Molecular Mechanisms of Eastern Equine Encephalitis Virus Pathogenesis

描述（由申请人提供）：节肢动物载体的甲病毒东部马脑炎病毒（EEEV）是美国（US）特有的最具毒性的病毒之一，在感染的人和马中引起毁灭性的疾病和死亡率很高。由于其极端的神经毒性，在美国东部的广泛分布以及用作生物武器的潜力，它被归类为Select Agent病毒和NIH B类优先病原体。然而，目前还没有抗病毒药物或获得许可的人类疫苗可用于对抗这种病毒，而且对这种病毒的研究严重不足。病毒-受体相互作用是抗病毒治疗的靶标，可用于合理设计疫苗载体。硫酸乙酰肝素（HS）是一种硫酸酸化多糖，被确定为多种甲型病毒和黄病毒实验室菌株的附着受体，但其与自然界病毒的相关性尚存疑问，因为其

DESCRIPTION (provided by applicant): The arthropod-vectored alphavirus eastern equine encephalitis virus (EEEV) is one of the most virulent viruses endemic to the United States (US), causing devastating disease and mortality in a high percentage of infected humans and equines. Due to its extreme neurovirulence, widespread distribution in the eastern US and potential for use as a bioweapon, it is categorized as a Select Agent virus and NIH Category B Priority Pathogen. Yet, no antiviral drugs or licensed human vaccines are available to combat this virus and it is critically understudied. The virus-receptor interaction represents a target fo antiviral therapeutics and can be used in rational design of vaccine vectors. Heparan sulfate (HS) is a sulfated polysaccharide identified as an attachment receptor for multiple alphavirus and flavivirus laboratory strains but its relevance to viruses in nature is in question because its use as a receptor is possibly an artifact of adaptation to in vitro growth. To address this question, we compared the E2 attachment protein amino acid sequence between a HS binding EEEV laboratory strain and over 60 EEEV strains, including viruses sequenced directly from unamplified field samples of animal tissues. This analysis confirmed that HS is a receptor for naturally circulating EEEV. By mutagenesis of the EEEV attachment protein eliminating the HS binding phenotype, we determined that HS binding was responsible for multiple unique aspects of EEEV disease in vertebrates including extreme neurovirulence, limited spleen replication and suppression of cytokines/chemokines involved in innate and adaptive immune responses. This suggests that HS binding promotes EEEV replicative fitness in vivo. The experiments in this application will investigate the role of HS binding in EEEV disease and tissue targeting in vertebrate and mosquito hosts identifying points in the arbovirus replication/transmission cycle vulnerable to therapeutic intervention and provide the basis for the rational design of anti-EEEV vaccines.