Biosafety of herpesvirus vectors

Herpesviruses are large DNA viruses, which possess a number of advantages as gene delivery vectors. These relate to an ability to package large DNA insertions and establish lifelong latent infections in which the viral genome exists as a stable episome in the nucleus. For gene therapy to become a potential future treatment option, biosafe therapeutically efficient gene transfer is a central, but more and more stringent requirement. This review highlights the progress in development of herpesvirus based vectors, describes their properties as wall as discusses the biosafety concerns that are associated with their use in gene therapy. Thought was also given to biosafety issues pertaining to design and production of herpesvirus vector systems in therapeutic gene delivery.     

Biosafety of adenoviral vectors

Adenoviral vectors can efficiently transduce a broad variety of different cell types and have been used extensively in preclinical and clinical studies. However, early generation of adenoviral vectors retained residual adenoviral genes that contribute to inflammatory immune responses and toxicity. In addition, these vectors often result in transient expression of the potentially therapeutic transgene. Some clinical trials based on early generation adenoviral vectors have been discontinued because of acute inflammatory responses and toxicity and even one patient has died as a direct consequence of adenoviral toxicity. The latest generation of high-capacity adenoviral vectors is devoid of viral genes, and is having a significantly improved safety profile and yielding more prolonged transgene expression compared to early generation vectors. Nevertheless, transgene expression gradually declines even when high-capacity adenoviral vectors are used, possibly due to the gradual loss of vector genomes. Despite their improved safety, high-capacity adenoviral vectors can still trigger transient toxic effects in animals and patients. Restricting the tropism of adenoviral vectors by immunologic or genetic re-targeting may further improve their therapeutic window. The safety of adenoviral vectors has been improved further through the development of safer packaging systems that eliminate the homologous overlap between vector and helper sequences and therefore prevent formation of replication-competent adenoviruses (RCA). RCA could exacerbate inflammatory responses and act as a helper to rescue adenoviral vectors, potentially increasing the effective vector dose. Conditionally replicating adenoviruses (CRAds) have been developed for cancer gene therapy, which replicate selectively in some cancer cells. The use of CRAds in combination with chemotherapy yielded therapeutic effects in patients suffering from cancer but dose-limiting toxicity was apparent. Although there appears to be a very low theoretical risk of malignancy that is predominantly associated with the occurrence of E1-positive recombinants, no malignancies have been reported that were associated with adenoviral vectors. Nevertheless, integrating adenoviral vectors carry a greater malignancy risk due to their ability to integrate randomly into the target genomes.     

Biosafety of lentiviral vectors

The characteristics of lentiviral vectors (stable integration in non-dividing and dividing cells, long-term expression of the transgene, absence of immune response) make them ideal gene transfer vehicula for future gene therapy. However, the most potent lentiviral vectors are derived from highly pathogenic human viruses, such as HIV. We describe how the field has engineered lentivectors with increasing biosafety both for the lab worker and for the patient. The risk associated with state-of-the-art lentivectors is therefore minimal, although a psychological barrier to use these vectors in the clinic may still have to be overcome. Due to their increased performance, care should be taken to avoid accidental transduction of the lab worker with potential hazardous genes. The precautions which have to be taken are described in detail.     

强的松龙纳米微球缓释膜的生物安全性

背景：如何用药物去抑制神经修复后瘢痕的生长成为周围神经损伤后功能恢复的关键。课题组以往研究借鉴广泛应用于抗肿瘤药物局部释放的纳米微球缓释技术设计了一种强的松龙纳米微球缓释膜,取得了良好的体外药物缓释效果。 目的：制备强的松龙纳米微球缓释膜,观察该膜的生物相容性及安全性。 方法：采用反胶束乳化溶剂挥发法和球膜结合的方法制备强的松龙纳米微球缓释膜,用细胞毒性实验、溶血实验、急慢性全身毒性实验对药膜的生物安全性进行初步评价。 结果与结论：培养第7天,L929小鼠成纤维细胞相对增殖率为92.6%,证实此膜无细胞毒性;该膜对新鲜的抗凝兔血溶血率为0.59%,无明显的溶血作用;此缓释膜的浸提液腹腔注射小鼠未见明显的生物学行为的异常,对大鼠肝肾功能无明显影响。结果证实,强的松龙纳米微球缓释膜具有良好的生物相容性,安全无毒性。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

胶原基骨修复材料生物安全性评价

为了评价胶原基骨修复材料的生物安全性,我们将供试品或对照品植入大鼠体内观察相关指标(动物体征观察、血常规检查、免疫器官系数分析、各器官和组织的病理学检查、NK细胞杀伤活性测定、淋巴细胞亚群分析、血清中IL-1、IL-6、TNF-α、免疫球蛋白含量测定)。最终结果显示:各处理组大鼠实验前后精神状态无异常,在血常规检查、免疫器官系数分析、各器官和组织的病理学检查、NK细胞杀伤活性测定、淋巴细胞亚群分析、血清中IL-1、IL-6、TNF-α含量的检测、免疫球蛋白含量检测方面,实验组与对照组相比无显著差异。该材料对大鼠会产生轻微而短暂的刺激作用,但未见明显的炎症反应。     

非病毒型基因载体的生物安全性

近年来,基因载体的生物安全性越来越受到人们的关注,本文介绍了近年来非病毒型基因载体生物安全性的研究进展,综述了非病毒型基因载体的毒性、纳米效应、血液相容性以及免疫反应等方面的研究成果.     

Retroviral Vector Biosafety: Lessons from Sheep

The safety of retroviral-based systems and the possible transmission of replication-competent virus to patients is a major concern associated with using retroviral vectors for gene therapy. While much effort has been put into the design of safe retroviral production methods and effective in vitro monitoring assays, there is little data evaluating the risks resulting from retroviral vector instability at post-transduction stages especially following in vivo gene delivery. Here, we briefly describe and discuss our observations in an in vivo experimental model based on the inoculation of retroviral vector-transduced tumor cells in sheep. Our data indicates that the in vivo generation of mosaic viruses is a dynamic process and that virus variants, generated by retroviral vector-mediated recombination,may be stored and persist in infected individuals prior to selection at the level of replication. Recombination may not only restore essential viral functions or provide selective advantages in a changing environment but also reestablish or enhance the pathogenic potential of the particular virus undergoing recombination. These observations in sheep break new ground in our understanding of how retroviral vectors may have an impact on the course of a preestablished disease or reactivate dormant or endogenous viruses. The in vivo aspects of vector stability raise important biosafety issues for the future development of safe retroviral vector-based gene therapy.     

医院实验室生物安全管理策略

近年来,新发突发传染病疫情在全球范围内时有发生,医院临床实验室在疾病的诊疗和研究过程中的生物安全应对策略再次成为了焦点.本文以首都医科大学附属北京地坛医院的生物安全管理工作为例,介绍了该院的管理策略,包括建立完善的管理体系、开展全面的生物安全培训、加强实验室生物安全自查与督导等,以期为医院实验室生物安全管理策略提供参考...     

茂名市疾病预防控制机构实验室生物安全现状分析

目的全面掌握广东省茂名市疾病预防控制机构实验室的生物安全现状,为卫生部门进行生物安全管理提供决策依据。方法采用发放调查表和现场核实相结合的方法对全市疾病预防控制机构实验室生物安全现状进行调查分析。结果全市7个疾病预防控制机构中有6个建立了微生物实验室,其中4个为2级生物安全实验室;6家实验室虽然都配备了一定的生物安全设备,但与国家的标准相比还有比较大的差距;6家实验室均制定了一定的实验室生物安全管理制度,但制度落实不到位,实验室的生物安全日常管理工作做得也较差;6家实验室都能正确处理医疗废弃物,但生物安全培训工作开展得不够,人员健康监护做得也不合要求。结论应加强对茂名市疾病预防控制机构实验室相关人员的培训,提高他们的生物安全意识,加大实验室生物安全硬件投入,制定完善的生物安全管理规范和加大监管力度。     

State-of-the-Art in Biosafety and Biosecurity in European Countries

The terms biosafety and biosecurity are widely used in different concepts and refer not only to protection of human beings and their surrounding environment against hazardous biological agent, but also to global disarmament of weapons of mass destruction. As a result, the biosafety and biosecurity issues should be considered interdisciplinary based on multilateral agreements against proliferation of biological weapons, public health and environmental protection. This publication presents information on both, international and national biosafety and biosecurity legislation. Status of national implementation of the Biological and Toxin Weapons Convention, penalization issues and measures to account for and secure production, use, storage of particularly dangerous pathogens or activities involving humans, plants and animals where infection may pose a risk have been analyzed. Safety and security measures in laboratories have been studied. Moreover, dual-use technology and measures of secure transport of biohazard materials have been also taken into account. In addition, genetic engineering regulations, biosecurity activities in laboratories and code of conducts have been investigated, as well.     

汽化过氧化氢灭菌器及其在生物安全实验室的应用

汽化过氧化氢生物消毒技术在很多科学研究机构和行业中得到认可。本文详细介绍了汽化过氧化氢灭菌器的工作原理,综述了两种灭菌器的差异,根据生物安全实验室的消毒需要,分析了灭菌器在生物安全实验室的应用情况。     

中山市医疗机构实验室生物安全管理现状调查

目的了解中山市医疗机构实验室生物安全管理现状,为进一步加强和规范医疗机构实验室生物安全管理工作提供依据。方法设计《实验室生物安全自查表》,对中山市各类医疗卫生机构共29家单位进行问卷调查,使用Excel软件对数据进行统计分析。结果中山市医疗机构生物安全实验室在安全管理制度的制定、防护设备使用方面与生物安全管理要求尚有一定差距．尤其在菌毒种管理和运送方面存在安全隐患。结论中山市生物安全实验室的管理工作需要加强,应尽快建立健全的实验室生物安全管理体制。     

Retroviral vectors.

Traditionally, the retrovirus is regarded as an enemy to be overcome. However, for the past two decades retroviruses have been harnessed as vehicles for transferring genes into eukaryotic cells, a process known as transduction. During this time, the technology has moved from being a scientific laboratory tool to a potential clinical molecular medicine to be used in gene therapy. This review explains the strategy for harnessing the retrovirus life cycle, the scientific research and clinical applications of this methodology, and its limitations, as well as possible future developments.     

肺炎链球菌自溶酶（LytA）黏膜免疫小鼠的生物安全性评价

目的开展肺炎链球菌自溶酶（LvtA）生物安全性的动物实验研究,为其申报生物制品鉴定提供实验数据。方法制备纯化的重组表达LytA蛋白,以6．5μg、13．0μg和19．5μg3种剂量黏膜免疫BALB／c小鼠,根据《中华人民共和国国家标准食品安全性毒理学评价程序》（GB15193．1—1994）进行LytA的90d喂养试验、传统致畸试验及遗传毒性试验检测,以分析其生物安全性。结果90d喂养试验结果显示各实验组小鼠与对照组小鼠的体重增长趋势一致,且各时间点检测的小鼠体重均无显著性差异（P〉0．05）。传统致畸试验检测发现各实验组小鼠与对照组小鼠心脏、肺、肝脏、肾、脾、胃、子宫重量、红细胞和白细胞数目、谷丙转氨酶、尿素氮、总胆固醇、甘油三脂、血糖、总蛋白、自蛋白及球蛋白等指标均元明显差异（P〉0．05）。小鼠骨髓嗜多染红细胞微核试验结果显示LytA经鼻腔黏膜免疫小鼠无遗传毒性。结论利用90d喂养试验、传统致畸试验及遗传毒性试验证明LytA鼻腔黏膜免疫BALB／c小鼠安全、毒副作用不明显,有良好的生物安全性,值得进一步研究。     

医疗机构中实验室生物安全培训现状与对策研究

新发突发传染病导致的实验室获得性感染事件引起了医学界的关注,已有研究表明大多数实验室获得性感染事件发生的主要原因是实验室生物安全培训不足.本文以医疗机构中实验室生物安全培训现状为切入点,讨论分析其中存在的问题,并初步提出了解决办法,以期进一步改进医院实验室生物安全培训工作,减少实验室获得性感染事件.     

Immunologic basis of vaccine vectors

Efforts to make vaccines against infectious diseases as well as immunotherapies for cancer, autoimmune diseases and allergy have utilized a variety of heterologous expression systems, including viral and bacterial vectors, as well as DNA and RNA constructs. This review explores the immunologic rationale and provides an update of insights obtained from preclinical and clinical studies of such vaccines.