title: High affinity human antibody fragments to dengue virus non-structural protein 3.
abstract: BACKGROUND
  The enzyme activities catalysed by flavivirus non-structural protein 3 (NS3) are essential for virus replication. They are distributed between the N-terminal protease domain in the first one-third and the C-terminal ATPase/helicase and nucleoside 5' triphosphatase domain which forms the remainder of the 618-aa long protein.
  
  
  RESULTS
  In this study, dengue full-length NS3 protein with residues 49 to 66 of NS2B covalently attached via a flexible linker, was used as bait in biopanning with a naïve human Fab phage-display library. Using a range of truncated constructs spanning the NS2B cofactor region and the full-length NS3, 10 unique Fab were identified and characterized. Of these, monoclonal Fab 3F8 was shown to bind α3″ (residues 526 through 531) within subdomain III of the helicase domain. The antibody inhibits the ATPase and helicase activites of NS3 in biochemical assays and reduces DENV replication in HEK293 cells that were previously transfected with Fab 3F8 compared with mock transfected cells.
  
  
  CONCLUSIONS
  Antibodies such as 3F8 are valuable tools for studying the molecular mechanisms of flaviviral replication and for the monospecific detection of replicating dengue virus in vivo.
authors.affiliation: Program in Emerging Infectious Diseases, DUKE-NUS Graduate Medical School, Singapore, Singapore.
authors.forename: Nicole J
authors.initials: NJ
authors.lastname: Moreland
authors.forename: Moon Y F
authors.initials: MY
authors.lastname: Tay
authors.forename: Elfin
authors.initials: E
authors.lastname: Lim
authors.forename: Prasad N
authors.initials: PN
authors.lastname: Paradkar
authors.forename: Danny N P
authors.initials: DN
authors.lastname: Doan
authors.forename: Yin Hoe
authors.initials: YH
authors.lastname: Yau
authors.forename: Susana
authors.initials: S
authors.lastname: Geifman Shochat
authors.forename: Subhash G
authors.initials: SG
authors.lastname: Vasudevan
mesh_terms: D000914:Antibodies, Viral / Q000235:genetics / Q000276:immunology*; D000918:Antibody Specificity; D003715:Dengue / Q000276:immunology* / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D057809:HEK293 Cells; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000235:genetics / Q000276:immunology*; D020365:RNA Helicases / Q000235:genetics / Q000276:immunology; D012697:Serine Endopeptidases / Q000235:genetics / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000276:immunology*; D014779:Virus Replication; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D000914:Antibodies, Viral; D007140:Immunoglobulin Fab Fragments; D020365:RNA Helicases; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; C060028:NS3 protein, flavivirus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases