BACKGROUND Hazara virus (HAZV) is a member of the Bunyaviridae family of segmented negative stranded RNA viruses, and shares the same serogroup as Crimean-Congo haemorrhagic fever virus (CCHFV). CCHFV is responsible for fatal human disease with a mortality rate approaching 30 %, which has an increased recent incidence within southern Europe. There are no preventative or therapeutic treatments for CCHFV-mediated disease, and thus CCHFV is classified as a hazard group 4 pathogen. In contrast HAZV is not associated with serious human disease, although infection of interferon receptor knockout mice with either CCHFV or HAZV results in similar disease progression. To characterise further similarities between HAZV and CCHFV, and support the use of HAZV as a model for CCHFV infection, we investigated the structure of the HAZV nucleocapsid protein (N) and compared it to CCHFV N. N performs an essential role in the viral life cycle by encapsidating the viral RNA genome, and thus, N represents a potential therapeutic target. RESULTS We present the purification, crystallisation and crystal structure of HAZV N at 2.7 Å resolution. HAZV N was expressed as an N-terminal glutathione S-transferase (GST) fusion protein then purified using glutathione affinity chromatography followed by ion-exchange chromatography. HAZV N crystallised in the P212121 space group with unit cell parameters a = 64.99, b = 76.10, and c = 449.28 Å. HAZV N consists of a globular domain formed mostly of alpha helices derived from both the N- and C-termini, and an arm domain comprising two long alpha helices. HAZV N has a similar overall structure to CCHFV N, with their globular domains superposing with an RMSD = 0.70 Å, over 368 alpha carbons that share 59 % sequence identity. Four HAZV N monomers crystallised in the asymmetric unit, and their head-to-tail assembly reveals a potential interaction site between monomers. CONCLUSIONS The crystal structure of HAZV N reveals a close similarity to CCHFV N, supporting the use of HAZV as a model for CCHFV. Structural similarity between the N proteins should facilitate study of the CCHFV and HAZV replication cycles without the necessity of working under containment level 4 (CL-4) conditions.

中文翻译：

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哈扎拉病毒核衣壳蛋白的晶体结构。

背景技术哈扎拉病毒（HAZV）是分段负链RNA病毒的Bunyaviridae家族的成员，并且与克里米亚-刚果出血热病毒（CCHFV）具有相同的血清群。CCHFV导致致命的人类疾病，死亡率接近30％，最近在南欧发生率上升。没有针对CCHFV介导的疾病的预防或治疗方法，因此CCHFV被分类为4类危险病原体。相反，尽管用CCHFV或HAZV感染干扰素受体敲除小鼠会导致相似的疾病进展，但HAZV与严重的人类疾病无关。为了表征HAZV与CCHFV之间的进一步相似性，并支持将HAZV用作CCHFV感染的模型，我们研究了HAZV核衣壳蛋白（N）的结构，并将其与CCHFV N进行了比较。N通过包裹病毒RNA基因组在病毒生命周期中起着至关重要的作用，因此N代表了潜在的治疗靶点。结果我们介绍了2.7Å分辨率的HAZV N的纯化，结晶和晶体结构。将HAZV N表示为N端谷胱甘肽S-转移酶（GST）融合蛋白，然后使用谷胱甘肽亲和色谱，然后进行离子交换色谱进行纯化。在P212121空间群中结晶的HAZV N的晶胞参数为a = 64.99，b = 76.10和c = 449.28Å。HAZV N由主要由衍生自N和C末端的α螺旋形成的球形结构域和包含两个长α螺旋的臂结构域组成。HAZV N的总体结构与CCHFV N相似，它们的球状结构域以RMSD = 0.70Å重叠，超过368个具有59％序列同一性的α碳。在不对称单元中结晶的四种HAZV N单体，其头尾组装揭示了单体之间的潜在相互作用位点。结论HAZV N的晶体结构显示出与CCHFV N极为相似，从而支持使用HAZV作为CCHFV的模型。N蛋白之间的结构相似性应有助于CCHFV和HAZV复制周期的研究，而无需在4级遏制（CL-4）条件下工作。结论HAZV N的晶体结构显示出与CCHFV N极为相似，从而支持使用HAZV作为CCHFV的模型。N蛋白之间的结构相似性应有助于CCHFV和HAZV复制周期的研究，而无需在4级遏制（CL-4）条件下工作。结论HAZV N的晶体结构显示出与CCHFV N极为相似，从而支持使用HAZV作为CCHFV的模型。N蛋白之间的结构相似性应有助于CCHFV和HAZV复制周期的研究，而无需在4级遏制（CL-4）条件下工作。