Neutralization of West Nile virus (WNV) in vivo correlates with the development of an antibody response against the viral envelope (E) protein. Using random mutagenesis and yeast surface display, we defined individual contact residues of 14 newly generated mAbs against domain III of the WNV E protein. MAbs that strongly neutralized WNV localized to a surface patch on the lateral face of domain III. Convalescent antibodies from human patients who had recovered from WNV infection also detected this epitope. One mAb, E16, neutralized 10 different strains in vitro, and demonstrated therapeutic efficacy in mice, even when administered as a single dose 5 d after infection. A humanized version of E16 was generated that retained antigen specificity, avidity, and neutralizing activity. In post-exposure therapeutic trials in mice, a single dose of humanized E16 protected mice against WNV-induced mortality, and thus, may be a viable treatment option against WNV infection in humans.WNV is a single-stranded, positive-polarity RNA Flavivirus that is related to dengue fever, yellow fever, and Saint Louis, tick-borne, and Japanese encephalitis viruses. Humans infected with WNV develop a febrile illness that can progress to meningitis or encephalitis, and the elderly and immunocompromised are at greatest risk for severe disease 1 . At present, treatment is supportive and no vaccine exists for human use.The innate and adaptive immune responses prevent dissemination to and within the central nervous system (CNS) 2,3 . Recently, two groups demonstrated therapeutic efficacy of immune human γ-globulin in mice infected with WNV 4,5 . Even after virus had spread to the CNS, passive administration of immune heterologous γ-globulin improved survival 5 . In theory, a potently neutralizing mAb could have the same or better benefit with a lower dose and improved safety profile.Most neutralizing antibodies against flaviviruses recognize the envelope (E) protein. In general, virus-specific rather than cross-reactive antibodies have the strongest neutralizing activity in NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript vitro and greatest protection in vivo 6 . Crystallographic analysis of the soluble ectodomain of flavivirus E proteins has revealed three domains 7,8 . Domain I is an 8-stranded β-barrel 7-9 that participates in the conformational changes associated with the acidification in the endosome 10 . Domain II contains 12 β-strands and has roles in dimerization, trimerization, and fusion 7,8,10 . Domain III (DIII) adopts an immunoglobulin-like fold, and contains the loops that are most distal from the surface in the mature virion 11,12 and the site for putative receptor attachment 6,8,13,14 . Based on the sequencing of in vitro neutralization escape variants, many neutralizing antibodies against flaviviruses localize to DIII 15-22 .Here, we define further the molecular basis of antibody-mediated neutralization of WNV using a large panel of newly generated mAbs against WNV E protein. Humanized versions o...

West Nile virus (WNV) (Flavivirus: Flaviviridae) is the most widespread arbovirus in the world. A significant range expansion occurred beginning in 1999 when the virus was introduced into New York City. This review highlights recent research into WNV epizootiology and epidemiology, including recent advances in understanding of the host-virus interaction at the molecular, organismal, and ecological levels. Vector control strategies, vaccines, and antivirals, which now must be considered on a global scale, are also discussed.

The complete nucleotide sequences of eight West Nile (WN) virus strains (Egypt 1951, Romania 1996-MQ, Italy 1998-equine, New York 1999-equine, MD 2000-crow265, NJ 2000MQ5488, NY 2000-grouse3282, and NY 2000-crow3356) were determined. Phylogenetic trees were constructed from the aligned nucleotide sequences of these eight viruses along with all other previously published complete WN virus genome sequences. The phylogenetic trees revealed the presence of two genetic lineages of WN viruses. Lineage 1 WN viruses have been isolated from the northeastern United States, Europe, Israel, Africa, India, Russia, and Australia. Lineage 2 WN viruses have been isolated only in sub-Saharan Africa and Madagascar. Lineage 1 viruses can be further subdivided into three monophyletic clades.