Flaviviruses are single-stranded RNA-containing, enveloped viruses that are primarily transmitted by insects (Figure 1). They include important human pathogens such as dengue virus, Zika virus, yellow fever virus, Japanese encephalitis virus, and west Nile virus (WNV). The most effective means to control these viral illnesses is through the development of vaccines; however, this has only been achieved in the case of yellow fever. An alternative approach is to discover new antiviral therapeutics, including the potential use of neutralizing antibodies that can be administered to exposed individuals or those at risk of exposure. To that end, Vanderbilt Institute of Chemical Biology member James Crowe and his collaborator Theodore Pierson (Viral Pathogenesis Section NIAID) announce the discovery of a highly potent human neutralizing monoclonal antibody (NmAb) against WNV that is protective in murine models of WNV infection [L. Goo, et al. (2018) Nat. Microbiol. published November 19, DOI: 10.1038/s41564-018-0283-7].