Identification of Critical Molecular Determinants of West Nile Virus PrM Protein: A Potential Site for Antiviral Targeting

T. Tan, R. Bhuvanakantham, J. Li, J. Howe, M.L. Ng
2008 International Journal of Infectious Diseases  
e294 13th International Congress on Infectious Diseases Abstracts, Poster Presentations get. This involves both oligomerization of the capsid (C) protein and packaging of the viral RNA. The RNA binding properties of the C protein is poorly understood. This study aims to characterize the C and RNA interaction. Method: Co-localization study was performed by transfecting in vitro transcribed WN virus RNA and C protein clones into BHK cells and visualized under fluorescence microscopy. RNA binding
more » ... roperties of C protein were further investigated with a Northwestern Blot assay and RNA pull-down assay. Synthesized C protein peptides were used to map out the RNA binding regions on C protein. In addition, C protein immunopurified from BHK cells were used to investigate the effect of phosphorylation of C protein on its RNA binding properties. Results: RNA and C protein have failed to show colocalization in BHK cells by immuno-fluorescence but interactions were observed at the molecular level. It showed that the first 465 and last 693 nucleotides of the WN virus RNA had specific affinity for the full length C protein. In addition, the amino-and carboxy-terminal of the C protein were shown to bind to the virus RNA. It was also found that the C protein had affinity for viral anti-sense RNA. Phosphorylated peptides of C protein and C protein expressed in BHK cells show attenuated binding to viral RNA. Conclusion: C protein interaction with anti-sense indicates that its interaction with viral sense RNA may not be specific. Phosphorylation of C protein could play a role in regulating C and RNA interaction and allow time for viral assembly. Understanding the interaction of C protein with viral RNA and role of phosphorylation in nucleocapsid assembly could help develop anti-viral strategies aimed at disrupting viral assembly. Background: West Nile virus (WNV), a member of Flaviviridae family is a viral agent that transmitted by numerous species of mosquitoes and birds. It is known to cause fever, paralysis and encephalitic maladies in infected humans and animals. The WNV particle is made up of premembrane (prM), envelope (E) and capsid proteins. The prM protein mediates the folding of the viral envelope (E) protein and protects the E protein against premature acidification during virus maturation. To date, critical residues responsible for prM function in viral assembly are yet to be defined. There is no antiviral drug or vaccine available for treatment of WNV infection in humans. Understanding the molecular mechanism of virus assembly will identify new vulnerable sites of virus replication and expedite the discovery and development of new therapeutics to treat WNV-induced diseases. Methods: In this study, multiple sequence analysis identified a number of highly conserved residues in the prM protein among the flaviviruses. To investigate the significance of these residues, multi-site and single point mutagenesis work in WNV infectious clone were carried out to generate
doi:10.1016/j.ijid.2008.05.788 fatcat:jmqu5q3kfvem3kymfcn6mwfr6m