Laboratory of Virology, NIAID, NIH, Hamilton, Montana, USA.
Rocky Mountain Veterinary Branch, Division of Intramural Research, NIAID, NIH, Hamilton, Montana, USA.
J Virol. 2019 Aug 28;93(18). doi: 10.1128/JVI.00554-19. Print 2019 Sep 15.
Crimean-Congo hemorrhagic fever virus (CCHFV) is a cause of severe hemorrhagic fever. Its tick reservoir and vector are widely distributed throughout Africa, Southern and Eastern Europe, the Middle East, and Asia. Serological evidence suggests that CCHFV can productively infect a wide variety of species, but only humans develop severe, sometimes fatal disease. The role of the host adaptive immunity in control or contribution to the severe pathology seen in CCHF cases is largely unknown. Studies of adaptive immune responses to CCHFV have been limited due to lack of suitable small animal models. Wild-type mice are resistant to CCHFV infection, and type I interferon-deficient mice typically develop a rapid-onset fatal disease prior to development of adaptive immune responses. We report here a mouse model in which type I interferon-deficient mice infected with a clinical isolate of CCHFV develop a severe inflammatory disease but ultimately recover. Recovery was coincident with development of CCHFV-specific B- and T-cell responses that were sustained for weeks postinfection. We also found that recovery from a primary CCHFV infection could protect against disease following homologous or heterologous reinfection. Together this model enables study of multiple aspects of CCHFV pathogenesis, including convalescence, an important aspect of CCHF disease that existing mouse models have been unsuitable for studying. The role of antibody or virus-specific T-cell responses in control of acute Crimean-Congo hemorrhagic fever virus infection is largely unclear. This is a critical gap in our understanding of CCHF, and investigation of convalescence following severe acute CCHF has been limited by the lack of suitable small animal models. We report here a mouse model of CCHF in which infected mice develop severe disease but ultimately recover. Although mice developed an inflammatory immune response along with severe liver and spleen pathology, these mice also developed CCHFV-specific B- and T-cell responses and were protected from reinfection. This model provides a valuable tool to investigate how host immune responses control acute CCHFV infection and how these responses may contribute to the severe disease seen in CCHFV-infected humans in order to develop therapeutic interventions that promote protective immune responses.
克里米亚-刚果出血热病毒(CCHFV)是一种严重出血热的病原体。其蜱虫储存库和传播媒介广泛分布于非洲、南欧和东欧、中东和亚洲。血清学证据表明,CCHFV 可以有效地感染多种物种,但只有人类会发展出严重的、有时是致命的疾病。宿主适应性免疫在控制或促成 CCHF 病例中严重病理方面的作用在很大程度上是未知的。由于缺乏合适的小动物模型,对 CCHFV 适应性免疫反应的研究受到限制。野生型小鼠对 CCHFV 感染具有抗性,而 I 型干扰素缺陷型小鼠在产生适应性免疫反应之前通常会迅速发展为致命疾病。我们在此报告了一种小鼠模型,其中 I 型干扰素缺陷型小鼠感染 CCHFV 的临床分离株会发展出严重的炎症性疾病,但最终会康复。康复与 CCHFV 特异性 B 细胞和 T 细胞反应的发展同时发生,并在感染后数周内持续存在。我们还发现,从初次 CCHFV 感染中恢复可防止同源或异源再感染后的疾病。总的来说,这种模型使我们能够研究 CCHFV 发病机制的多个方面,包括恢复期,这是 CCHF 疾病的一个重要方面,而现有的小鼠模型并不适合研究。抗体或病毒特异性 T 细胞反应在控制急性克里米亚-刚果出血热病毒感染中的作用在很大程度上尚不清楚。这是我们对 CCHF 理解的一个关键差距,并且由于缺乏合适的小动物模型,对严重急性 CCHF 后的恢复期的研究受到限制。我们在此报告了一种 CCHF 的小鼠模型,其中感染的小鼠会发展出严重的疾病,但最终会康复。尽管小鼠会发展出炎症性免疫反应以及严重的肝脏和脾脏病理学,但这些小鼠也会产生 CCHFV 特异性 B 细胞和 T 细胞反应,并免受再感染。该模型为研究宿主免疫反应如何控制急性 CCHFV 感染以及这些反应如何促成 CCHFV 感染人类的严重疾病提供了有价值的工具,以便开发促进保护性免疫反应的治疗干预措施。