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Clinical and Developmental Immunology
Volume 2013, Article ID 510396, 12 pages
Research Article

Microglia Play a Major Role in Direct Viral-Induced Demyelination

1Department of Biological Sciences, Indian Institute of Science Education and Research-Kolkata (IISER-K), Mohanpur Campus, P.O. Box BCKV Campus Main Office, Nadia, West Bengal Mohanpur 741252, India
2Central Animal Facility, Indian Institute of Science, Bangalore 560012, India

Received 7 March 2013; Revised 14 May 2013; Accepted 15 May 2013

Academic Editor: Anirban Basu

Copyright © 2013 Dhriti Chatterjee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Supplementary Material

CNS pathology of neurotropic isogenic spike protein recombinant strain RSA59: RSA59 upon intracranial inoculation can cause meningitis, encephalitis and demyelination. Inflammation reaches its peak inbetween day 5 and 7post infecdtion. Meningitis is characterized by the presence of inflammatory cells in the meningis where as encephalitis is confirmed by the accumulation of the inflammatory cells and perivascular cuffing. Inflammatory cells were positive for leukocyte common antigen (LCA; CD45) and majroty of the inmflammatory cells were positive for microglia /macrophage marker CD11b and or Iba1. No CD4 and CD19 positive cells but few CD8 positive cells were observed in the inflamed brain and spinal cord sections in RSA59 infected mice. Demyelination was observed by LFB staining as early as day 7 as examined and it reaches its peak at day 30 post infection. Combined histopathology and immunohistochemistry data indicate that RSA59 causes meningoencephalitis and demyelination. CNS inflammation consists of a mixed population of inflammatory cells, predominantly macrophages/microglia as well as a smaller population of T lymphocytes.

High-resolution electron micrographic analysis confirms the presence of vacuolated microglia with engulfed myelin debris in demyelinating plaque: Microglial accumulation was observed in the demyelinating plaque of RSA59 with an emphasis on the stripping of the myelin sheath. RSA59 infected spinal cords showed significant myelin loss and accumulation of phagocytotic microglia within plaques. High-resolution TEM images show accumulation of large number of microglia with no basement membrane which is the characteristic features of microglia/macrophages. Multiple vacuoles with myelin fragments were seen within the cytoplasm of the microglia in the plaque. No such microglial accumulation was observed in the control mock infected mice at high resolution TEM images.

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