Innate immune evasion and/or antagonism by eastern equine encephalitis virus

描述（由申请人提供）：东部马脑炎病毒（EEEV）是托加病毒科的一种阿尔法病毒，被美国国立卫生研究院列为B类优先病原体清单，并被美国农业部列为高度严重的牲畜病原体，因为它对人类和马具有高度致命性，并且由于缺乏有效的疫苗和治疗方法，EEEV。EEEV的福尔马林灭活疫苗株由于免疫原性差，可能存在残留毒力，不适合大规模用于人类。显然，需要疫苗生产的替代战略。我们的长期目标是开发一种减毒活疫苗，其减毒程度足以使人类安全。提出的研究目标是通过选择性删除（或禁用）先天免疫逃避特性来合理设计减毒菌株。这将基于EEEV具有拮抗受感染树突状细胞（dc）引发的干扰素α / β (IFN-a/b)反应的机制的假设，而树突状细胞（dc）可以被禁用以减弱病毒并增强免疫反应。几个关键的观察结果使我们相信，甲型病毒对IFN-a/b介导的抗病毒活性的相对敏感性是毒性和衰减的主要决定因素。我们对Sindbis病毒（SB）的研究表明，这种对哺乳动物IFN-a/b几乎没有或没有逃避或拮抗能力的甲病毒在小鼠体内的毒性非常弱，而对小鼠有毒性的甲病毒，如委内瑞拉马脑炎病毒（VEEV），对IFN-a/b的抗病毒活性相对更有抵抗力。对IFN-a/b敏感性增加的VEEV突变体在小鼠中被减弱。由于EEEV在面对功能性IFN-a/b反应时也保持毒力，并且甲型病毒的毒力似乎与IFN-a/b耐药性密切相关，我们假设EEEV逃避和/或禁用IFN-a/b反应的成分。为了更好地了解EEEV与SB相比克服IFN-a/b抗病毒活性的方式，我们建议通过确定哪些IFN-a/b介导的途径被EEEV拮抗或逃避，从而开发出对IFN-a/b敏感的活减毒EEEV菌株。具体而言，我们将确定相对于SB EEEV是否能够：i)拮抗抗病毒效应物；ii)避免/抑制IFN-a/b的诱导；和/或iii)抑制IFN-a/b介导的信号传导。我们预计这些研究将为未来鉴定和禁用eeev编码的拮抗IFN-a/b活性的产物提供基础。预期产品：我们的长期目标是合理设计减毒甲型病毒毒株，通过选择性灭活先天免疫逃避特性，使其具有足够的衰减程度，对人类安全。

DESCRIPTION (provided by applicant): Eastern equine encephalitis virus (EEEV), an Alphavirus in the family Togaviridae, is classified in Category B of the NIH Priority Pathogens List, and as a high consequence livestock pathogen by the USDA because it is highly lethal for humans and equines, and because effective vaccines and therapies are lacking, EEEV. The formalin-inactivated vaccine strain of EEEV is not suitable for wide-scale human use due to poor immunogenicity and possible residual virulence. Clearly alternative strategies for vaccine production are required. Our long-term goal is to develop a live-attenuated virus vaccine with sufficient degree of attenuation to be safe for human populations. The objective of the proposed research is the rational design of attenuated strains via the selective deletion (or disabling) of innate immune evasion properties. This will be based on the hypothesis that EEEV possesses mechanism(s) to antagonize the interferon alpha/beta (IFN-a/b) response elicited by infected dendritic cells (DCs) which can be disabled to attenuate the virus and enhance the immune response. Several key observations lead us to believe that the relative sensitivity of alphaviruses to IFN-a/b-mediated antiviral activity is a primary determinant of virulence and attenuation. Our studies with Sindbis virus (SB) have revealed that this alphavirus with little or no ability to evade or antagonize mammalian IFN-a/b is extremely attenuated in mice whereas, a mouse-virulent alphavirus, such as Venezuelan equine encephalitis virus (VEEV), is relatively much more resistant to the antiviral activity of IFN-a/b. Mutants of VEEV with increased sensitivity to IFN-a/b are attenuated in mice. As EEEV also remains virulent in the face of a functional IFN-a/b response, and alphavirus virulence appears to be strongly correlated with IFN-a/b resistance, we hypothesize that EEEV evades and/or disables components of the IFN-a/b response. We propose to gain a better understanding of the way(s) in which EEEV overcomes the antiviral activity of IFN-a/b by comparison to SB with the goal of developing an IFN-a/b sensitive, live-attenuated EEEV strain by determining which IFN-a/b-mediated pathway(s) are antagonized or evaded by EEEV. Specifically we will determine relative to SB whether EEEV is able to: i) antagonize/resist antiviral effectors; ii) avoid/suppress induction of IFN-a/b; and/or iii) suppress IFN-a/b- mediated signaling. We anticipate that these studies will provide the foundation for future identification and disablement of EEEV-encoded product(s) that antagonize IFN-a/b activity. Anticipated product(s): Our long-term goal is the rational design of attenuated alphavirus strains with sufficient degree of attenuation to be safe for human populations via the selective inactivation of innate immune evasion properties.