Mouse Hepatitis Virus (MHV) infection may play a role in alteration of Cellular Prion Protein (PrPᶜ) expression in neural cells

Chatterjee, Madhurima (2014) Mouse Hepatitis Virus (MHV) infection may play a role in alteration of Cellular Prion Protein (PrPᶜ) expression in neural cells. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Our studies highlighted that MHV infection modulates PrPᶜ expression in Neuro2A cell line as well as in N9 microglial cell line and C8D1A astrocytic cell line. This is the first time our studies revealed that MHV infection up-regulates PrPC expression in all three cell lines tested. More significantly, this is first time, we have shown that C8D1A,the astrocytic cell line expresses PrPᶜ which gets up regulated the most with MHV infection among the neural cell lines. Astrocytes maintain the homeostasis in the CNS, microglia acts in viral replication and phagocytosis of myelin debris and neurons get degenerated and cause axonal loss. PrPᶜ is known to play major role in normal functioning of all the cell lines in the CNS. But the significance of up regulation of PrPC during MHV infection warrants further studies. It would be interesting to find out whether up-regulation of PrP restricts the viral replication or virus is taking the advantage of PrP for their replication and propagation. Measuring viral titre from infected cells before and after Prnp knockdown may shade some light to answer this question. Further it is also possible that virus might change the conformation of PrPᶜ and drive its conformation towards its infectious isoform which has higher β-sheet content. This can be confirmed by using biophysical techniques such as Circular Dichorism. As physiological role of PrPᶜ is largely unknown, the role played by it inside the cell during infection will help in unveiling some of its functions and its role in certain molecular pathways. From the results it can be concluded that N9 cell line expresses microglial phenotype, C8D1A expresses astrocytic phenotype and Neuro2a expresses neuronal phenotype as expected and they express Prnp as seen by quantifying copy number of Prnp mRNA by qPCR. The highest copy number of Prnp was found in Neuro2a followed by C8D1A astrocytes and N9 microglia. The presence of PrPᶜ protein was also confirmed in all the cell lines and primary astrocytes. Moreover, it was found that all the cell lines get infected with RSA59.On RSA59 infection both PrPᶜ and Prnp may be up-regulated slightly as suggested by the results of Western blotting and qPCR. Although there is not much change in copy number of Prnp in infected and uninfected samples. The reason behind PrPC up-regulation after virus infection requires further investigation.

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