J Immunology：HSV-2抗宿主免疫机制

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HSV-2病毒是生殖器疱疹的主要病原，一旦感染，患者将终身携带这种病毒并周期性地出现生殖器疱疹性损伤，HSV-2感染还会增加HIV-1传播的风险，且目前没有针对HSV-2的有效疫苗问世。由于HSV-2的高阳性率及与HIV-1共同的传播途径，针对HSV-2的相关研究越来越受到重视。

前人研究表明HSV-2建立持续性感染须抑制宿主细胞的抗病毒I型干扰素（IFNα/β）信号通路，但机制不明。中国科学院武汉病毒研究所胡勤学学科组研究发现，HSV-2通过其极早期蛋白US1抑制IFN-β的产生，逃避宿主天然免疫的控制。这个发现为双链DNA病毒家族如何阻断I型IFN信号通路提供了新的机制。

生殖道黏膜部位不易建立针对HSV-2长期有效的记忆性免疫保护，这成为疱疹病毒疫苗研制的主要瓶颈。胡勤学学科组利用了趋化因子CCL19能够靶向性地趋化和招募免疫细胞到次级淋巴器官及黏膜组织的特性，将候选免疫原HSV-2 gB蛋白与CCL19 制成嵌合的DNA疫苗。结果发现“gB-CCL19”嵌合疫苗能够在小鼠体内诱导很好的保护作用，从而为设计针对HSV-2或其他性传播病毒的疫苗奠定了基础。

来源：武汉病毒研究所

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HSV-2 Immediate-Early Protein US1 Inhibits IFN-β Production by Suppressing Association of IRF-3 with IFN-β Promoter

Mudan Zhang*,†, Yalan Liu*, Ping Wang*,†, Xinmeng Guan*,†, Siyi He*,†, Sukun Luo*,†, Chang Li*,†, Kai Hu*, Wei Jin*,†, Tao Du*, Yan Yan*,†, Zhenfeng Zhang*, Zhenhua Zheng*, Hanzhong Wang* and Qinxue Hu*,‡

HSV-2 is the major cause of genital herpes, and its infection increases the risk of HIV-1 acquisition and transmission. After initial infection, HSV-2 can establish latency within the nervous system and thus maintains lifelong infection in humans. It has been suggested that HSV-2 can inhibit type I IFN signaling, but the underlying mechanism has yet to be determined. In this study, we demonstrate that productive HSV-2 infection suppresses Sendai virus (SeV) or polyinosinic-polycytidylic acid-induced IFN-β production. We further reveal that US1, an immediate-early protein of HSV-2, contributes to such suppression, showing that US1 inhibits IFN-β promoter activity and IFN-β production at both mRNA and protein levels, whereas US1 knockout significantly impairs such capability in the context of HSV-2 infection. US1 directly interacts with DNA binding domain of IRF-3, and such interaction suppresses the association of nuclear IRF-3 with the IRF-3 responsive domain of IFN-β promoter, resulting in the suppression of IFN-β promoter activation. Additional studies demonstrate that the 217–414 aa domain of US1 is critical for the suppression of IFN-β production. Our results indicate that HSV-2 US1 downmodulates IFN-β production by suppressing the association of IRF-3 with the IRF-3 responsive domain of IFN-β promoter. Our findings highlight the significance of HSV-2 US1 in inhibiting IFN-β production and provide insights into the molecular mechanism by which HSV-2 evades the host innate immunity, representing an unconventional strategy exploited by a dsDNA virus to interrupt type I IFN signaling pathway.

http://www.jimmunol.org/content/194/7/3102.abstract