| Objective we first established a aged mouse model with HCMV latent infection. From this model ,we observed the pathological alterations of the cerebral cortex of infected mice. The study aimed at providing a new idea and appropriate model for studing the etiology and mechanism of Alzheimer's diseases.Methods First to establish a model for HCMV latency in the mouse brain.Twenty-four 8 week BALB/c mice were divided into 2 groups, six femal and six male mice in each group. The mice in infected group and in DMEM control group were inoculated with 1.0 ml 1X 105PFU/ml HCMV per mouse and 1.0 ml DMEM per mouse by the intraperitoneal injection, respectively .After bred for 14 months, then half of the all mice were sacrificed and brains were removed. Each brain was divided into different parts for assays as follows: (1) homogenized and inoculated on HF cells for HCMV isolation and for reactivation of latent CMV in vitro. (2) HCMV UL83 gene HCMV IE gene and transcripts were analyzed by polymerase chain reaction (PCR) and RT-PCR. (3) slices of brain were embedded with paraffin for location of HCMV gene through in situ hybridization, detection of the expression of HCMV pp65 gene by immunofluorescent assay. (4) observed the ultrastructural features of neuron and the herpers virus-like particles by electron microscope.On the basis of mouse model with HCMV latency ,we study the relationship between HCMV latency in the mouse brain and neuropathology of Alzheimer's Diseases.The slices of brain was embedded with paraffin for assays below: (1) stained with hematoxylin-eosin(H.E.) for pathology research.(2)observed the amyloid plaques by Congo red stain.(3) observed the neurofibrillary tangles by silver stain and count the number of neuron and neurofibrillary tangles.(4)detected the expression oftau protein by immunofluorescent assay.(5) counted the numerical densities of synapse in the mouse cerebral cortex. At the same time,the immunosuppressant-cyclophosphamide was injected into the intraperitoneum of the remained mice(150mg/kg) every six days for three times. 6 days after the last injection,then all mice were killed, slices of brain were fixed with Glutaraldehyde for observing the herpers virus-like particles through electron microscope.Results (1) The results of infected group: virus counld't be recovered from virus isolation, but the assay of reactivation provided the evidence that the latent cytomegalovirus in the cerebral cortex can be reactivated in vitro. HCMV UL83DNA and HCMV IEDNA were detected in the brain of infected mice, and we have localized HCMV DNA in the plasma of neurons .HCMV pp65 antigen was not detected by immunofluorescent assay. Electron microscope examination didn't show the appearance of HCMV-specific intracytoplasmic inclusion bodies and virus particles, the ultrastructures of neuron were severely damaged and filaceous inclusion appeared in the neuronal nucleus, but the herpers virus-like particles were observed in the plasma of neurons and vascular endothelial cells in the cerebral cortex of reactivated mice through electron microscope,which provided further evidence that latent HCMV presented in the cerebral cortex of infected mice. Phathological injury were found in the infected mouse brain, there did exist amyloid plaque and abundant neurofibrillary tangles (NFTs) in the cerebral cortex. (2) The results of control group:there were no obvious pathological alterations in the cerebral cortex by HE staining , but several neurofibrillary tangles existed in the cerebral cortex, the other results of detection were negative.(3) the numerical densities of synapse and the number of neuron of mice in infected group were lower than the control mice (p<0.01) .Compared with control group, the number of neurofibrillary tangles in the cerebral cortex of infected mice was higher.Conclusion On the basis of these results, we found that HCMV can establish latency in the mouse brain,the pathological changes in the mice brain with HCMV latent infection and the pathological features of Alzheimer's disease were una... |
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