The I22V and L72S substitutions in West Nile virus prM protein promote enhanced prM/E heterodimerisation and nucleocapsid incorporation.

Yin Xiang Setoh,Natalie A Prow,Paul R Young,Cindy Si En Tan,Roy A Hall,Jody Hobson-Peters,Alexander A Khromykh

doi:10.1186/s12985-015-0303-7

Abstract

BackgroundAmino acid substitutions I22V and L72S in the prM protein of West Nile virus Kunjin strain (WNVKUN) were previously shown to enhance virus secretion and virulence, but a mechanism by which this occurred was not determined.FindingsUsing pulse-chase experiments followed by co-immunoprecipitation with anti-E antibody, we demonstrated that the I22V and L72S substitutions enhanced prM/E heterodimerization for both the E-glycosylated and E-unglycosylated virus. Furthermore, analysis of secreted particles revealed that I22V and L72S substitutions also enhanced nucleocapsid incorporation.ConclusionsWe have demonstrated mechanistically that improved secretion of virus particles in the presence of I22V and L72S substitutions was contributed by more efficient prM/E heterodimerization.

Highlights

Amino acid substitutions I22V and L72S in the prM protein of West Nile virus Kunjin strain (WNVKUN) were previously shown to enhance virus secretion and virulence, but a mechanism by which this occurred was not determined
Mutagenesis studies have led to the discovery of motifs and specific amino acid residues within prM that encode important functions such as virus particle assembly [9,10,11], prM/E heterodimerisation [12], and virus particle secretion [13,14]
We have previously characterised two amino acid substitutions in Kunjin virus (WNVKUN) prM, which when substituted with the corresponding residues of the virulent American New York 1999 strain (WNVNY99) (I22V and L72S) resulted in a more stable antigenic structure of the prM protein, and promoted efficient secretion of prME and virus particles, as well as increased virulence in weanling mice [15]

Summary

Introduction

Amino acid substitutions I22V and L72S in the prM protein of West Nile virus Kunjin strain (WNVKUN) were previously shown to enhance virus secretion and virulence, but a mechanism by which this occurred was not determined. Findings The pre-membrane (prM) and envelope (E) proteins together form the outer structure of West Nile virus (WNV) particles [1,2]. * Correspondence: roy.hall@uq.edu.au 1Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia Full list of author information is available at the end of the article

Results

Conclusion