Mechanisms of entry of poliovirus into the central nervous system in a mouse model

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Poliovirus has been proposed to enter the central nervous system (CNS) by the hematogenous route and/or by axonal transport along nerves. The objective of this research, using a mouse model, was to determine the possible routes by which poliovirus enters the CNS. According to the experimental results presented here poliovirus may gain access to the CNS via the neural pathway. Following different routes of inoculation of neurovirulent Lansing type II poliovirus, the forms of paralysis displayed were correlated with the sites of viral inoculation. Histological studies showed that the lesions in the CNS correlated with the anatomical distribution of clinical paralysis. Polioviral antigens were detected in the motor neurons in the spinal cord of the paralyzed mice using immunofluorescence. Moreover, using electron microscopy poliovirus-like particles were detected in the neuronal axons and within the post synaptic neuronal processes. The hematogenous route is not supported by the following: 1) Experimental mice did not develop paralysis when Lansing type II poliovirus was injected intravenously, 2) Using electron microscopy nopoliovirus-like particles were detected in either the endothelial cells or inflammatory cells, 3) Using immunofluorescence no viral antigens were detected in either the endothelial cells or inflammatory cells, and 4) No cytopathic effect (CPE) was observed in the poliovirus infected cerebrovascular endothelial cells and macrophages. Taken together these findings suggest that poliovirus may not gain access to the CNS via the hematogenous pathway. Persistent infection of poliovirus in the cerebrovascular endothelial cells and macrophages is possible since intact viral particles were detected from the poliovirus infected cells in the absence of CPE. However the mechanisms of such persistence warrant further research