倒置荧光显微镜观察，测定rAAV—GFP，LyoVec—GFP及rAAV—GFP-LyroVec对定量C6细胞的转染率，筛选出高转染率载体。结果rAAV—GFP组24、48、72和96h转染率分别为16％、23％、21％和9％；LyoVec-GFP组为28．5％、33％、32％和11％；rAAV—GFP—Lyovec组为49％、59％、64％和20％。rAAV-GFP—LyoVec纽分别在24、48、72和96h的转染率显著高于rAAV—GFP组（P〈0．01）及LyoVec—GFP组（P〈0．01）。结论新构建rAAV—LyoVec复合载体基因的转染效率远远高于rAAV或LyoVec独立转染。     

Inverted terminal repeat sequences of adeno-associated virus enhance the antibody and CD8(+) responses to a HIV-1 p55Gag/LAMP DNA vaccine chimera

The immune responses to an HIV-1 p55Gag vaccine encoded as a DNA chimera with the lysosomal associated membrane protein-1 (LAMP) have been examined for the effect of the addition of the inverted terminal repeat (ITR) sequences of the adeno-associated virus (AAV) to the DNA plasmid construct, and of packaging the LAMP/gag gene as a recombinant AAV vector (rAAV). DNA plasmids encoding Gag and the LAMP/Gag protein chimera were constructed in two vectors, the pcDNA3.1 and a corresponding plasmid containing the ITR sequences (pITR) flanking the expression elements of the plasmid, and the pITR LAMP/gag DNA plasmid was encapsidated in the rAAV vector. Human 293 cells transfected in vitro with LAMP/gag plasmids either in pcDNA3.1 or pITR produced much Gag protein in cell extracts (1.6 and 2.2 ng of Gag/mg of protein, respectively). The immune responses of mice to immunization with these constructs were examined under three protocols: DNA prime/DNA boost, DNA prime/rAAV boost, and a single rAAV immunization. The results demonstrated that under DNA prime/DNA boost protocol, the "naked" DNA vaccines encoding the LAMP/gag chimera, either as pcDNA3.1 or pITR DNA plasmid constructs, elicited strong CD4(+) T cell responses. In contrast, significantly higher levels of CD8(+) and antibody responses were observed with the pITR-DNA constructs. Immunization with the rAAV vector under the DNA prime/rAAV boost protocol resulted in sustained T cell responses and a markedly increased antibody response, predominantly of the IgG(1) isotype resulting from the activation of the Th2 subset of CD4(+) T cells, that was sustained for at least 5 months after immunization.     

Galanin gene transfer curtails generalized seizures in kindled rats without altering hippocampal synaptic plasticity

Gene therapy–based overexpression of endogenous seizure-suppressing molecules represents a promising treatment strategy for epilepsy. Viral vector–based overexpression of the neuropeptide galanin has been shown to effectively suppress generalized seizures in various animal models of epilepsy. However, it has not been explored whether such treatment can also prevent the epileptogenesis. Using a recombinant adeno-associated viral (rAAV) vector, we induced hippocampal galanin overexpression under the neuron specific enolase promoter in rats. Here we report that in animals with galanin overexpression, the duration of electrographic afterdischarges was shortened and initiation of convulsions was delayed at generalized seizure stages. However, the hippocampal kindling development was unchanged. Short-term plasticity of mossy fiber–cornu ammonis (CA) 3 synapses was unaltered, as assessed by paired-pulse and frequency facilitation of field excitatory postsynaptic potentials (fEPSPs) in hippocampal slices, suggesting that despite high transgene galanin expression, overall release probability of glutamate in these synapses was unaffected. These data indicate that hippocampal rAAV-based galanin overexpression is capable of mediating anticonvulsant effects by lowering the seizure susceptibility once generalized seizures are induced, but does not seem to affect kindling development or presynaptic short-term plasticity in mossy fibers.     

Antigen expression level threshold tunes the fate of CD8 T cells during primary hepatic immune responses

CD8 T-cell responses to liver-expressed antigens range from deletional tolerance to full effector differentiation resulting in overt hepatotoxicity. The reasons for these heterogeneous outcomes are not well understood. To identify factors that govern the fate of CD8 T cells activated by hepatocyte-expressed antigen, we exploited recombinant adenoassociated viral vectors that enabled us to vary potential parameters determining these outcomes in vivo. Our findings reveal a threshold of antigen expression within the liver as the dominant factor determining T-cell fate, irrespective of T-cell receptor affinity or antigen cross-presentation. Thus, when a low percentage of hepatocytes expressed cognate antigen, high-affinity T cells developed and maintained effector function, whereas, at a high percentage, they became functionally exhausted and silenced. Exhaustion was not irreversibly determined by initial activation, but was maintained by high intrahepatic antigen load during the early phase of the response; cytolytic function was restored when T cells primed under high antigen load conditions were transferred into an environment of low-level antigen expression. Our study reveals a hierarchy of factors dictating the fate of CD8 T cells during hepatic immune responses, and provides an explanation for the different immune outcomes observed in a variety of immune-mediated liver pathologic conditions.The liver is acknowledged to possess unique tolerogenic properties, which have likely evolved to maintain immunological unresponsiveness toward food-derived and microbial antigens that enter the circulation via the gut (1, 2). This tolerogenic capability of the liver is demonstrated in animal models of liver transplantation, in which liver allografts are accepted across complete MHC mismatch barriers and are able to protect other donor tissues from rejection (reviewed in ref. 3). In humans, the tolerogenic hepatic environment is likely to contribute to impaired immune clearance of the hepatitis B virus (HBV) and hepatitis C virus (HCV), which result in persistent infection in a significant proportion of exposed individuals and are associated with major morbidity and mortality. In contrast, effective immune responses to hepatotropic pathogens leading to resolution of infection are observed in most hepatitis A and E virus infections, the majority of individuals infected with HBV during adulthood, and a minority of those infected by HCV (reviewed in refs. 4, 5). The liver is also susceptible to a variety of autoimmune-mediated conditions (6). Collectively, these observations indicate that effective immune responses can be initiated and/or sustained in the liver despite its apparent predisposition toward the generation of tolerance. Unfortunately, there is no small animal model in which to study the parameters that determine the balance between intrahepatic immunity and tolerance in viral hepatitis. Thus, the factors that shape immune outcome have not yet been identified.By studying the fate of antigen-specific CD8 T cells transferred into mice expressing antigen in the liver, it has been shown that, despite being a nonlymphoid organ, the liver is able to support primary CD8 T-cell activation (7). However, depending on the choice of antigen expressed and mode of delivery, the outcome of intrahepatic CD8 T-cell activation has been varied, ranging from deletion and/or functional silencing (8–10) to cytotoxic T lymphocyte (CTL) development (11, 12). This observed diversity of T-cell fates parallels the heterogeneous outcomes of liver-immune interactions observed during hepatotropic viral infections in humans. Thus, reconciliation of these findings holds the potential to yield critical insights into the immunopathological basis of immune-mediated liver disease as well as liver-associated tolerance.In this study, we developed an integrated system in which we manipulated parameters predicted to influence the generation of effector CD8 T cells encountering their cognate antigen on hepatocytes. By identifying three key determinants of the generation of functional effector cells in response to hepatocyte-expressed antigen, this study provides, for the first time to our knowledge, a unified model that explains and predicts the functional outcome of CD8 T-cell activation by liver-expressed antigen and reconciles findings from a number of previous studies that addressed this question.     

Brain-derived neurotrophic factor prevents the nigrostriatal degeneration induced by human immunodeficiency virus-1 glycoprotein 120 in vivo

Glycoprotein 120 (gp120) from the T-tropic strain of the human immunodeficiency virus type 1 has been shown to cause neuronal apoptosis through activation of the chemokine receptor CXCR4. Therefore, reducing CXCR4 expression may prevent gp120-mediated apoptosis. Brain-derived neurotrophic factor (BDNF) is known to reduce both gp120 neurotoxicity and CXCR4 expression in vitro. The scope of this work is to establish whether BDNF is neuroprotective against gp120 in vivo and, if so, whether this effect correlates with its ability to down-regulate CXCR4. Serotype 2 adeno-associated viral vector encoding for BDNF (rAAV-BDNF) or control vector was microinjected into the striata of adult rats. Two weeks later gp120 was injected into the same striatum, and apoptosis determined. Pretreatment with rAAV-BDNF prior to gp120 microinjection prevented caspase-3 activation as well as in situ terminal deoxynucleotidyl transferase biotin-dUTP nick end labelling in the striatum and substantia nigra. In addition, rAAV-BDNF reversed the loss of tyrosine hydroxylase immunoreactivity induced by gp120 in both areas. CXCR4 expression was then determined by immunohistochemistry and RT-PCR, and found to be decreased in striata of rAAV-BDNF-treated rats. Conversely, BDNF heterozygous mice exhibited an increase in CXCR4 mRNA levels compared to wild-type littermates. Our data suggest that down-regulation of CXCR4 expression may contribute to the neuroprotective activity of BDNF against gp120 toxicity in the basal ganglia.     

rAAV—IGF—I诱导大鼠下颌髁突生长发育的实验研究

目的评价局部注射重组腺相关病毒介导胰岛素样生长因子-I（rAAV—IGF-I）对大鼠下颌髁突生长发育的影响。方法选用5周龄Sprague-Dawley（SD）大鼠20只，随机分为4组。在每只大鼠的左侧颞下颌关节腔内注射rAAV-IGF-I，右侧关节腔内注射生理盐水。手术后2周、4周、8周及12周后分别处死并取出下颌骨，拍摄两侧下颌骨的数码照片进行测量比较。结果实验组下颌髁突长度、髁突头宽度、髁突头中点及髁突头下点到下颌平面的距离从实验4周时出现明显差异。实验组下颌骨的长度及髁突前点到下颌平面的距离在实验8周及12周中明显长于对照组。4周及8周时实验组髁突长轴与下颌平面的夹角均大于对照组。结论局部注射rAAV—IGF-I能够促进大鼠下颌骨长度及高度的增加，为治疗下颌发育不足提供了新的方法。     

腺相关病毒载体对心肌细胞感染和外源基因表达的作用

目的:为进一步研究肌质网钙ATP酶转基因在心力衰竭中的质粒价值,并观察腺相关病毒对心肌细胞感染的动态过程和对外源基因的表达能力。方法:构建含肌质网钙ATP酶的腺相关病毒载体(recombinantade-no-associatedvirus-sarcoplasmicreticulumcalciumATPase2a,rAAV-SERCA2a),利用激光共聚焦显微镜观察了活体异硫氰酸荧光素标记的腺相关病毒(fluoresceinisothiocyanate-rAAV,FITC-rAAV)进入心肌细胞的过程,利用流式细胞仪检测含绿色荧光蛋白的腺相关病毒rAAV-GFP感染心肌细胞后绿色荧光蛋白表达细胞的百分率。结果:构建、生产的重组病毒rAAV-SERCA2a的滴度为7×1014v·g/L,并可以有效介导肌质网钙ATP酶基因转录;FITC-rAAV感染心肌细胞后,大约15min可见病毒吸附在细胞膜上,30min时可大部分进入细胞内;未加丁酸钠组腺相关病毒介导的绿色荧光蛋白表达效率最高达33.3%,加用丁酸钠组该数据为48.7%。结论:成功构建了含肌质网钙ATP酶的腺相关病毒载体,该病毒可有效介导目的基因的表达。在体外腺相关病毒能有效感染心肌细胞,感染后的心肌细胞能有效表达外源基因。     

Divergent innervation of the olfactory bulb by distinct raphe nuclei

The raphe nuclei provide serotonergic innervation widely in the brain, thought to mediate a variety of neuromodulatory effects. The mammalian olfactory bulb (OB) is a prominent recipient of serotonergic fibers, particularly in the glomerular layer (GL), where they are thought to gate incoming signals from the olfactory nerve. The dorsal raphe nucleus (DRN) and the median raphe nucleus (MRN) are known to densely innervate the OB. The majority of such projections are thought to terminate in the GL, but this has not been explicitly tested. We sought to investigate this using recombinant adeno-associated viruses (rAAV)-mediated expression of green fluorescent protein (GFP)-synaptophysin targeted specifically to neurons of the DRN or the MRN. With DRN injections, labeled fibers were found mostly in the granule cell layer (GCL), not the GL. Conversely, dense labeling in the GL was observed with MRN injections, suggesting that the source of GL innervation is the MRN, not the DRN, as previously thought. The two raphe nuclei thus give dual innervation within the OB, with distinct innervation patterns. J. Comp. Neurol. 523:805–813, 2015. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.     

通用腺相关病毒载体构建及表达报告基因GFP的研究

目的　构建基因治疗通用型 AAV载体并检测它转导外源基因作用。方法　使用限制性内切酶切出p SSV9int-质粒中的 AAV病毒 Rep和 Cap基因元件后 ,插入了重组腺病毒专用穿梭质粒 -p ACCMVp L p A的含有CMV启动子、多克隆位点 (MCS)和多聚腺苷酸信号 (Poly A)的表达盒 ,构建了重组 AAV通用载体质粒 p SSHG-CMV。在该质粒 MCS插入 GFP基因后 ,我们使用 p SSHG-CMV-GFP、p GF14 0和 p AAV/Ad 3种质粒共转染 2 93包装细胞 ,制备 GFP重组 AAV,应用斑点杂交实验检测重组病毒滴度度 ,并将该病毒感染新生大鼠星形胶质细胞 ,荧光显微镜观察 GFP表达。结果　重组 AAV的滴度在浓缩前可达 2× 10 11,浓缩后可达 2× 10 13 ,表明成功的构建了重组 AAV载体 ,插入外源基因 GFP后 ,在包装病毒和辅助质粒的联合作用下 ,能产生具有感染性的重组AAV。感染了重组 GFP-AAV的大鼠星形胶质细胞表达了明显的 GFP荧光。结论　本文构建的重组 AAV通用载体 p SSHG-CMV,可转导外源基因 ,用于基因治疗的研究     

血管组织工程种子细胞的建立及意义

目的：利用人Nanog基因转染血管组织工程的种子细胞（血管内皮细胞ECV304）,提高其增殖能力,以在较短时间内获得大量种子细胞,从而为克服血管组织工程种子细胞来源的匮乏及组织工程血管的快速构建提供新途径。方法：制备含有人Nanog基因的复制缺陷型重组腺相关病毒血清2型病毒颗粒rAAV2-hNanog,用rAAV2-hNanog转染ECV304细胞,然后采用RT-PCR检测hNanog基因在转染的ECV304细胞中的表达,再用MTT、免疫荧光及激光共聚焦技术检测hNanog基因对血管内皮细胞ECV304生长的影响。结果：（1）rAAV2-hNanog转染ECV304细胞后,RT-PCR检测表明hNanog基因能在血管内皮细胞ECV304中稳定表达;同时,血管内皮细胞在转染后的增殖能力也显著增强（P〈0.05）。光镜下观察发现,转染的血管内皮细胞的形态无明显改变。结论：转染hNanog基因后,血管内皮细胞的形态无显著变化,但其增殖能力明显增强。利用hNanog基因提高血管内皮细胞的增殖能力,能够克服血管组织工程种子细胞来源不足的瓶颈,为组织工程血管的快速构建及应用提供一种新的方法。