title: Identification of residues in West Nile virus pre-membrane protein that influence viral particle secretion and virulence.
abstract: The pre-membrane protein (prM) of West Nile virus (WNV) functions as a chaperone for correct folding of the envelope (E) protein, and prevents premature fusion during virus egress. However, little is known about its role in virulence. To investigate this, we compared the amino acid sequences of prM between a highly virulent North American strain (WNV(NY99)) and a weakly virulent Australian subtype (WNV(KUN)). Five amino acid differences occur in WNV(NY99) compared with WNV(KUN) (I22V, H43Y, L72S, S105A and A156V). When expressed in mammalian cells, recombinant WNV(NY99) prM retained native antigenic structure, and was partially exported to the cell surface. In contrast, WNV(KUN) prM (in the absence of the E protein) failed to express a conserved conformational epitope and was mostly retained at the pre-Golgi stage. Substitutions in residues 22 (Ile to Val) and 72 (Leu to Ser) restored the antigenic structure and cell surface expression of WNV(KUN) prM to the same level as that of WNV(NY99), and enhanced the secretion of WNV(KUN) prME particles when expressed in the presence of E. Introduction of the prM substitutions into a WNV(KUN) infectious clone (FLSDX) enhanced the secretion of infectious particles in Vero cells, and enhanced virulence in mice. These findings highlight the role of prM in viral particle secretion and virulence, and suggest the involvement of the L72S and I22V substitutions in modulating these activities.
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: Y X
authors: YX
authors: Setoh
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: N A
authors: NA
authors: Prow
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: J
authors: J
authors: Hobson-Peters
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: M
authors: M
authors: Lobigs
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: P R
authors: PR
authors: Young
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: A A
authors: AA
authors: Khromykh
authors: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, 4072, QLD, Australia.
authors: R A
authors: RA
authors: Hall
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D005260:Female; D051379:Mice; D008969:Molecular Sequence Data; D021381:Protein Transport; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D057074:Virus Release; D014779:Virus Replication; D014901:West Nile Fever / Q000821:virology*; D014902:West Nile virus / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*
chemical_list: D014759:Viral Envelope Proteins; C074932:prM protein, Flavivirus