Yellow Fever Research Today is a free monthly online journal that collates and summarizes the latest research about Yellow Fever, including details on immunization, vaccines, symptoms, transmission. | ||||||||
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FUNCTIONAL REQUIREMENTS OF THE YELLOW FEVER VIRUS CAPSID PROTEIN.Patkar CG, Jones CT, Chang YH, Warrier R, Kuhn RJ Department of Biological Sciences, 915 W. State Street, Purdue University, West Lafayette, IN 47907-2054. Although it is known that the flavivirus capsid protein is essential for genome packaging and formation of infectious particles, the minimal requirements of the dimeric capsid protein for virus assembly/disassembly have not been characterized. Utilizing a trans-packaging system that involved packaging of a yellow fever virus (YFV) replicon into pseudo-infectious particles (PIPs) by supplying the yellow fever virus structural proteins using a Sindbis virus helper construct, the functional elements within the YFV capsid protein (YFC) were characterized. Various N- and C-terminal truncations, internal deletions and point mutations of YFC were analyzed for their ability to package the YFV replicon. Consistent with previous reports in the tick-borne encephalitis virus capsid protein, YFC demonstrates remarkable functional flexibility. Nearly 40 residues of YFC from the N-terminus could be removed while still retaining the ability to package replicon RNA. Additionally, YFC containing a deletion of approximately 27 residues of the C-terminus, including a complete deletion of the C-terminal helix 4, was functional. Internal deletions encompassing the internal hydrophobic sequence in YFC were, in general, tolerated to a lesser extent. Site-directed mutagenesis of helix 4 residues predicted to be involved in inter-monomeric interactions were also analyzed and, although single mutations did not affect packaging, a double mutation of leucine 81 and valine 88 was non-functional. Effects of mutations in YFC on the viability of YFV infection were also analyzed and these results were similar to those obtained using the replicon packaging system, thus underscoring the flexibility of YFC for its function. Published 5 April 2007 in J Virol.
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