Assessment of the Immunogenicity and Protective Efficacy of a Multiagent DNA Vacc

描述(申请人提供)：埃博拉(EBOV)和马尔堡(MARV)病毒是NIAID A类病原体，可引起人类和非人类灵长类动物的严重出血热，死亡率高达90%。目前还没有获得许可的疫苗来预防由这些病毒引起的疾病。最近用重组水泡性口炎病毒(VSV)或腺病毒载体的EBOV或MARV疫苗在非人类灵长类动物中诱导保护性免疫的成功表明，可以开发出有效的疫苗。尽管结果很有希望，但人们对这些疫苗平台在人类身上的使用提出了担忧。重组腺病毒疫苗是复制缺陷的；因此，需要非常高的剂量来诱导保护性免疫。更重要的是，由于腺病毒是人类常见的病原体，大多数人都具有预先存在的免疫力，这极大地干扰了载体诱导对重组基因产物的免疫反应的能力。除了自然产生的预先存在的免疫外，重组腺病毒载体的广泛使用使疫苗开发领域变得复杂，因为疫苗接种产生的载体抗体将抑制对使用类似递送策略的独立疫苗的反应。相比之下，VSV载体是一种活病毒疫苗，通常不会感染人类；然而，它是一种人类病原体，人们对其使用提出了重大的安全担忧。相比之下，DNA疫苗在许多人类临床试验中已被证明是安全的，不存在媒介免疫的可能性。虽然DNA疫苗在人类身上缺乏足够的效力，但体内电穿孔递送系统的开发有可能解决这一缺点。申请的资金不仅将促进安全有效的埃博拉(EBOV)和马尔堡(Marv)病毒联合疫苗的进展，还将推动疫苗交付平台的开发，该平台有能力解决生物防御领域所需的许多性能属性，即易于制造、稳定的疫苗，其效力足以在很少接种后对多种病原体提供保护效果。因此，提出的研究直接解决了这次征集的目标。这项研究的具体目的是：(1)通过对两种EBOV病毒和两株MARV病毒GP基因的密码子优化，构建出适用于两种EBOV病毒和两株MARV病毒的改良DNA疫苗构建体；(2)比较不同剂量的EBOV和MARV DNA疫苗通过肌肉内或皮内途径注射给小鼠时的免疫原性；(3)评估和比较联合DNA疫苗与单独DNA疫苗在小鼠电穿孔免疫后的保护效力；(4)展示EBOV和MARV联合DNA疫苗对非人灵长类动物的免疫原性和保护效力。

DESCRIPTION (provided by applicant): Ebola (EBOV) and Marburg (MARV) viruses are NIAID Category A pathogens and cause severe hemorrhagic fevers in humans and nonhuman primates with mortalities as high as 90%. There are currently no licensed vaccines for preventing disease caused by these viruses. Recent successes in eliciting protective immunity in nonhuman primates with recombinant vesicular stomatitis virus (VSV) or adenovirus- vectored EBOV or MARV vaccines suggest that effective vaccines can be developed. Despite the promising results, concerns have been raised about the use of these vaccine platforms in humans. The recombinant adenovirus vaccines are replication deficient; thus, very high doses are needed to induce protective immunity. More importantly, because adenoviruses are common human pathogens, most humans have pre- existing immunity, which greatly interferes with the ability of the vector to induce an immune response to the recombinant gene product. In addition to naturally occurring preexisting immunity, the broad use of recombinant adenovirus vectors complicates the field of vaccine development because vector antibodies induced as the result of vaccination would suppress the responses to an independent vaccine utilizing a similar delivery strategy. In contrast, the VSV vector is a live virus vaccine that does not commonly infect humans; however, it is a human pathogen and significant safety concerns about its use have been raised. By comparison, DNA vaccines have been proven safe in many human clinical trials and there is no possibility of vector immunity. While DNA vaccines have lacked sufficient potency in humans, the development of in vivo electroporation delivery systems has the potential to address this shortcoming. The requested funding will not only facilitate progress toward safe and effective combination vaccines for Ebola (EBOV) and Marburg (MARV) viruses, but will also advance the development of a vaccine delivery platform that has the capacity to address many of the performance attributes desired in the field of biodefense, namely a readily manufactured, stable vaccine with sufficient potency to provide protective efficacy against multiple pathogens after few immunizations. As such, the research proposed directly addresses the goals of this solicitation. Specific aims of the research are to: (1) Generate improved DNA vaccine constructs for two species of EBOV and two strains of MARV through codon-optimization of the GP genes of each virus; (2) Compare the immunogenicity of the individual DNA vaccine candidates when delivered to mice in various dosages using electroporation via intramuscular or intradermal routes; (3) Evaluate and compare the protective efficacy of combined vs. individual DNA vaccines in mice after immunization by electroporation; (4) Demonstrate the immunogenicity and protective efficacy of combined EBOV and MARV DNA vaccines in non-human primates.