4株狂犬病毒感染小鼠的临床症状及脑组织病理学观察

Clinical symptoms of mice infected with four rabies viruses and brain tissue histopathology observation

【目的】对比狂犬病毒固定强毒株CVS-24、广西街毒株GX074、弱毒株r RC-HL和重组毒株r RC-HL△G感染小鼠后的临床症状及脑组织病理学变化,为揭示狂犬病毒的致病机理提供参考依据。【方法】将CVS-24、GX074、r RCHL和r RC-HL△G分别通过脑内注射SPF级昆明小鼠,以注射DMEM为对照,每只小鼠注射30μL,攻毒后连续观察测量小鼠的体重和死亡情况,采取濒临死亡小鼠的脑组织制作石蜡切片,经HE染色后观察脑组织的病理变化。【结果】与DMEM组的小鼠相比,r RC-HL组小鼠攻毒后的体重先下降后恢复正常,而其他攻毒组小鼠的体重迅速下降直至死亡。DMEM组和r RC-HL组的小鼠在整个试验周期内未见死亡;CVS-24组、GX074组和r RC-HL△G组的小鼠在攻毒后全部发病死亡,其中,CVS-24组小鼠出现死亡的时间最早(攻毒后第5 d),且在攻毒后第6 d全部死亡。通过观察小鼠脑组织的病理学变化,发现r RC-HL组小鼠脑组织的炎症反应最严重,其神经纤维紊乱,神经元细胞变形,细胞边缘不清晰,少量细胞固缩甚至消失,海马回神经胶质细胞浸润,嗜神经现象明显,血管套现象严重;r RC-HL△G组次之;GX074组和CVS-24组小鼠的脑组织病变轻微,可见少量嗜神经现象。【结论】r RC-HL△G、GX074和CVS-24等3株狂犬病毒强毒株的临床症状更明显,发病死亡率达100%,但与弱毒株相比,其炎症反应较轻微,说明狂犬病毒强毒株可能是通过抑制机体脑组织中促炎因子的产生而抑制炎症反应出现,阻断其固有免疫反应,不利于机体对病毒的清除。

【Objective】Clinical symptoms and pathological change of mice brain infected with four strains rabies viruses including fixed virulent virus strain CVS-24,Guangxi street virus strain GX074,avirulent virus strain rRC-HL and recombinant virus strain rRC-HL△G were compared to provide reference for revealing pathogenesis of rabies virus.【Method】Strains CVS-24,GX074,rRC-HL and rRC-HL△G were injected into the brain of the SPF Kunming mice respectively,and the mice injected DMEM were as control.Each mouse was injected 30μL virus.After the mice were injected,body weight and death situation of them were observed continuously.Brain tissue from the dying mice was made into paraffin sections and the pathological change of brain tissue could be observed after H&E staining.【Result】Compared with mice in DMEM group,the weight of mice in rRC-HL group first decreased and then returned to normal,whereas the weight of mice in other injected groups rapidly decreased until death.The mice in DMEM group and rRC-HL group did not die during the entire test period.Mice in CVS-24 group,GX074 group and rRC-HLΔG group all died after the injection.In addition,dead mice in CVS-24 group occurred the earliest(day 5 after infection),and the mice all died on day 6 after infection.By observing the pathological changes of mouse brain tissue,it was found that the inflammatory response of brain tissue in rRC-HL group was the most serious.The nerve fibers were disordered,the neuronal cells were deformed,the edges of the cells were not clear,a small amount of cells contracted or even disappeared.Hippocampalglial cells infiltrated,neurotropic phenomena was obvious,and severe vascular cuffing were observed.The inflammatory response in rRC-HLΔG group was less serious.In GX074 and CVS-24 groups,slight pathological changes in mice brain tissues were observed,and a spot of neurotropic phenomena was found.【Conclusion】The clinical symptoms of the three virulent strains(rRC-HLΔG,GX074,and CVS-24)are more obvious and the fatality rates are 100%.However,the inflammatory response is milder than that of avirulent strains.It shows that the virulent strain of rabies virus might inhibit the occurrence of inflammatory reaction by inhibiting the production of pro-inflammatory cytokines in mice brain,thereby blocking the innate immune response of the mice brain,which is not conducive to elimination of the virus.