Immune responses and central nervous system dysfunction are two main factors to be considered during rabies virus (RABV) infection. However, the mechanisms by which RABV strains of different virulence regulate with chemokine expression and the signaling pathways responsible for the immune responses in the terminal stage of infection both in vivo and in vitro have not been fully elucidated. In this study, we found low expression levels of proinflammatory chemokines in the mouse brain upon infection with street RABV strains (CXZ17 and HN10) at the late stage of infection. We also examined the difference in inflammatory response upon infection with RABV strains of different virulence in a mouse model. We found that the expression of proinflammatory chemokines increased to a varying degree upon infection with street RABV (CXZ17 and HN10) or laboratory-fixed RABV (CVS-11, aG, and CTN); CXCL10, CCL5, and CCL2 were the most significantly upregulated chemokines in brain tissue and microglial BV-2 cells in response to infection with RABV strains of different virulence. Our data also demonstrate significant activation of the MAPK and NF-κB pathways in mouse brain tissue at the late stage of RABV infection. We also found (i) low phosphorylation signals of MAPK and NF-κB p65 in neuronal cells upon infection with CXZ17 and HN10 in the mouse brain and (ii) strong phosphorylation signals in cerebrovascular endothelial cells and neuronal cells upon CTN or aG infection. Moreover, we quantified the nuclear localization status of MAPK signals and NF-κB p65 upon infection with CVS-11, aG, and CTN in BV-2 cells in vitro. We also found (i) that the activation of the p38, ERK1/2, and NF-κB p65 pathway, which stimulates CXCL10, CCL5, and CCL2 expression upon infection with RABV strains of different virulence (aG, CTN, and CVS-11), is triggered after virus entry into BV-2 cells and (ii) that the expression of CXCL10, CCL5, and CCL2 is required for the activation of NF-κB, p38, and ERK1/2, but not JNK. Overall, our study provides insight into the regulation of inflammatory responses mediated by MAPK and NF-κB in the mouse brain and in microglial cells upon RABV infection of different virulence.

免疫应答和中枢神经系统功能障碍是狂犬病毒（RABV）感染期间要考虑的两个主要因素。然而，在体内和体外，不同毒力的RABV毒株通过趋化因子表达调控机制以及负责感染终末期免疫反应的信号通路尚未完全阐明。在这项研究中，我们发现在感染后期感染街头RABV株（CXZ17和HN10）后，小鼠脑中促炎性趋化因子的表达水平较低。我们还检查了小鼠模型中不同毒力的RABV株感染后炎症反应的差异。我们发现，在感染街道RABV（CXZ17和HN10）或实验室固定的RABV（CVS-11，aG和CTN）后，促炎性趋化因子的表达增加了不同程度。CXCL10，CCL5和CCL2是响应于不同毒力的RABV株感染后脑组织和小胶质BV-2细胞中最明显上调的趋化因子。我们的数据还表明，在RABV感染的晚期，小鼠脑组织中MAPK和NF-κB通路的显着激活。我们还发现（i）在小鼠脑中感染CXZ17和HN10后，神经元细胞中MAPK和NF-κBp65的磷酸化信号低，以及（ii）在CTN或aG感染后脑血管内皮细胞和神经元细胞中的磷酸化信号较强。此外，我们量化了在BV-2细胞中感染CVS-11，aG和CTN后MAPK信号和NF-κBp65的核定位状态体外。我们还发现（i）p38，ERK1 / 2和NF-κBp65途径的激活，在感染了不同毒力的RABV株（aG，CTN和CVS-11）后会刺激CXCL10，CCL5和CCL2表达）是在病毒进入BV-2细胞后触发的；（ii）激活NF-κB，p38和ERK1 / 2而不是JNK时需要CXCL10，CCL5和CCL2的表达。总体而言，我们的研究提供了对不同毒力的RABV感染后小鼠大脑和小胶质细胞中MAPK和NF-κB介导的炎症反应调控的见解。