Over the past decade, West Nile virus (WNV) has spread across the United States. We aggregated blood donor data from 2010-2012 and then calculated the incidence of WNV RNA-positive donations and compared the incidence with neuroinvasive disease (NID) case data from the ArboNET surveillance system. Of 10,107,853 donations, 640 were confirmed positive. The seasonal WNV incidence rate per 100,000 ...

West Nile virus (WNV) typically leads to asymptomatic infection but can cause severe neuroinvasive disease or death, particularly in the elderly. Innate NK cells play a critical role in antiviral defenses, yet their role in human WNV infection is poorly defined. Here we demonstrate that NK cells mount a robust, polyfunctional response to WNV characterized by cytolytic activity, cytokine and che...

West Nile virus (WNV) was detected in the United States in 1999, has reoccurred every summer since, and has become endemic. Transfusion transmission was documented in 2002, and screening of blood donations for WNV began in 2003. We investigated genetic variation of WNV in human isolates obtained from specimens collected from 30 infected blood donors who tested positive for WNV RNA during 2002-2...

Crow deaths were observed after West Nile virus (WNV) was introduced into North America, and this phenomenon has subsequently been used to monitor the spread of the virus. To investigate potential differences in the crow virulence of different WNV strains, American Crows were inoculated with Old World strains of WNV from Kenya and Australia (Kunjin) and a North American (NY99) WNV genotype. Inf...

Semaphorin 7A (Sema7A) is a membrane-associated/secreted protein that plays an essential role in connecting the vertebrate neuronal and immune systems. However, the role of Sema7A has not been elucidated in viral pathogenesis. In this study, we show that abrogation of Sema7A protects mice from lethal West Nile virus (WNV) infection. Mice lacking Sema7A showed increased survival, reduced viral b...

Passerine birds have played an important role in the establishment, maintenance, and spread of West Nile virus (WNV) in North America, and some are susceptible to WNV-associated mortality. Characterization of passive transfer of anti-WNV antibodies in passerines is important to understanding transmission and demographic effects of WNV on wild birds. We showed passively acquired maternal antibod...

West Nile virus (WNV) is a neurotropic, arthropod-borne flavivirus that is maintained in an enzootic cycle between mosquitoes and birds, but can also infect and cause disease in horses and humans. WNV is endemic in parts of Africa, Europe, the Middle East, and Asia, and since 1999 has spread to North America, Mexico, South America, and the Caribbean. WNV infects the central nervous system (CNS)...

Dengue virus (DENV) and West Nile virus (WNV) are important reemerging arboviruses that are under-recognized in many parts of Africa due to lack of surveillance. As a part of a study on flavivirus, alphavirus, and parasite exposure in coastal Kenya, we measured neutralizing antibody against DENV and, to evaluate assay specificity, WNV in serum samples that tested positive for serum anti-DENV Ig...

RIG-I and MDA5, two related pathogen recognition receptors (PRRs), are known to be required for sensing various RNA viruses. Here we investigated the roles that RIG-I and MDA5 play in eliciting the antiviral response to West Nile virus (WNV). Functional genomics analysis of WNV-infected fibroblasts from wild-type mice and RIG-I null mice revealed that the normal antiviral response to this virus...

After several years of low West Nile virus (WNV) occurrence in the United States of America (USA), 2012 witnessed large outbreaks in several parts of the country. In order to understand the outbreak dynamics, spatial clustering and landscape, demographic and climatic associations with WNV occurrence were investigated at a regional level in the USA. Previous research has demonstrated that there ...