Construction of multivalent DNA vaccines forMycobacterium tuberculosis and its immunogenicity

The coding regions of Ag85B MPT-64, and ESAT-6 secreted proteins were cloned initially into the eukaryotic expression vector pJW4303, then transformed to E. coli Top 10 strain for plasmid DNA extraction and further analysis. Plasmids containing the right insertion were sequenced to confirm their identity. COS7 cells were transfected with a mixture containing serially diluted plasmid DNA encoding three secreted proteins and Lipofectin (Gibco). The supernatants and pellets prepared from various cell lines were run on SDS-PAGE gel and the expression of these proteins in COS7 cells were demonstrated by immunoblot using polyclonal or monoclonal antiserum of M.TBH37Rv. 21 days after first vaccination of C57BL-6 mice by all three recombinant eukaryotic expressing vectors, antibody titer for Ag85B reached 1∶3200. 21 days after second vaccination, the antibody titer reached 1∶102400. The highest antibody levels induced by multivalent vaccines after the second injection were equal to or even greater than the highest antibody levels of single DNA vaccine reported in literature after third injections. Antibody titer of MPT-64 was 1∶50 after the first injection and it reached 1∶200 after the second injection. No antigen-specific antibody against ESAT-6 was detected in sera harvested from immunized mice 21 days after both injections. Antigen-specific IFN-g level of Ag85B was 110 pg/mL while no antigen-specific IFN- g level of ESAT-6 and MPT-64 was detected even after third injections. To our knowledge, it is the first time that studies of polyvalent recombinant DNA vaccines against TB were carried out in C57BL-6 mice. Our results indicated that multiple DNA vaccines could be used to enhance protective responses against M.TB.     

Immune responses to DNA vaccines

DNA vaccines, based on plasmid vectors expressing an antigen under the control of a strong promoter, have been shown to induce protective immune responses to a number of pathogens, including viruses, bacteria and parasites. They have also displayed efficacy in treatment or prevention of cancer, allergic diseases and autoimmunity. Immunologically, DNA vaccines induce a full spectrum of immune responses that include cytolytic T cells, T helper cells and antibodies. The immune response to DNA vaccines can be enhanced by genetic engineering of the antigen to facilitate its presentation to B and T cells. Furthermore, the immune response can be modulated by genetic adjuvants in the form of vectors expressing biologically active determinants or by more traditional adjuvants that facilitate uptake of DNA into cells. The ease of genetic manipulation of DNA vaccines invites their use not only as vaccines but also as research tools for immunologists and microbiologists. Received 26 October 1998; received after revision 3 December 1998; accepted 3 December 1998     

Immunotherapy against antigenic tumors: a game with a lot of players

Our understanding of how immune responses are generated and regulated drives the design of possible immunotherapies for cancer patients. For that reason, we first describe briefly the actual immunological theories and their common perspectives about cancer vaccine development. Second, we describe cancer vaccines that are able to induce tumor-specific immune responses in cancer patients. However, these responses are not always followed by tumor rejection. At the end of the review, we discuss two possible reasons that might explain this dichotomy of cancer immunology. First, the immune response generated, although detectable, may not be quantitatively sufficient to reject the tumor. Second, the tumor microenvironment may modulate tumor cell susceptibility to the systemic immune response induced by the immunization. Finally, we discuss what, in our opinion, might be the best way to improve cancer vaccine strategies and how the relationship between the tumor and its surroundings might be studied in more details. Received 21 June 2001; received after revision 15 August 2001; accepted 15 August 2001     

Schistosome vaccines

Summary Schistosomiasis control currently relies primarily on chemotherapy which is both expensive and temporary. There is an urgent need for an effective vaccine. Studies in animal models and man have demonstrated the existence of protective immunity. Antibody-dependent cell-mediated cytotoxicity mechanisms involving eosinophils and macrophages have been implemented in destruction of the parasites. Antigens expressed on the surface of the schistosomulum are among the targets of protective immune responses. Vaccines comprising recombinant antigens are now being tested in vivo for their capacity to evoke protective responses. Live oral vaccines based on attenuatedSalmonella expressing schistosomular surface antigens are being developed.     

具有双线性感染率和免疫接种SIRS模型分析

根据传染病动力学,建立了一类具有双线性感染率和免疫接种的SIRS传染病模型.利用微分方程定性和稳定性理论,讨论了平衡点的性态和全局渐近稳定性,得到了一些新结果.     

2022年生命科学热点回眸

2022年,为应对全球新冠疫情和其他各种严重疾病,病毒疫苗开发和基因治疗领域的研究都取得了突破性进展,对于粮食作物种植和人类基因组学的研究也有了振奋人心的发现。选取了Omicron变异株、猴痘、呼吸道合胞病毒疫苗、EBV可能导致多发性硬化症、猪器官移植到人体、猪心停跳后恢复全身多器官功能、持续生产的多年生水稻、小麦条锈病分子机制、提高玉米蛋白含量和氮利用率、基因编辑技术和疗法、人类基因组无间隙序列、古基因组学等方面的研究成果进行解读。     

新型冠状病毒疫苗潜在不良反应的研究进展

新型冠状病毒(Severe Acute Respiratory Syndrome Coronavirus 2,SARS-CoV-2)感染引起的新型冠状病毒肺炎(Coronavirus Disease-2019,COVID-19,简称新冠肺炎)在全球流行暴发,严重威胁人类生命健康,给全球造成了巨大的医疗、经济和社会破坏。在目前缺乏特异性治疗方法的情况下,预防性疫苗是全球新冠肺炎防控最有效的手段,国内外已有17个(其中我国5个)新型冠状病毒疫苗(简称新冠疫苗)获批附条件上市或紧急使用。为了应对大规模疫苗接种潜在的不良反应挑战,本文对全球已投入使用的新冠疫苗的安全性进行总结,分析其潜在的不良反应,提出加强应对新冠疫苗接种不良事件及医疗应急保障的思考。     

植物基因工程疫苗研究进展

可口服免疫(oral immunization)绿色疫苗(green vaccine)研究是植物基因工程与分子医学相结合而发展起来的新的研究方向．对当前植物基因工程疫苗的研究方法、疫苗的作用机理进行介绍,总结近10年来国内外植物基因工程疫苗研究进展,并对未来发展方向作出展望．     

森林脑炎灭活疫苗对新西兰白兔肌肉刺激及豚鼠全身过敏试验

摘要: 目的比较生产场地变更前后森林脑炎灭活疫苗对新西兰白兔肌肉的刺激性和豚鼠的全身过敏反应,评估生产场地变更后森林脑炎灭活疫苗的动物安全性。方法采用两个生产场地各3 批森林脑炎灭活疫苗,其对新西兰白兔肌肉刺激试验进行对比分析,将12 只新西兰白兔随机分为两组,每组6 只,雌雄各半。两个生产场地均设佐剂对照组和森脑疫苗试验组,采用同体左、右侧自身对比法。分别于左、右侧股四头肌肌内注射佐剂和森脑疫苗。临床观察至第3 天解剖。大体剖检、常规病理制片、病理组织学检查及显微摄影记录。全身过敏试验取豚鼠6只,每只腹腔注射0. 5 mL,间日一次,连续3 次,每日观察每只豚鼠的行为和特征。首次致敏和激发前称量每只豚鼠的体质量,然后分成两组,每组3 只,分别在第一次注射后第14 日及第21 日静脉注射供试品1 mL,观察30 min。结果注射森脑疫苗后,有与佐剂对照组相似的肌肉刺激性损伤。生产场地变更前后,注射森脑疫苗局部肌肉组织的病理改变未见明显差异。结论生产场地变更后森脑疫苗与生产场地变更前森脑疫苗效力相同,具有可靠的动物安全性。     

三联疫苗对大黄鱼常见细菌性疾病免疫保护的实验研究

采用0.5%福尔马林4℃灭活和65℃热灭活2种不同的方法制备三联疫苗作为抗原,以多次腹腔注射或浸泡的方式免疫大黄鱼,通过测定受免大黄鱼血清中抗体凝集效价变化并进行攻毒实验以评估保护效果.结果表明:以福尔马林灭活疫苗注射免疫途径效果最佳,其血清抗体效价平均达1536,攻毒后1周内免疫保护率为88.9%;热灭活疫苗注射免疫途径效果也比较明显,其血清抗体效价平均达1024,攻毒后1周内免疫保护率为76.6%;福尔马林和热灭活疫苗浸泡免疫大黄鱼也有一定效果,免疫保护率分别为55.7%和44.6%.