title: Abrogation of TLR3 inhibition by discrete amino acid changes in the C-terminal half of the West Nile virus NS1 protein.
abstract: West Nile virus (WNV) is a mosquito-transmitted pathogen, which causes significant disease in humans. The innate immune system is a first-line defense against invading microorganism and many flaviviruses, including WNV, have evolved multifunctional proteins, which actively suppress its activation and antiviral actions. The WNV non-structural protein 1 (NS1) inhibits signal transduction originating from Toll-like receptor 3 (TLR3) and also critically contributes to virus genome replication. In this study we developed a novel FACS-based screen to attempt to separate these two functions. The individual amino acid changes P320S and M333V in NS1 restored TLR3 signaling in virus-infected HeLa cells. However, virus replication was also attenuated, suggesting that the two functions are not easily separated and may be contained within overlapping domains. The residues we identified are completely conserved among several mosquito- and tick-borne flaviviruses, indicating that they are of biological importance to the virus.
authors.affiliation: Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
authors.forename: Clayton R
authors.initials: CR
authors.lastname: Morrison
authors.affiliation: Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA. Electronic address: frank_scholle@ncsu.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: Scholle
mesh_terms: D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D057131:Immune Evasion; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology; D051196:Toll-Like Receptor 3 / Q000037:antagonists & inhibitors / Q000276:immunology*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication; D014902:West Nile virus / Q000235:genetics / Q000276:immunology* / Q000502:physiology*
chemical_list: D050505:Mutant Proteins; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D017361:Viral Nonstructural Proteins; C531936:nonstructural protein 1, West Nile virus
keywords: Flavivirus; Innate immunity; NS1; TLR3; West Nile virus