de Souza Kátia Paulino Ribeiro, Silva Emanuele Guimarães, de Oliveira Rocha Eliseu Soares, Figueiredo Leandra Barcelos, de Almeida-Leite Camila Megale, Arantes Rosa Maria Esteves, de Assis Silva Gomes Juliana, Ferreira Gustavo Portela, de Oliveira Jaquelline Germano, Kroon Erna Geessien, Campos Marco Antônio
Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil.
Virol J. 2013 Aug 26;10:267. doi: 10.1186/1743-422X-10-267.
The clinical presentation of dengue is classified by the World Health Organization into dengue without warning signs, dengue with warning signs and severe dengue. Reports of neurological disease caused by Dengue virus (DENV) are becoming frequent, with symptoms that include reduced consciousness, severe headache, neck stiffness, focal neurological signs, tense fontanelle and convulsions. However, the immune mechanisms involved in neurovirulence remain poorly understood. Here we present a mouse model in which one genotype of DENV is inoculated by the intracranial route and infects C57/BL6 mice and replicates in the brain, causing death of mice.
Mice were infected with different serotypes/genotypes of DENV by the intracranial route to evaluate viral replication, host cytokine and nitric oxide synthase 2 (Nos2) expression in the brain via real-time PCR. Histological analysis of the brain tissues was also performed. An analysis of which cells were responsible for the expression of cytokines and Nos2 was performed using flow cytometry. Survival curves of infected animals were also generated
DENV 3 genotype I infected mice and replicated in the brain, causing death in our murine model. The increased levels of NOS2 could be the cause of the death of infected mice, as viral replication correlates with increased Nos2 and cytokine expression in the brain of C57BL/6 mice. In Nos2-/- mice that were infected with DENV, no clinical signs of infection were observed and cytokines were expressed at low levels, with the exception of interferon gamma (Ifng). Additionally, the Ifng-/- mice infected with DENV exhibited a severe and lethal disease, similar to the disease observed in C57BL/6 mice, while the DENV- infected Nos2-/- mice did not display increased mortality. Analyses of the brains from infected C57BL/6 mice revealed neuronal degeneration and necrosis during histopathologic examination. IFNg and NOS2 were produced in the brains of infected mice by CD4+ T cells and macrophages, respectively.
The neurovirulence of DENV 3 genotype I is associated with a deleterious role of NOS2 in the brain, confirming this murine model as an appropriate tool to study DENV neurovirulence.
世界卫生组织将登革热的临床表现分为无警示体征的登革热、有警示体征的登革热和重症登革热。登革病毒（DENV）引起的神经疾病报告日益增多，症状包括意识减退、严重头痛、颈部僵硬、局灶性神经体征、囟门紧张和抽搐。然而，神经毒力所涉及的免疫机制仍知之甚少。在此，我们展示了一种小鼠模型，其中一种基因型的DENV通过颅内途径接种，感染C57/BL6小鼠并在脑中复制，导致小鼠死亡。
通过颅内途径用不同血清型/基因型的DENV感染小鼠，通过实时PCR评估病毒复制、宿主细胞因子和脑中一氧化氮合酶2（Nos2）的表达。还对脑组织进行了组织学分析。使用流式细胞术分析哪些细胞负责细胞因子和Nos2的表达。还生成了感染动物的生存曲线。
DENV 3基因型I感染小鼠并在脑中复制，在我们的小鼠模型中导致死亡。NOS2水平升高可能是感染小鼠死亡的原因，因为病毒复制与C57BL/6小鼠脑中Nos2和细胞因子表达增加相关。在感染DENV的Nos2-/-小鼠中，未观察到感染的临床体征，细胞因子表达水平较低，但干扰素γ（Ifng）除外。此外，感染DENV的Ifng-/-小鼠表现出严重的致命疾病，类似于在C57BL/6小鼠中观察到的疾病，而感染DENV的Nos2-/-小鼠未显示死亡率增加。对感染的C57BL/6小鼠的脑分析显示，在组织病理学检查期间存在神经元变性和坏死。IFNg和NOS2分别由感染小鼠脑中的CD4+T细胞和巨噬细胞产生。
DENV 3基因型I的神经毒力与NOS2在脑中的有害作用相关，证实该小鼠模型是研究DENV神经毒力的合适工具。
