The use of goat model to test human Brucella vaccines in Argentina

描述（由申请人提供）：我们拟议研究的目标是开发安全有效的布鲁氏菌感染疫苗。我们的一般方法集中在减毒活疫苗（LAV）的使用。减毒活生物体的使用通常被认为是细胞内细菌如布鲁氏菌属的疫苗选择。这种策略利用了生物体的自然特性，包括细胞侵袭和组织嗜性，同时提供了完整的免疫原，并得到了成功历史的支持。然而，目前可用的疫苗对人类使用是不安全的。我们一直在寻求鉴定可安全用于人类的改良减毒活疫苗候选物。潜在布鲁氏菌疫苗的常规检测利用小鼠模型来评价毒力和免疫保护。然而，小鼠没有表现出“布鲁氏菌”感染的外部迹象。因此，评价候选疫苗的下一步是在 目标物种。对于人类疫苗开发，这可能表明在此评价阶段使用非人灵长类动物。然而，可以在小型反刍动物模型（如绵羊或山羊）中进行疫苗评价，以排除产生与疾病相关症状（包括流产）的候选动物，从而提供最终的安全性评价。虽然胎盘组织嗜性在反刍动物中仍然是一个有充分记录的现象，但布鲁氏菌并不被认为是人类流产的重要原因。然而，最近的证据表明，在流行地区，接触与堕胎率上升之间存在着很强的相关性。此外，有强有力的证据支持羊种布鲁氏菌在人滋养层细胞中生长。综上所述，这些数据为我们的LAV的持续发展提供了强有力的支持，因为我们显然需要改进保护策略，以减少人类疾病的可能性。在山羊中的实验预计将为在非人灵长类动物中测试这些候选物的实验提供支持，最终目标是开发一种对人类使用安全有效的布鲁氏菌疫苗。所概述的努力利用了我们最近开发的平台（包封）来延长免疫系统刺激，而不延长疫苗株的存活。使用这种创新方法，我们通过多层次的研究取得了进展，以证明LAV的有效性和安全性，为实现开发提供了强有力的理由。的 所提出的方法的竞争优势和创新包括：（1）在良好建立的、稳定的遗传背景下评价高度减毒的、安全的基因敲除;（2）在尽可能严格的条件下评价安全性;（3）支持非人灵长类动物模型的开发;（4）降低生物防护水平的潜力，以及对生产（GMP）和临床试验、生产和分销的未来进展的支持。

DESCRIPTION (provided by applicant): The goal of our proposed research is the development of vaccines against Brucella infection that are safe and efficacious. Our general approach has focused on the use of live attenuated vaccines (LAV). The use of live attenuated organisms are generally considered to be the vaccine of choice for intracellular bacteria such as Brucella spp. This strategy take advantage of the natural properties of the organism, including cell invasion and tissue tropism while presenting a full complement of immunogens, and is supported by a history of success. However, currently available vaccines are unsafe for use in humans. We have sought to identify improved live, attenuated vaccine candidates that are safe for use in humans. Routine testing of potential Brucella vaccines utilizes the mouse model to evaluate virulence and immune protection. However, mice fail to exhibit the outward signs of "Brucella" infection. As a result the next step in evaluation of vaccine candidates has been in the target species. For human vaccine development this might suggest the use of nonhuman primates at this stage of evaluation. However, evaluation of vaccines may be performed in a small ruminant model such as sheep or goats to eliminate candidates that produce symptoms associated with disease including abortion, providing an ultimate evaluation of safety. Although placental tissue tropism remains a well-documented phenomenon in ruminants, Brucella has not been considered to be a significant cause of human abortion. However, recent evidence revealed a strong correlation between exposure and elevated rates of abortion in endemic regions. Furthermore, there is strong evidence supporting growth of Brucella melitensis in human trophoblasts. Taken together, these data provide strong support for continued development of our LAV based on the obvious need for improved protection strategies to reduce the potential for human disease. Experiments in goats are expected to provide the support for experimentation to test these candidates in nonhuman primates with the ultimate goal of developing a Brucella vaccine that is safe and efficacious for human use. The efforts outlined have taken advantage of our recently developed platform (encapsulation) to prolong immune system stimulation without prolonging the survival of the vaccine strain. Using this innovative approach we have progressed through multiple levels of investigation to demonstrate efficacy and safety of the LAV providing strong justification to bring development to fruition. The competitive advantages and innovations of approach presented include: (1) evaluation of highly attenuated, safe, gene knockouts in well-established, stable genetic background; (2) safety evaluation under the most stringent conditions possible, (3) support for development of a nonhuman primate model; (4) potential to reduce biocontainment level and support for manufacturing (GMP) and future progress for clinical trials, production and distribution.