共表达HIV—1的gag—gp120与IL—2的pGPIL—2诱导小鼠产生细胞毒性T细胞的研究

目的：研究HIV－1CN融合基因与IL－2基因共表达基因质粒pGPIL-2诱导产生细胞毒性T细胞（CTL）。方法：脂质体介导共表达中国流行株HIV－1gag-gp120基因与IL－2基因的基因疫苗质粒pGPIL-2转染BHK－21细胞，以间接免疫荧光法鉴定其表达。取pGPIL-2免疫鼠脾细胞，检测pGPIL-2诱导的细胞毒性T细胞杀伤活性。结果：杀伤实验结果证明，经基因免疫获得的CTL效应细胞，可杀伤HIV－1CN融合基因转染的靶细胞。结果：pGPIL-2可有效地诱导CTL的产生，该研究结果为进一步设计中国流行株HIV-1基因疫苗提供了重要实验依据。     

pcIL-18-MAGE-1共表达基因疫苗对肝癌细胞株SMMC-7721、Hepal-6增殖的影响

目的观察pc IL-18-MAGE-1共表达基因疫苗接种小鼠所引起的免疫应答情况以及对肝癌细胞株SMMC-7721、Hepal-6增殖抑制情况,探究pc IL-18-MAGE-1共表达基因疫苗抗肿瘤作用。方法用pc IL-18-MAGE-1基因疫苗免疫小鼠,同时设空白对照组和阴性对照组,免疫后收集脾细胞作为效应细胞,分别作用于靶细胞即肝癌细胞株SMMC-7721、Hepal-6。应用流式细胞仪(FCM)检测小鼠T细胞亚群情况及自然杀伤(NK)细胞活性,MTT法检测肿瘤特异性细胞毒性T淋巴细胞(CTL)对靶细胞的杀伤作用。结果与对照组比较,共表达pc IL-18-MAGE-1基因疫苗对靶细胞均有明显的杀伤作用(P<0.01);对SMMC-7721细胞杀伤作用高于Hepal-6细胞(P<0.05)。免疫组CD4+、CD8+、CD4+/CD8+均高于阴性对照组(P<0.05)。结论 pc IL-18-MAGE-1共表达基因疫苗通过同时激活CD4+T细胞及CD8+T细胞、增加NK细胞活性及诱导肿瘤特异性CTL直接杀伤肿瘤细胞,发挥抗肿瘤作用。     

人类免疫缺陷病毒-2 gag重组鸡痘病毒疫苗的构建及实验免疫研究

目的构建并探讨人类免疫缺陷病毒(HIV)-2 gag重组鸡痘病毒(FPV)在小鼠体内的免疫应答,为开发HIV-2基因重组活载体疫苗提供实验依据。方法将HIV-2结构基因gag插入到转移载体pUTA2复合启动子ATI-P7．5×20下游．构建出鸡痘病毒重组转移质粒pUTA2-gag;经转染和BrdU加压筛选,以基因组聚合酶链反应(PCR)和Western blot法鉴定重组病毒;将获得的重组病毒大量制备并纯化后,肌内注射免疫Balb/c小鼠,酶联免疫吸附实验(ELISA)检测小鼠血清HIV-2抗体,流式细胞仪测定CD4~+、CD8~+T淋巴细胞亚类数量,乳酸脱氢酶(LDH)释放法检测脾特异性细胞毒性T淋巴细胞(CTL)杀伤活性。结果构建出重组鸡痘病毒转移质粒pUTA2-gag;从重组病毒的基因组中可扩增出大小为766bp的目的基因,其表达产物可与人HIV-2阳性血清发生反应,目的蛋白的相对分子质量约为55000;重组病毒免疫组小鼠的血清出现HIV-2抗体．脾T细胞亚类的数量增加,并产生针对HIV-2靶细胞的特异性CTL杀伤活性。结论获得一株重组鸡痘病毒,该病毒可稳定表达HIV-2结构蛋白Gag,并能诱导小鼠产生特异性细胞和体液免疫应答。     

共表达pcIL-18/MAGE-1 DNA疫苗对JEG-3细胞HLA-G基因表达的影响

目的观察共表达基因疫苗pc IL-18/MAGE-1对绒癌JEG-3细胞株HLA-G基因表达的影响,探究pc IL-18/MAGE-1抗肿瘤作用机制。方法应用构建的共表达pc IL-18/MAGE-1 DNA疫苗免疫小鼠,同时设阴性对照组和空白对照组,免疫后分别收集脾细胞,作用于靶细胞JEG-3,应用FCM检测小鼠T细胞亚群情况及NK细胞活性,MTT法检测肿瘤特异性CTL对靶细胞的杀伤率,RT-PCR法检测HLA-G基因表达情况。结果免疫组HLA-G基因表达降低,且对JEG-3细胞杀伤活性增加,与对照组比较,差异显著(P<0.05)。免疫组NK细胞活性及CD4+/CD8+、CD8+、CD4+值均高于对照组(P<0.05)。结论共表达基因疫苗pc IL-18/MAGE-1通过降低HLA-G基因的表达,进而增加NK细胞活性以及诱导肿瘤特异性CTL直接杀伤肿瘤细胞,发挥抗肿瘤作用。     

vJ38gag/IFNα-2b基因共表达核酸疫苗免疫程序的优化

目的　观察国际流行株HIV - 1gag与IFNα - 2b基因共表达颗粒化抗原疫苗与质粒DNA核酸疫苗免疫程序优化的效果。方法　将质粒 pJ38gag/IFNα- 2b经脂质体介导转染RK细胞 ,并在痘苗病毒中共表达HIV - 1gag与IFNα - 2b基因 ,以间接免疫荧光与斑点酶联免疫法鉴定其表达产物。以表达产物与质粒DNA联合免疫小鼠实验 ,检测淋巴细胞转化率、细胞毒性T细胞杀伤活性、CD+ 4 、CD+ 8细胞计数与体液免疫水平。结果　pJ38gag/IFNα - 2b基因表达的颗粒化抗原疫苗具有良好的免疫原性 ,3vJ38gag/IFNα- 2b +pJ38gag/IFNα- 2b联合免疫效果优于vJ38gag/IFNα - 2b单独免疫。 结论　pJ38gag/IFNα- 2b基因表达的颗粒化抗原疫苗能诱导机体产生细胞免疫与体液免疫。     

白细胞介素-15重组体对HBsAg核酸疫苗的免疫佐剂作用

白细胞介素-15(IL-15)属螺旋结构细胞因子家族，它能促进T细胞、自然杀伤(NK)细胞和B细胞增殖及分化；具有诱导淋巴细胞产生γ干扰素(IFN-γ)及肿瘤坏死因子α的作用。IL-15与疫苗共同免疫时可刺激抗体产物增加，细胞毒性T淋巴细胞(CTL)活性加强。将IL-15表达质粒与HBsAg DNA疫苗共同免疫小鼠，以观察其对小鼠免疫应答的影响。     

柯萨奇B2病毒VP1基因疫苗诱导细胞免疫的初步研究

目的构建柯萨奇B2病毒(CVB2)VP1侯选基因疫苗,评价其诱导细胞免疫的效果.方法采用逆转录PCR技术扩增CVB2的主要中和抗原 VP1基因,通过分子克隆构建pcDNA3-CVB2VP1基因免疫质粒并免疫BALB/c小鼠, 51Cr释放法测定CTL杀伤效应.结果基因免疫质粒表达载体为pcDNA3,亚克隆片段为CVB2VP1,pcDNA3-CVB2VP1接种组CTL特异性杀伤百分率均高于pcDNA3组(P＜0.01),E/T为50∶1时特异性CTL杀伤百分率最高,为(31.2±6.8)%(P＜0.05).结论 pcDNA3-CVB2VP1可诱导小鼠产生细胞免疫.     

柯萨奇B2病毒VP1基因疫苗诱导细胞免疫的初步研究

目的　构建柯萨奇B2 病毒 (CVB2 )VP1侯选基因疫苗 ,评价其诱导细胞免疫的效果。方法　采用逆转录PCR技术扩增CVB2 的主要中和抗原VP1基因 ,通过分子克隆构建 pcDNA3 CVB2 VP1基因免疫质粒并免疫BALB/c小鼠 ,51Cr释放法测定CTL杀伤效应。结果　基因免疫质粒表达载体为 pcDNA3 ,亚克隆片段为CVB2 VP1,pcDNA3 CVB2 VP1接种组CTL特异性杀伤百分率均高于 pcDNA3 组 (P <0 0 1) ,E/T为 5 0∶1时特异性CTL杀伤百分率最高 ,为 (31 2± 6 8) % (P <0 0 5 )。结论　pcDNA3 -CVB2 VP1可诱导小鼠产生细胞免疫。     

两种不同抗原致敏方式负载DC疫苗对Lovo细胞的体外杀伤作用

目的比较重组痘苗病毒负载人癌胚抗原（CEA）基因转染方式与Lovo细胞裂解物诱导方式对产生DC疫苗的影响。方法分别采用重组痘苗病毒负载CEA基因转染方式及Lovo肿瘤细胞裂解物转染方式转染未成熟DC,诱导特异性细胞毒性T淋巴细胞（CTL）。体外培养CTL并检测其活性;MTT法检测两组CTL对kovo细胞的杀伤作用。结果两种方式致敏DC均可诱导激活CTL并分泌INF-γ,而重组痘苗病毒转染Dc组CTL诱导率高于细胞裂解物组;重组痘苗病毒转染组诱导的CTL对Lovo细胞的特异性杀伤活性显著高于细胞裂解物组。结论两种不同抗原致敏方式负载DC疫苗均能够诱导高效而特异的CTL杀瘤活性,而使用重组痘苗病毒转染CEA至DCs的方式明显优于肿瘤细胞裂解物的抗原负载方式,为DC疫苗用于结肠癌的免疫治疗奠定基础。     

树突状细胞HBsAg疫苗抗乙型肝炎病毒免疫的体外研究

目的 研究人单核细胞来源的树突状细胞（DC）激活的HBsAg特异性细胞毒性T淋巴细胞（CTL）对表达HBsAg的HepG2/S靶细胞的杀伤效应，以探索DC-HBsAg疫苗在抗乙型肝炎病毒（HBV）中的作用。方法 从健康外周血中分离邮单核细胞，在粒细胞-巨噬细胞集落刺激因子（GM-CSF）和白细胞介素4（IL-4）的作用下培养7d诱导出DC，然后以DC为刺激细胞在体外诱导出HBsAg特异性CTL；将携有HBV-S基因的pLXSN/S重组质粒电击导入肝癌细胞系（HepG2)，建立表达HBsAg的靶细胞模型HepG2/S；用染色法检测HBsAg特异性CTL对HepG2/S靶细胞的杀伤效应。结果 DC激活的HBsAg特异性CTL对HepG2/S靶细胞具有较强的杀伤效应，不同浓度HBsAg(0μg/L，50μg/L和100μg/L）诱导的CTL的杀伤率分别为3.8%,69.5%和85.1%，而CTL对HepG2细胞无明显杀伤效应。结论 由DC激活的HBsAg特异性CTL具有较强制 特异性抗HBV作用。     

Virus-specific cytotoxic T-lymphocytes in HIV-2-infected cynomolgus macaques.

OBJECTIVE: Specific cytotoxic T-lymphocytes (CTL) are induced in humans or monkeys after infection with HIV-1 or SIVmac, respectively. Since, like HIV-1, HIV-2 causes AIDS, our objective was to determine the characteristics of the HIV-2-specific CTL response. DESIGN: Since it is rarely possible to study cellular immunity in individuals, because of the small number of HIV-2-infected patients available in Europe and the necessity for co-operation in the performance of sequential CTL assays, cynomolgus macaques were infected with HIV-2. Autologous transformed B-lymphoblastoid cell lines infected with recombinant vaccinia viruses were used as target cells for cytotoxicity assays. METHODS: Recombinant vaccinia viruses expressing HIV-2 genes were constructed to infect B-lymphoblastoid cell lines from macaques. These cells were used as target cells for cytotoxicity assays with peripheral blood mononuclear cells from HIV-2BEN-infected cynomolgus macaques. To characterize the effector cells, CD8+ cells were separated with immunomagnetic beads. Major histocompatibility complex (MHC) restriction of the cytotoxic cells was determined by incubation with matched or mismatched target cells. RESULTS: HIV-2BEN-infected cynomolgus macaques raised CTL against proteins of the three major viral structural genes, gag, pol and env. The cytotoxic cells were CD8+ and their activity was MHC class I-restricted. In contrast to SIVmac-infected macaques, env-specific lysis was mediated exclusively by CD8+ cells. CTL from individual animals recognized different viral proteins and the recognition pattern varied over time. CONCLUSIONS: Like HIV-1 and SIVmac, HIV-2 induces virus-specific CTL. The variation of antigen recognition between individual animals and over time indicates that sequential experiments are necessary to determine the complete spectrum of the CTL response of infected animals. HIV-2-infected macaques represent a suitable model for investigations into the cellular immune response against HIV.     

Cytotoxic T lymphocytes against HIV.

HIV-1 infection has clearly been shown to induce a vigorous CTL response in infected people, and this response is present at a time when immune function otherwise is globally impaired. HIV-1-specific CTL are detectable both in peripheral blood and tissues of infected people, and are aimed at multiple viral proteins. The precise epitopes recognized by these CTL are now being defined, and the establishment of CTL clones should facilitate further functional analysis of these cells. However, the central question as to the clinical relevance of HIV-1-specific CTL remains. By analogy with animal model systems of virus infection, it is reasonable to postulate that HIV-1-specific CTL serve a protective role as a host defense. In this regard, in vitro data indicate that HIV-1-specific CTL can suppress viral replication, and longitudinal clinical studies indicate that the vigorous CTL activity seen in the early stages of infection declines with disease progression. Alternatively, the presence of HIV-1-specific CTL in tissues such as the lung and brain have to at least raise the possibility that these cells may be contributing to the pathologic consequences of infection. In addition, the relative protective effects of virus-specific CTL compared to other effector mechanisms such as ADCC and neutralizing antibodies remain to be determined. Nevertheless, recent data in the SIV vaccine model give reason for encouragement that a state of protective immunity can be achieved in AIDS-like illness caused by retroviruses. The search continues presently not only for the parameters which define protective immunity in HIV-1 infection, but also for the ideal HIV-1 immunogens to be used for vaccination of human populations.     

Cytotoxic T-cell recognition of HIV-1 cross-clade and clade-specific epitopes in HIV-1-infected Thai and Japanese patients

OBJECTIVE: To identify and characterize cytotoxic T-cell (CTL) epitopes for HIV-1 clade E using eight known HLA-A*1101-restricted HIV-1 clade B epitopes. METHODS: Induction of clade E-specific CTL was examined by stimulating peripheral blood mononuclear cells (PBMC) from clade E-infected Thai individuals with the clade E-specific peptide corresponding to the clade B epitopes. Cross-clade and clade-specific CTL recognition for these epitopes was analysed using CTL clones and bulk CTL specific for these epitopes. To clarify the presentation of these epitopes in HIV-1-infected T cells, CTL recognition for the clade E-specific and cross-clade epitopes was investigated using CD4CXCR4 cells infected with an HIV-1 clade E clone. RESULTS: Three epitopes, which are identical among clades A-E, were recognized as cross-clade CTL epitopes in both individuals. Clade B and E sequences corresponding to three epitopes were recognized as clade-specific epitopes in clade B-infected and clade E-infected individuals, respectively. In contrast, clade E-specific peptides corresponding to two other clade B epitopes failed to elicit clade E-specific CTL. CTL specific for the three cross-clade and three clade E-specific epitopes effectively lysed target cells infected with HIV-1 clade E virus. CONCLUSIONS: These six epitopes are found to be processed naturally in HIV-1 clade E-infected cells. We show here that a strategy utilizing HIV-1 clade B epitopes is very useful for identifying clade E CTL epitopes.     

Equivalent recognition of HIV proteins, Env, Gag and Pol, by CD4+ and CD8+ cytotoxic T-lymphocytes.

OBJECTIVES: Cytotoxic T-lymphocytes (CTL) appear to be an important defense mechanism against HIV infection. This study proposes to examine the major histocompatibility complex (MHC)-restricted HIV-1 Env-, Gag- and Pol-specific CTL activities in HIV-infected asymptomatic patients. DESIGN: CD4+ and CD8+ CTL were examined to establish whether the same HIV-1 protein (Env, Gag or Pol) was recognized by both CD4+ and CD8+ CTL with MHC antigen restriction. METHODS: Peripheral blood mononuclear cells, CD4+ and CD8+ T-cells from 17 HIV-infected asymptomatic patients and 10 HIV-seronegative individuals were examined for HIV-1 Env-, Gag- and Pol-specific MHC-restricted cytotoxicity using autologous and heterologous B-lymphoblastoid cell lines infected with vaccinia recombinant expressing HIV-1 Env, Gag and Pol proteins as targets. RESULTS: CD4+ and CD8+ CTL specific for the HIV-1 Env, Gag and Pol were demonstrated in the peripheral blood. DR4 and DQw2 were possible sites of MHC class II restriction of CD4+ CTL. Possible MHC class I restriction sites of CD8+ CTL included A2 and B8 for Env, A1 and A2 for Gag, and A2 and B8 for Pol antigen. CONCLUSIONS: These observations should help to define more precisely the nature and elements of protective immunity and to evaluate AIDS vaccine strategies.     

Qualitative and quantitative analysis of human cytotoxic T-lymphocyte responses to HIV-1 proteins.

OBJECTIVE: To study the degree of immunogenicity of each HIV-1 protein. DESIGN: In most viral systems, antiviral cytotoxic T-lymphocytes (CTL) from a given donor preferentially recognize only one or a small number of viral proteins. METHODS: Anti-HIV CTL were generated by in vitro stimulation of peripheral blood mononuclear cells from seropositive donors and tested against multiple HIV-1 proteins or groups of proteins encoded by seven genes (env, gag, pol, nef, rev, tat and vif). Using autologous target cells infected with recombinant vaccinia viruses expressing one of the HIV-1LAI proteins, we compared the cytolytic activities obtained from bulk culture with those found in limiting dilution analysis (LDA). RESULTS: Our results were noteworthy for the following reasons. (1) Each responding donor reacted simultaneously to multiple proteins; this is very unusual in other viral systems. Anti-Gag CTL were detected in most, and anti-Pol in approximately three-quarters, of the patients, together with very high amounts of the corresponding CTL precursors in LDA. CTL against Env and Nef were found in two-thirds of the patients, while Vif- and Rev-specific CTL were less frequent. Finally, Tat was seldom recognized by CTL, but its antigenicity was revealed in LDA. (2) All responding cells revealed in bulk cultures as well as in LDA were CD8+ T-cells, and their in vitro differentiation did not require the help of CD4+ T-cells. (3) Proteins from the HIV-1LAI isolate were recognized with high frequency by CTL from seropositive donors, most certainly being infected by other isolates, which suggests that relatively conserved epitopes are predominant targets of CTL. CONCLUSION: Taken together, these results are encouraging for vaccine purposes, since anti-HIV-1 CTL stimulation is thought to be a requirement for such a vaccine.     

Cellular immune response to cryptic epitopes during therapeutic gene transfer

The immune response has been implicated as a critical factor in determining the success or failure of clinical gene therapy trials. Generally, such a response is elicited by the desired transgene product or, in some cases, the delivery system. In the current study, we report the previously uncharacterized finding that a therapeutic cassette currently being used for human investigation displays alternative reading frames (ARFs) that generate unwanted protein products to induce a cytotoxic T lymphocyte (CTL) response. In particular, we tested the hypothesis that antigenic epitopes derived from an ARF in coagulation factor IX (F9) cDNA can induce CTL reactivity, subsequently killing F9-expressing hepatocytes. One peptide (p18) of 3 candidates from an ARF of the F9 transgene induced CD8⁺ T cell reactivity in mice expressing the human MHC class I molecule B0702. Subsequently, upon systemic administration of adeno-associated virus (AAV) serotype 2 vectors packaged with the F9 transgene (AAV2/F9), a robust CD8⁺ CTL response was elicited against peptide p18. Of particular importance is that the ARF epitope-specific CTLs eliminated AAV2/F9-transduced hepatocytes but not AAV2/F9 codon-optimized (AAV2/F9-opt)-transduced liver cells in which p18 epitope was deleted. These results demonstrate a previously undiscovered mechanism by which CTL responses can be elicited by cryptic epitopes generated from a therapeutic transgene and have significant implications for all gene therapy modalities. Such unforeseen epitope generation warrants careful analysis of transgene sequences for ARFs to reduce the potential for adverse events arising from immune responses during clinical gene therapy protocols.     

Inter-clade cross-reactivity of HIV-1-specific T cell responses in human immunodeficiency virus type 1 infection in China

To determine the degree of HIV-1-specific cytotoxic-T-lymphocyte (CTL) cross-responses to the clade B and C consensus sequences at the single peptide level. We assessed CTL responses in 46 HIV-1 clade B chronically infected individuals using an interferon-gamma Elispot assay with a total of 826 overlapping peptides spanning HIV-1 clade B and C consensus sequences. In general, 583 peptides were recognized by HIV-1-specific T cells in the study subjects (292 clade B, 291 clade C respectively), of which 204 peptides in both clades were recognized simultaneously. The HIV-1-specific CTL responses to both clade peptides contributed 54.23% (954/1759) to the total responses. No significant difference was observed between the overall magnitude or frequency of CTL responses to clade B proteins and those to clade C proteins. According to the profiles of CTL magnitude and CTL frequency, the top 44 and 35 synthetic peptides were identified as immunodominant regions in the clade B and C consensus sequences respectively and 27 corresponding peptides in two immunodominant regions were cross-reactive. These peptides with cross-reactivity had a significantly higher ability to elicit CTL responses (P< 0.01) and preferentially had a trend of lower entropy and higher inter-clade homology. A wide degree of cross-clade reactivity of HIV-1-specific T cells exist in clade B and clade C variants. Most of immunodominant peptides with cross-reactivity are vigorous to elicit CTL responses and preferentially be conservative. This result may make future HIV-1 vaccines including multiple copies of CTL epitopes in these immunodominant peptides effective for this population.     

Activation of HIV type 1 specific cytotoxic T lymphocytes from semen by HIV type 1 antigen-presenting dendritic cells and IL-12

Seminal HIV-1-specific cytotoxic T lymphocytes (CTLs) could provide an important immune defense against local HIV-1 infection, and be important in impeding the spread of HIV-1 infection. In this study, we demonstrate that autologous blood-derived dendritic cells (DCs) loaded in vitro with synthetic HIV-1 peptides representing known CTL epitopes activated HLA class I restricted, anti-HIV-1 CTLs and interferon gamma responses in seminal CD8+ T cells from subjects with chronic HIV-1 infection on antiretroviral therapy. CTLs specific for the same HLA-restricted epitopes were detected in semen and blood of the same individuals by stimulation with peptide-loaded DCs. Anti-HIV-1 CTL responses from semen were enhanced by stimulation with DCs loaded with HIV-1 peptides and interleukin 12. Our results suggest that blood-derived DCs have HIV-1 antigen-presenting capacity for seminal CTL in HIV-1-infected subjects. The DC-T cell system can serve as a model for immunotherapy of HIV-1 infection in the local genital tract as well as systemic blood circulation.     

Relationship between human immunodeficiency virus type 1 (HIV-1)-specific memory cytotoxic T lymphocytes and virus load after recent HIV-1 seroconversion.

Human immunodeficiency virus type 1 (HIV-1)-specific memory, or precursor, cytotoxic T lymphocytes (CTL) in 14 subjects who had recently experienced seroconversion were evaluated with respect to virus set point, defined as plasma HIV-1 RNA level 6 months after seroconversion. Env-, Gag-, Pol-, and Nef-specific precursor CTL were detected in (51)Cr-release assays, using antigen-stimulated peripheral blood mononuclear cells as effectors and B cell lines infected with HIV-1-vaccinia recombinants as targets. All subjects tested had precursor CTL specific to at least 2 HIV-1 antigens. Detection of Env-specific precursor CTL was associated with a high set point (P=.0221). The number of antigens recognized tended to be greater in subjects with higher set points (rho=.45621; P=.1171). Gag-specific precursor CTL frequency correlated inversely with set point (rho=-.8478; P=.0003). Two heterozygotes for a 32-bp deletion in CCR5 had the lowest set points (P=.0220) and highest Gag precursor CTL frequencies (P=.0128). These data suggest that host factors that restrict viral replication may be important determinants of the level of HIV-1-specific precursor CTL.