Tropism and toxicity of adeno-associated viral vector serotypes 1, 2, 5, 6, 7, 8, and 9 in rat neurons and glia in vitro

Recombinant adeno-associated viral (rAAV) vectors are frequently used for gene delivery to the central nervous system and are capable of transducing neurons and glia in vitro. In this study, seven serotypes of a rAAV vector expressing green fluorescent protein (GFP) were characterized for tropism and toxicity in primary cortical cells derived from embryonic rat brain. At 2 days after transduction, serotypes 1 and 5 through 8 expressed GFP predominately in glia, but by 6 days post-transduction expression was neuronal except for AAV5. AAV2 and 9 produced minimal GFP expression. Using cell viability assays, toxicity was observed at higher multiplicities of infection (MOI) for all serotypes except AAV2 and 9. The toxicity of AAV1 and 5-8 affected mostly glia as indicated by a loss of glial-marker immunoreactivity. A frameshift mutation in the GFP gene reduced overall toxicity for serotypes 1, 5 and 6, but not 7 and 8 suggesting that the toxicity was not solely due to the overexpression of GFP. Collectively, a differential tropism and toxicity was observed among the AAV serotypes on primary cortical cultures with an overall preferential glial transduction and toxicity.     

腺相关病毒介导胰岛素样生长因子Ⅰ对高糖诱导神经元凋亡的保护作用

目的 研究重组腺相关病毒(AAV)载体介导胰岛素样生长因子Ⅰ(IGF Ⅰ)在体外神经元表达的情况,及其对高糖诱导神经元凋亡的保护作用.方法 利用分子克隆技术将大鼠IGF Ⅰ基因克隆到pSNAV2.0质粒上,构建包含重组质粒pSNAV2.0-IGF Ⅰ的杂合型重组AAV载体rAAV2/1-IGF Ⅰ.将人神经母细胞瘤SH-SY5Y细胞分为正常组(A组)、无血清组(B组)、无血清高糖组(C组),无血清高糖+rAAV2/1-IGF Ⅰ组(D组),其中A组不做任何处理;B组使用无血清培养基培养;C组用含100mmol/L D-葡萄糖的无血清培养基培养;D组则先用rAAV2/1-IGF Ⅰ病毒载体感染后再用含100 mmol/LD-葡萄糖的无血清培养基处理.干预24 h后应用RT-PCR和Western免疫印迹检测各组IGF Ⅰ基因和蛋白的表达情况;应用Hoechst33342荧光染色法、AnnexinV-FITC/PI双染法流式细胞仪检测细胞凋亡.观察rAAV2/1-IGF Ⅰ感染后对高糖诱导SH-SY5Y细胞凋亡的保护作用.结果 成功构建rAAV2/1-IGF Ⅰ重组AAV载体.感染SH-SY5Y细胞后,RT-PCR显示SH-SY5Y能表达大鼠IGF Ⅰ基因;Western免疫印迹检测发现D组IGF Ⅰ蛋白的表达水平(0.44±0.04)显著高于其他3组(A组0.29±0.02,B组0.17+0.02,C组0.08±0.02,均P<0.05).rAAV2/1-IGF Ⅰ能明显降低高糖诱导细胞捌亡的凋亡率:Hoechst33342荧光染色检测总凋亡率分别为A组(2.71±1.03)%,B组(9.17±1.72)%,C组(25.63±1.81)%,D组(14.50±2.27)%,各组间差异均有统计学意义(P<0.05);流式细胞仪分析结果表明AnnexinV-FITC~+/PI~+的早期凋亡细胞加上AnnexinV-FITC~+/PI~+的晚期凋亡细胞的总细胞凋亡率A组为(5.01±1.17)%,B组为(9.87±1.38)%,C组为(27.56±2.25)%,D组为(17.34±2.08)%,各组间差异均有统计学意义(P<0.05).结论 rAAV2/1-IGF Ⅰ感染体外神经元SH-SY5Y细胞能显著表达IGF Ⅰ蛋白,并有效地降低高糖对神经元的诱导凋亡作用.     

9型腺相关病毒介导RNA干扰抑制p65基因表达对血管紧张素Ⅱ诱导H9c2细胞凋亡的影响

目的:以9型腺相关病毒(AAV9)介导的RNA干扰抑制大鼠心室肌H9c2细胞中p65基因表达,研究其在血管紧张素II(Ang II)诱导下对H9c2细胞凋亡的影响,并阐明其可能机制。方法:分别将r AAV9-eGFP及r AAV9-eGFP-NF-κB p65-siRNA按转染复数(MOI)=4×106vg/cell转染至H9c2细胞,在荧光倒置显微镜下观察e GFP的阳性表达情况,采用流式细胞术检测其转染效率,并用Western blot法分析p65的表达情况。CCK-8法检测病毒对H9c2细胞活力的影响。流式细胞术分析各组细胞的凋亡情况。结果:病毒转染48 h后e GFP开始有表达,并且表达强度随着时间延长而增加,第5天达最高值,此时流式细胞术检测转染率为(52. 7±1. 9)%。与空白组相比,转染病毒后H9c2细胞的活力无明显变化。静息状态下H9c2细胞的NF-κB p65有一定活性,给予Ang II刺激后NF-κB p65的活性明显增高,而转染r AAV9-eGFP-NF-κB p65-siRNA可有效抑制NF-κB p65的活性。流式细胞术检测发现Ang II刺激组的凋亡程度明显高于空白组,而r AAV9-eGFP-NF-κB p65-siRNA组的细胞凋亡明显受到抑制。结论:通过r AAV9介导的RNA干扰能有效抑制H9c2细胞NF-κB p65基因的表达;抑制p65基因表达对H9c2细胞活力无明显抑制,但能减少Ang II诱导下的细胞凋亡。     

腺相关病毒介导胰岛素样生长因子I对高糖诱导神经元凋亡的保护作用

目的研究重组腺相关病毒（AAV）载体介导胰岛素样生长因子I（IGFI）在体外神经元表达的情况,及其对高糖诱导神经元凋亡的保护作用。方法利用分子克隆技术将大鼠IGFI基因克隆到pSNAV2．0质粒上,构建包含重组质粒pSNAV2．0-IGFI的杂合型重组AAV载体rAAV2／1-IGFI。将人神经母细胞瘤SH—SY5Y细胞分为正常组（A组）、无血清组（B组）、无血清高糖组（C组）,无血清高糖＋rAAV2／1-IGFI组（D组）,其中A组不做任何处理;B组使用无血清培养基培养;C组用含100mmol／LD．葡萄糖的无血清培养基培养;D组则先用rAAV2／1-IGFI病毒载体感染后再用含100mmol／LD．葡萄糖的无血清培养基处理。干预24h后应用RT—PCR和Western免疫印迹检测各组IGFI基因和蛋白的表达情况;应用Hoechst 33342荧光染色法、AnnexinV—FITC／PI双染法流式细胞仪检测细胞凋亡。观察rAAV2／1-IGFI感染后对高糖诱导SH—SY5Y细胞凋亡的保护作用。结果成功构建rAAV2／1-IGFI重组AAV载体。感染SH-SY5Y细胞后,RT—PCR显示SHSY5Y能表达大鼠IGFI基因;Western免疫印迹检测发现D组IGFI蛋白的表达水平（0．44±0．04）显著高于其他3组（A组0．29±0．02,B组0．17±0．02,C组0．08±0．02,均P〈0．05）。rAAV2／1-IGFI能明显降低高糖诱导细胞凋亡的凋亡率：Hoechst33342荧光染色检测总凋亡率分别为A组（2．71±1．03）％,B组（9．17±1．72）％,C组（25．63±1．81）％,D组（14．50±2．27）％,各组间差异均有统计学意义（P〈0．05）;流式细胞仪分析结果表明Annexin V-FITC^＊／PI^-的早期凋亡细胞加上Annexin V—FITC^＊／PI^＊的晚期凋亡细胞的总细胞凋亡率A组为（5．01±1．17）％,B组为（9．87±1．38）％,C组为（27．56±2．25）％,D组为（17．34±2．08）％,各组间差异均有统计学意义（P〈0．05）。结论rAAV2／1-IGFI感染体外神经元SH—SY5Y细胞能     

腺病毒伴随病毒载体介导的Ⅰ型单纯疱前病毒胸苷 …

目的 研究腺病毒伴随病毒（ＡＡＶ）载体介导杀肿瘤瘤基因的转移及其在肿瘤治疗方面的应用。方法 应用作者构建的腺病毒伴随病毒载体，克隆Ⅰ型单纯疱疹病毒胸苷激酶（ＨＳＶＩ－ＴＫ）基因，构建质粒ｐＡＣＴＫ－１９。用ｐＡＣＴＫ－１９转染５型腺病毒（Ａｄ５）感染的重组ＡＡＶ包装细胞系ＡＥ１２０１，获得重组病毒ｒＡＡＶ／ＡＣＴＫ。再用此重组病毒感染肺癌细胞系Ａ５４９，并联合现氧鸟苷（ＧＣＶ）作用，研究其体外对肺     

反义细胞周期蛋白B1重组AAV抑制骨肉瘤U2OS细胞增殖和诱导凋亡

目的 研究携带反义细胞周期蛋白B1(CCNB1)的腺相关病毒载体(rAAV-AS-CCNB1/Neo)对骨肉瘤细胞U2OS的细胞增殖抑制和诱导凋亡的影响. 方法 将构建的重组AAV载体pd16-95-AS-CCNB1/neo和AAV/腺病毒辅助质粒pSH3共转染HEK293细胞,得到表达AS-CCNB1的重组AAV,纯化并浓缩病毒,测定病毒滴度.用重组AAV感染人骨肉瘤U2OS细胞(感染复数为105～106 v.g./细胞),采用Western blotting、RT-PCR、四甲基偶氮唑盐(MTT)法、流式细胞术等检测或观察重组AAV对细胞周期蛋白B1表达,瘤细胞体外增殖、凋亡和细胞周期的影响.结果 成功构建rAAV-AS-CCNB1,病毒滴度为1.0×1011 v.g./ml,体外感染U2OS细胞后可明显降低其增殖活性,Western blotting和RT-PCR提示,rAAV-AS-CCNB1可抑制细胞周期蛋白B1表达,流式细胞术提示,细胞出现明显凋亡和G1期阻滞. 结论 反义CCNB1重组AAV具有明显的抗骨肉瘤U2OS细胞体外增殖作用,其作用可能与其诱导细胞凋亡和周期阻滞有关.     

Immune responses to AAV in clinical trials

Recent findings in a clinical trial in which an adeno-associated virus (AAV) vector expressing coagulation factor IX (F.IX) was introduced into the liver of hemophilia B subjects highlighted a new issue previously not identified in animal studies. Upon AAV gene transfer to liver, two subjects enrolled in this trial developed transient elevation of liver enzymes, likely as a consequence of immune rejection of transduced hepatocytes mediated by AAV capsid-specific CD8(+) T cells. Studies in healthy donors showed that humans carry a population of antigen-specific memory CD8(+) T cells probably arising from wild-type AAV infections. The hypothesis formulated here is that these cells expanded upon re-exposure to capsid, i.e. upon AAV-2 hepatic gene transfer, and cleared AAV epitope-bearing transduced hepatocytes. Other hypotheses have been formulated which include specific receptor-binding properties of AAV-2 capsid, presence of capsid-expressing DNA in AAV vector preparations, and expression of alternative reading frames from the transgene. Absence of a valid animal model has prevented an in-depth mechanistic study of the phenomenon. Several possible solutions to the problem are discussed, including the administration of a short-term anti-T cell immunosuppression regimen concomitant with gene transfer. While more studies will be necessary to further define mechanisms and risks associated with capsid-specific immune responses in humans, monitoring of these responses in clinical trials will be essential to achieving the goal of long-term therapeutic gene transfer in humans.     

6A8 α-甘露糖苷酶基因的mRNA表达与染色体定位

目的 对6A8α－甘露糖苷酶基因作染色体定位,比较6A8α－甘露糖苷酶mRNA在人多种免疫细胞株的表达。方法 用Fish原位杂交作染色体定位,用RT－PCR检测mRNA表达。结果 6A8α－甘露糖苷酶基因定位于人第13号染色体长臂的31－32区。6A8α－甘露糖苷酶mRNA在B细胞株SKW6高表达,在B细胞株3D5、BJAB、DESS、Daudi、Nalm6中度表达,在B细胞株Navalm,T细胞株GM、Jurkat,细胞细胞瘤细胞株U937弱表达,在T细胞株Peer,慢性髓性白血病细胞株K562极弱表达。结论 6A8α－甘露糖苷酶基因定位于人第13号染色体长臂的31－32区,其mRNA表达水平在各种人免疫细胞株不同。     

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.     

通用型腺病毒伴随病毒载体的构建

目的构建含腺病毒伴随病毒（ＡＡＶ）基因组两端的反向重复序列（ＩＴＲｓ）和表达必须元件如启动子、多克隆位点和ＰｏｌｙＡ信号的通用型载体质粒ｐＡＣＲ－Ｎｅｏ，并获得重组ＡＡＶ（ｒＶＶ／ＡＣＲ－Ｎｅｏ）。方法通过ＤＮＡ重组技术，将ＳＶ４０ＰｏｌｙＡ、Ｎｅｏ基因、ＣＭＶ－ＩＥ启动子和多克隆位点组成表达盒子，取代含ＡＡＶ全基因组质粒ｐＳＳＶ９中ＡＡＶ结构基因部分，构建成质粒ｐＡＣＲ－Ｎｅｏ。用ｐＡＣＲ－Ｎｅｏ转染５型腺病毒（Ａｄ５）感染的重组ＡＡＶ包装细胞系ＡＥ１２０１，能获得重组病毒ｒＡＡＶ／ＡＣＲ－Ｎｅｏ。提取ｒＡＡＶ／ＡＣＲ－Ｎｅｏ感染细胞的染色体，用Ｓｏｕｔｈｅｍ杂交分析重组病毒基因组在感染细胞中的存在情况。结果质粒ｐＡＣＲ－Ｎｅｏ转染包装细胞系后所得ｒＡＡＶ／ＡＣＲ－Ｎｅｏ滴度为４．２×１０５ＣＦＵ／ｍｌ，并且ｒＡＡＶ／ＡＣＲ－Ｎｅｏ能在转导细胞内实现其基因组与细胞染色体的整合。结论成功地构建了通用型ＡＡＶ载体，为今后的ＡＡＶ载体研究、基因治疗和临床应用打下了基础     

Interleukin 6-induced differentiation of a human B cell line into IgM-secreting plasma cells is mediated by c-fos.

The role of the protooncogene c-fos in interleukin (IL) 6-induced B cell differentiation was assessed. Treatment of SKW 6.4 cells with IL 6 induced a transient and early stimulation of c-fos sense mRNA expression. The effect appeared within 30 min and returned to basal levels after 2 h. The addition of antisense oligonucleotides to c-fos significantly inhibited IL 6-induced IgM production by SKW 6.4 cells (p less than 0.001), whereas control oligonucleotides had no inhibitory effect. These results indicate that activation of c-fos is involved in IL 6-induced differentiation of SKW 6.4 cells into IgM-secreting cells.     

Distinct patterns of gene transfer to gerbil hippocampus with recombinant adeno-associated virus type 2 and 5

Genetic modification of the gerbil hippocampal neuronal cells in vivo helps us understand the mechanisms of neuronal function under various circumstances such as ischemic insult. In this study, we examined the distinct distribution of the recombinant adeno-associated virus type 2 (rAAV2) and rAAV5 vectors for gene delivery to primary cultured cells and the gerbil hippocampus. Mixed cortical cultures containing both neurons and astrocytes from E17 rat embryos were infected with rAAVs containing the Cytomegalovirus virus (CMV) promoter. rAAV2 was preferably transduced to neurons, whereas rAAV5 was inclined to be transduced to astrocytes in vitro. rAAV2 and rAAV5 vectors, each with the CMV or Rous sarcoma virus (RSV) promoter, were injected into the gerbil hippocampus using a stereotaxic apparatus. Five days after injection, transgene expression was analyzed with X-gal staining. In the gerbil hippocampus, rAAV5 with the CMV promoter achieved a higher overall transgene expression than rAAV2 with the CMV promoter. The transgene expression of rAAV2 with the RSV promoter was found in the pyramidal and granular cells, while the transgene expression of rAAV5 with the RSV promoter was preferentially found in the granular cells. These findings would be valuable in optimizing rAAV-mediated gene transfer to the gerbil hippocampus.     

Two novel adeno-associated viruses from cynomolgus monkey: pseudotyping characterization of capsid protein

We demonstrated the presence of two adeno-associated viruses (AAVs), designated AAV10 and AAV11, in cynomolgus monkeys by isolating and sequencing the entire viral coding regions from the monkey DNA. AAV10 and AAV11 capsid proteins shared 84% and 65%, respectively, of amino acids with AAV2. A phylogenetic analysis of AAV capsid proteins showed that AAV10 and AAV11 resembled most AAV8 and AAV4, respectively. To characterize the capsid protein, we pseudotyped an AAV2 vector with the monkey AAV capsid proteins and examined the resulting pseudotypes AAV2/10 and AAV2/11, in comparison with the AAV2 vector, for their host ranges in cell lines and tissue tropism in mice. AAV2/10 and AAV2/11 transduced primate cells less efficiently than AAV2. Whereas AAV2 transduced undifferentiated C2C12 mouse myoblasts more efficiently than differentiated ones, AAV2/10 and AAV2/11 transduced the undifferentiated myoblasts less efficiently than differentiated ones. Three weeks after injection to the muscle of the hind legs, AAV2/10 and AAV2 induced transgene expression similarly, but AAV2/11 did not transduce the skeletal muscle. Six weeks after systemic administration, transduced vector DNA was detected by PCR in the liver and spleen of mice inoculated with AAV2, in the liver, heart, muscle, lung, kidney, and uterus of mice with AAV2/10, and the muscle, kidney, spleen, lung, heart, and stomach of mice with AAV2/11. Mouse antisera against capsid protein VP2 of the three AAVs neutralized the respective vector particles in a type-specific manner. The results indicate that AAV10 and AAV11 capsid proteins, which are antigenically distinct from each other and AAV2, are likely to determine their host ranges and tissue tropism that are different from AAV2s, suggesting that cynomolgus AAVs could provide a broader choice of pseudotype AAV vectors for gene therapy.     

Immune responses to AAV in clinical trials

Findings in the first clinical trial in which an adeno-associated virus (AAV) vector was introduced into the liver of human subjects highlighted an issue not previously identified in animal studies. Upon AAV gene transfer to liver, two subjects developed transient elevation of liver enzymes, likely as a consequence of immune rejection of transduced hepatocytes mediated by AAV capsid-specific CD8(+) T cells. Studies in healthy donors showed that humans carry a population of antigen-specific memory CD8(+) T cells probably arising from wild-type AAV infections. The hypothesis formulated at that time was that these cells expanded upon re-exposure to capsid, i.e. upon AAV-2 hepatic gene transfer, and cleared AAV epitope-bearing transduced hepatocytes. Other hypotheses have been formulated which include specific receptor-binding properties of AAV-2 capsid, presence of capsid-expressing DNA in AAV vector preparations, and expression of alternate open reading frames from the transgene; emerging data from clinical trials however fail to support these competing hypotheses. Possible solutions to the problem are discussed, including the administration of a short-term immunosuppression regimen concomitant with gene transfer, or the development of more efficient vectors that can be administered at lower doses. While more studies will be necessary to define mechanisms and risks associated with capsid-specific immune responses in humans, monitoring of these responses in clinical trials will be essential to achieving the goal of long-term therapeutic gene transfer in humans.     

Adeno-associated virus DNA replication is induced by genes that are essential for HSV-1 DNA synthesis

Adeno-associated virus (AAV) DNA replication is not detectable unless cells are coinfected with a helper adenovirus (Ad) or herpesvirus or unless AAV infection is carried out in certain established cell lines that have been treated with various metabolic inhibitors or uv irradiation. In helper-dependent infections, it has been shown that AAV DNA synthesis depends on one or more early Ad genes, whereas little is known concerning any herpesvirus gene that promotes AAV DNA synthesis. In this study we tested the ability of four cloned Xbal fragments of herpes simplex virus type 1 (HSV-1) DNA to induce AAV DNA synthesis in Vero cells. Cotransfections, which were carried out with pAV1 (an infectious AAV2 plasmid), revealed that AAV DNA synthesis could be optimally induced by three of these clones (C,D, and F) plus a clone of the HSV-1 ICP4 (IE 175) gene. ICP4, an immediate early gene, was presumably required to activate expression of other HSV genes. To help identify the additionally needed HSV genes, we tested Xbal C,D, and F subclones that contain genes previously found necessary for origin-dependent HSV DNA synthesis and found that at least five of these genes (UL 5, 8, 9, 29, and 30) contributed to the induction of AAV DNA synthesis. In contrast to their absolute requirement for HSV DNA synthesis, none of these genes were strictly necessary for AAV DNA replication. Because they are all known to specify proteins that are directly involved in HSV DNA synthesis, our results suggest that some or all of their products also may directly participate in the replication of AAV DNA.     

Adeno-associated virus mediated gene transfer into lung cancer cells promoting CD40 ligand-based immunotherapy

Expression of the CD40 ligand (CD40L) on tumors can activate host immune systems and produce antitumor effects against the tumors. To deliver the CD40L gene efficiently, we evaluated the efficiency of transduction of different serotypes of adeno-associated virus (AAV) vectors in lung cancer A549 cells and compared the transduction efficiency of a conventional AAV vector with that of self-complementary AAV (scAAV) vectors as well. We determined that serotype AAV2/5 transduced A549 cells much more efficiently than serotypes AAV2/1, AAV2/2, AAV2/6, AAV2/7, AAV2/8, AAV2/9 and AAV2/10. And the transduction efficiency of scAAV2/5 was significantly higher than conventional AAV2/5. Furthermore, pre-treatment with carboplatin, which is a chemotherapeutic agent used in lung cancer chemotherapy, substantially increased AAV-mediated transgene expression. The scAAV2/5 vectors encoding human CD40L were used to tranduce CD40L into A549 cells, which were then co-cultivated with immature human dendritic cells (DCs). Interleukin 12 (IL-12) that was released was measured in the culture supernatant. Specificity of the immunostimulatory effect of CD40L was confirmed by blocking with a monoclonal antibody binding to human CD40L. The in vivo antitumor activity was evaluated in BALB/c nude mice bearing A549 lung cancer. scAAV2/5-CD40L showed significant inhibitory effects on the growth of transplanted tumor cells as compared with control group. These studies suggest that recombinant AAV2/5-CD40L may provide an effective form of therapy for lung cancer.     

Transduction of PACAP38 protects primary cortical neurons from neurotoxic injury

Neurotrophic factors such as pituitary adenylate cyclase activating polypeptide (PACAP38) are promising therapeutics for neurodegenerative diseases. However, delivery of trophic factors into brain neurons remains a challenge. The objective of this study is to determine whether adeno-associated virus (AAV) can mediate PACAP38 gene delivery into neurons in vitro and if transduction of AAV/PACAP38 into cortical neurons protects cells against neurotoxic insult. Primary cortical neuronal cultures are transduced with rAAV/PACAP38/GFP and cell survival against the nitric oxide releasing neurotoxin sodium nitroprusside (SNP) determined. GFP expression, a surrogate marker for successful transduction, is detected using fluorescent microscopy. The results show expression of GFP transgene and AAV capsid proteins in neurons. PACAP38 transduction significantly increases cell survival of neurons exposed to SNP. These results support the feasibility of using AAV-mediated delivery of PACAP38 to enhance neuronal survival and suggest that AAV-delivered PACAP38 maybe a therapeutic strategy for neurodegenerative diseases.     

Stable transduction of large DNA by high-capacity adeno-associated virus/adenovirus hybrid vectors

Viral vectors with high cloning capacity and host chromosomal integration ability are in demand for the efficient and permanent genetic modification of target cells with large DNA molecules. We have generated a hybrid gene transfer vehicle consisting of recombinant adeno-associated virus (AAV) replicative intermediates packaged in adenovirus (Ad) capsids. This arrangement allows cell cycle-independent nuclear delivery of recombinant AAV genomes with lengths considerably above the maximum size (i.e., 4.7 kb) that can be accommodated within AAV capsids. Here we show that high-capacity AAV/Ad hybrid vector gene transfer mediates cellular genomic integration of large fragments of foreign DNA and accomplishes stable long-term transgene expression in rapidly proliferating cells. Southern blot and polymerase chain reaction analyses of chromosomal DNA extracted from clones of stably transduced cells revealed that most of them contained a single copy of the full-length hybrid vector genome with AAV inverted terminal repeat (ITR) sequences at both ends. The high-capacity AAV/Ad hybrid vector system can thus be used for the transfer and expression of transgenes that cannot be delivered by conventional integrating viral vectors.