某动物园圈养的环尾狐猴发生了一种以高烧不退,精神沉郁,活动减少等症状为特征的急性疾病。笔者对发病死亡的动物进行剖检,采集肺、脑、肝等组织,接种vero细胞,72小时后细胞出现明显病变。在病原核酸背景未知的情况下,应用非序列依赖性单引物扩增法结合DNA酶处理(DNase-sequence independent single primer amplificmion,DNase-SISPA)对病原基因进行扩增。结果显示:其中以DNA为模板的扩增产物测序后与Genbank中序列进行BLAST分析,与数据库中华诊体衣原体(Waddlia chondrophila)核苷酸序列有97%的相似性,而以cDNA为模板的扩增片段测序在NCBI中没有找到序列相似性高于50%的基因片段,初步诊断导致此次环尾狐猴疫病的病原为华诊体衣原体(Waddlia chondrophila)。
Background Deoxyribonuclease 2(DNaseⅡ)plays a key role in clearing cytoplasmic double-stranded DNA(dsDNA).Deficiency of DNaseⅡleads to DNA accumulation in the cytoplasm.Persistent dsDNA in neurons is an early pathological hallmark of senescence and neurodegenerative diseases including Alzheimer’s disease(AD).However,it is not clear how DNaseⅡand neuronal cytoplasmic dsDNA influence neuropathogenesis.Tau hyperphosphorylation is a key factor for the pathogenesis of AD.The effect of DNaseⅡand neuronal cytoplasmic dsDNA on neuronal tau hyperphosphorylation remains unclarified.Methods The levels of neuronal DNaseⅡand dsDNA in WT and Tau-P301S mice of different ages were measured by immunohistochemistry and immunolabeling,and the levels of DNaseⅡin the plasma of AD patients were measured by ELISA.To investigate the impact of DNaseⅡon tauopathy,the levels of phosphorylated tau,phosphokinase,phosphatase,synaptic proteins,gliosis and proinflammatory cytokines in the brains of neuronal DNaseⅡ-deficient WT mice,neuronal DNaseⅡ-deficient Tau-P301S mice and neuronal DNaseⅡ-overexpressing Tau-P301S mice were evaluated by immunolabeling,immunoblotting or ELISA.Cognitive performance was determined using the Morris water maze test,Y-maze test,novel object recognition test and open field test.Results The levels of DNaseⅡwere significantly decreased in the brains and the plasma of AD patients.DNaseⅡalso decreased age-dependently in the neurons of WT and Tau-P301S mice,along with increased dsDNA accumulation in the cytoplasm.The DNA accumulation induced by neuronal DNaseⅡdeficiency drove tau phosphorylation by upregulating cyclin-dependent-like kinase-5(CDK5)and calcium/calmodulin activated protein kinaseⅡ(CaMKⅡ)and downregulating phosphatase protein phosphatase 2A(PP2A).Moreover,DNaseⅡknockdown induced and significantly exacerbated neuron loss,neuroinflammation and cognitive deficits in WT and Tau-P301S mice,respectively,while overexpression of neuronal DNaseⅡexhibited therapeutic benefits.Conclu
